Food Science and Technology Lecture Notes

Flashcards about food science, food technology, food composition, food additives, and enzymes.

Food Science

A multidisciplinary subject involving primarily bacteriology, chemistry and engineering; deals with the nature of food materials and principles underlying their spoilage, preservation and modification.

Food Technology (Processing)

Application of physics, chemistry and engineering to transform food for purposes of preservation or for convenience.

Food Safety

The causes, prevention and communication dealing with foodborne illness.

Food Microbiology

The positive and negative interactions between micro-organisms and foods.

Food Preservation

The causes and prevention of quality degradation in food.

Food Engineering

The industrial processes used to manufacture food.

Product Development

The invention of new food products.

Sensory Analysis

The study of how food is perceived by the consumer's senses.

Food Chemistry

The molecular composition of food and the involvement of these molecules in chemical reactions.

Food Packaging

The study of how packaging is used to preserve food after it has been processed and contain it through distribution.

Food Physics

The physical aspects of foods such as viscosity, creaminess, and texture.

Perishable food products

Have water content above 50% and include fresh fruits, vegetables, meat and milk.

Stable food products

Have water content less than 50% and include dried intact grains and other dried products.

Preservation of food quality

Safety, nutritional value, flavor and other organoleptic qualities, and ease of preparation.

Processing for convenience

Fruits processed to beverages, wheat processed to bread and other baked goods, and barley processed to beer.

Minimally processed foods

Leafy vegetables sorted, washed, cut and packaged; meat cut and packaged; fruits washed, peeled, cut and packaged.

Main groups of constituents in food

Carbohydrates, fats, and proteins.

Four chemical groupings of carbohydrates

Monosaccharides, disaccharides, oligosaccharides, and polysaccharides.

Reducing sugars

Sugars that contain a free carbonyl group and give brown colors to baked goods when they combine with free amino acid groups in a browning reaction.

Caramelization

Sugars caramelize on heating giving a brown colour; caused by decomposition of the sugars and occurs at extremely high temperatures.

Sugar alcohols

Reduction of the carbonyl group to a hydroxyl group gives sugar alcohols such as xylitol, sorbitol and mannitol; sweet, not fermented as readily, and so they are noncariogenic

Properties of lipids

Aerate batters and doughs, contribute flakiness, contribute tenderness, emulsify, transfer heat, provide satiety, prevent sticking, and provide flavor.

Building blocks of proteins

Each amino acid has a carboxyl group COOH, an amino group (NH2), a hydrogen atom, and an amino acid radical -R-.

Four types of structures proteins have

Primary, secondary, tertiary and quaternary structure.

Amphoteric (proteins)

Able to act as an acid or a base, depending on the pH.

Isoelectric point

The pH at which the protein is electrically neutral.

Denaturation of proteins

Breakdown of the quaternary, tertiary and secondary structure of protein as a result of heat, pH change, ionic strength change (salt concentrations), freezing and surface changes.

Enzymes

Proteins formed by the body that act as organic catalysts that speed up desired chemical reactions.

Three groups of enzymes

Metabolic enzymes, digestive enzymes, and food enzymes.

Categories of food enzymes

Lipase, lactase, protease, amylase, cellulase

Competitive inhibition

If an inhibitor molecule binds to the same active site as the substrate.

Allosteric or non-competitive inhibition

If, however, the inhibitor binds to a site on the enzyme other than the active site

Molecular weight (enzymes)

Enzymatic proteins are substances of high molecular weight.

Amphoteric nature (enzymes)

Each molecule of enzyme possess numerous groups which yield Hydrogen ions in slightly alkaline solutions and groups which yield OH ions in slightly acidic solutions.

Specificity of enzymes

Enzymes are highly specific in nature i. e., a particular enzyme can catalyze only a particular type of reaction

Heat sensitivity (enzymes)

Enzymes are inactivated or destroyed at temperatures considerably below the boiling point of water

Reversibility of reaction (enzymes)

Enzymes have been found to accelerate the chemical reaction in either direction.

Enzymatic browning

A chemical process which occurs in fruits and vegetables by the enzyme polyphenol oxidase which results in brown pigments

Uses of enzymes

Meat tenderizing, making of cheese, development of cheese flavours and development of lactose free product

Food additive

Any substance or a mixture of substances other than the basic foodstuff which is present in food as a result of any aspect of production, processing, storage or packaging

Functions of food additives

Maintaining product consistency, improving or maintaining nutritive value and maintaining palatability and wholesomeness.

Broad classes of food additives

Direct food additives and indirect food additives.

Antioxidants

Chemical additive which when added to food retards or prevents oxidative deterioration of food e.g. lecithin, ascorbic acid, tocopherol.

Preservatives

Substances added to food to retard, inhibit or arrest the activity of microorganisms.

Food colours

Substances used to correct loss of colour due to food processing or to correct natural variations in food colour.

Flavouing agents

Add flavour or correct losses in flavour.

Emulsifying and stabilizing agents

Substances capable of facilitating a uniform dispersion of oils and fats in aqueous media or vice versa and / or stabalizing such emulsions

Sweetening agents

Include calorie sweeteners, low-calorie sweeteners and non-calorie sweeteners

Anti-caking agents

Anhydrous substances that can pick up moisture without themselves becoming wet and these are added to products such as table salt and dry mixes.

Sequesterants

Substances that form a complex with transition metal ions like copper, iron, cobalt and nickel.

Buffering agents

Materials used to counter acidic and alkaline changes during storage or processing of food, thus improving flavour and increasing stability of foods

Anti- foaming agents

Reduce foaming on heating, slow down deteriorative changes e.g. dimethyl polysiloxane in edible oils and fats for deep-fat frying.

Enzymes (food additives)

Mainly used in industry to split carbohydrates, proteins, lipids, used in cheese, bread production, tenderizing meat.

Leavening agents

Introduction of gas in batter or dough leading to its expansion, improves appearance, texture and taste of foods.