Question

Cooked flavour and brown colour in the heat desiccated dairy products are caused mainly due to __________.

• A. Enzymatic browning
• B. Non-enzymatic browning
• C. Lipid peroxidation
• D. Whey protein denaturation

Hint:

The sweet, caramelized, and brown characteristics of evaporated or desiccated milk products (like Khoa) are produced by non-enzymatic browning (primarily the Maillard reaction between lactose and lysine).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Heat-desiccated traditional dairy products (such as Khoa, Rabdi, and Basundi) undergo severe, prolonged heating during their manufacture.
This thermal processing produces a characteristic light-brown to dark-brown color and a sweet, caramelized, cooked flavor.

Step 2: Detailed Explanation:
The development of color and flavor in these products is primarily driven by chemical reactions:
- Non-enzymatic browning (B): This is the primary reaction responsible for these changes.
It consists of two pathways: the Maillard reaction and caramelization.
The Maillard reaction occurs between the carbonyl groups of reducing sugars (lactose) and the nucleophilic amino groups of milk proteins (specifically the lysine residues of casein).
As heating continues, intermediate compounds form and polymerize into nitrogenous brown pigments called melanoidins, which impart the characteristic brown color.
This pathway also generates volatile flavor compounds such as furans, pyrazines, and maltol, which produce a rich, cooked, and malty flavor.
Caramelization also occurs at high temperatures, where lactose undergoes thermal degradation to produce sweet, caramel-like volatiles.
- Enzymatic browning (A) does not occur in dairy, as it requires polyphenol oxidase enzymes commonly found in fruits and vegetables.
- Lipid peroxidation (C) causes oxidized off-flavors, not the typical cooked flavor.
- Whey protein denaturation (D) contributes to initial cooked flavor notes by releasing sulfhydryl groups, but it does not produce the brown color or caramelization characteristic of heat-desiccated products.

Step 3: Final Answer:
The cooked flavor and brown color in heat-desiccated dairy products are primarily caused by non-enzymatic browning.