How is bacteria used to make yogurt?

Answer 1

Yogurt is made by inoculating certain bacteria Streptococcus thermophilus andLactobacillus bulgaricus, into milk This is called - starter culture.

You can make it at home, if you place a tablesppon of yogurt in a glass of milk, the bacteria will reproduce and spread through the milk, and within 6 to 12 hours, transform the milk to yogurt. But yogurt cultures are "fussy" -- the milk must be boiled first in order to remove any competing bacteria and then cooled to a lukewarm temperature so that the yogurt bacteria won't be killed by high heat. You could also use sterile powdered milk, or a combination of the two (boiled and sterile).

Answer 2

It is my understanding that in the USA, the USDA requires Lactobacillus bulgaricus and Streptococcus thermophilus to be used to culture a dairy product like milk for the result to be called "yogurt." After that, anything goes - some yogurts have as many as 5 strains of bacteria.

Answer 3

When making yogurt, bacteria is added to milk that has been pasteurized and homogenized. These bacteria then ferment the lactose in milk in order to produce lactic acid which gives yogurt its distinct taste and texture.

Answer 4

Basically, bacteria (present in the starter) use the milk sugar lactose to derive energy and multiply. In this process, lactic acid is produced, which reduces the pH (increases acidity in the medium), which, in turn, leads to precipitation of milk proteins. What makes yogurt thick is precipitated milk proteins. What makes yogurt somewhat sour is lactic acid. The optimum temperature for yogurt making is about 44o C (~110o F). At temperatures below 38o, bacteria grow so slowly and do not produce enough lactic acid for protein precipitation. At temperatures above 50o C (~122 F), bacteria are killed. Therefore, it is essential that the temperature of the milk is near 50o C when the starter is added and must be maintained between 40o and 45o C for 3-4 hours thereafter.

Answer 5

The bacteria causes the milk to thicken and the yogurt flavor to develop.

Answer 6

They do not use bacteria, but heat the yogurt up to where all of it dies.

Answer 7

bacteria helps with fermentation the types of bacteria used are common bacterias such asLactobacillus bulgaricus or Streptococcus thermophilus

Answer 8

must heat the milk directly, Allow the yogurt bacteria to incubate. Keep the yogurt warm and still encourage bacteria, Don't let the too hot or too cold...

Answer 9

bacteria has two kinds: good, and bad. bad bacteria causes sickness, but good bacteria helps us in making yogurt, eatable cream and butter.