JC Home Economics flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Basal metabolic rate

The energy, in kilocalories or kilojoules, the body uses at complete rest to maintain breathing, heartbeat, body temperature and cell activity; roughly 60–70% of daily energy needs.

Indispensable amino acids

Nine amino acids the adult body cannot make in sufficient amounts, so they must come from food: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.

Complementary protein pairing

Combining a cereal low in lysine with a legume rich in lysine, such as rice and beans or maize and groundnuts, so the mixed meal supplies all the essential amino acids.

Soluble fibre

Fibre that dissolves or swells in water, found in oats, barley, legumes, apples and citrus; it slows glucose absorption and binds bile acids, helping to lower blood LDL cholesterol.

Fat-soluble vitamins

Vitamins A, D, E and K, absorbed with dietary fat, transported in lymph and stored mainly in the liver and adipose tissue; excess intake can accumulate and become toxic.

Scurvy

Deficiency disease caused by lack of vitamin C (ascorbic acid); it impairs collagen synthesis, causing bleeding gums, loose teeth, poor wound healing, bruising and joint pain.

Glycaemic index

A 0–100 ranking of carbohydrate foods by how quickly they raise blood glucose compared with glucose or white bread; 55 or below is low, 70 or above is high.

Essential fatty acids

Linoleic acid (omega-6) and alpha-linolenic acid (omega-3), which the body cannot synthesise and must obtain from foods such as vegetable oils, nuts and oily fish.

Haem and non-haem iron

Haem iron comes from animal foods such as red meat and is well absorbed; non-haem iron comes from plants and eggs and is absorbed better when eaten with vitamin C.

Energy values of macronutrients

Protein and carbohydrate supply about 4 kcal per gram (17 kJ), fat supplies 9 kcal per gram (37 kJ), alcohol 7 kcal per gram, and water, minerals and vitamins supply none.

Iron deficiency anaemia

A condition where low iron stores reduce haemoglobin, so blood carries less oxygen; signs include tiredness, pale skin, breathlessness on exertion and poor concentration, especially in menstruating women.

Temperature danger zone

The range 5°C to 60°C in which food-poisoning bacteria multiply most rapidly; keep hot food above 60°C and cold food below 5°C, and limit time in this range.

Convection heat transfer

Heat carried by moving currents in a fluid or air, as when hot water rises in a saucepan or a fan oven circulates hot air around food for even cooking.

Gelatinisation

When starch granules heated with water absorb liquid, swell and burst, releasing starch that thickens the mixture; it happens roughly between 60°C and 80°C and thickens sauces and custards.

Maillard reaction

Browning that occurs above about 140°C when amino acids and reducing sugars react, giving brown crusts and savoury flavours to toasted bread, roasted meat and baked goods.

Roux

A thickener made by cooking equal weights of fat and plain flour together; white roux cooks 2–3 minutes, brown roux longer, and milk added to white roux makes béchamel sauce.

Emulsifying agent

A substance with molecules that attract both water and fat, holding droplets of one dispersed in the other; egg-yolk lecithin stabilises mayonnaise, and mustard helps vinaigrette.

Gluten

An elastic protein network formed when wheat flour is mixed with water and kneaded; glutenin gives strength and gliadin gives stretch, so more kneading makes bread chewier.

Protein coagulation

The setting of protein when heated, as egg white firms at 60–65°C and meat fibres shrink; overcooking squeezes out water, making food dry and tough.

Blanching

Briefly immersing food in boiling water then cooling it rapidly in iced water; it loosens skins, sets colour, reduces enzymes before freezing and pre-cooks vegetables for later finishing.

Cross-contamination

Transfer of harmful bacteria from raw food, hands, boards or utensils to ready-to-eat food; prevent it by using separate colour-coded boards and washing hands and surfaces.

Caramelisation

Dry heating of sugar until it melts and browns, producing new colours and flavours; it begins around 160°C and is used for caramel, toffee and golden syrups.

Opportunity cost

The value of the next best alternative given up when a household spends money or time on one choice, such as buying a phone instead of saving for school fees.

Unit price

The cost of a product divided by its quantity, for example price per kilogram or per 100 grams; comparing unit prices in the same units shows which pack is better value.

Waste hierarchy

An order of preference for managing waste: prevent, reduce, reuse, recycle, recover energy, then dispose; the higher options save the most resources and energy.

Food miles

The distance food travels from where it is grown or processed to where it is eaten; buying local and seasonal produce generally lowers the transport fuel and emissions involved.

Composting

Controlled rotting of fruit and vegetable scraps, garden waste and paper into humus-rich compost; it diverts waste from landfill and returns nutrients to the soil.

Consumer redress

A buyer's right to a remedy when goods are faulty or unsafe, such as repair, replacement, refund or compensation; it usually requires a receipt or proof of purchase.

Ingredient list order

Food labels list ingredients in descending order by weight at the time of manufacture, so an ingredient listed first is the largest component; additives appear by name or E number.

Greywater

Relatively clean wastewater from baths, showers, hand basins and washing machines, which can be reused for flushing toilets or watering gardens after suitable treatment and care.

Preservation by pickling

Preserving food in acid, usually vinegar, sometimes with salt or sugar; low pH stops most spoilage bacteria and moulds growing, as with pickled cucumbers, onions and beetroot.

Needs and wants

Needs are essentials for survival and health such as food, shelter and clothing; wants are desirable extras such as entertainment or branded items, and a budget should cover needs first.