How to produce yeast?

Strain Screening and Propagation

• Strain Library Management: Use pure yeast strains (such as Saccharomyces cerevisiae and Kluyveromyces marxianus).
• Gradual Propagation:

1. Laboratory Stage: Slant Culture Activation → Shake Flask Culture (28–30°C, 160–180 rpm, overnight).

2. Production Stage: Seed Tank → Fermentation Tank (volume up to several hundred cubic meters). Maintain dissolved oxygen saturation (20–100%) with sterile air, pH 6.0–7.0, and temperature 28–32°C.

Fermentation Process Optimization

• High-Density Culture: Use molasses (a byproduct of sugar production) or corn saccharification liquid as the carbon source, supplemented with a nitrogen source (ammonium sulfate), phosphate, and trace elements (Mg²⁺, Zn²⁺, etc.).
• Continuous fermentation technologies, such as the self-flocculating yeast process, involve self-immobilization of yeast into millimeter-sized particles. This process operates continuously in a suspended bed reactor, shortening fermentation time by over 50% and achieving an alcohol concentration of 12% (v/v).

Yeast separation and concentration

• Centrifugation: The fermentation broth is centrifuged at 0–10°C and 3000–6000 rpm to obtain yeast milk (45–55% moisture content).
• Washing and impurity removal: The broth is resuspended and centrifuged in sterile water to remove residual culture medium and metabolites (such as ethanol).

Drying and molding technology

• Fluidized bed drying (active dry yeast):

1. Three-stage temperature control: Stage 1 (60–70°C, moisture reduced to 25–35%) → Stage 2 (50–60°C, moisture 15–25%) → Stage 3 (35–50°C, moisture ≤6%).

2. Key Innovation: Addition of protective agents (Span 80, sodium alginate, glycine, etc., accounting for 0.1–1% of dry matter) reduces cell damage and achieves a viable bacterial count of 4.5×10¹⁰ CFU/g.

• Freeze-Drying (High-End Bacteria Powder):

1. Pre-freezing (-80°C, 3–12 hours) → Vacuum drying (-40°C, 10 Pa, 24–48 hours). Protective agents are skim milk powder + trehalose + sucrose (ratio 5–15%: 5–15%: 2–10%).

Packaging and Storage

• Vacuum packaging under inert gas (nitrogen), moisture ≤ 6%. Viable bacterial retention rate ≥ 85% (1 year) when stored at room temperature.

Low-Cost Carbon Source Utilization

• Molasses (a byproduct of sugarcane/beet sugar production), corn saccharification liquid (hydrolyzed by phospho-saccharifying enzyme, saccharification rate >90%).
• Innovation Direction: High-lactic acid industrial byproducts (such as lactic acid fermentation wastewater) are modified and used as culture media, reducing raw material costs by 30%.

Waste Recycling and Pollution Control

• Wastewater Recycling Process: A wastewater reuse rate of 90% is achieved in corn yeast production, achieving "zero emissions."
• Byproduct High-Value Utilization: Corn residue is used to produce protein feed (26–30% protein), and COD emissions from alcohol lees are reduced by 60%.

Strict Quality Inspection Standards

• Viable bacterial count (≥10¹⁰ CFU/g), moisture (≤6%), and contaminant bacterial rate (≤0.1%).
• Storage Stability Testing: Accelerated aging test (37°C/90 days) simulates a one-year shelf life.

Specific Applications

• Fuel Ethanol: Self-flocculating yeast process is used in a 200,000-ton capacity plant, achieving residual sugar levels of <10 g/L.
• Feed Additive: Mixed dry yeast (Kluyveromyces marxianus + Saccharomyces cerevisiae) improves digestibility in livestock and poultry.
• Beer Industry: Freeze-dried yeast powder replaces traditional propagation, offering the same fermentation speed and flavor as traditional yeast culture, while also increasing flexibility.

Industrial yeast production has established a closed technical loop: "strain optimization → continuous fermentation → energy-efficient drying → by-product value-added." The core goals are to reduce costs (raw materials/energy consumption) and increase efficiency (viable count/stability).

If you are interested in industrial yeast production equipment, please feel free to contact us.