Question

Which among the following is a foamy, effervescent milk product resulting from mixed lactic acid and alcoholic fermentation of milk

• A. Villi
• B. Kefir
• C. Skyr
• D. Trahana

Hint:

Effervescence or "fizz" in fermented milk always indicates the production of carbon dioxide gas, which is a hallmark of yeast fermentation in products like Kefir and Koumiss.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Fermented dairy products are classified into lactic acid-fermented or yeast-lactic fermented categories based on the microflora involved.
Yeast-lactic fermented products undergo dual fermentation, producing both lactic acid and carbon dioxide/ethanol.
Detailed Explanation:
Kefir is an ancient fermented milk product originating from the Caucasus Mountains.
It is produced using "kefir grains", which are complex gelatinous matrices of proteins and polysaccharides (kefiran) containing a symbiotic mixture of lactic acid bacteria, acetic acid bacteria, and yeasts.
During fermentation:
- Lactic acid bacteria ferment lactose to produce lactic acid, which coagulates milk proteins and provides a sour taste.
- Yeasts (such as Saccharomyces kefir and Kluyveromyces marxianus) ferment lactose into ethanol and carbon dioxide (\(\text{CO}_2\)) gas.
- The trapped \(\text{CO}_2\) gas gives Kefir its characteristic fizzy, foamy, effervescent texture and refreshing mouthfeel.
Let us review the other options for clarity:
- Villi: A traditional Finnish mesophilic fermented milk characterized by a ropy, viscous texture.
- Skyr: An Icelandic high-protein, strained dairy product with a thick, yogurt-like consistency.
- Trahana: A dried granular mixture of fermented milk and cracked wheat.
Therefore, Kefir is the correct effervescent fermented milk product.
Final Answer:
Kefir is a foamy, effervescent milk product produced by mixed fermentation. Hence, the correct option is (B).