Technical application of fermentation technology

Application of microorganism in food fermentation and bacteria in fermented food.

1, lactic acid bacteria fermentation

Distribution of lactic acid bacteria:

be unresolved/unsettled

On the surface of meat, milk, fruits and vegetables.

On the surface of water and utensils, etc.

Type: spherical, rod, etc. Most of them are both angry and angry, and some are angry.

Generally speaking, the optimum temperature for growth and development is 26 ~ 30℃.

Fermentation types of lactic acid bacteria: According to the different characteristics of sugar fermentation, it can be divided into homotype fermentation and heterotype fermentation.

(1) Homotypic fermentation means that 80% ~ 90% of sugar can be converted into lactic acid by lactic acid bacteria during fermentation, and only a small amount of other products are available. The lactic acid bacteria that cause this fermentation are called homolactic acid bacteria.

The strains are Lactobacillus casei, Lactobacillus bulgaricus, Lactobacillus acidophilus and Lactobacillus germ.

② Heterotypic fermentation means that some lactic acid bacteria convert about 50% of the sugar in the fermentation broth into lactic acid, and the other part of the sugar into other organic acids, alcohols, carbon dioxide, hydrogen and so on. The lactic acid bacteria that cause this fermentation are called heterotypic lactic acid bacteria.

There are Bifidobacterium, Leuconostoc aureus and Leuconostoc pentosaceus.

Lactic acid fermentation technology of vegetables

Example-Yogurt

It is made of high-quality fresh milk through degreasing, disinfection, adding lactic acid fermentation bacteria and fermentation.

Bacteria include: Lactobacillus bulgaricus, Lactobacillus acidophilus, Streptococcus lactis, Streptococcus thermophilus, etc.

Generally, after two or more mixed strains ferment 12 ~ 48h at a certain temperature, the emulsion will form a uniform paste-like liquid with an acidity of about 1%, which has a special flavor.

In this fermented yogurt, according to different tastes and requirements, substances such as sugar, citric acid, fruit juice and spices can be added to make various yogurts. This kind of yogurt containing live lactic acid bacteria can be directly eaten by people without disinfection under the condition of ensuring hygiene.

4. Acetobacter fermentation

Acetic acid fermentation is aerobic fermentation with Acetobacter.

Acetic acid fermentation conditions:

Generally, the fermentation broth is kept at about 30℃, and the fermentation broth is acidic.

Because acetic acid bacteria are aerobic, they are usually fermented by aeration.

Under the above conditions, acetic acid bacteria can grow and multiply in large quantities, so that ethanol in the fermentation broth can be converted into acetic acid, and the vinegar content in the high-acid fermentation broth of ester acid bacteria can reach more than 10%.

After filtration, cooking and sterilization, the fermentation stock solution is diluted to 2% ~ 3% acetic acid concentration, and after seasoning, it is edible vinegar.

Application of Yeast in Fermented Wine and Bread

1. Yeast is used to produce drinks and wine.

Make bread with yeast

Brewing raw materials

Grains and wild plants containing more starch, such as barley, rice and sorghum; Planting tuberous plants, such as sweet potato and cassava;

Fruits with more sugar, such as grapes, hawthorn and oranges.

Generally, all starch raw materials used for liquor-making must be gelatinized and saccharified by enzymes, and then certain yeast species are added for alcohol fermentation.

Beer is made from barley through germination, saccharification and beer yeast fermentation.

Grapes specially used for wine-making are rich in sugar and can be directly used for wine-making under the action of wine yeast. Active dry yeast made from grape juice yeast is often used to produce wine.

In the process of alcohol fermentation, closed fermentation is carried out, and aeration fermentation is needed when cultivating yeast species.

Application of mold in fermented food

1. Mould makes fermented bean curd.

Application of mold in soy sauce production