Concept of fermentation technology

Utilization of microorganisms in food fermentation, Utilization of bacteria in fermented foods

1, lactic acid bacteria fermentation

lactic acid bacteria distribution:

in the air

meat, milk, fruits and vegetables and other food on the surface

On the surface of water and utensils, etc.

Types: spherical, rod-shaped, etc., which belong to the majority of people who are both gas-like, and some are exclusively gas-like.

The optimum temperature for general growth and development is 26~30 ℃.

Lactic acid bacteria fermentation type: according to the different characteristics of sugar fermentation, can be divided into homofermentation and heterofermentation.

Homozygous fermentation refers to lactic acid bacteria in the fermentation process, can make 80% ~ 90% of the sugar into lactic acid, only a small amount of other products, causing this fermentation of lactic acid bacteria called the same type of lactic acid bacteria.

The strains are: Lactobacillus casei, Lactobacillus bulgaricus, Lactobacillus acidophilus, Lactobacillus germ

② heterotypic fermentation refers to some lactic acid bacteria in the fermentation process so that about 50% of the sugar in the fermentation broth into lactic acid, the other sugar into other organic acids, alcohol, carbon dioxide, hydrogen, etc., causing this fermentation of lactic acid bacteria called heterotypic lactic acid bacteria.

The strains include bifidobacterium, leuconostoc orange and leuconostoc pentosaceae.

Lactic acid fermentation process of vegetables

Example-Yogurt

It is made of high-quality fresh milk after defatting, disinfection, adding lactic acid fermentation bacteria, after fermentation.

The strains are: Lactobacillus bulgaricus, Lactobacillus acidophilus, Streptococcus lactis, Streptococcus thermophilus, etc.

Generally, more than two kinds of mixed strains are used. After 12~48h fermentation process at a certain temperature, the emulsion will form a uniform paste liquid with an acidity of about 1% and a special flavor.

In this fermented yogurt, according to different tastes and requirements, you can also add sugar, citric acid, fruit juice and spices and other substances into a variety of yogurt, this containing live lactic acid bacteria yogurt, in ensuring health conditions do not need to be disinfected, can be directly for people to drink.

2. Acetic acid bacteria fermentation

Acetic acid fermentation is aerobic fermentation using Acetobacter.

acetic acid fermentation conditions:

The fermentation broth is generally maintained at a temperature of about 30°C, and the fermentation feedstock is acidic.

Because Acetobacter is an aerobic bacterium, it is usually aerated for fermentation.

Under the above conditions, acetic acid bacteria can grow and multiply in large numbers, so that ethanol in the fermentation broth is converted to acetic acid, and the vinegar content in the fermentation broth with high acid production of Acidobacter esteroides can reach more than 10%.

The fermentation stock solution is filtered, cooked and sterilized, and then diluted to 2% ~ 3% acetic acid concentration. After seasoning, it is edible vinegar.

Utilization of Yeast in Fermented Wine and Bread

The yeast used in the production of beverage wine

Making bread with yeast

Raw materials for wine making

Starch-rich cereals and wild plants, such as barley, rice, sorghum; plant roots, such as sweet potato, cassava;

Fruits with more sugar, such as grapes, hawthorn, oranges, etc;

All starch raw materials for brewing, generally must first go through gelatinization and enzymatic saccharification, and then add certain yeast strains for alcohol fermentation.

Beer is made from barley as the main raw material, through germination, saccharification, beer yeast fermentation. When brewing beer, hops are usually added.

Grapes for winemaking are rich in sugar and can be directly brewed under the action of wine yeast. Active dry yeast made from grape juice yeast is used in the production of wine.

The alcohol fermentation process is closed fermentation, in the cultivation of yeast species must be aerated fermentation.

Utilization of Mold in Fermented Food

1. Mold makes fermented bean curd

The use of mold in the manufacture of soy sauce