Maharashtra HSC Food Science and Technology key terms

The ratio of the vapour pressure of water in a food to that of pure water at the same temperature. It measures water available for microbial growth and chemical reactions rather than total moisture content.

The total amount of water present in a food, usually expressed as a percentage of its mass. It is measured by oven drying or similar methods and differs from the fraction of that water that is chemically available.

A food formulated to a water activity of roughly 0.60 to 0.85 by adding humectants such as sugar or salt, so it stays soft and shelf-stable without refrigeration. Examples include jams, jellies and some traditional sweets.

The process in which starch granules heated in water absorb moisture, swell and lose their crystalline order, thickening the mixture. On cooling, the released amylose can reassociate and set into a gel.

The slow reassociation of starch molecules, mainly amylose, into ordered crystalline regions after a cooked starch paste cools and is stored. It causes staling of bread and syneresis in gels.

The breakdown of starch into shorter chains called dextrins by dry heat or mild acid, producing browning and toasted flavours. It occurs on the surface of bread during toasting and in baked crusts.

A non-enzymatic browning reaction between reducing sugars and amino groups of proteins that produces brown pigments and aroma compounds. It develops colour and flavour in baking, roasting and frying, and can reduce protein quality.

The thermal decomposition of sugars when heated strongly without proteins, giving brown colour and characteristic caramel flavour. It begins at different temperatures depending on the sugar and is used in confectionery and syrups.

An amino acid the human body cannot synthesise in adequate amounts and must obtain from food, such as lysine, methionine and tryptophan. Cereals are typically low in lysine while pulses are low in methionine.

The essential amino acid present in the lowest proportion relative to body requirements in a given protein, so it restricts how well the whole protein can be used. It is the first nutrient to fall short in that food.

The proportion of nitrogen in a food protein that is absorbed from the digestive tract. It is high for animal proteins and lower for plant proteins, and it is combined with amino acid score in quality ratings.

The development of unpleasant odours and flavours in fats, caused by hydrolysis releasing free fatty acids or by oxidation of unsaturated fatty acids. It is accelerated by light, heat, oxygen and trace metals.

A measure of the concentration of peroxides formed during the early stages of fat oxidation, usually expressed as milliequivalents of active oxygen per kilogram of fat. It is a standard indicator of oxidative rancidity.

The number of grams of iodine that react with 100 grams of a fat, indicating the degree of unsaturation of its fatty acids. A higher value means more double bonds and a more liquid, oxidisable oil.

The addition of hydrogen to unsaturated fatty acids in the presence of a catalyst, raising the melting point of oils to make vanaspati and shortening. Partial hydrogenation can generate trans fatty acids.

A vitamin that dissolves in water and is not stored in the body in large amounts, so regular intake is needed. The group includes the B-complex vitamins and vitamin C, and many are lost during washing and cooking.

A vitamin soluble in fats and absorbed with dietary fat, stored mainly in the liver and adipose tissue. Vitamins A, D, E and K belong to this group and are sensitive to oxidation but stable to ordinary cooking losses.

The loss of water-soluble nutrients such as vitamin C and B vitamins into cooking water when foods are washed, soaked or boiled. It can be reduced by cutting vegetables large, using less water and reusing cooking liquid.

A substance added to food to help it retain moisture and reduce water activity, such as glycerol, sorbitol or sugar. Humectants keep products soft and extend shelf life by limiting microbial growth.

A substance that slows oxidation of fats, vitamins or pigments by reacting with free radicals or oxygen. Natural examples are tocopherols and ascorbic acid; synthetic ones include BHA and BHT.

A substance intentionally added in small amounts to food for a technological purpose such as preservation, colouring, emulsifying or improving texture. Its use is regulated, and it must not be used to disguise poor quality or spoilage.

A surface-active molecule with both water-loving and fat-loving parts that helps two immiscible liquids such as oil and water stay mixed. Lecithin and mono- and diglycerides are common food emulsifiers.

The deliberate addition of inferior, cheap or harmful substances to food, or the removal of valuable components, to increase profit. Examples include starch in milk powder and coloured sawdust in spices.

A microorganism that causes illness in humans, such as Salmonella, Listeria and Staphylococcus aureus. Pathogens may not change the appearance, smell or taste of food, so control depends on process and hygiene measures.

A microorganism that makes food unfit to eat by producing off-odours, slime, gas or discolouration, without necessarily causing disease. Bacteria, yeasts and moulds cause spoilage, and their type depends on storage conditions.

The time needed at a given temperature to reduce a microbial population by 90 percent, or one log cycle. It is used to design heat processes and compare the heat resistance of different microorganisms.

The use of controlled heat such as pasteurisation, sterilisation or blanching to inactivate microorganisms and enzymes in food. The time and temperature chosen depend on the product's pH, texture and intended shelf life.

A heat process that destroys all microorganisms capable of growing in a food under normal storage, including heat-resistant spores. Commercial sterilisation, as in canning, aims for shelf stability rather than absolute sterility.

A short heat treatment, usually in hot water or steam, applied to fruits and vegetables before freezing or drying. It inactivates enzymes, fixes colour and removes tissue gases but causes some leaching of nutrients.

Drying in which food is frozen and water is removed as vapour by sublimation under low pressure. It preserves shape, colour and nutrients well and gives a porous product that rehydrates quickly, but the process is costly.

The period during which a stored food keeps acceptable safety, quality and nutritional value under stated conditions. It is set by product formulation, processing, packaging and storage, and is confirmed by storage trials.

The first principle of HACCP, in which biological, chemical and physical hazards associated with each processing step are identified and their significance assessed. It forms the basis for setting critical control points.

A step in food processing where a control measure can be applied to prevent, eliminate or reduce a significant hazard to an acceptable level. Each CCP has defined critical limits and monitoring procedures.

The condition in which food is free from hazards that could harm the consumer when prepared and eaten as intended. It is ensured through good hygiene, process control, and adherence to standards and regulations.

The set of documented practices covering premises, equipment, personnel hygiene and process control that a food business must follow to produce safe, consistent food. GMP underpins HACCP systems and audits.

The scientific measurement of how food is perceived through sight, smell, taste, touch and hearing, using trained or consumer panels. Tests may be difference, descriptive or hedonic, and results guide product development and quality control.

A rating scale, often from 1 to 9, on which panellists state how much they like or dislike a product. It measures consumer preference rather than detecting small differences between samples.

Packaging in which the air around the food is replaced by a controlled gas mixture, typically carbon dioxide, nitrogen and reduced oxygen. It slows respiration and microbial growth and extends the shelf life of fresh produce and meats.

The structured process of creating a new or improved food from concept and market research through formulation, testing, packaging and launch. It balances consumer needs with cost, safety, regulation and production capability.

The separation of liquid from a gel or curd, such as whey leaking from curd or water weeping from a jam. It results from retrogradation, freezing damage or excessive mechanical stress on the gel network.