Making Yoghurt | Health | Biology | FuseSchool

Summary

This video explains the process of making yogurt, starting with sterilizing equipment and pasteurizing milk to remove unwanted bacteria. The milk is then homogenized, cooled, and combined with special bacteria known as lactic acid bacteria. These bacteria ferment the milk, converting lactose into lactic acid, which lowers the pH and causes the milk to solidify. The result is yogurt, which is then cooled, flavored, and ready to be packaged. The video highlights the key stages in yogurt production, from milk to the final product, while also emphasizing the role of probiotics in supporting gut health.

Takeaways

• 😀 Yogurt is made from milk, but bacteria, specifically probiotics, are also essential ingredients.
• 😀 The bacteria used in yogurt production are beneficial for digestion and are called probiotics.
• 😀 The gut has thousands of good bacteria that help with digestion, and yogurt helps increase their presence.
• 😀 The yogurt-making process starts with sterilizing equipment to eliminate unwanted bacteria.
• 😀 Milk is heated to between 85 and 95 degrees Celsius for 15 to 30 minutes, a process called pasteurization, to kill harmful microorganisms.
• 😀 After pasteurization, milk is homogenized to break down fat droplets and prevent lumps in yogurt.
• 😀 The milk is then cooled to 40-45 degrees Celsius before adding specific yogurt-making bacteria.
• 😀 Lactic acid bacteria, including lactobacilli and streptococci, are used to ferment the milk and turn it into yogurt.
• 😀 During fermentation, bacteria convert lactose into lactic acid, lowering the pH of the milk and creating yogurt's characteristic tangy taste.
• 😀 Once the pH drops to about 4.4, the yogurt solidifies due to protein coagulation, and the bacteria stop working, preventing further solidification.
• 😀 After fermentation and coagulation, the yogurt is stirred and cooled to 5 degrees Celsius, after which flavorings and fruits can be added.

Q & A

Why are bacteria added to the milk during yogurt production?

Bacteria are added to ferment the milk, converting the lactose into lactic acid. This process is essential for transforming the milk into yogurt.

What is the purpose of pasteurization in the yogurt-making process?

Pasteurization heats the milk to a high temperature to kill unwanted bacteria and microorganisms, ensuring the milk is safe for yogurt production.

What does homogenization do to the milk?

Homogenization breaks down the fat droplets in the milk, preventing them from separating and forming lumps in the yogurt.

What are the two types of bacteria used to make yogurt?

The two types of bacteria used are lactobacilli and streptococci, which are also involved in cheese production.

What is the function of lactic acid bacteria in yogurt production?

Lactic acid bacteria ferment the milk, converting lactose into lactic acid, which lowers the pH and helps the milk solidify into yogurt.

Why does yogurt have a tangy taste?

The tangy taste comes from the lactic acid produced during fermentation, which lowers the pH of the milk to around 4.4.

What happens to the milk proteins during yogurt fermentation?

During fermentation, the milk proteins coagulate, causing the milk to turn from a liquid state into a more solid yogurt texture.

Why is the temperature of 40 to 45 degrees Celsius important during fermentation?

This temperature range is optimal for the bacteria to work most efficiently, allowing the fermentation process to occur at its fastest rate.

What is coagulation in the context of yogurt-making?

Coagulation is the process where liquid milk proteins solidify during fermentation, resulting in the formation of yogurt.

At what point does the lactic acid bacteria stop working in the yogurt-making process?

The lactic acid bacteria stop working when the pH drops too low, around pH 4.4, preventing the yogurt from becoming overly solid.