Dairy Extension Officer — 2023 — Final Answer Key — Kerala PSC PYQ Practice with Answers

Correct answer (Option D):\nHydrogen peroxide (H₂O₂) is widely utilized in aseptic packaging lines for ultra-high temperature (UHT) processed milk. It effectively eliminates highly resistant bacterial spores on the packaging film when applied at concentrations of 30% to 35% followed by hot air drying to evaporate residues. Option D is correct.\n\nWhy others are wrong:\nOption A is highly toxic to humans and unsafe for food packaging. Option B is an effective surface sanitizer but leaves undesirable chemical residues on films. Option C is a strong oxidizer but stains surfaces pink and is impractical for packaging machinery.\n\nStudy tip:\nIn UHT packaging, the maximum residual hydrogen peroxide permitted in the final food package is strictly regulated, usually limited to less than 0.5 ppm.

Correct answer (Option D):\nA tri-purpose cream separator is a versatile piece of dairy equipment designed to execute three crucial tasks simultaneously or sequentially: separation of cream from skim milk, centrifugal clarification to remove somatic cells and dirt, and precise standardization of fat content in milk. Option D is correct.\n\nWhy others are wrong:\nOptions A, B, and C represent individual actions, but because the machine executes all three tasks together dynamically within a modern dairy processing setup, selecting any single option is incomplete.\n\nStudy tip:\nStandardization in a tri-process separator is regulated by adjusting a precise throttling valve on the cream discharge line, which changes the fat ratio.

Correct answer (Option D):\nAccording to food safety regulations in India, if milk is sold without any specific label or declaration indicating its class (such as cow, buffalo, or toned), it must legally comply with the minimum legal standards prescribed for mixed milk to prevent adulteration and consumer deception. Option D is correct.\n\nWhy others are wrong:\nOption A and Option B have distinct legal fat and SNF limits specific to animal origins. Option C represents a processed, fortified milk with fixed standards that cannot be applied to generic raw milk sales.\n\nStudy tip:\nMixed milk regulatory standards vary slightly by state in India but generally demand a minimum of 4.5% milk fat and 8.5% Solid-Not-Fat (SNF).

Correct answer (Option C):\nHuman milk naturally does not contain β-lactoglobulin, which is the principal whey protein found in bovine milk. The absence of β-lactoglobulin makes human milk less allergenic to human infants compared to unmodified cow milk. Option C is correct.\n\nWhy others are wrong:\nOption A is a dominant whey protein found in human milk. Option B and Option D are present in human milk and play structural or immunological roles in infant digestion.\n\nStudy tip:\nBecause β-lactoglobulin is entirely missing from human breast milk, it is often identified as a major allergen when infants are introduced to infant formulas derived from cow milk.

Correct answer (Option C):\nThe Recknagel phenomenon refers to the gradual, slow increase observed in the specific gravity or density of raw milk during cold storage. This physical change is primarily caused by the slow solidification of milk fat globules and alterations in the hydration state of casein micelles at low temperatures. Option C is correct.\n\nWhy others are wrong:\nOption A and Option B are incorrect because warm temperatures generally decrease density and accelerate thermal degradation. Option D describes viscosity rather than the density changes defined by Recknagel.\n\nStudy tip:\nDue to the Recknagel phenomenon, specific gravity measurements should ideally be conducted after aging milk or heating it briefly to standardize fat crystal behavior.