Question

The major flavouring compound present in Dahi is

• A. Acetone
• B. Acetaldehyde
• C. Diacetyl
• D. Methylketones

Hint:

Fermented Dairy Flavor Compounds:
DAHI Cultured Butter = DIACETYL (Buttery aroma from citrate).
YOGHURT = ACETALDEHYDE (Green-apple tart aroma from threonine).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Flavor chemistry of indigenous cultured dahi: mesophilic citrate-fermenting lactic starters (Lactococcus lactis subsp. diacetylactis and Leuconostoc mesenteroides) convert milk citrate into diacetyl (2,3-butanedione), providing the characteristic pleasant buttery aroma of traditional dahi.
Key Formula or Approach:
\[ \text{Citrate} \xrightarrow{\text{Citrate Lyase}} \text{Oxaloacetate} \xrightarrow{-\text{CO}_2} \text{Pyruvate} \longrightarrow \alpha\text{-Acetolactate} \xrightarrow{\text{Oxidative Decarboxylation}} \mathbf{Diacetyl (2,3-Butanedione)} \]

Step 2: Detailed Explanation:
In the fermentation biochemistry and flavor chemistry of Dahi (Indian curd):
- Traditional Dahi is manufactured using mesophilic mixed starter cultures (Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. cremoris, and the aroma-producing Lactococcus lactis subsp. diacetylactis Leuconostoc):
1. These aroma bacteria take up native milk citrate ($0.15 - 0.20\%$) and metabolize it via the $\alpha$-acetolactate pathway into Diacetyl (2,3-butanedione) (C) and acetoin.
2. Diacetyl imparts the characteristic, delicate, rich buttery aroma and pleasant flavor that distinguishes traditional Dahi and cultured buttermilk from yoghurt (where acetaldehyde dominates).

Step 3: Final Answer:
Hence, the major flavouring compound present in Dahi is Diacetyl, matching option (C).