Why is solid-state fermentation irreplaceable for thousands of years?
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- Issue Time
- Jun 11,2025
Summary
Why is solid-state fermentation irreplaceable for thousands of years?
Solid state fermentation refers to a biotechnology process that utilizes the metabolic activities of microorganisms (such as fungi, bacteria, yeast, etc.) to achieve substance transformation in a solid matrix with almost no free flowing water.
Its core is to produce enzymes and metabolites through the growth and reproduction of microorganisms on solid substrates such as grains, straw, potatoes, etc., to achieve fermentation goals.
1、 The advantages of solid-state fermentation
High utilization rate of substrate: Solid substrate has a wide range of sources, low cost, and can be directly used as a carrier and nutrient source for microbial growth, reducing the cost of culture medium preparation.
Low energy consumption and pollution: No need for a large amount of water as a medium, low energy consumption in the fermentation process, and less wastewater discharge. High product concentration: Microbial metabolites (such as enzymes, antibiotics, and flavor compounds) in solid systems are prone to accumulate in the matrix, and the difficulty of separation and purification is relatively low.
Strong process flexibility: The equipment is simple and can adjust parameters such as substrate composition, humidity, and temperature according to demand, making it suitable for small-scale personalized production.
2、 The challenge of solid-state fermentation
Difficulty in mass and heat transfer: The solid matrix structure is dense and lacks free water, resulting in low diffusion efficiency of oxygen, heat, and metabolic products, which can easily lead to local temperature unevenness and insufficient substrate utilization.
Complex process control: humidity in solid-state systems pH、 The real-time monitoring of microbial growth status is difficult and relies on experience or specific sensor technology.
Large scale production is limited: traditional solid-state fermentation equipment is difficult to achieve large-scale automation control, and the development of new reactors is still being promoted.
3、 The form of solid-state fermentation
Single strain fermentation: such as solid-state fermentation of cellulase using Aspergillus niger, with high strain purity and strong product controllability.
Mixed strain fermentation: for example, in traditional Baijiu brewing, complex flavor substances are produced by the synergistic effect of natural flora (yeast, lactic acid bacteria, mold, etc.).
4、 Typical application areas
Food: Baijiu (such as the koji making process of Moutai and Wuliangye), soy sauce (solid fermentation of soybean meal by Aspergillus oryzae), Fermented bean curd (solid fermentation of tofu by Mucor), vinegar (solid fermentation of grains by Acetobacter spp.), etc. Use solid fermentation to produce unique flavor and functional ingredients.
Functional foods: By solid-state fermentation, plant substrates such as kudzu root and brown rice are transformed into foods rich in dietary fiber, polyphenols, or probiotics, enhancing their nutritional value (such as fermented brown rice tea).
Feed: Utilizing solid-state fermentation to degrade crude fibers in straw and residue, producing high protein feed (such as silage and fermented soybean meal).
Biopesticides and fertilizers: Solid state fermentation produces microbial agents (such as Bacillus subtilis) for soil improvement or pest control.
Biofuels: Solid state fermentation degrades lignocellulose (such as corn stover) to produce fermentable sugars, which are then converted into ethanol by yeast and used as biofuels.
Enzymes: Solid state fermentation is an important method for producing industrial enzymes such as cellulase, amylase, protease, etc.
Traditional Chinese Medicine: By solid-state fermentation modification of traditional Chinese medicine components (such as conversion of ginsenosides), the efficacy can be improved or toxicity can be reduced (such as fermentation of Astragalus membranaceus).
