Question

In the manufacture of Yakult, fermentation time given is -----------------.

• A. 24 hours
• B. 48 hours
• C. 72 hours
• D. More than 72 hours

Hint:

Yakult fermentation using L. casei Shirota is a very slow process compared to yogurt, requiring up to 5-7 days (well over 72 hours) to reach the target probiotic cell counts and acidity.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Yakult is a globally recognized probiotic fermented milk drink produced by fermenting skimmed milk with a specific strain of lactic acid bacteria, Lacticaseibacillus casei strain Shirota.
The fermentation process is critical for achieving a high concentration of viable probiotic cells and generating the characteristic flavor profile of the beverage.

Step 2: Detailed Explanation:
Due to the slow growth rate of this specific strain under dairy conditions, the fermentation requires a prolonged incubation period.
The milk base is inoculated and incubated at a controlled temperature of 37 $^\circ\text{C}$ to 38 $^\circ\text{C}$.
To reach the required high acidity and cell density, the fermentation is allowed to continue for more than 72 hours (typically up to 120-140 hours, or 5-7 days).
This long incubation distinguishes Yakult from standard yogurt fermentations, which typically take only 4 to 6 hours.
The extended fermentation time allows the bacteria to produce high levels of lactic acid and volatile flavor compounds, contributing to the product's unique sweet-and-sour taste profile.

Step 3: Final Answer
The fermentation time given in the manufacture of Yakult is more than 72 hours.