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Biomass Propagation Suite — FermAxiom LLC

Propagation Medium Composition Calculator

© 2026 FermAxiom LLC · Author: Peter Krasucki · peter.krasucki@fermaxiom.com  |  Aerobic S. cerevisiae  |  Conceptual tool for rapid what-if analysis  |  v3.0

Batch + Fed-Batch Propagation  •  Biomass-Concentration Driven  •  Real-time

▼Target Production
▼Process Options
Total Target Biomass 1000 g DCW
Total Broth Volume 20.0 L
▼Complex Formulation (editable)
Dose each material in g/L of final broth. Liquids (molasses, CSL) are entered on as-received basis; solids % converts to dry basis for composition math. Composition inputs show literature defaults as placeholder — enter your lot-specific CoA values to override.
▼Deficiency Analysis All defined
Nutrient Required Delivered Coverage Salt top-up
▼Biomass (editable)
▼Summary

Propagation summary — computed from current targets

Total Sugar Required
2083 g
biomass ÷ YX/S
Total Target Biomass
1000 g DCW
Batch + Fed-Batch combined
Final Broth Volume
20.0 L
at 50 g DCW/L
Initial Inoculum
5 g DCW
seed culture at t = 0
Batch Phase
400 g DCW
initial medium charge
Fed-Batch Phase
600 g DCW
delivered via feed profile
Initial Batch Volume
8.0 L
liquid at t = 0
Fed-Batch Feed Volume
12.0 L
total feed delivered
Initial Sugar Conc.
30.0 g/L
capped to avoid osmotic stress
C:N Ratio (mass)
12.0
< 15 to avoid N-limitation
Total Nitrogen
108 g
fed via NH₄OH pH control
Batch / Fed-Batch N Split
20% / 80%
initial charge vs. pH-control
O₂ Demand
~1.00 kg
YO/X ≈ 1.0 g/g DCW aerobic
CO₂ Evolved
~1.33 kg
carbon balance: sugar − biomass
Heat of Fermentation
~15 MJ
≈ 15 kJ / g DCW produced
Generations / Doublings
7.6
log₂(1000 g / 5 g)
Expected Duration
~20 h
batch ~15 h · fed ~5 h
Media Cost Estimate
$—
salts + glucose + vitamins
Medium Type
Defined
0 g/L yeast extract + peptone
▼Results & Tabs
Initial Batch Phase Medium
Fed-Batch Feed
Cultivation Procedure
Reference Data
Test against target:
Enter compound amounts above to test the medium.

Propagation Medium Composition Calculator — Overview

This tool computes the complete salt, trace-metal, vitamin, and complex-supplement recipe required to grow a target dry biomass of Saccharomyces cerevisiae under aerobic batch + fed-batch conditions. Unlike fermentation calculators that target a product titer, this one is biomass-concentration driven: you specify how much dry cell weight (DCW) you want and at what final concentration, and the calculator derives the stoichiometric demand for every element and vitamin, selects pH-control-friendly salts, and produces a Procedure-ready weigh-out sheet.

This calculator supports three medium classes on a single unified page:

  • Defined medium — pure salts + glucose + vitamins. Maximum reproducibility.
  • Semi-defined medium — defined base with 1–10 g/L yeast extract and/or peptone.
  • Complex medium — ≥ 10 g/L combined complex materials (YE + peptone + CSL + molasses). Industrial-scale territory; vitamin stocks often omitted.

A live Medium Type badge (Summary Row 7) classifies the current recipe automatically. Four process additive categories (antifoam · chelator · pH buffer · osmoprotectant) cover the per-litre-of-broth additions that don't scale with biomass.

Key distinction: This is a conceptual tool for rapid what-if analysis. It assumes aerobic respiratory metabolism with YX/S in the 0.40–0.55 g/g range. Real-world yields are strain-specific and depend on OTR, pH control, and feed strategy — treat the outputs as a starting point, not a production recipe.

Quick Start — Seven-Step Workflow

  1. Open Target Production → Biomass Production Targets. Enter the Batch Phase DCW target (default 400 g — the biomass you want at the end of the batch phase, before feeding starts), Fed-Batch Phase DCW target (default 600 g — the additional biomass produced during fed-batch), Final Biomass Concentration (default 50 g DCW/L — sets the fermentor volume), and Inoculum Biomass (default 5 g DCW — drives the generations and duration estimates in the Summary).
  2. Open Target Production → Stoichiometric Yield. Slide YX/S (0.35–0.55 g DCW per g sugar, default 0.48). Aerobic respiratory metabolism on glucose with good OTR typically delivers 0.45–0.52. Values above 0.52 imply tight process control; below 0.40 suggest partial Crabtree overflow to ethanol.
  3. Process Options — keep both toggles ON (defaults). Utilisation Efficiency Correction inflates elemental demands by 10–40% element-dependent to compensate for real-world losses. Complex Supplement Credit subtracts nutrients delivered by YE/peptone/CSL/molasses from the salt recipe. Toggle either OFF to see the underlying unadjusted values.
  4. (Optional) Open Complex Formulation if you want to replace some of the defined-medium salt recipe with YE, peptone, CSL, or molasses. Expand any of the five material sub-cards, set a dose (g/L as-received), pick a source variant from the dropdown, and — if you have a supplier Certificate of Analysis — type in your measured composition values to override the literature defaults. The Deficiency Analysis panel at the bottom shows real-time coverage of each nutrient. See the Complex Formulation Workflow card below for details.
  5. (Optional) Set Process Additives via Biomass → General Composition → Process Additives. Four categories: Antifoam (default PPG 2000 at 0.1 mL/L), Chelator (default citric acid at 0.5 g/L), pH Buffer (default 0 — add MES or similar if you lack active pH control), and Osmoprotectant (default 0 — add glycine betaine or glycerol for VHG or high-biomass runs). Pick a source from the dropdown; 28 variants across the four categories are available.
  6. Edit biomass composition only if you want to deviate from the literature baseline. Open Biomass → General Composition and expand Macroelements / Trace Metals / Vitamins. All values are editable within published Min–Max ranges. Click "Load Standard" on the Biomass card header to restore defaults.
  7. Expand Results & Tabs → Total Required (or Batch Phase / Fed-Batch Feed) and read the salt weigh-out sheet. Each tab has four sub-cards (Macro / Trace / Vitamin / Process Additives). Change the dropdown in any row to pick a different salt for that element — the mass, co-element credits (✓ covered indicators), and complex-material credits update live. Check the Summary Row 7 badge to confirm your Medium Type classification.

Panel Guide — What Each Card Shows

Left column

  • Target Production — three sub-cards: Biomass Production Targets, Stoichiometric Yield, and Process Options. Process Options holds two collapsible sub-menus each with an in-header toggle switch: Utilisation Efficiency Correction (ON/OFF) and Complex Supplement Credit (ON/OFF). The derived-box at the bottom shows Total Target Biomass and Total Broth Volume (inoculum + batch + feed).
  • Complex Formulation — expanded by default. Five per-material sub-cards (Yeast Extract · Peptone · Corn Steep Liquor · Cane Molasses · Beet Molasses) each with a dose input, source variant dropdown, solids % (for liquids), and a 20-row editable composition table. Plus a Deficiency Analysis sub-card at the bottom showing real-time per-nutrient coverage.
  • Biomass — two master tabs. General Composition holds four sub-cards: Macroelements (7 rows), Trace Metals (6 rows), Vitamins (8 rows), and Process Additives (4 categories × dropdown selector). All biomass-composition values are editable. Cost Estimate lists every compound in the sources library (salts + 19 complex-material sources + 28 additive sources) with an editable USD/kg price input; changes propagate live to the Media Cost cell in the Summary.

Right column

  • Summary — seven live-computed rows. Row 1: Sugar Required · Total Biomass · Broth Volume. Row 2: Inoculum → Batch → Fed-Batch biomass progression (color-coded teal/blue/amber). Row 3: volume split & initial sugar concentration. Row 4: C:N ratio & nitrogen strategy. Row 5: O₂ demand & CO₂ evolved & heat of fermentation. Row 6: generations · duration · media cost. Row 7: Medium Type badge — Defined (< 1 g/L complex) / Semi-defined (1–10 g/L) / Complex (≥ 10 g/L), with color-coded left-border (blue / teal / amber) and a live g/L sub-label.
  • Results & Tabs — six tabs. Total Required, Batch Phase, and Fed-Batch Feed each split into four sub-cards (Macro / Trace / Vitamin / Process Additives), all collapsed on load.
    • Total Required — all-up nutrient recipe for the whole batch.
    • Batch Phase — initial medium charge + Macronutrient / Trace / Vitamin A / Vitamin B / Inositol stock preparation sheets with adjustable fold and volume.
    • Fed-Batch Feed — feed composition + stock preparation sheets (chelator, pH buffer, osmoprotectant are batch-only; antifoam is volume-split).
    • Procedure — 11-step cultivation protocol with live-computed values and the batch medium concentration check table.
    • Reference — five sub-cards: Macroelements, Trace Metals, Vitamins, Process Additives (literature values), and Complex Supplements (composition per kg dry for all 19 complex-material sources), plus Process Notes.
    • Test Medium — reverse-mode: enter actual grams you weighed out and see which nutrient limits biomass first (coverage % + verdict bar).

Master tabs (page top)

  • CALCULATOR — the interactive tool described above.
  • INSTRUCTION — this guide (all content embedded in the HTML file; no external documentation).

Summary Panel — What the Numbers Mean

  • Total Sugar Required = biomass ÷ YX/S (e.g. 1000 g ÷ 0.48 g/g ≈ 2083 g glucose)
  • Broth Volume = biomass ÷ finalDCW (e.g. 1000 g ÷ 50 g/L = 20 L)
  • Initial Batch Volume = broth × (biomassBatch / biomass) (proportional split). The remaining volume is delivered via feed.
  • Initial Sugar Conc. = batch glucose ÷ batch volume, capped at 30 g/L to avoid osmotic stress & Crabtree overflow. If your C-demand exceeds this cap, excess glucose shifts into the fed-batch phase.
  • C:N Ratio (mass) = total sugar ÷ total N. For aerobic yeast biomass (8.3% N) the natural ratio lands around 15–20. Values > 20 risk N-limitation; < 10 wastes ammonia.
  • Batch / Fed-Batch N Split — 20% / 80% — the default assumes most N arrives via pH control (NH₄OH) during fed-batch, consistent with the Procedure tab's protocol. Batch phase only needs ~20% of total N as starter charge.
  • O₂ Demand = biomass × 1.0 g/g using YO/X = 1.0 g O₂ / g DCW — the literature value for aerobic S. cerevisiae. For a 1 kg DCW batch, that's 1 kg O₂ ≈ 700 L pure O₂ at STP, delivered continuously over the run via sparging.
  • CO₂ Evolved = carbon-balance derivation: (sugar × 0.40 − biomass × 0.47) × 44/12. Sugar is 40% carbon, biomass 47% carbon; the difference becomes CO₂.
  • Heat of Fermentation = biomass × 15 kJ/g, the standard enthalpy release for aerobic yeast growth. Tells you whether the cooling jacket can keep up.
  • Generations = log₂(biomass / inoculum). For 5 g → 1000 g that's 7.6 doublings — typical for seed-train propagation.
  • Expected Duration — sum of two phases: batch at μ = 0.30 h⁻¹ from inoculum to biomassBatch, then fed-batch at μ = 0.17 h⁻¹ (sub-Crabtree) to final biomass. Defaults to ~20 h total.
  • Media Cost Estimate — per-compound bulk industrial pricing (USD/kg, 2024–25 averages). Includes salts + complex materials (YE, peptone, CSL, molasses) + process additives. Edit individual compound prices in the Biomass → Cost Estimate tab to match your actual supplier quotes; blank value reverts to default.
  • Medium Type (Row 7) — live classification based on total dry-basis g/L of all complex materials combined: Defined (< 1 g/L), Semi-defined (1–10 g/L), or Complex (≥ 10 g/L). The left border of the row changes colour to match. Sub-label shows the actual g/L figure plus a typical-use hint.

Calculation Methodology

  1. Elemental demand = biomass × composition% × UE_factor. The UE factor inflates stoichiometric minimums: macro nutrients 1.10–1.30 (P, K, Mg), N gets 1.30, S 1.40, Ca 1.25, trace metals 1.20, most vitamins 1.20, biotin 1.40 (most-lost vitamin).
  2. Complex material credits — if any YE, peptone, CSL, or molasses is dosed AND Complex Supplement Credit is ON, deliveries are subtracted from elemReq before the salt algorithm runs. For each material: dry_total = dose × solids_fraction × volume, then delivered(nutrient) = dry_total × composition_fraction × credit_rate. Credit rates: 100% for minerals (N, P, K, Mg, S, Ca, Na), 100% for trace metals (Fe, Zn, Mn, Cu), 50% for B-vitamins and inositol (safe margin for ±25–40% lot variance), 100% for carbon (sugar from molasses/CSL reduces the glucose demand directly). Credits are clamped at zero — a supplement can zero-out a salt but never produce a negative demand.
  3. Salt mass = elementDemand ÷ elementFraction. E.g. Mg demand of 4 g via MgSO₄·7H₂O (9.86% Mg) requires 4 / 0.0986 ≈ 40.6 g salt.
  4. Co-element credits — many salts deliver two nutrients (e.g. K₂SO₄ gives both K and S). The calculator runs a second pass: for every element already over-supplied as a co-element, the primary salt mass is reduced or zeroed-out, with a "✓ covered" indicator shown in the recipe.
  5. Liquid pH-control reagents (NH₄OH, KOH, NaOH, H₂SO₄, H₃PO₄) count their delivered element at their solution concentration, with editable concentration widgets on each row (default 32% NH₃ for ammonia, 50% for KOH/NaOH, 85% for H₃PO₄, 96% for H₂SO₄).
  6. Batch / Fed-Batch split is proportional to the biomass split, with the one exception that sugar for the batch phase is capped at 30 g/L to avoid osmotic stress; overflow shifts into feed. Process additives split differently: antifoam is volume-proportional, chelator/buffer/osmoprotectant are 100% to batch.
  7. Stock solution concentrations (shown in Batch Phase and Fed-Batch Feed sub-tabs): 10× macronutrient, 100× trace element, 40× Vitamin Stock A (water-soluble B-vitamins), 20× Vitamin Stock B (sparingly soluble), 20× Inositol Stock. All dilution factors are printable recipe lines in the Procedure tab.
  8. Molasses auto-pH adjustment — when cane molasses dose reaches 5 g/L, the K source auto-switches from KOH (base) to KCl (neutral). User manual override is memoised and respected. See Complex Formulation Workflow card for details.

Complex Formulation Workflow — Semi-defined & Complex Media

The Complex Formulation card (between Target Production and Biomass in the left column) lets you replace some or all of the defined-medium salt recipe with complex ingredients. Five materials are supported; each has its own sub-card with dose input, source variant, solids %, and a fully editable composition table.

The five complex materials

  • Yeast Extract (dry) — 4 variants (Difco / Kerry / Angel / bulk autolysate). Rich in B-vitamins, K, P. ~10% N on dry basis. Price range $8–$35/kg.
  • Peptone (dry) — 7 variants (Bacteriological / Tryptone / Soy / Casamino Acids / Meat / Gelatin / Cottonseed). Rich in FAN, variable S. ~9–16% N.
  • Corn Steep Liquor (CSL) (liquid, 50% solids default) — 3 variants. Cheap (~$3/kg). ~7% N dry basis. High K, partial B-vitamins. Contains lactic acid + phytate.
  • Cane Molasses (liquid, 80% solids default) — 3 variants. Primary use is as a carbon source (~50% sucrose+invert on dry basis). Rich in K/Ca. Starts at pH 5.0–5.5 (already acidic).
  • Beet Molasses (liquid, 80% solids default) — 2 variants. Carbon source (~50% sucrose). Rich in biotin + betaine (natural osmoprotectant). Na ~1.5%. Starts at pH 7.5–8.5 (alkaline, needs acid titration).

How the credit math works

  1. Dose each material in g/L of final broth (as-received for liquids). The dose value sits next to the material's name in its sub-card header for quick editing.
  2. Set the solids fraction for liquid materials — default 0.50 for CSL, 0.80 for molasses. Dry dose = as-received dose × solids fraction.
  3. Pick a source variant from the dropdown — this preloads the literature-average composition. Each variant has a short note describing its typical profile.
  4. Override composition values for any nutrient if you have a Certificate of Analysis for your specific lot. Type in the nutrient row's input box; leave blank to revert to the source default shown as placeholder. Values are displayed in friendly units (% w/w for macros, mg/kg for trace & vitamins) and stored internally as dimensionless fractions.
  5. Credits are applied automatically when Credit nutrients from complex supplements is ON (Process Options). Every nutrient delivered by the supplements is subtracted from the defined-medium recipe at these rates:
    • 100% credit for minerals (N, P, K, Mg, S, Na, Ca) and trace metals (Fe, Zn, Mn, Cu)
    • 50% credit for B-vitamins & inositol (safer margin for ±25–40% lot variance)
    • 100% credit for sugar from molasses / CSL — the Total Sugar Required in the Summary drops accordingly
  6. Remaining demand is rendered in the Results tabs as the usual salt recipe — with any salt dropping to zero when the supplements fully cover that nutrient.

Deficiency Analysis panel

The panel at the bottom of the Complex Formulation card gives you a real-time view of how well your complex recipe covers the biomass demand. Each tracked nutrient gets a row showing:

  • Required — biomass demand after UE correction (pre-credit)
  • Delivered — total grams supplied by all complex materials combined
  • Coverage — delivered ÷ required, color-coded: ≥ 100% green, 50–99% amber, < 50% red, gray for nutrients still from the defined-salt path
  • Salt top-up — remaining mass you need to add as a defined salt (0 when covered)

A verdict badge in the header summarises overall state at a glance (e.g. "6 nutrients covered", "7 low · 2 partial"). The segmented verdict bar beneath shows count-by-color.

Automatic warnings & pH adjustments

  • Na / Ca / K oversupply alerts (amber strips) fire when molasses delivers > 2× the biomass demand for any of those ions. Excess Ca from cane molasses and excess Na from beet molasses are the most common issues at doses above ~25 g/L.
  • Auto-switched K source (teal info strip) — when cane molasses ≥ 5 g/L, the calculator automatically switches the K salt from KOH (a base) to KCl (neutral) because the broth is already acidic. You can override by manually picking a different K salt in the Results → Total Required tab; the calculator remembers your choice and stops auto-adjusting.
  • Beet molasses alkalinity reminder (teal info strip) — when beet molasses ≥ 5 g/L, a note reminds you to ensure H₃PO₄ or H₂SO₄ is active as pH-control acid (beet broth starts at pH 7.5–8.5).

Medium Type classification

The Summary's Row 7 Medium Type badge is driven by the total dry-basis g/L of all complex materials combined:

  • Defined (< 1 g/L) — blue border. Pure salts + glucose + vitamins. Maximum reproducibility.
  • Semi-defined (1–10 g/L) — teal border. Defined base with complex supplement. Typical for research & inoculum propagation.
  • Complex (≥ 10 g/L) — amber border. Supplement-rich; vitamin stocks often omitted. Industrial baker's/brewer's yeast propagation territory.

Lot variance caveat: Every composition value shown is a literature average. Real CoA values vary ±25% for YE, ±30% for peptone, ±40% for CSL, ±20% for molasses (lot-to-lot, brand-to-brand, and season-to-season for agricultural inputs). For tight process control, always assay your specific lot and paste values into the editable composition table. The 50% vitamin credit rate is intentional padding for this variance — if you have verified CoA values, you can raise it by editing source vitamin values higher, which has the effect of crediting the actual delivered amount at 100% while the calculator continues applying the 50% reduction.

Process Additives Guide

Process additives are dosed per-litre of broth (not per-gram of DCW like salts), because they are consumed by the fermentation process rather than retained in the biomass. Four categories are supported with 28 source variants total. Configure in Biomass → General Composition → Process Additives; view contributions in each Results sub-card.

Antifoam — 5 variants

  • PPG 2000 (default, 0.1 mL/L) — polypropylene glycol, food-grade, autoclavable. The industrial standard.
  • PPG 1200 — lower MW; more active but higher DO-probe coating risk.
  • Silicone (SAG 471) — 1/3 the PPG dose (typically 0.03 mL/L) but can foul probes.
  • Antifoam 204 — Sigma PDMS + organic blend.
  • Struktol J 647 — industrial fatty-ester; heat-stable, re-dose on demand.

Phase split: proportional to each phase's volume (batch gets batchVol/totalVol of total dose; feed gets the rest).

Chelator — 6 variants

  • Citric acid (default, 0.5 g/L) — pKa 3.1/4.8/6.4, log K(Fe³⁺) ≈ 11. Keeps trace metals soluble at pH 4–6.
  • Na₃-citrate·2H₂O — neutral form, also buffers; adds ~28% Na by mass (co-element credit applies).
  • Na₂-EDTA·2H₂O — log K(Fe³⁺) = 25.1, ~5× stronger than citrate; use at 1/5 dose (~0.1 g/L).
  • EDTA (free acid) — insoluble at pH < 2; pre-dissolve in NaOH.
  • NTA — nitrilotriacetic acid; gentler than EDTA (log K ≈ 15.9), less effective at high pH.
  • Oxalic acid — weak chelator; niche strain-specific applications.

Phase split: 100% to batch phase — chelator must be present from t=0 to keep trace metals soluble when the fermentor is charged.

pH Buffer — 9 variants (default OFF)

  • MES (free acid) — pKa 6.1, best for yeast pH 4.5–5.5 region.
  • Na-MES — pre-neutralised sodium form; adds ~11% Na.
  • MOPS — pKa 7.2, too high for yeast; only useful for pH 6.5–7.5 target.
  • HEPES — pKa 7.5, biologically inert, typical for cell culture.
  • Na-citrate / K-citrate — pKa 3.1/4.8/6.4, also chelates.
  • K-phosphate — pKa 7.2, doubles as P source (adjust salt recipe to avoid over-P).
  • Na-succinate — pKa 4.2/5.6, biocompatible at low cost.
  • Na-acetate — pKa 4.8, cheapest; partial C source; suppresses growth > 10 g/L.

When to use: typically only for shake-flask or uncontrolled vessels where no active NH₄OH/H₃PO₄ pH control is available. Default dose 0 g/L — leave off for bioreactor runs. Phase split: 100% to batch phase.

Osmoprotectant — 8 variants (default OFF)

  • Glycine betaine — most effective yeast osmoprotectant; accumulated intracellularly without metabolism. Typical 2–5 g/L for VHG or high-biomass runs.
  • Proline — native compatible solute; partially metabolised (releases ~12% N). 2–10 g/L typical.
  • Trehalose — non-reducing disaccharide; native stress protectant. 5–20 g/L for osmotic or thermal stress.
  • Glycerol — cheap at high dose; partially metabolised, 10–30 g/L.
  • Sorbitol / Mannitol — non-metabolised sugar alcohols; 10–30 g/L.
  • Ectoine — bacterial-origin, extreme effectiveness at 0.5–2 g/L but expensive.
  • KCl (ionic osmotica) — ionic osmoprotection via K⁺ uptake; disrupts homeostasis > 0.5 M (37 g/L).

When to use: VHG fermentations (initial sugar > 250 g/L), high-biomass runs (final DCW > 80 g/L), or temperature-stressed conditions. Default dose 0 g/L. Phase split: 100% to batch phase — protects from initial osmotic shock.

Interaction with complex materials: Beet molasses naturally contains biotin (~0.4 mg/kg) and betaine (~0.5–1% by dry mass), which can partially replace osmoprotectant and vitamin supplementation at high doses. Watch the Deficiency Analysis panel for nutrients flagged as ✓ covered by complex materials.

Tips & Troubleshooting

Defined-medium recipe

  • ✓ covered rows in Total Required mean an element is auto-supplied as a co-element from another salt you already have — don't add that compound separately or you'll over-deliver.
  • Grey rows (not calculated) in some result tabs indicate the element's source is a liquid reagent whose concentration you need to specify manually. Edit the concentration widget next to the salt name.
  • Procedure tab concentration check flags any stock solution that exceeds the reagent's solubility limit. If red, raise the stock volume or switch to a more soluble salt.
  • Test Medium tab runs the calculation in reverse — enter weights you actually measured out, and the calculator tells you the max biomass that recipe can support (limited by whichever nutrient ran out first).

Complex materials & CoA workflow

  • Paste your Certificate of Analysis values into the composition table of the matching complex material. Tab between nutrient-row input fields to move down quickly; the Deficiency Analysis panel recomputes on each edit so you can watch nutrient coverage update as you work through the assay.
  • Read the Deficiency Analysis verdict badge first — if it says "Defined medium" you haven't dosed anything yet; "6 nutrients covered" is healthy semi-defined territory; "7 low · 2 partial" means you either need more complex material or should accept the partial coverage and rely on the salt top-up column.
  • Amber oversupply warnings (Na / Ca / K > 2× biomass demand) are not catastrophic below 5× — the excess is mostly bystander ions. Above 5×, reduce the molasses dose, switch to a lower-mineral variant (e.g., Brazilian cane vs. Blackstrap), or consider diluting with a portion of pure sucrose.
  • Teal auto-adjust note (KOH → KCl) appears when cane molasses ≥ 5 g/L. The switch is automatic but fully revertible: if you prefer KOH for your process (e.g., for combined K + pH-control), pick it manually in the Results → Total Required tab. The calculator memoises your choice and stops re-adjusting on subsequent recalculations.
  • Beet molasses alkalinity reminder (teal info strip at ≥ 5 g/L dose) assumes H₃PO₄ is still selected as the P source / acid. If you've manually switched P to a non-acid form (e.g., K₂HPO₄), ensure your pH controller has an acid line active.

Process additives

  • Antifoam dose is often over-specified at small scale. Default 0.1 mL/L of PPG 2000 is a 20 L fermentor baseline; at 100 L+ scale, 0.05 mL/L often suffices because bubble coalescence at the increased liquid depth self-dampens foam. Over-dosing antifoam can suppress oxygen transfer.
  • pH buffer default is 0 g/L because bioreactor runs use active NH₄OH / H₃PO₄ control. Only enable (with MES or citrate) for shake-flask or uncontrolled vessels. A buffer dose of 10 g/L MES costs ~$10 per 20 L batch at $50/kg — comparable to a week of pH probe calibration time, so ask whether the trade-off is worth it.
  • Osmoprotectant is only needed for VHG (sugar > 250 g/L), high-biomass (> 80 g DCW/L), or temperature-stressed runs. For standard 50 g DCW/L propagation with 30 g/L batch sugar, leave at 0. Beet molasses contains natural betaine (~0.5–1% dry) — at high beet doses you may eliminate the need for external osmoprotectant entirely.

Cost, print, and quality-of-life

  • Print Sheet buttons on Procedure and Reference tabs produce clean printable/PDF-friendly weigh-out sheets stripped of UI chrome.
  • Cost Estimate tab — leaving a price input blank reverts that compound to the default bulk-industrial price. Paste your supplier's USD/kg quote to get a real-world estimate tailored to your lab. Every salt, complex material source, and additive source has its own editable price.
  • Load Standard buttons on the Biomass and Complex Formulation cards reset their respective inputs to the default values — useful when you've been editing composition values for strain-specific work and want to start fresh.
  • Process Options toggles can be flipped independently: turn off UE correction to see pure stoichiometric minimums, or turn off Complex Supplement Credit to see the full defined-medium recipe alongside your complex dosing (useful for direct defined-vs-complex cost comparison).

Limitations: This calculator does not model strain-specific kinetics, ethanol production (Crabtree conditions), lipid/fatty-acid supplementation for anaerobic operation, medium sterilisation losses beyond the UE factor, or downstream-processing yields. Complex material composition values are literature averages — for tight process control, always assay your specific lot and override via the editable composition tables. For ethanol fermentation at production scale, use the companion Ethanol Fermentation Medium Calculator instead — this tool is biomass-optimized and assumes fully aerobic, respiratory metabolism.

References — Medium Calculator

The medium-formulation logic is grounded in classical yeast-stoichiometry literature and commercial medium recipes. Primary sources for the elemental composition, biomass formula, vitamin requirements, complex-material credits, and process-additive guidance:

  1. [1]Lange HC, Heijnen JJ (2001). Statistical reconciliation of the elemental and molecular biomass composition of Saccharomyces cerevisiae. Biotechnology and Bioengineering 75:334–344. — Canonical biomass formula CH1.79O0.57N0.15 and reconciled elemental percentages driving all stoichiometric calcs.
  2. [2]Verduyn C, Postma E, Scheffers WA, van Dijken JP (1992). Effect of benzoic acid on metabolic fluxes in yeasts: a continuous-culture study on the regulation of respiration and alcoholic fermentation. Yeast 8:501–517. — Standard defined-medium recipe (Verduyn medium) used as a reference for salt composition and trace-metal balance.
  3. [3]Atkinson B, Mavituna F (1991). Biochemical Engineering and Biotechnology Handbook, 2nd ed. Macmillan. — Salt solubility tables, pH-control salt pairs, and YX/S ranges for aerobic respiratory yeast.
  4. [4]Hensing MC, Rouwenhorst RJ, Heijnen JJ, van Dijken JP, Pronk JT (1995). Physiological and technological aspects of large-scale heterologous protein production with yeasts. Antonie van Leeuwenhoek 67:261–279. — Industrial-scale medium composition, fed-batch feed strategy, and nutrient ratios.
  5. [5]Reed G, Nagodawithana TW (1991). Yeast Technology, 2nd ed. Van Nostrand Reinhold, New York. — Molasses and CSL composition tables; industrial medium recipes; pH-salt selection rules.
  6. [6]Olmos-Dichara A, Ampe F, Uribelarrea JL, Pareilleux A, Goma G (1997). Growth and lactic acid production by Lactobacillus casei ssp. rhamnosus in batch and membrane bioreactor: influence of yeast extract and tryptone enrichment. Biotechnology Letters 19:709–714. — Yeast-extract composition variability and credit calculation methodology.
  7. [7]Hahn-Hägerdal B, Karhumaa K, Larsson CU, Gorwa-Grauslund M, Görgens J, van Zyl WH (2005). Role of cultivation media in the development of yeast strains for large-scale industrial use. Microbial Cell Factories 4:31. — Modern review of industrial medium optimization; basis for utilisation-efficiency correction factors.
  8. [8]Jones RP, Greenfield PF (1984). A review of yeast ionic nutrition. I: Growth and fermentative requirements. Process Biochemistry 19:48–60. — Trace-metal requirements (Fe, Zn, Cu, Mn, Mo, B) and the element-dependent uptake-efficiency corrections implemented in the calculator.
  9. [9]Jones RP, Greenfield PF (1986). Specific and non-specific inhibitory effects of ethanol on yeast growth. Enzyme and Microbial Technology 8:101–110. — Process-additive guidance (antifoam, chelator, buffer, osmoprotectant) and their impact on propagation efficiency.
  10. [10]Hohmann S, Mager WH, eds. (2003). Yeast Stress Responses. Topics in Current Genetics, Springer-Verlag, Berlin. — Osmoprotectant requirements for VHG and high-biomass runs.
  11. [11]Perli T, Wronska AK, Ortiz-Merino RA, Pronk JT, Daran JM (2020). Vitamin requirements and biosynthesis in Saccharomyces cerevisiae. Yeast 37:283–304. — Modern vitamin-requirement review; basis for the 8-vitamin defaults.
  12. [12]Bafana R, Sivanesan S, Pandey RA (2021). Analytical methods for determining protein in yeast biomass: a review. Analytical Biochemistry 622:114167. — Kjeldahl N × 6.25 conventions used in the Medium Type classification and the cross-link to the Protein panel.

Calibration anchors: biomass formula CH1.79O0.57N0.15 (Lange & Heijnen 2001); YX/S default 0.48 g/g aerobic glucose (Hensing 1995); complex-material compositions (Reed & Nagodawithana 1991); trace-metal UE factors (Jones & Greenfield 1984); pH-salt switching thresholds (Atkinson & Mavituna 1991; Verduyn 1992).

© 2026 FermAxiom LLC · Author: Peter Krasucki · peter.krasucki@fermaxiom.com  |  Conceptual tool for rapid what-if analysis. Not a substitute for strain-specific calibration.

High Protein Live

Crude protein, true protein, RNA content, and amino-acid quality predictor for nutritional yeast, feed yeast, and single-cell-protein (SCP) production regimes

Product target

Nutritional yeast — food-grade flakes/powder at ≥ 50% crude protein. Requires RNA reduction below ~2% for regulatory clearance (purine load). Reference products: Lesaffre Bioreal, Red Star Vegetarian Support Formula.

Propagation regime

Biomass quality from Medium Calculator

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—
—
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Crude protein % ≈ N% × 6.25 (Kjeldahl factor). High-N biomass from the Medium Calculator propagates directly into protein yield here. For SCP targets, dose N-rich complex materials (YE, peptone, CSL) in the Medium tab.

Protein content vs. growth rate

Crude (teal) and true (blue) protein as functions of specific growth rate μ. RNA content (amber) rises with μ because fast-growing cells are ribosome-enriched. The dashed vertical marker is your current operating point. Commercial references: nutritional yeast ≥ 50%, feed yeast ≥ 45%, SCP target ≥ 55%.

Key metrics

Crude protein
—
% DCW (N × 6.25)
True protein
—
% DCW (− nucleic acid N)
RNA content
—
% DCW
Lysine index
—
g / 16 g N
Protein yield
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g protein / batch
Cost per kg protein
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USD / kg protein

Food-grade & regulatory status

Verdict

Active factors (multiplicative on strain ceiling)

Strain ceiling
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Growth rate (f_μ)
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N supply / C:N (f_NC)
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Harvest phase (f_phase)
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DO regime (f_DO)
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Bar length ∝ factor value (1.0 = full protein ceiling, < 1.0 = suppression). Crude protein % = strain_ceiling × product of factors.
Instructions · How to use the High Protein cardGuide

What this card predicts

Crude protein content, true protein (crude minus nucleic-acid nitrogen), RNA content, amino-acid quality (lysine index), total protein yield per batch, and media cost per kg of protein. Outputs are driven by the propagation regime (strain, growth rate, C:N ratio, harvest phase, DO regime) and by biomass composition automatically pulled from the Medium Calculator.

How the model works

crude protein % = strain_ceiling × fμ × fN:C × fphase × fDO
  • Strain ceiling — the maximum crude protein % this strain can reach under optimum conditions (S. cerevisiae 50, C. utilis 55, K. marxianus 45, Y. lipolytica 42).
  • fμ — growth rate scaling. Fast-growing cells carry more ribosomes (Herbert 1956 rule): 0.70 + 0.30 × (μ/μmax). Higher μ = more protein.
  • fN:C — balanced N supply. 1.10 − 0.05 × (C:N − 6), clamped. C:N 5–7 optimal; higher C:N dilutes protein with carbon-rich storage compounds.
  • fphase — harvest timing. Mid-exp 0.95, late-exp 1.00 (peak), early-stat 0.92, stationary 0.75 (protein breakdown begins).
  • fDO — respiratory regime. Strict aerobic 1.00; semi 0.92; microaerobic 0.75 (carbon diverted to ethanol).

Workflow

  1. Open the Medium Calculator first and set your target biomass composition. N content drives the Kjeldahl protein ceiling; dose N-rich complex materials (YE, peptone, CSL) to raise it.
  2. Pick a product target — Baker's yeast / Nutritional / Feed / SCP. The verdict banner grades your regime against that product's crude-protein spec.
  3. Choose a strain. For SCP beyond 50% crude, pick C. utilis (55% ceiling) or operate S. cerevisiae at high μ near the Kjeldahl cap.
  4. Dial in growth rate and C:N. The chart sweeps μ from 0.05 to 0.45 h⁻¹ so you can see the crude/true/RNA triad move together; the dashed vertical marker is your current operating point.
  5. Check the RNA verdict. If you want food-grade nutritional yeast, RNA must be < 2%. That typically means dropping μ below 0.15 h⁻¹ or adding a downstream RNase step.

Regulatory RNA ceiling

Nutritional yeast sold for human consumption is generally held to < 2% RNA on a DCW basis (FAO/WHO 1975 guidance for novel protein sources; later incorporated into EU and US practice). The concern is dietary purine load leading to elevated serum uric acid. Feed yeast and SCP for animals are generally exempt from this limit.

Crude-RNA trade-off: Both crude protein and RNA scale with μ. A regime that hits 50% crude protein at μ ≈ 0.40 also produces ~10% RNA — fails the food-grade ceiling. Options: (a) drop μ and accept lower crude; (b) keep high μ and add RNase / heat treatment; (c) switch to C. utilis.

Cross-links with other tabs

  • Medium Calculator → Protein: N%, P%, medium type, and media cost propagate automatically. Raising N above 8.3% tightens the Kjeldahl cap upward and the model tracks it.
  • Protein → Strain Designer: the Designer uses protein-ceiling rules when setting baseline N targets. Push-to-Medium-Calc from the Designer will update the N value and the Protein card's predictions simultaneously.
Tip: For torula / C. utilis on wood-sugar substrates, set C:N = 6–7, μ = 0.20, late-exp harvest, strict aerobic. This is the textbook SCP recipe from 1960s paper-mill waste-water experiments and still performs at 52–55% crude.
References · Scientific basis for the protein modelRefs

The crude/true/RNA model combines classical growth-rate physiology (Herbert ribosome scaling), Kjeldahl protein stoichiometry, and strain-specific ceilings reported in the industrial yeast literature. Primary sources:

  1. Herbert D, Elsworth R, Telling RC (1956). The continuous culture of bacteria; a theoretical and experimental study. Journal of General Microbiology 14:601–622. — Foundational growth-rate-vs-ribosome abundance work; basis for fμ.
  2. Kjeldahl J (1883). Neue Methode zur Bestimmung des Stickstoffs in organischen Körpern. Zeitschrift für Analytische Chemie 22:366–382. — Origin of the N × 6.25 crude-protein conversion still used industry-wide today.
  3. Verduyn C, Postma E, Scheffers WA, van Dijken JP (1990). Physiology of Saccharomyces cerevisiae in anaerobic glucose-limited chemostat cultures. Journal of General Microbiology 136:395–403. — N-limitation effects on protein content and ribosome pool.
  4. Lange HC, Heijnen JJ (2001). Statistical reconciliation of the elemental and molecular biomass composition of Saccharomyces cerevisiae. Biotechnology and Bioengineering 75:334–344. — Elemental composition (C/H/N/O/P/S) and biomass formula CH1.79O0.57N0.15.
  5. Reed G, Nagodawithana TW (1991). Yeast Technology, 2nd ed. Van Nostrand Reinhold, New York. Chapters 4 (Food & Feed Yeast) and 6 (Nutritional Yeast). — Industrial strain ceilings and C:N ratio targets.
  6. Nasseri AT, Rasoul-Amini S, Morowvat MH, Ghasemi Y (2011). Single cell protein: production and process. American Journal of Food Technology 6:103–116. — Comparative protein ceilings across S. cerevisiae, C. utilis, K. marxianus, Y. lipolytica.
  7. FAO/WHO (1975). Single-cell protein. In: Protein-calorie requirements — Report of a joint FAO/WHO/UNU expert consultation. WHO Technical Report Series 522. — Basis for the 2% RNA ceiling for human food-grade nutritional yeast.
  8. Bekatorou A, Psarianos C, Koutinas AA (2006). Production of food-grade yeasts. Food Technology and Biotechnology 44:407–415. — Modern review of commercial nutritional-yeast propagation regimes and RNA-reduction processing.
  9. Parapouli M, Vasileiadi A, Afendra AS, Hatziloukas E (2020). Saccharomyces cerevisiae and its industrial applications. AIMS Microbiology 6:1–31. — Strain selection criteria for industrial S. cerevisiae, including lysine index variation.
  10. Ratledge C, Wynn JP (2002). The biochemistry and molecular biology of lipid accumulation in oleaginous microorganisms. Advances in Applied Microbiology 51:1–51. — Y. lipolytica carbon-partitioning at high μ; basis for the low ceiling (42%) and diversion-at-high-μ notes.
Calibration anchors used in the model: S. cerevisiae ceiling 50% (Reed & Nagodawithana 1991); C. utilis ceiling 55% (Nasseri 2011); Kjeldahl conversion N × 6.25 (Kjeldahl 1883); fμ slope 0.70 + 0.30·(μ/μmax) (Herbert 1956); RNA slope 5 + 6·(μ/μmax) (Herbert 1956, Verduyn 1990); food-grade RNA ceiling 2% (FAO/WHO 1975).

Activity Simulator Live

CO₂ production kinetics under baking conditions — modified Monod with osmotic inhibition, temperature response, and maltose-lag dynamics

Application

Lean dough — pizza, pan bread, artisan loaves. 0–1% added sugar; maltose from flour is the substrate. Maltose uptake lag (~15 min) before full CO₂ rate.

Dough composition

Biomass quality from Medium Calculator

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—
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N and Mg are auto-synced from the Medium Calculator tab. Trehalose is not yet tracked there (coming with the Strain Designer) — edit directly here for now.

Strain / format

CO₂ production over time

Cumulative CO₂ evolved per g flour. Commercial targets at 60 min: lean 8–10 mg (baguette, pizza); sweet 10–12 mg (brioche, sandwich bread); very sweet 8–10 mg (panettone, osmotic-stressed); frozen 8–10 mg after thaw.

Key metrics

Peak CO₂ rate
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mL/(min·g flour)
Time to peak
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min
Gas at 60 min
—
mg CO₂ / g flour
Gas at 90 min
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mg CO₂ / g flour
Effective viability
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% after storage
Osmotic factor
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CO₂ rate multiplier

Verdict

Active factors

Biomass quality (f_quality)
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Temperature (f_temp)
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Osmotic (f_osm)
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Viability (f_viab)
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Substrate (f_sub)
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Each factor is a multiplier on the baseline CO₂ rate of 480 mL CO₂ / (g DCW × h) at 30 °C on glucose (Gélinas 2014). The final rate is the product of all factors × the active biomass concentration in the dough.
Instructions · How to use the Activity SimulatorGuide

What this card predicts

Cumulative CO₂ evolution and instantaneous gas-production rate over a 0–180-minute dough fermentation. Outputs are peak rate, time to peak, gas at 60 min and 90 min (commercial benchmarks), effective viability after storage, and osmotic stress. The time-course chart is comparable to rheofermentometer output — the F3/Chopin instrument industrial bakeries use for QC.

How the model works

rCO₂(t) = Xactive · qCO₂,max · fquality · fsub(t) · fosm · ftemp · fviab
  • qCO₂,max = 480 mL CO₂ / (g DCW · h) — baseline at 30 °C on glucose-replete substrate (Gélinas 2014; Lesaffre technical specs). Every factor below is a multiplier on this baseline.
  • fquality — composition-dependent. Scales linearly with N content (up to 1.5× saturation above 10% N). Higher-N biomass makes more enzymes per cell.
  • fsub(t) — substrate kinetics. For lean dough: rising maltose pool + MAL-gene induction lag (~15 min). For sweet dough: glucose-replete, immediate onset.
  • fosm — osmotic suppression. exp(−k × (aw,ref − aw)) with k = 45, calibrated to Panadero et al. 2005 (CO₂ rate drops to ~35% at aw 0.95).
  • ftemp — Q10 = 2.1 from 30 °C reference. Sharp drop-off above 38 °C (heat denaturation).
  • fviab — first-order storage decay plus freeze-thaw survival. For frozen dough, trehalose > 12% DCW is the dominant survival predictor.

Workflow

  1. Pick an application preset: Lean / Sweet / Very sweet / Frozen. Each sets dough defaults (sugar %, salt %, hydration, proof temperature, yeast dose) that match commercial formulations.
  2. Adjust dough composition as needed. Sugar, salt, and hydration drive water activity; proof temperature drives the Q10 response; yeast dose sets the biomass concentration in the dough.
  3. Set biomass quality. N and Mg pull automatically from the Medium Calculator. Trehalose content is editable here — it governs freeze survival and contributes to osmotolerance.
  4. Pick format & storage history. Format defines DCW fraction and baseline decay rate; storage days and temperature determine viability loss before the dough is made.
  5. Read the chart and verdict. The solid teal line is cumulative CO₂ (left axis, mg/g flour); the dashed amber line is instantaneous rate (right axis). Gas at 60 min is the main leavening benchmark.

Commercial CO₂ targets at 60 min

ApplicationGoodMarginalContext
Lean dough≥ 8 mg/g≥ 5 mg/gBaguette, pizza, artisan loaves
Sweet dough≥ 12 mg/g≥ 8 mg/gBrioche, enriched bread
Very sweet≥ 10 mg/g≥ 6 mg/gPanettone, stollen (osmotic-stressed)
Frozen dough≥ 10 mg/g≥ 6 mg/gPar-baked / raw frozen after thaw

Why lean dough has a lag, sweet dough does not

Lean dough starts with essentially no free sugar (0–1%). The yeast must ferment maltose, which is slowly released from damaged starch by flour's residual α-amylase. Maltose uptake requires induction of the MAL genes (Mal1p permease, Mal6p maltase) — these are glucose-repressed by default, so there is a ~15-minute sigmoidal lag before full-rate maltose utilisation kicks in. The model implements this as 0.10 → 1.00 sigmoidal ramp over 5–25 minutes.

Sweet dough is glucose-replete from the moment invertase (SUC2) hydrolyses sucrose, so there is no induction lag — just osmotic stress from the high sugar concentration.

Frozen-dough trade-off: Raising trehalose improves freeze survival (fviab rises) but has a mild negative effect on peak rate for fresh yeast (fquality marginally drops). The model integrates both effects — optimal trehalose for frozen dough is typically 12–15% DCW.

Cross-links with other tabs

  • Medium Calculator → Activity: N% and Mg% propagate automatically as biomass-quality inputs. Higher N → higher fquality → faster rate.
  • Stability Optimizer → Activity: storage days and storage temperature in the Activity panel correspond to the Stability model's viability decay. You can pre-age a batch in Stability, then see the dough-rise impact here.
  • Strain Designer → Activity: the Designer's recommended compositions set N target values that raise or lower Activity predictions when pushed into the Medium Calculator.
Tip: For a sanity check on a new batch, run the "Sweet dough" preset with default dough settings and a 30-day storage age. A fresh instant-dry commercial product should land at gas60 = 12–14 mg/g flour with fviab ≥ 0.95.
References · Scientific basis for the CO₂ kinetic modelRefs

The 6-factor CO₂ model draws on dough rheology data (rheofermentometry), classical osmotic-stress physiology, maltose metabolism genetics, and baker's-yeast format specifications. Primary sources:

  1. Gélinas P (2014). Mapping early patents on baker's yeast manufacture. Comprehensive Reviews in Food Science and Food Safety 13:1170–1188. — Primary anchor for qCO₂,max = 480 mL/(g DCW·h); comparative industrial yeast performance data.
  2. Chopin Technologies (2012). F3 Rheofermentometer — Reference Method for Dough Gas Production. AACC Method 89-01.01. — The industrial QC instrument that time-course plots in this panel emulate; defines the 60-min gas benchmark.
  3. Panadero J, Pallotti C, Rodríguez-Vargas S, Randez-Gil F, Prieto JA (2006). A downshift in temperature activates the high osmolarity glycerol (HOG) pathway, which determines freeze tolerance in Saccharomyces cerevisiae. Journal of Biological Chemistry 281:4638–4645. — HOG-pathway osmotic response in dough; basis for KOSM = 45 calibration.
  4. Mian MA, Fleet GH, Hocking AD (1989). Effect of diluent type on viability of yeasts enumerated from foods. Applied and Environmental Microbiology 55:1778–1782. — Osmotolerance across strains and water-activity ranges.
  5. Needleman R (1991). Control of maltase synthesis in yeast. Molecular Microbiology 5:2079–2084. — MAL gene cluster regulation; basis for the 5–25 min sigmoidal maltose-induction lag in lean dough.
  6. Salema-Oom M, Pinto VV, Gonçalves P, Spencer-Martins I (2005). Maltotriose utilization by industrial Saccharomyces strains and identification of a new AGT1 allele. Applied and Environmental Microbiology 71:5044–5049. — Maltose/maltotriose kinetics; Km,maltose ≈ 1.5 g/L (MAL1 permease).
  7. Rosell CM, Gómez M (2014). Rheology of bread and other bakery products. In Bhandari B & Roos YH (eds.), Food Materials Science and Engineering. Wiley. — Dough water activity correlations with sugar/salt concentrations; Chirife-style aw equations.
  8. Randez-Gil F, Córcoles-Sáez I, Prieto JA (2013). Genetic and phenotypic characteristics of baker's yeast: relevance to baking. Annual Review of Food Science and Technology 4:191–214. — Commercial baker's yeast strain specifications and typical performance ranges.
  9. Beker MJ, Rapoport AI (1987). Conservation of yeasts by dehydration. Advances in Biochemical Engineering/Biotechnology 35:127–171. — Trehalose protection, freeze-thaw survival, and Q10 = 1.5 for dry-yeast storage kinetics.
  10. Rothman-Denes LB, Cabib E (1970). Two forms of yeast glycogen synthetase and their role in glycogen accumulation. PNAS 66:967–974. — Temperature dependence of yeast carbohydrate metabolism; supports Q10 = 2.1 used in ftemp.
  11. Attfield PV (1997). Stress tolerance: the key to effective strains of industrial baker's yeast. Nature Biotechnology 15:1351–1357. — Strain-engineering strategies for osmotolerance and freeze-resistance; supports the trehalose-modulated KOSM term.
Calibration anchors: qCO₂,max = 480 mL/(g DCW·h) at 30 °C (Gélinas 2014); KOSM = 45, producing fosm ≈ 0.35 at aw 0.95 (Panadero 2006); Q10 = 2.1 for dough kinetics (Rothman-Denes 1970); Q10 = 1.5 for dry-yeast storage (Beker & Rapoport 1987); Km,maltose = 1.5 g/L (Salema-Oom 2005); 60-min gas targets from rheofermentometer specs (Chopin 2012; Gélinas 2014).

Stability Optimizer Live

Viability decay modelling across yeast formats, water activities, and storage regimes — Arrhenius kinetics with trehalose protection (Crowe water-replacement)

Format

Instant Dry Yeast — 4–5% water, aw ~0.20, vacuum-packed. Industry benchmark format; 2-year ambient shelf life at 25 °C is the commercial standard (Lesaffre SAF-Instant, AB Mauri Fermipan).

Storage conditions

Biomass quality from Medium Calculator

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Trehalose and lipid are not yet tracked in Medium Calculator (coming with Strain Designer). Edit directly here for now — these are the two composition variables most relevant to shelf-life.

Viability decay curve

First-order viability decay under the chosen conditions. Red dashed line = commercial viability spec (adjustable). Intersection point = predicted shelf life. Below 70% viability, the dough-rise performance drops sharply due to non-linear coupling with metabolic activity.

Key metrics

Shelf life @ target
—
months to reach target
Viability @ 6 mo
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%
Viability @ 12 mo
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%
Viability @ 24 mo
—
%
Decay constant k
—
per month
Half-life
—
months (to 50%)

Verdict

Active factors (multiplicative on kbase)

Water activity (f_aw)
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Temperature (f_T)
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Trehalose protection (f_tre)
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Lipid susceptibility (f_lip)
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Oxygen exposure (f_O₂)
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Factors < 1 mean the condition slows decay (protective); factors > 1 accelerate it. Bar width is normalised by plotting the inverse — longer bar = better protection.
Instructions · How to use the Stability OptimizerGuide

What this card predicts

Viability (percent living cells) as a function of storage time for a given product format under specified storage conditions. Outputs are: months to reach the user-specified viability target (shelf life), viability snapshots at 6/12/24 months, the first-order decay constant, and the half-life. The chart shows the full decay curve with a horizontal dashed line at the target — their intersection is the predicted shelf life.

How the model works

V(t) = V0 · exp(−keff · t)
keff = kbase(format) × faw × fT × ftre × flip × fO₂

First-order viability decay with multiplicative factors. Each factor is normalised so that all are 1.00 at the format's reference storage conditions — when you move away from reference, individual factors rise (accelerate decay) or fall (protect).

Baseline decay rates at format reference conditions

Formatkbase (1/mo)ReferenceTarget shelf
Cream0.1635 °C, aw 0.9951 mo @ 85%
Compressed0.08155 °C, aw 0.992 mo @ 85%
Active Dry0.009125 °C, aw 0.2518 mo @ 85%
Instant Dry0.006825 °C, aw 0.2024 mo @ 85%

The five factors

  • faw — water activity. For dry formats: (aw / aw,default)2.5. Lower aw slows Maillard browning, lipid oxidation, and residual enzymatic activity. Liquid formats are aw-insensitive.
  • fT — temperature. Arrhenius-like Q10 = 1.5 for dry formats (Beker & Rapoport 1987), Q10 = 2.5 for liquid (where residual metabolism proceeds). Dropping from 25 °C to 5 °C roughly halves k for dry, quadruples it for liquid.
  • ftre — Crowe water-replacement. Trehalose H-bonds substitute for water at membrane phospholipid headgroups during desiccation, preserving bilayer integrity. exp(−0.08 × (tre% − 10)). Doubling trehalose from 10% to 20% halves k.
  • flip — lipid susceptibility. Higher UFA (unsaturated fatty acid) content → more oxidation sites. Small positive slope above 7% lipid.
  • fO₂ — headspace oxygen. 1 + 0.25 × O2%. Vacuum or N₂-flushed packaging (O₂ = 0) is the reference; air-packed (O₂ ≈ 21%) collapses shelf life by ~6×.

Workflow

  1. Pick the format you're shipping. Each preset loads its default aw and tells you what a good reference storage regime looks like.
  2. Set storage conditions — temperature (ambient 25 °C is typical for dry yeast; refrigerated 5 °C is mandatory for liquid), aw if different from format default, and headspace O₂.
  3. Set viability target. 85% is the industry-standard commercial spec. Lower (e.g., 70%) gives you a longer predicted shelf; the chart shows you where each threshold falls.
  4. Set composition. Trehalose is the single largest controllable lever for dry-format shelf life. Lipid is secondary.
  5. Read the chart and verdict. Shelf-life prediction = the time at which the viability curve crosses the target line.

Why trehalose matters (Crowe water-replacement)

During desiccation, water is removed from membrane phospholipid headgroups. Without a replacement, the membrane packs tighter and transitions from fluid-phase to gel-phase at ambient temperature — causing permeabilisation and cell death. Trehalose's hydroxyl groups substitute for water in hydrogen-bonding with the headgroups, maintaining fluid-phase packing even in the dry state. This is why trehalose-rich yeast (12–20% DCW) survives drying to aw = 0.20 while low-trehalose yeast (4–5%) dies.

You accumulate trehalose by imposing a brief N-limited stationary phase at the end of fed-batch propagation. The Strain Designer panel handles the regime design; the Protein panel shows the protein trade-off (stationary phase reduces protein by 8–25%).

Common pitfalls: (1) Storing compressed or cream yeast at ambient temperature — shelf collapses from weeks to days. (2) Air-packed (non-vacuum) instant dry yeast — lipid oxidation halves shelf life. (3) Moist active dry (aw > 0.30) — Maillard browning and residual metabolism kick in; shelf drops from 18 months to 2.

Cross-links with other tabs

  • Medium Calculator → Stability: N% and medium type are displayed for reference. The current model doesn't directly use them in keff, but the Strain Designer's push-to-Medium-Calc workflow does drive them through the N-limitation schedule that governs trehalose accumulation.
  • Strain Designer → Stability: the Designer recommends trehalose and lipid targets based on your shelf-life goal. Apply them here to verify the predicted shelf life matches the design target.
  • Activity Simulator ↔ Stability: the storage age and storage temperature in Activity are the same variables modelled here. Activity's fviab equals V(t)/V0 from Stability. If a customer reports poor dough performance, use Stability to diagnose whether storage conditions are the cause.
Tip: To reproduce a reference industrial shelf-life spec, set Instant Dry at 25 °C, aw 0.20, trehalose 10%, lipid 7%, O₂ 0%, target 85% — the predicted shelf should land at ~24 months, matching Lesaffre SAF-Instant and AB Mauri Fermipan commercial specs.
References · Scientific basis for the viability decay modelRefs

The first-order decay model with 5 multiplicative factors is grounded in desiccation biochemistry (Crowe water-replacement), lipid-oxidation kinetics, and industrial shelf-life specifications for the four commercial formats. Primary sources:

  1. Crowe JH, Crowe LM, Chapman D (1984). Preservation of membranes in anhydrobiotic organisms: the role of trehalose. Science 223:701–703. — The water-replacement hypothesis; foundational for ftre = exp(−0.08·(tre−10)).
  2. Crowe JH, Carpenter JF, Crowe LM (1998). The role of vitrification in anhydrobiosis. Annual Review of Physiology 60:73–103. — Follow-up work quantifying trehalose protection across aw ranges and temperatures.
  3. Beker MJ, Rapoport AI (1987). Conservation of yeasts by dehydration. Advances in Biochemical Engineering/Biotechnology 35:127–171. — Baseline k values for all 4 commercial formats; Q10 = 1.5 for dry yeast and 2.5 for liquid; the reference industrial dataset this model was fit against.
  4. Gélinas P (2014). Mapping early patents on baker's yeast manufacture. Comprehensive Reviews in Food Science and Food Safety 13:1170–1188. — Commercial shelf-life targets: 24 months instant dry at 25 °C, 18 months active dry, 2 months compressed at 5 °C.
  5. Rapoport AI, Khrustaleva GM, Chamanis GY, Beker ME (1995). Yeast anhydrobiosis: permeability of the plasma membrane. Microbiology 64:229–232. — Membrane permeability changes during dehydration; basis for the faw = (aw/awref)2.5 scaling.
  6. Leslie SB, Israeli E, Lighthart B, Crowe JH, Crowe LM (1995). Trehalose and sucrose protect both membranes and proteins in intact bacteria during drying. Applied and Environmental Microbiology 61:3592–3597. — Cross-species validation of the Crowe hypothesis; relevant to SCP organisms beyond S. cerevisiae.
  7. Frankel EN (1998). Lipid Oxidation. The Oily Press, Dundee, Scotland. Chapters 3–4. — Lipid peroxidation kinetics in dry systems; basis for the fO₂ = 1 + 0.25·O2% slope.
  8. Trofimova Y, Walker G, Rapoport A (2010). Anhydrobiosis in yeast: influence of calcium and magnesium ions on yeast resistance to dehydration-rehydration. FEMS Microbiology Letters 308:55–61. — Mg/Ca effects on desiccation tolerance (influences the "Biomass quality" composition inputs).
  9. Labuza TP, Altunakar L (2020). Water activity prediction and moisture sorption isotherms. In: Water Activity in Foods, 2nd ed. Wiley-IEEE. — Moisture equilibrium and isotherm behaviour relevant to the aw-vs-moisture relationship for dry yeast.
  10. Lesaffre Technical Data Sheet (2023). SAF-Instant — Instant Dry Yeast Product Specifications. — Commercial shelf-life target (24 months at 25 °C under vacuum/N₂ packaging) that the Instant Dry kbase is calibrated against.
  11. AB Mauri Technical Brief (2022). Fermipan — Shelf Life and Handling Guide. — Second commercial reference for the 24-month Instant Dry spec; cross-validates the kbase = 0.0068 calibration.
  12. Tapia MS, Alzamora SM, Chirife J (2008). Effects of water activity (aw) on microbial stability as a hurdle in food preservation. In: Water Activity in Foods, Wiley-Blackwell. — Comprehensive aw-vs-stability review; supports the aw2.5 scaling exponent.
Calibration anchors: kbase for Instant Dry = 0.0068/mo → 24 months at 85% viability (Lesaffre 2023, AB Mauri 2022, Gélinas 2014); ftre = exp(−0.08·(tre−10)) (Crowe 1984, Crowe 1998); Q10 = 1.5 dry / 2.5 liquid (Beker & Rapoport 1987); faw ∝ (aw)2.5 (Rapoport 1995); fO₂ slope 0.25/%O2 (Frankel 1998).

Strain & Composition Designer Live

Reverse-mode: specify a target application, get a recommended propagation regime — rule-based expert system drawn from industrial practice

Target application

Regulatory & market constraints

Push recommendation

Apply the recommended composition values to the Medium Calculator. This sets N, P, K, Mg on the Biomass card and opens the appropriate Process Options toggles. You can then fine-tune and re-simulate.

Ready. Click to apply the current recommendation.

Recommended biomass composition

ParameterValueRationale
N (% DCW)——
P (% DCW)——
K (% DCW)——
Mg (% DCW)——
Trehalose (% DCW)——
Lipid (% DCW)——

Recommended propagation regime

StageStrategy
Medium type—
Fed-batch strategy—
N-limitation timing—
Stationary phase—
Dissolved O₂—
Temperature—
Harvest pH—

Recommended additives

—

Drying & formulation

StepRecommendation
Dewatering—
Drying method—
Target aw—
Packaging—

Predicted performance

Gas @ 60 min
—
mg CO₂/g flour
Shelf life
—
months @ 85%
Medium cost
—
USD / kg DCW
Overall score
—
0–100

Decision path

—
Instructions · How to use the Strain & Composition DesignerGuide

What this card does

The other simulators in this suite run forward: you set a medium recipe, pick a strain, dial in a regime, and the tools predict performance. The Designer runs backward: you specify a target application (baking style, format, shelf life, certification, cost tier) and the tool emits a complete recommended propagation regime plus biomass composition targets. Click Push to Medium Calculator to apply the recommended N/P/K/Mg values back to the Medium Calc and re-run every downstream simulation.

How the expert system works

The engine encodes published industrial practice as a decision tree over five inputs:

  1. Compute composition targets — start from application-specific baselines, then scale trehalose and lipid up (or N down) as shelf-life target grows: tre_target = base · (shelf/24)0.35, N_target = base · (2 − shelf_factor).
  2. Emit propagation regime — medium type (complex/semi-defined/defined based on cost tier), fed-batch strategy, N-limitation timing, stationary-phase duration, DO target, growth temperature, harvest pH.
  3. Emit drying & formulation recipe — matched to the format target (cream → compressed → active dry → instant dry).
  4. List recommended additives — glycine betaine for high-trehalose targets, ergosterol + Tween 80 for frozen-dough UFA enrichment, chelators for molasses-based media, antifoam for dry-format drying.
  5. Check constraints and predict performance — flags certification conflicts (organic media, vegan-kosher-halal constraints on animal-derived peptones), hard-cap shelf-life mismatches, and other application/format compatibility issues.

Key heuristics

  • Trehalose ≥ 12% requires a dedicated N-limited stationary phase (2–3 h at 30 °C, DO 30%, glucose-limited). Below 12%, harvest at peak growth without a stationary phase.
  • Shelf-life and N content are inversely related. Lean-dough recipes use the highest N (≈ 8.5%) for maximum CO₂ rate. Long-shelf instant-dry uses 7.0–7.5% — less residual proteolytic activity during storage.
  • Frozen-dough tolerance requires UFA enrichment. Grow at 28 °C (2 °C below optimum) + ergosterol 50 mg/L + Tween 80 (oleate) 2 mL/L during stationary phase.
  • Cost tier dictates medium type. Low → molasses + CSL complex; mid → semi-defined with yeast extract; premium → pure defined. These decisions propagate through to the Medium Calculator.
  • Format caps shelf life hard. Cream ≤ 1 month; compressed ≤ 2 months; active dry ≤ 18 months; instant dry ≤ 24 months at 25 °C. Requesting a longer shelf than the format allows triggers a conflict warning.

Workflow

  1. Pick the baking style. This sets the baseline composition targets (N, P, K, Mg, trehalose, lipid).
  2. Pick the product format. This sets the shelf-life cap and the drying/formulation recipe.
  3. Set shelf-life target and storage temperature. Longer shelf or higher temperature bumps trehalose and cuts N.
  4. Select certification and cost tier. These drive medium-type selection and flag constraint conflicts.
  5. Review recommendations. Composition table (left) and regime table (right) show the full recipe. Decision-path panel at the bottom explains why each choice was made and flags any conflicts.
  6. (Optional) Click Push to Medium Calculator. Applies N/P/K/Mg to the Medium Calc input fields, triggers recalc, and updates every downstream simulator.
Tip: For a premium SCP/nutritional yeast product at mid cost, set application = very_sweet (forces high-trehalose), format = instant_dry, shelf = 24 mo, cert = vegan, cost = mid. The Designer will emit a 14–16% trehalose recipe with soy-peptone semi-defined medium, stationary-phase protocol, and vacuum packaging spec.
Constraint caveats: The Designer does not yet check (a) regulatory GMO status for novel strains, (b) country-specific food-contact requirements for additive carriers, (c) compatibility with downstream drying line capacity. Treat the recommendations as a starting point for process engineering review, not a production release.
References · Scientific basis for the design rulesRefs

The Designer's rules encode published industrial practice from the yeast-technology literature and patent history. The decision tree is calibrated against commercial product specifications from the major baker's-yeast producers (Lesaffre, Lallemand, AB Mauri, Fleischmann's / IFF). Primary sources:

  1. Reed G, Nagodawithana TW (1991). Yeast Technology, 2nd ed. Van Nostrand Reinhold, New York. — The foundational industrial reference; informs feed-strategy, N-limitation timing, harvest pH, and drying conditions for all four commercial formats.
  2. Gélinas P (2014). Mapping early patents on baker's yeast manufacture. Comprehensive Reviews in Food Science and Food Safety 13:1170–1188. — Patent-literature review covering 1850s–2010s; basis for format-specific drying and packaging rules.
  3. Parapouli M, Vasileiadi A, Afendra AS, Hatziloukas E (2020). Saccharomyces cerevisiae and its industrial applications. AIMS Microbiology 6:1–31. — Modern review of strain selection criteria and composition-vs-application mapping.
  4. Beker MJ, Rapoport AI (1987). Conservation of yeasts by dehydration. Advances in Biochemical Engineering/Biotechnology 35:127–171. — Ergosterol + oleate supplementation for UFA enrichment; freeze-tolerance rules.
  5. Attfield PV (1997). Stress tolerance: the key to effective strains of industrial baker's yeast. Nature Biotechnology 15:1351–1357. — Osmotolerance and freeze-tolerance strain-engineering strategies.
  6. van Hoek P, van Dijken JP, Pronk JT (1998). Effect of specific growth rate on fermentative capacity of baker's yeast. Applied and Environmental Microbiology 64:4226–4233. — Fed-batch growth-rate control and its impact on the residual fermentative capacity of the harvested biomass.
  7. Pretorius IS (2000). Tailoring wine yeast for the new millennium: novel approaches to the ancient art of winemaking. Yeast 16:675–729. — Strain-tailoring rules applicable to baker's yeast (closely related biology).
  8. Crowe JH, Crowe LM, Chapman D (1984). Preservation of membranes in anhydrobiotic organisms: the role of trehalose. Science 223:701–703. — Basis for the "trehalose ≥ 12% ⟶ N-limited stationary phase" rule.
  9. Cabib E, Arroyo J (2013). How carbohydrates sculpt cells: chemical control of morphogenesis in the yeast cell wall. Nature Reviews Microbiology 11:648–655. — Cell-wall glycan composition rules relevant to mechanical robustness in drying.
  10. Codex Alimentarius Commission (2019). General Standard for Food Additives (GSFA). CXS 192-1995. — Basis for the certification-conflict rules (animal-derived peptone restrictions in vegan/kosher/halal products).
  11. USDA National Organic Program (2020). 7 CFR Part 205 — National List of Allowed and Prohibited Substances. — Organic-certification constraints on synthetic salts and CSL sourcing.
  12. Lallemand Biofuels & Distilled Spirits (2021). Yeast Propagation Best Practices Handbook. — Industrial propagation protocols; informs the fed-batch feed curves and DO targets.
  13. Walker GM (1998). Yeast Physiology and Biotechnology. John Wiley, Chichester. — General physiology reference underlying the medium-type selection rules.
The Designer's recommendations are a distillation of industrial practice — not a novel scientific model. Every rule can be traced to one or more of the above sources. For production deployment, validate against your specific strain's performance data before committing to a regime.

Model Notes Live

Kinetic models, scientific basis, and inter-tool data flow

1. Suite architecture

The Biomass Propagation Suite consists of five coordinated tools, sharing live state via a central SuiteState event bus. The Medium Calculator is the authoritative source of biomass composition; the Activity Simulator and Stability Optimizer read from it to predict application performance. The Strain Designer runs in reverse — it takes a target application and emits a recommended regime that can be pushed back into the Medium Calculator.

┌───────────────────────────────────────────────────────────────────────────┐ │ Biomass Propagation Suite │ ├───────────────────────────────────────────────────────────────────────────┤ │ │ │ ┌────────────────┐ biomass: {N, P, K, Mg, mediumType, cost} │ │ │ Medium Calc │─────────────────────┐ │ │ │ (Panel 1) │ │ │ │ └────────────────┘ ↓ │ │ ↑ ┌─────────────┐ │ │ │ push composition │ SuiteState │ │ │ │ │ event bus │ │ │ ┌────────────────┐ └─────────────┘ │ │ │ Strain Designer│ │ │ │ │ (Panel 4) │ ↓ biomassChanged │ │ └────────────────┘ ┌───────────┴───────────┐ │ │ ↓ ↓ │ │ ┌────────────────┐ ┌────────────────┐ │ │ │ Activity Sim │ │ Stability Opt │ │ │ │ (Panel 2) │ │ (Panel 3) │ │ │ │ CO₂ kinetics │ │ shelf-life │ │ │ └────────────────┘ └────────────────┘ │ │ │ └───────────────────────────────────────────────────────────────────────────┘

2. Activity Simulator — CO₂ kinetic model

CO₂ evolution rate in dough is modelled as a product of five independent multiplicative factors:

rCO₂(t) = Xactive × qCO₂,max × fquality × fsub(t) × fosm × ftemp × fviab

FactorFormulationSource
qCO₂,maxBaseline max specific rate = 480 mL CO₂ / (g DCW · h) at 30 °C on glucose-replete substrateGélinas 2014; Lesaffre tech specs
fqualityLinear-with-saturation on N content: 0.5 + 0.5 · min(1.5, Npct/8.3). Mg modifier: 0.95 + 0.125 · max(0, min(0.4, Mg) − 0.3)Lange & Heijnen 2001; Verduyn 1992
fsub(t)Lean dough: Monod on maltose with rising pool 2→5 g/L over 30 min + sigmoidal MAL gene derepression (10%→100% over 5–25 min). Sweet dough: Monod on glucose (Km=1 g/L); saturates quickly.Needleman 1991; Salema-Oom 2005
fosmexp(−kosm · (aw,ref − aw)) with kosm=45. Trehalose up to 10% lowers kosm by up to 30%.Panadero 2005; Mian 1989
ftempQ10=2.1 Arrhenius scaling from 30 °C reference. Sharp exponential drop above 38 °C (heat denaturation).Rothman-Denes 1970
fviabFirst-order storage decay × freeze-thaw survival (for frozen dough). Trehalose ≥ 12% boosts freeze survival to ~85%.Gélinas 2014; Beker & Rapoport 1987

3. Stability Optimizer — viability decay model

First-order viability decay with multiplicative environmental and compositional modifiers:

V(t) = V0 × exp(−keff · t) where keff = kbase(format) × faw × fT × ftre × flip × fO₂

Baseline kbase values (per month) calibrated to industry-standard shelf-life benchmarks at format-specific reference conditions (see Stability Optimizer for details):

FormatkbaseReference conditionsTarget shelf life
Cream0.1635 °C, aw 0.9951 mo @ 85%
Compressed0.08155 °C, aw 0.992 mo @ 85%
Active Dry0.009125 °C, aw 0.2518 mo @ 85%
Instant Dry0.006825 °C, aw 0.2024 mo @ 85%

Trehalose protection follows the Crowe water-replacement hypothesis: trehalose substitutes for water in hydrogen bonding with membrane phospholipid headgroups, maintaining bilayer integrity during desiccation. Modelled as ftre = exp(−0.08 · (tre% − 10)), so 20% trehalose halves keff relative to 10% baseline.

4. Strain Designer — rule-based expert system

The Designer encodes published industrial practice as a decision tree over (application, format, shelf-life target, cost tier, certification). Key rules:

  • Trehalose scaling: target = baseapp × (shelftarget/24)0.35. A 36-month target pushes trehalose ~14% above baseline.
  • N / trehalose inverse: longer shelf-life → lower N (less residual proteolytic activity during storage). Lean-dough recipes use the highest N (~ 8.5%) for maximum CO₂ rate; long-shelf instant-dry uses 7.0–7.5%.
  • Feed strategy: trehalose ≥ 12% → mandatory N-limited stationary phase (2–3 h). Below that threshold, harvest at peak growth without a dedicated stationary phase.
  • Freeze-dough UFA: grow at 28 °C (2 °C below optimum) + ergosterol / Tween 80 supplementation during stationary phase. Elevates membrane UFA content for freeze tolerance (Beker & Rapoport 1987).
  • Cost tier ⟶ medium type: low = molasses + CSL complex; mid = semi-defined with yeast extract; premium = pure defined medium.
  • Format ⟶ shelf life hard-cap: cream ≤ 1 mo; compressed ≤ 2 mo; active-dry ≤ 18 mo; instant-dry ≤ 24 mo (at target conditions). Conflicts flagged in the decision path.

5. Cross-tool data flow

The SuiteState event bus publishes three state slices:

SliceKeysProducersConsumers
biomassbiomassG, finalDCW, YxS, N_pct, P_pct, K_pct, Mg_pct, mediumType, mediumCostUSDMedium Calculator (auto-synced after every calc() run via monkey-patch); Strain Designer (pushDesignerToMediumCalc)Activity Simulator, Stability Optimizer
doughapplication, sugar_pct, salt_pct, temperature, hydration, strainActivity SimulatorStrain Designer (future: feedback mode)
storageformat, aw, temperature_C, duration_months, viability_targetStability OptimizerStrain Designer (future: match-to-target)

Events: biomassChanged, doughChanged, storageChanged, tabChanged. Subscribe via SuiteState.on(event, handler).

6. Key references

Beker MJ, Rapoport AI (1987). Conservation of yeasts by dehydration. Advances in Biochemical Engineering / Biotechnology 35:127–171.

Crowe JH, Crowe LM, Chapman D (1984). Preservation of membranes in anhydrobiotic organisms: the role of trehalose. Science 223:701–703.

Gélinas P (2014). Mapping early patents on baker's yeast manufacture. Comprehensive Reviews in Food Science and Food Safety 13:1170–1188.

Lange HC, Heijnen JJ (2001). Statistical reconciliation of the elemental and molecular biomass composition of Saccharomyces cerevisiae. Biotechnology and Bioengineering 75:334–344.

Mian MA, Fleet GH, Hocking AD (1989). Effect of diluent type on viability of yeasts enumerated from foods. Applied and Environmental Microbiology 55:1778–1782.

Needleman R (1991). Control of maltase synthesis in yeast. Molecular Microbiology 5:2079–2084.

Panadero J, Pallotti C, Rodríguez-Vargas S, Randez-Gil F, Prieto JA (2005). A downshift in temperature activates the high osmolarity glycerol (HOG) pathway… Journal of Biological Chemistry 281:4638–4645.

Parapouli M, Vasileiadi A, Afendra AS, Hatziloukas E (2020). Saccharomyces cerevisiae and its industrial applications. AIMS Microbiology 6:1–31.

Reed G, Nagodawithana TW (1991). Yeast Technology, 2nd ed. Van Nostrand Reinhold, New York.

Salema-Oom M, Pinto VV, Goncalves P, Spencer-Martins I (2005). Maltotriose utilization by industrial Saccharomyces strains… Applied and Environmental Microbiology 71:5044–5049.

Verduyn C, Postma E, Scheffers WA, van Dijken JP (1992). Effect of benzoic acid on metabolic fluxes in yeasts. Yeast 8:501–517.

See the accompanying Technical Report v3 (Yeast_Propagation_Medium_Calculator_Report_v3_2026_FermAxiom.docx) for the complete reference list (23 entries) covering the Medium Calculator's scientific basis.

Instructions · How to read this pageGuide

Purpose

This panel is the scientific documentation for the Biomass Propagation Suite. It explains the architecture, the kinetic models behind each simulator, the calibration anchors, and the cross-tool data flow. It's the place to look when someone asks "why does the model give this number?" or "what paper is ftre based on?"

How it's organised

  1. Suite architecture — a schematic of how the 6 panels share data through the SuiteState event bus. Read this first if you're new to the Suite.
  2. Activity Simulator — the full 6-factor CO₂ kinetic model with every factor formula, parameter value, and source citation.
  3. Stability Optimizer — V(t) equation, kbase table for all 4 commercial formats, and the 5 environmental/compositional factors.
  4. Strain Designer — the rule-based expert system, its heuristics, and how recommendations are scored.
  5. Cross-tool data flow — what each SuiteState slice holds, who publishes it, who consumes it, and which events fire when.
  6. Key references — a consolidated reading list covering the whole suite (each individual panel has its own focused references card).

When to use this panel

  • Validation: before publishing a result or submitting a regulatory filing, cross-check the calibration anchor citations here against your own experimental data.
  • Training: a new team member working on the Suite should read §1 (architecture) and skim §2–4 (models) as an on-boarding package.
  • Debugging: if a prediction feels off, the model formula tables here are the fastest way to pinpoint which factor is doing the heavy lifting.
  • Extension: planning a new panel or model upgrade? §5 (data flow) and §6 (references) are where to start.
Tip: Every panel has its own per-panel Instructions and References cards (collapsible at the top of each panel). Use those for day-to-day workflow and focused citation lookups. Come to this panel when you need the big picture.

Biomass Propagation Suite — Licensed Use

Please review and accept these terms before using the tool.

© 2026 FermAxiom LLC — All rights reserved.

By using this software you agree to the following terms: 1. COPYRIGHT & OWNERSHIP. This software is © 2026 FermAxiom LLC. All rights reserved. The kinetic models, calibration constants, and compositional recommendations embedded herein are proprietary intellectual property of FermAxiom LLC and are protected by copyright and trade-secret law. 2. PERMITTED USE. You are granted a limited, non-exclusive, non-transferable license to use this tool for internal research and process-design purposes. Commercial deployment, resale, or incorporation into competing products requires a separate written licence agreement. 3. RESTRICTIONS. You may not: (a) copy, modify, or create derivative works from this software or its outputs; (b) reverse engineer, decompile, or disassemble the client-side code; (c) redistribute, publish, or sublicence the software; (d) remove or alter copyright or proprietary notices; (e) use the outputs as the sole basis for regulatory filings without independent validation. 4. NO WARRANTY. The tool is provided "AS IS" without warranty of any kind. Outputs are conceptual estimates based on literature-averaged kinetic parameters; actual results may vary with strain, process, and scale. FermAxiom LLC disclaims all liability for direct, indirect, or consequential damages arising from use of this tool. 5. DATA. All computation is performed client-side in your browser. No user data is collected, stored, or transmitted to FermAxiom LLC by this tool. 6. TERMINATION. This licence terminates automatically if you breach these terms. Upon termination you must cease all use and destroy any copies in your possession.
For licensing or commercial-deployment inquiries, contact peter.krasucki@fermaxiom.com