Food Science: Cooking Principles, Sensory Quality and Preservation
What the exam tests
Food Science tests the principles behind cooking, sensory quality and preservation: why foods set, brown, spoil or keep.
Core rules
- Gelatinization: starch granules absorb water and swell on heating (rice, custard). Gelation is the setting of a gel (jam, jelly).
- Caramelization = sugar alone browns; Maillard browning = sugar + protein + heat (bread crust, toast).
- Coagulation: protein sets (egg, paneer). Emulsification: oil and water are held by an emulsifier (milk, mayonnaise).
- Fermentation uses microorganisms (curd, idli, bread). Osmosis moves water across a membrane (salting vegetables).
- Leavening agents: air, steam, yeast/CO2, baking soda or powder.
- Preservation controls microbial growth and enzyme action: heat (canning), cold, drying, irradiation, chemicals, fermentation.
- Sensory evaluation: appearance, aroma, taste, texture and overall acceptability.
Worked example
Why does a slice of bread become brown and crisp on toasting, while sugar heated alone also browns? Reasoning: toast browns mainly by the Maillard reaction between amino acids and reducing sugars; table sugar alone undergoes caramelization. Crispness comes from water loss. If the question asks which reaction adds flavour compounds, Maillard is the better answer for bread; caramelization applies to sugar syrups.
Traps
- Using caramelization for bread crust.
- Confusing gelatinization (starch + water + heat) with gelation (set gel).
- Saying preservation “kills all microbes” when some methods only inhibit.
- Forgetting that prolonged cooking destroys vitamin C and thiamine.