Kitchen safety and hygiene
Most food illness comes from bacteria. Follow the 4 Cs:
- Cleaning: wash hands for 20 seconds, wipe surfaces, tie hair back.
- Cross-contamination: keep raw meat away from ready-to-eat food. Use different boards (often red for raw meat, green for vegetables).
- Chilling: fridge at 0–5 °C.
- Cooking: heat food until the centre is at least 75 °C (check with a probe thermometer).
Between 5 °C and 63 °C is the danger zone: bacteria can double about every 20 minutes. Do not leave cooked food out for more than 2 hours.
Using equipment safely
Turn pan handles inwards, use oven gloves, keep the floor dry, and carry knives point down.
Knife skills and food preparation
Two safe grips: the claw (fingertips curled under, knuckles guide the blade) and the bridge (hand makes an arch over the food, cut under it).
Common cuts and terms:
- Slice: thin flat pieces. Dice: small even cubes. Chop: rough pieces. Julienne: thin matchsticks.
- Peel, grate, mince, marinate (soak in a flavoured mix), season (add salt, spices, herbs).
Even pieces matter: small pieces cook faster than big ones, so mixed sizes give some burnt and some raw.
How heat reaches food
- Conduction: heat passes from particle to particle by touch. Hob → pan → food. Metals conduct well; wooden spoons do not, so they are safe to hold.
- Convection: hot liquid or air rises, cooler sinks, making a current. Boiling water and fan ovens cook this way.
- Radiation: heat travels as infrared rays from a hot surface, with no contact. Grills, toasters and the walls of a tandoor.
Most methods use two or three at once: in an oven, the hot tin conducts, the air convects and the walls radiate.
Cooking methods: moist and dry
Moist methods use water or steam: boiling (100 °C, big bubbles), simmering (just below boiling, small bubbles), steaming (idli, momos), poaching, stewing and pressure cooking (about 120 °C, so faster). Food stays soft; water-soluble vitamins can leak into the water, so use less water or keep it for soup.
Dry methods use hot air, metal or oil: baking and roasting (160–220 °C), grilling, shallow frying, stir-frying and deep frying (about 170–190 °C). Above about 140 °C the surface browns (the Maillard reaction and caramelisation), giving colour and flavour. Frying adds fat.
Ingredients: source and seasonality
Ingredients are grown (cereals, fruit, vegetables), reared (meat, milk, eggs) or caught (fish). Seasonal food is harvested at its natural time: it tastes better, is cheaper and needs less heated greenhouses or long transport. Local, seasonal choices cut food miles. Examples: mangoes in summer, peas and carrots in winter in North India; strawberries in early summer in Europe.
Scaling recipes, cost and serving
Scale factor = new number of portions ÷ original portions. Multiply every ingredient by it. Cooking time changes less than amounts; check by colour and temperature.
Cost of a dish: for each ingredient, cost = (amount used ÷ pack size) × pack price. Add them up. Cost per portion = total ÷ number of portions.
Serving and table setting
Plate food neatly, wipe the rim, add a garnish. A simple setting: plate in the centre, fork on the left, knife (blade inward) and spoon on the right, glass above the knife, napkin on the left or on the plate.
Try it: the potato test
Cut one potato into 1 cm dice and another into 3 cm chunks. Boil both in the same pan. Test with a fork every 3 minutes. The small dice are soft first: even cutting really matters.
Key formulas and definitions
- Danger zone: 5 °C to 63 °C
- Safe core temperature: at least 75 °C
- Scale factor = new portions ÷ original portions
- Ingredient cost = (amount used ÷ pack size) × pack price
- Cost per portion = total cost ÷ number of portions
Worked examples
1. A recipe for 4 uses 300 g rice. How much rice for 10 people?
Scale factor = 10 ÷ 4 = 2.5. Rice = 300 × 2.5 = 750 g.
2. A 1 kg bag of lentils costs ₹120. A dish uses 250 g. Find the cost of the lentils.
Cost = (250 ÷ 1000) × 120 = 0.25 × 120 = ₹30.
3. A dish for 6 people costs ₹119 in total. Find the cost per portion.
119 ÷ 6 ≈ ₹19.83 per portion.
4. Which method suits a crisp, golden potato: boiling or roasting? Why?
Roasting. It is a dry method at about 200 °C, so the surface browns and crisps. Boiling stays at 100 °C, too cool for browning.
Common mistakes
- Using the same board for raw chicken and salad without washing it.
- Cutting pieces in mixed sizes, so some burn while others stay raw.
- Thinking you can boil food hotter by turning up the gas. Open boiling water stays at about 100 °C.
- Multiplying only some ingredients when scaling, or forgetting salt and spices.