TASC Food and Nutrition Level 3 cheat sheet

Macronutrients supply energy: carbohydrate and protein each yield 4 kcal/g, fat yields 9 kcal/g, and alcohol yields 7 kcal/g.

Energy contribution (%) of a nutrient = (kcal from that nutrient ÷ total kcal) × 100; label claims such as "low fat" are defined per 100 g or 100 mL.

Protein is built from amino acids joined by peptide bonds; nine amino acids are indispensable for adults, and limiting amino acids determine protein quality.

Complementary proteins pair low-lysine cereals with high-lysine pulses to supply a complete indispensable amino acid profile in one meal.

Fatty acids are classified as saturated (no double bonds), monounsaturated (one), or polyunsaturated (two or more); trans fats arise from partial hydrogenation.

Carbohydrate classification: monosaccharides (glucose, fructose), disaccharides (sucrose, lactose, maltose), polysaccharides (starch, glycogen, fibre).

Fat-soluble vitamins A, D, E and K require dietary fat for absorption and are stored in the liver and adipose tissue; water-soluble vitamins are excreted more readily.

Key micronutrient functions: vitamin C supports collagen synthesis, calcium and vitamin D maintain bone mineral density, iron carries oxygen in haemoglobin, iodine supports thyroid hormones.

The Eatwell-style balance rule: base meals on starchy carbohydrate, include 5 portions of fruit and vegetables daily, favour unsaturated oils, and limit free sugars, salt and saturated fat.

Study designs ranked by strength of causal evidence: systematic review and meta-analysis > randomised controlled trial > cohort > case-control > cross-sectional > case report.

Validity types: internal validity concerns whether the design supports the claimed cause; external validity concerns generalisability to other populations and settings.

Reliability means repeated measurement gives consistent results; a valid method must be reliable, but a reliable method can still be invalid.

Sampling decision rule: random or stratified sampling supports inference to a population; convenience sampling permits description of the sample only.

Bias categories to screen for: selection, measurement, recall, observer and publication bias; confounding occurs when a third variable links exposure and outcome.

A 24-hour recall captures recent intake with low respondent burden but depends on memory; a weighed food diary is more precise but risks reactivity and under-reporting.

Food frequency questionnaires estimate habitual intake over weeks or months and suit large cohorts, but portion size is imprecise and quantification is limited.

Correlation does not establish causation; Bradford Hill considerations (temporality, dose-response, consistency, plausibility) strengthen causal inference.

Referencing rule: record author, year, title, source and access date for every source, and distinguish peer-reviewed evidence from commercial or anecdotal claims.

Cooking methods by heat transfer: moist (boiling, steaming, poaching), dry (baking, roasting, grilling), fat-based (frying, sautéing), and microwave.

Water-soluble vitamin losses rise with longer cooking time, greater surface area, and leaching into cooking water; steaming minimises leaching compared with boiling.

Maillard browning occurs between reducing sugars and amino acids above roughly 140 °C; caramelisation involves sugars alone at high heat.

Gelatinisation: starch granules absorb water and swell on heating, then thicken a mixture; cooling and ageing cause retrogradation and staling.

Gluten forms when wheat flour is hydrated and kneaded; gluten-free baking requires hydrocolloids such as xanthan gum to mimic structure.

Emulsions combine immiscible fat and water; an emulsifier such as lecithin lowers interfacial tension, and homogenisation reduces droplet size for stability.

Food safety control: keep high-risk foods out of the 5–63 °C danger zone, cook poultry to at least 74 °C, and chill rapidly to below 5 °C.

Cross-contamination control uses colour-coded boards, separate raw and ready-to-eat storage, and hand washing; HACCP identifies critical control points.

Standard recipe costing: portion cost = total ingredient cost ÷ number of portions; food cost percentage = (food cost ÷ selling price) × 100.

Front-of-pack traffic-light thresholds are set per 100 g (solid) or 100 mL (liquid); low, medium and high bands apply to fat, saturated fat, sugars and salt.

Per-portion comparison rule: compare products using the same basis (per 100 g or per serving) because portion sizes differ between brands.

Nutrition labelling decision rule: the ingredient list is ordered by descending weight, so a sugar listed first indicates a sugar-dominant product.

Cost-effectiveness measure: cost per 100 kcal or cost per portion of key nutrients allows comparison of nutrient density against price.

Dietary reference values: RNI covers about 97.5% of a population group, EAR meets the needs of half the group, and LRNI is adequate for only a small minority.

Allergen decision rule: 14 major allergens must be declared and emphasised in the ingredient list; "may contain" statements flag cross-contamination risk, not an ingredient.

Sustainability criteria for food choice include greenhouse gas emissions per kilogram, water use, seasonality, food miles, packaging and waste.

Sensory evaluation methods: paired comparison for preference between two samples, triangle test for detectable difference, and hedonic scales for acceptability.

Ethical and marketing considerations: health claims require substantiation, and promotions of high fat, sugar or salt foods to children are restricted in many jurisdictions.