ICAR AIEEA PG Dairy Technology 09 July 2023 (Shift 1) Paper

Physiological characteristics of Brevibacterium linens in surface-ripened cheese:

• Statement (A) is correct: B. linens is a Gram-positive, strictly aerobic, mesophilic, rod-shaped non-sporing coryneform bacterium.
• Statement (B) is correct: it synthesizes orange-yellow carotenoids on the cheese smear, with pigment production markedly stimulated by light.
• Statement (C) is incorrect: B. linens is non-fermentative and cannot ferment lactose or use it as an energy source; it relies on deacidification of the rind by yeasts (Debaryomyces hansenii) to grow.
• Statement (D) is correct: it secretes potent extracellular proteinases and peptidases that hydrolyze casein to produce volatile sulphur compounds (methanethiol), imparting characteristic aroma.

Correlation of milk quality control tests with analytes:

• Walker Formal titration is used for rapid volumetric estimation of casein (IV) and total protein in milk.
• Horrall and Elliker test is a standard starter culture (I) activity test evaluating lactic acid production rate.
• Dye modification test evaluates starter inhibition or bacteriophage (II) infection in starter cultures.
• Charm test (Charm II / ROSA) is an established rapid receptor assay used for the screening of antibiotic (III) residues in milk.

Food additive categorization in cheese manufacture:

• Statement (I) is incorrect: under Codex and FSSAI standards, whey protein and sodium chloride are classified as raw ingredients or seasonings, not functional food additives permitted at GMP level.
• Statement (II) is correct: additives such as annatto (colour, max limits apply), sorbic acid/sorbates (preservative, max $1000\text{--}2000\text{ ppm}$), nitrates (max $50\text{ ppm}$ in Gouda/Edam), nisin (max $12.5\text{ mg/kg}$), and calcium chloride (max $200\text{ mg/kg}$ milk) have strictly prescribed legal maximum limits.
• Thus, Statement (I) is incorrect and Statement (II) is correct.
• Therefore, option 4 is the correct answer.