Food Science and Nutrition
Food Science and Nutrition tests nutrient classification, energy calculation, balanced diets, cooking losses and deficiency conditions. Questions often ask candidates to interpret a meal or correct a food myth rather than simply list vitamins.
Nutrients and energy
- Macronutrients are carbohydrates, proteins and fats. Micronutrients are vitamins and minerals. Water and fibre are also essential.
- Energy factors: carbohydrate 4 kcal/g, protein 4 kcal/g, fat 9 kcal/g. Alcohol gives about 7 kcal/g but is not a nutrient.
- A balanced diet supplies energy and nutrients from varied food groups, appropriate to age, sex, activity and physiological state.
Cooking losses and deficiency
- Vitamin C is heat- and oxygen-sensitive; cut vegetables just before cooking, use minimal water, cover and avoid long holding.
- B vitamins leach into cooking water; use that water in gravies where safe.
- Fat-soluble vitamins A, D, E and K need fat for absorption. Deficiency examples: vitamin A and night blindness, vitamin D and rickets, iron and anaemia, iodine and goitre.
Worked example
A portion contains 60 g carbohydrate, 20 g protein and 10 g fat. Energy = (60×4)+(20×4)+(10×9)=240+80+90=410 kcal. Protein contributes 80 kcal, or 19.5% of energy. Reasoning: multiply each gram figure by its own factor, then divide the nutrient's kcal by total kcal for percentage.
Traps
- Using 9 kcal/g for protein or 4 kcal/g for fat.
- Treating brown sugar or honey as micronutrient-rich healthy alternatives; they are mainly sugars.
- Ignoring portion size when comparing nutrient labels.
- Assuming boiling always destroys all vitamins; loss depends on time, temperature, surface area and water.