Proses Produksi Yogurt (ChemEngUntirtaAcId)

Summary

This presentation covers the process of making yogurt using Lactobacillus bulgaricus and Streptococcus thermophilus. It details the fermentation process, which involves converting lactose into lactic acid, lowering the pH and giving yogurt its characteristic sour taste. The experiment used fresh milk and Biokul yogurt starter, and it tested different fermentation conditions. The results showed that sealed glass containers led to faster fermentation and thicker yogurt, while plastic containers caused slower fermentation. The study concluded that optimal yogurt production occurs in airtight conditions at around 43°C for faster and more effective bacterial growth.

Takeaways

• 😀 Yogurt is a fermented product, popular worldwide, made from milk or cream and contains beneficial bacteria.
• 😀 Lactobacillus bulgaricus and Streptococcus thermophilus are the main bacteria responsible for yogurt fermentation.
• 😀 Yogurt fermentation involves breaking down lactose into lactic acid, which lowers the pH and gives yogurt its sour taste.
• 😀 The process of making yogurt starts with sterilizing the equipment, followed by heating milk to the right temperature for fermentation.
• 😀 The yogurt starter culture (BioKul) is added to heated milk to initiate fermentation.
• 😀 Sterilizing the containers and using air-tight jars promotes anaerobic conditions for optimal bacterial growth.
• 😀 Yogurt should be stored in a dark, warm place at room temperature (28-30°C) for 24 to 48 hours to allow fermentation to occur.
• 😀 The pH of the milk decreases during fermentation, from an initial pH of 6.7 to around 4.4, indicating successful acid production.
• 😀 Yogurt made in glass containers ferments more effectively and results in thicker, better-textured yogurt compared to plastic containers.
• 😀 The bacterial growth phases include adaptation (0-3 days), rapid growth (3-5 days), and stabilization (5-7 days), which affect the final yogurt product.
• 😀 Optimal yogurt fermentation conditions include using a sealed container, maintaining a temperature around 43°C, and ensuring rapid bacterial metabolism for a more sour, thick yogurt.

Q & A

What is yogurt, and how is it produced?

Yogurt is a fermented dairy product made by using bacterial cultures. It is produced through the fermentation of milk by bacteria, specifically *Lactobacillus bulgaricus* and *Streptococcus thermophilus*. These bacteria convert lactose into lactic acid, lowering the pH of the milk and resulting in yogurt's characteristic tart flavor and thicker texture.

Why are *Lactobacillus bulgaricus* and *Streptococcus thermophilus* used in yogurt production?

*Lactobacillus bulgaricus* and *Streptococcus thermophilus* are the primary bacterial strains used in yogurt production because they are specifically chosen for their ability to ferment milk efficiently, producing lactic acid. This acidification process lowers the pH of the milk, which is essential for creating yogurt's texture and flavor.

What factors affect the fermentation process of yogurt?

The fermentation process of yogurt is influenced by factors such as temperature, the type of bacteria used, and the oxygen levels in the fermentation environment. Optimal temperatures between 28°C and 43°C are crucial for bacterial growth, with higher temperatures accelerating fermentation. Additionally, oxygen-free environments (anaerobic conditions) are ideal for the bacteria used in yogurt making.

How does the pH level change during yogurt fermentation?

During yogurt fermentation, the pH level decreases as the bacteria produce lactic acid. Initially, the pH of the milk is around 6.7, but as the fermentation progresses, the pH drops to around 4.4, which indicates increased acid production and the development of the characteristic sour taste of yogurt.

What impact does the fermentation container have on the final yogurt product?

The type of fermentation container significantly affects the final yogurt product. Yogurt fermented in an air-tight container (like a glass jar) has a thicker texture and more intense flavor due to better control over fermentation conditions. In contrast, yogurt fermented in a plastic container without a seal tends to be thinner and less acidic.

Why does yogurt in a plastic container ferment more slowly compared to a glass jar?

Yogurt in a plastic container ferments more slowly because plastic containers are not air-tight, allowing oxygen to interfere with the anaerobic fermentation process. This lack of proper sealing slows down the bacterial growth, leading to a less efficient fermentation and a thinner yogurt.

What is the optimal temperature range for yogurt fermentation?

The optimal temperature range for yogurt fermentation is between 28°C and 43°C. Maintaining this range helps ensure that the bacteria grow and metabolize effectively, leading to a faster fermentation process and a higher production of lactic acid.

What role does lactic acid play in yogurt production?

Lactic acid is produced by the bacteria during fermentation and plays a key role in yogurt production by lowering the pH of the milk. This acidification process thickens the milk and gives yogurt its characteristic sour taste.

What differences were observed between the yogurt fermented for 24 hours and that fermented for 7 days?

The yogurt fermented for 24 hours in an air-tight container (glass jar) was thicker, had a stronger acidic taste, and showed a more consistent drop in pH. In contrast, the yogurt fermented for 7 days in a plastic container was thinner, less acidic, and showed less pH reduction due to slower fermentation.

What conclusions can be drawn from the experiment on yogurt fermentation?

The experiment concluded that yogurt made using an air-tight container at an optimal temperature (around 43°C) produces the best results. The bacteria grow effectively under these conditions, leading to faster fermentation, more lactic acid production, and thicker, more flavorful yogurt.