Food Science & Technology Flashcards

Which thermal processing method uses superheated steam to sterilize low-acid canned foods?

Answer: Retort processing (autoclaving)

Retort processing uses steam under pressure at 121°C (250°F) to achieve commercial sterility in low-acid foods (pH > 4.6).

Transglutaminase is an enzyme used in food processing primarily to:

Answer: Cross-link proteins to improve texture

Transglutaminase catalyzes covalent cross-links between glutamine and lysine residues in proteins, improving texture and binding.

In food packaging, modified atmosphere packaging (MAP) commonly replaces oxygen with which gas to extend shelf life of fresh produce?

Answer: Carbon dioxide and nitrogen

MAP uses CO₂ to inhibit microbial growth and N₂ as an inert filler gas, reducing O₂ to slow oxidation and respiration.

The HLB (Hydrophilic-Lipophilic Balance) value of an emulsifier determines:

Answer: Whether it preferentially stabilizes oil-in-water or water-in-oil emulsions

High HLB values (8–18) favor oil-in-water emulsions, while low HLB values (3–6) favor water-in-oil emulsions.

Which spoilage mechanism is primarily responsible for rancidity in potato chips stored at ambient temperature?

Answer: Autoxidation (free radical lipid oxidation)

Potato chips have low moisture and no active lipases, so autoxidation—driven by oxygen, light, and trace metals—is the dominant rancidity pathway.

What is the primary function of calcium chloride when added to firming canned vegetables?

Answer: Cross-linking pectin to strengthen cell walls

Calcium ions cross-link free carboxyl groups in pectin molecules, forming a calcium pectate gel that maintains vegetable firmness.

During spray drying of a liquid food, the 'stickiness' problem of amorphous powders is most often resolved by:

Answer: Adding encapsulants or raising the glass transition temperature (Tg)

Raising Tg—by adding maltodextrin or other encapsulants—keeps amorphous particles below their stickiness threshold during drying.