Regulatory standards for irradiation sterilization of packaging materials:

• Under the statutory provisions of FSSR (2011) and AERB guidelines for radiation processing, sterilization of food packaging materials requires an absorbed radiation dose with a minimum of $10\text{ kGy}$ and a maximum of $25\text{ kGy}$ to achieve complete commercial sterility (destroying high-resistance bacterial endospores).
• $5\text{ to } 10\text{ kGy}$ is applied for microbial decontamination/radicidation of spices, not package sterilization.
• $0.25\text{ to } 1.0\text{ kGy}$ is used for sprout inhibition in onions and potatoes.
• $1.0\text{ to } 5.0\text{ kGy}$ is used for insect disinfestation and shelf-life extension of fruits.

In modern liquid milk processing plant lines, unit operations follow a logical sequence:

• Clarification (B): Centrifugal removal of extraneous dirt, somatic cells, and leucocytes from raw milk.
• Separation (A): Centrifugal partitioning of milk into skim milk and high-fat cream.
• Standardisation (C): Blending calculated proportions of skim milk and cream to adjust fat and SNF to legal requirements (e.g. Toned, Double Toned, Full Cream).
• Homogenization (D): Mechanical reduction of fat globule size ($\lt 2\,\mu\text{m}$) under high pressure to prevent creaming.
• Pasteurisation (E): Heat treatment ($72^\circ\text{C}$ for $15\text{ s}$) to destroy pathogens and ensure safety.

Calculation of Casein to Fat (C/F) ratio from Formol titration:

• In the Pyne formol titration method for rapid estimation of casein in milk using $10\text{ ml}$ of milk neutralized to phenolphthalein (1st titration) followed by addition of formalin ($40\%$ formaldehyde) and titration with $0.1\text{ N NaOH}$ (2nd titration):
  $\text{Casein }\% = \text{Formol titer (ml)} \times 3.2$.
• Here, the net formol titration reading (2nd titration) $= 0.65\text{ ml}$.
• Percentage of Casein ($C$) $= 0.65 \times 3.2 = 2.08\%$.
• Fat percentage ($F$) from butyrometer $= 3.6\%$.
• The Casein to Fat ratio:
  $\text{C/F ratio} = \frac{\%\text{ Casein}}{\%\text{ Fat}} = \frac{2.08}{3.6} = 0.5777... \approx 0.58$.
  
  Option analysis:
• 0.63: Incorrect.
• 0.56: Incorrect.
• 0.60: Incorrect.
• 0.58: Correct. Calculated C/F ratio is $2.08 / 3.6 = 0.578 \approx 0.58$.

Raw cow milk naturally contains inherent antimicrobial/protective factors such as lactoferrin (iron chelator), lysozyme (cell wall lysis), immunoglobulins (especially IgG1), and lactoperoxidase. Haemagglutinin (phytohaemagglutinin) is a plant lectin (found in legumes like raw kidney beans) and is not an inherent protective factor of bovine milk.

Option analysis:

• Lactoferrin: Inherent antimicrobial glycoprotein in milk that binds iron.
• Haemagglutinin: Correct, it is a plant-derived toxic lectin, not a milk constituent.
• IgG: Major protective immunoglobulin naturally present in bovine colostrum and milk.
• Lysozyme: Natural antibacterial enzyme present in milk that hydrolyzes peptidoglycan.