Incorrect Statement Regarding Yoghurt

The incorrect statement regarding yoghurt is option 'B', which states that yoghurt is mixed with an inoculum containing Streptococcus faecalis.

Explanation

Yoghurt is a popular dairy product that is made by fermenting milk. It is a nutritious food that provides various health benefits. The process of making yoghurt involves the fermentation of milk using specific strains of bacteria.

Fermentation Process
- Yoghurt is made by adding a starter culture to milk. The starter culture contains specific strains of lactic acid bacteria, primarily Lactobacillus bulgaricus and Streptococcus thermophilus.
- These bacteria convert lactose, the natural sugar present in milk, into lactic acid.
- This fermentation process results in the thickening of milk and the characteristic tangy flavor of yoghurt.
- The conversion of lactose to lactic acid also gives yoghurt its slightly sour taste.

Inoculum in Yoghurt Preparation
- An inoculum is a substance that contains microorganisms and is used to initiate fermentation.
- In the case of yoghurt, the inoculum is a small amount of previously fermented yoghurt or a commercially available yoghurt starter culture.
- The starter culture contains a mixture of the specific strains of bacteria required for the fermentation process.
- Streptococcus faecalis is not a commonly used strain in yoghurt production. It is a bacterium that is found in the human gastrointestinal tract and is not typically used in the production of yoghurt.

Time Required for Yoghurt Preparation
- The statement in option 'C' that the preparation of yoghurt takes approximately 4-5 hours is generally accurate.
- The fermentation process of yoghurt usually takes around 4-5 hours, depending on various factors such as temperature, desired consistency, and the specific strains of bacteria used.
- The milk is heated and then cooled to a specific temperature before adding the starter culture. The fermentation process occurs at a slightly elevated temperature.

Original Flavor of Yoghurt
- The statement in option 'D' that the original flavor of yoghurt is of acetaldehyde is correct.
- Acetaldehyde is a compound that is naturally produced during the fermentation process of milk into yoghurt.
- It is responsible for the distinct tangy flavor and aroma of yoghurt.

In conclusion, the incorrect statement regarding yoghurt is option 'B' which suggests that yoghurt is mixed with an inoculum containing Streptococcus faecalis. The commonly used starter cultures for yoghurt production include Lactobacillus bulgaricus and Streptococcus thermophilus, not Streptococcus faecalis.