ANWSER
Question 1:
Answer:
Starch functionality in food systems is governed by four key principles:
1. Gelatinization: Occurs when starch granules absorb water and swell upon heating, leading to viscosity increase. This process is critical in thickening agents (e.g., sauces, soups).
2. Gelation: As the gelatinized starch cools, hydrogen bonds reform between amylose molecules, forming a gel network (e.g., in puddings or pie fillings).
3. Pasting: Refers to the combined phenomena of gelatinization and subsequent breakdown of starch granules under shear and heat, influencing texture in products like bread and pasta.
4. Retrogradation: The recrystallization of amylose and amylopectin upon cooling/storage, leading to staling in baked goods. Retrogradation can be reversed by reheating (e.g., refreshing bread in an oven).
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Question 3:
Answer:
Hydrogenation is a chemical reaction where hydrogen atoms are added to unsaturated fatty acids in lipids, converting double bonds to single bonds. This process:
– Uses metal catalysts (e.g., nickel) under high pressure and temperature.
– Converts liquid oils into semi-solid fats (e.g., margarine), improving shelf life and thermal stability.
– May produce *trans fats* as a byproduct, which are linked to cardiovascular diseases.
– Enhances texture and melting properties in foods like shortenings and snacks but is now limited due to health concerns.
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Question 5:
Answer:
(a) Humectants: Substances that retain moisture in food (e.g., glycerol in baked goods, sorbitol in candies).
(b) Sequestrants: Chelate metal ions to prevent oxidation and discoloration (e.g., EDTA in canned foods, citric acid in beverages).
(c) Flavorings: Enhance or impart taste; include natural (vanilla extract) and artificial (ethyl vanillin) types.
(d) Antioxidants: Inhibit lipid oxidation, extending shelf life (e.g., vitamin E in oils, BHA in processed meats).
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Question 6:
Answer:
(a) Food additives: Substances added to food to preserve flavor, enhance texture, improve appearance, or extend shelf life.
(b) Uses of additives:
– Preservation (e.g., sodium benzoate).
– Flavor enhancement (e.g., MSG).
– Color retention (e.g., carotenoids).
– Nutritional fortification (e.g., vitamin D in milk).
(c) Basic principles:
– Safety: Must be GRAS (Generally Recognized As Safe).
– Necessity: Used only when no alternative exists.
– Regulatory compliance: Adherence to standards (e.g., FDA, Codex Alimentarius).
– No deception: Must not mislead consumers about food quality.
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