Lactic acid fermentation

Lactic acid fermentation is caused by some fungi and bacteria. The most important lactic acid producing bacteria is Lactobacillus. Other lactic acid producing bacteria include:

• Leuconostoc mesenteroides
• Pediococcus cerevisiae
• Streptococcus lactis
• Bifidobacterium bifidus.

Lactic acid fermentation is used throughout the world to produce specialty foods:

• Western world: yoghurt, sourdough bread, sauerkraut, pickles and olives
• Middle East: pickled vegetables
• Korea: kimchi (fermented mixture of Chinese cabbage, radish, red pepper, garlic and ginger)
• Russia: kefir
• Egypt: laban rayab and laban zeer (fermented milk), kishk (fermented mixture of grain and milk)
• Nigeria: gari (fermented cassava)
• South Africa: magou (fermented maize porridge)
• Thailand: nham (fermented fresh pork)
• Philippines : balao balao (fermented rice and shrimp mixture)

The presence of lactic acid, produced during lactic acid fermentation, is responsible for the sour taste and improved microbiological stability and safety of the food. This lactic acid fermentation is responsible for the sour taste of dairy products such as cheese, yogurt and kefir.

Lactic acid fermentation also gives the sour taste to fermented vegetables such as traditionally cultivated sauerkraut and pickles. The sugars in cabbage are converted to lactic acid and serve as a preservative.

Yogurt fermentation

Yogurt is made by fermenting milk with friendly bacteria, mainly Lactobacillus bulgaricus and Streptococcus thermophilus. Yogurt fermentation was probably accidentally invented by Balkan tribes thousands of years ago. Yogurt remained mainly a food of Eastern Europe until the 1900s, when the biologist Mechnikov theorized that the lactobacillus bacteria in yogurt were responsible for the unusually long life of the Bulgarian people. These bacteria ferment milk sugar, or lactose, into lactic acid, which forms the characteristic curd. The acid also limits the growth of food poisoning bacteria. During yogurt fermentation, several flavors are produced that give yogurt its characteristic taste. Yogurt can easily be made at home using a live yogurt as a starter culture. To make your own yogurt, use the following process. Bring milk (or soy milk) to the boil and cool to 40-45°C. Pour this milk into a sterile container and add about 100 ml of live yogurt per liter of milk. Mix with a sterile spoon and incubate at 40-44°C for 4 to 6 hours or until the yogurt has set. Store the yogurt in the refrigerator. If you have worked under hygienic conditions, you can use your own yogurt as a starter for your next batch.

Magou fermentation

Magou is very popular in South Africa, especially among the Bantu people. Magou is a lactic acid fermented porridge made from corn. To make magou, a 10 percent maize meal slurry is cooked, cooled, and inoculated with wheat flour, which contains the bacteria. Magou is also produced on an industrial scale and then packaged in cartons. In the industrial process, magou is inoculated with Lactobacillus delbreuckii cultures.

Kefir fermentation

Kefir fermentation is similar to yogurt fermentation. Yogurt is fermented only by bacteria, but kefir fermentation involves the help of both bacteria and yeast. These yeasts produce some alcohol and carbon dioxide, which gives kefir its fizzy aspect. Kefir is inoculated with special kefir grains. These grains are a mixture of bacteria and yeast in a matrix of proteins, lipids and carbohydrates. Kefir fermentation is done at room temperature, which makes the process easier. On the other hand, not everyone likes the taste of kefir.