Choosing products: quality, labels and processing level
A product in the kitchen is any ingredient you buy. Before you buy, check three things.
Quality: look at colour, smell, firmness and freshness. Labels: read the date, the ingredients, and signs such as organic or origin marks. A label tells you where it comes from and how it was made. Level of processing: a whole tomato is raw. A chopped tomato is lightly processed. A tinned tomato is cooked and sealed. A ready sauce is fully processed.
More processing usually means longer life and less work for the cook, but less fresh taste and often more salt, sugar or oil. Choose the level that fits the dish and the time you have.
Buying rules, supply chains and seasons
A supply chain is the path from farm or factory to your kitchen: grower, trader, market, shop, cook. The shorter the chain, the fresher the food and the fewer hands it passes.
Purchasing rules for a kitchen: compare two or three suppliers, check the delivery temperature of cold food, check quantity against the order, store at once, and use older stock first (first in, first out).
Season means the months when a fruit or vegetable grows naturally in your area. In season it is plentiful, cheaper and tastier, and it travels less far. Out of season it may come from far away or from a cold store.
Recipe cards and portion sheets
A recipe card lists the dish name, ingredients with weights, steps, time and the number of portions. A portion sheet says how much one serving should be, so every plate looks the same and the cost is known.
To change the number of portions use one rule: amount per portion × new number of portions. Example: 150 g tomato per portion × 20 portions = 3,000 g. Salt, spice and cooking time do not always scale in a straight line, so taste again and check the time.
Cost per portion = total cost of ingredients ÷ number of portions.
Preliminary and base preparations
Preliminary preparation is everything before cooking: washing, peeling, cutting, weighing, soaking. Do it first and keep it tidy, because mistakes here show in the final dish.
Base preparations are building blocks used in many dishes.
Stock: water simmered with bones or vegetables so flavour moves into the water. Skim the foam, simmer gently and strain.
Sauce: a liquid thickened with starch, for example milk with a cooked paste of flour and fat. The starch grains swell and make it thick.
Dough: flour and water kneaded. Kneading builds gluten, a stretchy net that holds air from yeast so bread rises.
Cream: for example pastry cream, made from milk, egg yolk, sugar and starch. Gentle heat makes egg and starch set into a smooth custard. Stir well and do not boil too hard or it will curdle.
Sensory evaluation: tasting like a cook
Sensory evaluation means judging food with the senses in a fair way. Check four things: look (colour, shine, shape), smell (aroma), taste (sweet, salty, sour, bitter, umami) and texture (crisp, soft, creamy, tough).
Taste with a clean spoon, in small amounts, and compare with a note of what you wanted. Score each sense from 0 to 5 and write what to change. Water between tastings keeps your mouth fresh.
Try it: make a quick white sauce at home
With an adult: melt 1 spoon butter, stir in 1 spoon flour for one minute, then add 1 cup milk slowly while stirring. Watch it thicken. Add more flour next time to see a thicker sauce. Score the look, smell, taste and texture in the 3D.
Key formulas and definitions
- Scaled amount = amount per portion × number of portions
- Cost per portion = total ingredient cost ÷ number of portions
- Dough: about 5 parts flour to 3 parts water (bread-style) by weight
- Sensory score = look + smell + taste + texture (each 0 to 5, total 20)
Worked examples
1. A recipe uses 150 g tomato per portion. How much for 20 portions?
150 × 20 = 3,000 g = 3 kg.
2. Ingredients for 20 portions cost 600. What is the cost per portion?
600 ÷ 20 = 30 per portion.
3. A bread dough uses 500 g flour in the ratio 5 flour : 3 water. How much water?
One part = 500 ÷ 5 = 100 g, so water = 3 × 100 = 300 g.
4. A stock reduces from 2.5 litres to 1.5 litres. What fraction was lost?
Lost = 1 litre. Fraction = 1 ÷ 2.5 = 0.4 = 40 percent. It is more concentrated now.
Common mistakes
- Buying only by price and ignoring quality and date on the label.
- Multiplying spice and salt exactly when scaling a recipe without tasting again.
- Boiling a stock hard. Fast boiling makes it cloudy; keep it at a gentle simmer.
- Adding hot milk to flour paste all at once, which makes lumps. Add slowly and stir.