FermAxiom LLC — Home Page HDYC Slides v2.0

High-Density Yeast Cultivation (HDYC)

Products 2026

The High-Density Yeast Cultivation (HDYC) Technology Platform was initially developed by FermAxiom LLC
for batch ethanol fermentation processes. Since then it has been implemented in other processes, as it allows
for the production of the robust yeast biomass inocula required as the starter culture for Batch, Fed-Batch,
or Continuous ethanol fermentation. HDYC enables advanced yeast cultivation through a Yeast Cell
Recycle Fed-Batch process, in which the propagated population is retained and re-fed under
controlled substrate and oxygen supply rather than discarded at the end of each batch.
The result is a high-viability, high-density inoculum delivered to the fermenter at
a pitching rate that shortens the lag phase and improves fermentation consistency.
HDYC allows for optimal ethanol manufacturing where Fed-Batch or Continuous
processes are combined with Pre-Fermentation and the HDYC option, and it
is compatible with both natural and genetically enhanced yeast strains
supplied by FermAxiom or already in use at the plant. The platform
is delivered as a combination of process design, equipment
specification, operating procedures, and on-site support,
and is supported by the yeast quantification and
pitching calculators available on this site.

HDYC Performance

Products 2026

HDYC produces the ethanol fermentation inoculum in two stages. Stage 1 produces the yeast biomass
starting culture; Stage 2 enhances its ethanol fermentative performance using a site-specific process and
medium formulation. Stage 1 is operated semi-continuously and Stage 2 as fed-batch, and the system can
also be run as a single fermenter with alternate fermenter usage, so the configuration follows the
target values selected for the site. The primary medium is modified corn mash and backset,
with automated additions of nitrogen source, trace elements, and air. Temperature
(88–95 °F), pH (controlled within the 6–4 range), glucose concentration, and
dissolved oxygen (100–30 %) are controlled at below 25 psi, under process control
loops covering temperature, pH, dissolved oxygen, nutrient utilization, biomass,
and exhaust gas composition. Yeast biomass output reaches up to 1,000 kg
as a high-density, low-volume inoculum, ready as required and available
for multiple injections. Against conventional propagation, where the
amount, composition, and quality of the biomass are not controlled,
HDYC delivers improved inoculum quality and fermentative
capacity, stringent control over fermentation kinetics,
improved fermentation stability, decreased risk of
infection, and full process control automation.

HDYC Return on Investment

Products 2026

Grain-price volatility and the narrow margins of a commodity product such as ethanol require every unit
operation to be re-examined for its material and energy balance. Conventional low-density batch propagation
introduces process variability at excessive cost, and its output is set by commercial yeast purchasing
rather than by the plant. HDYC addresses both sides of that account. On the cost side, commercial
yeast usage is reduced by up to 95 % and overall yeast management cost by roughly 50 %;
the propagation footprint is smaller, production cycles are long, and consumption of
cleaning agents and water is low. On the revenue side, a consistent high-density
inoculum stabilizes fermentation, eliminates commercial-yeast product variability,
and improves the plant’s material and energy balance, while feedstock
flexibility beyond C6 carbohydrates and additional bioproduct options
open further value. Site-specific payback depends on plant capacity,
current yeast spend, and fermentation strategy; FermAxiom prepares
that estimate from the plant’s own operating data as
part of an HDYC evaluation, so the business case
is built on the numbers the plant
already reports.

HDYC System Yeast Biomass

3D concept model. Two 10 m³ fermenters on a 9 hour cycle, run singly or staggered, with fresh or recycled inoculum.

View

Zoom

Layers

Equipment

Vessels

Packages and exchangers

Pump schedule

Control valves

Automated and manual valves

Line list and fittings

Simulation

Liquids and flow

Standard fed-batch baker's yeast protocol on a 9 h cycle: CIP and steam, charge water with vitamins, inoculate with recycled cream, feed sugar for 7 h under DO control, harvest, separate, acid-wash the recycle cream. Fermenter 2 runs 4.5 h behind fermenter 1. Levels are illustrative.

Display

Lines, valves, and pumps

Select an entry to highlight it across the plant.

Process lines

Utilities

Valves and pumps

Design basis

Figures and assumptions

Fixed by the equipment
Fermenters	2 × 10 m³, 1.7 m × 4.4 m
Working volume	5.5 to 8 m³ per batch
Turnaround	1.5 h between batches
Oxygen transfer	up to about 225 mmol/L·h on air
Air	1.5 vvm, 24 Nm³/min total
Head pressure	0.8 bar g, controlled
Cooling	600 kW chilled water
Sugar feed	500 g/L, up to about 12 m³/day
Vessel bottoms	0.7 to 1.0 m above floor
Chosen per campaign
Fermenters in use	one, or two staggered 4.5 h
Inoculum	fresh from pure culture, or recycled cream
Inoculum amount	set by the operator; the harvest split valve fixes the recycled fraction
Operating envelope
Inoculum	10 to 100 kg dry weight
Growth rate	0.10 to 0.35 h⁻¹
Feed phase	7 to 13 h
Inoculation to harvest	8 to 14 h
Final biomass	about 60 g/L, so 480 kg total at the 8 m³ fill limit
Output per batch	12 kg at the low corner (10 kg, 0.10 h⁻¹, 8 h) to 470 kg at the vessel limit (10 kg, 0.30 h⁻¹ or more, 14 h)
Output per day, one fermenter	up to about 1,090 kg (50 kg inoculum, 0.35 h⁻¹, 8 h, 9.5 h cycle)
Output per day, two fermenters	up to about 2,200 kg

Outputs are from a fed-batch integration over the envelope, with growth capped by oxygen transfer and by 60 g/L at full fill. At 60 g/L the oxygen transfer limit only bites in the last hour of the fastest cases, so air alone covers the envelope. The utilities above were sized for a denser earlier case and are conservative for this envelope. Concept level only. Vessel sizes are to scale; equipment positions, pipe routes, and nozzle locations are illustrative and not for fabrication. Product dewatering and drying, the steam boiler, and effluent treatment are outside the model.

Drag to rotate and tilt, right through to a view from below. To move the model: press the ✥ button, then drag (or right-drag, Shift-drag, two fingers). Scroll or pinch to zoom. Select a line, valve, or pump to identify it.

This model needs WebGL, which this browser or device has switched off.