Question

Which of the following compounds is available in sterilized milk?

• A. Caseinate
• B. Lactone
• C. Lactulose
• D. Fatty acid

Hint:

Lactulose is an isomerization product of lactose formed during severe heating. It is the standard chemical indicator used to verify if milk has undergone sterilization.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Sterilization of milk involves severe thermal treatment designed to destroy all viable microorganisms and spores.
This intense heating induces distinct chemical changes and isomerizations that do not occur during milder treatments like pasteurization.

Step 2: Detailed Explanation:
Lactulose is a synthetic disaccharide composed of galactose and fructose.
It is not naturally present in raw milk.
During severe thermal processing (such as in-bottle sterilization or UHT treatment), the lactose in milk undergoes the Lobry de Bruyn-Alberda van Ekenstein transformation.
In this reaction, the glucose moiety of lactose is isomerized into fructose under the influence of heat and milk proteins acting as weak bases.
Because the concentration of lactulose formed is proportional to the severity of the heat treatment, it serves as an established chemical marker to distinguish sterilized or UHT milk from pasteurized milk.
While caseinates, lactones, and fatty acids are present in milk, they are also found in raw and pasteurized milks and are not unique indicators of sterilization.
Therefore, lactulose is the characteristic compound formed and available in sterilized milk.

Step 3: Final Answer
The correct option is (C).