Properties And Functions Of Food

Properties and Functions of Food Thickening

Gelatinization - Starches thicken by absorbing water and swelling to many times their original size. Corn flour – often used in Asian cooking - It has twice the thickening power of wheat flour and it produces a clearer sauce. Arrowroot- starch extract of the root of a tropical plant native to the Americas called maranta. Arrowroot is used for thickening sauces, juices and syrups; when heated the starch turns to jelly and so thickens the liquid. A roux is a mixture of equal quantities of melted butter and flour that is cooked in a pan and used as the base for thickening sauces such as white sauce and béchamel. Pectin - A natural gelling agent found in ripe fruit. The main use for pectin is as a gelling agent, thickening agent and stabilizer in food. The classical application is giving the jelly-like consistency to jams or marmalades, which would otherwise be sweet juices.

Bulking

Some foods are used to make up the main part of a recipe and ‘bulk-it-out’. Flour is a good bulking agent for bread and pastry. Oats are used in muesli and oat cakes. Rice is the main bulk food in risottos; rice puddings, kedgeree; Asian dishes like byriani and fried rice.

Setting Food

Gelatin - A colourless, tasteless and odourless setting agent made from the boiled bones, skins and tendons of animals. When dissolved in boiling water and then cooled it turns into a jelly-like form that is used to thicken and stabilise desserts such as jelly, custard and fillings.

Gelatin

Gelatin is a pure, unique, nutritional protein providing many of the essential amino acids.

Gelatin is a hydrocolloid (water-loving) material, high in amino acids, and can absorb up to ten times its weight in water.

Gelatin is not chemically modified, nor produced from genetically modified materials—gelatin is entirely natural. In its solid dry state, gelatin is a vitreous, brittle, solid material, faintly yellow to honey-like in colour, with about 10% moisture content. When gelatin is ground to its commercial granular form, it is usually in particles the size of sand or sugar. Gelatin has an almost indefinite shelf life when properly stored Gelatin is derived from collagen, by partial hydrolysis. Collagen is present in three materials suitable for producing gelatin on a commercial scale. Collagen is the basic structure of all the skin, tendon, bone, membrane and connective tissue in our bodies and in the bodies of those creatures. Collagen is thus the structural protein of the animal kingdom and that of humans. It is to humankind and to animals to what cellulose is to plants.  pork skin,  cattle skin, and  bone. Probably best known as a gelling agent in cooking, different types and grades of gelatin are used in a wide range of food and non-food products: Common examples of foods that contain gelatin are gelatin desserts, trifles, aspic, marshmallows, and confectioneries such as Peeps and gummy bears. Gelatin may be used as a stabilizer, thickener, or texturizer in foods such as ice cream, jams, yogurt, cream cheese, and margarine; it is used, as well, in fat-reduced foods to simulate the mouthfeel of fat and to create volume without adding calories.

Sweetening

Sweeteners are added to foods for flavoring. Sweeteners other than sugar are added to keep the food energy (calories) low, or because they have beneficial effects for diabetes mellitus and tooth decay and diarrhea.

Emulsifying

Emulsifiers allow water and oils to remain mixed together in an emulsion, as in mayonnaise, ice cream, and homogenized milk. Other examples include include butter and margarine, cream, and vinaigrettes

Shortening

Shortening is a soft fat used in food preparation (usually hydrogenated vegetable oil that is solid at room temperature, and is so called because it promotes a "short" or crumbly texture (as in shortbread). The term "shortening" can be used more broadly to apply to any fat that is used for baking and which is solid at room temperature, such as butter, lard, or margarine, but as used in recipes it refers to a hydrogenated vegetable oil that is solid at room temperature. Shortening has a higher smoke point than butter and margarine, and it has 100% fat content, compared to about 80% for butter and margarine. Shortening works by inhibiting the formation of long protein (gluten) strands in wheat-based doughs.

Binding

Beefburgers, vegetables burgers, meatballs need binding together. Water and eggs can be used to bind ingredients together and the addition of flour will also help

Adding Flavour

Savoury dishes – salt, pepper, herbs and spices. Strong flavoured foods like bacon, garlic, onion, cheese and tomato are good for sauces. Sweet foods – chocolate, nuts and dried fruits. Cinnamon. Delicate flavours – vanilla, nutmeg,

Adding Colour

For food to be appetizing it needs to be colourful and attractive.

Adding

Examples are a crunchy salad to accompany a soft salad dish.

Examples are parsley for garnish, grated cheese or a cherry on top of a desert, tomatoes in a sauce, turmeric in curry, beetroot in a salad.

Peas or sweet corn will provide colour and texture to a rice dish.

Properties and Functions of Food Texture

Fresh fruit in a pudding or with cream, yoghurt, custard.

Aerating

Eggs are often used in cooking in order to incorporate air into a mixture and hold it there, as in soufflés, meringues and cake mixtures. This property of eggs is called aeration. When air is incorporated by whisking, whipping or beating, the air bubbles in the liquid become coated with protein; the molecules uncoil (denature) so that they extend and surround the globules of air to create and stabilise the foam.

Egg whites have good foaming properties as they contain a number of different proteins with the desired properties and perform best at a temperature of about 14°C. Traces of fat will inhibit foaming properties as fat is present in egg yolks, contamination with even small amounts of yolk has to be avoided for the best results.

Preserving

Preservatives prevent or inhibit spoilage of food due to fungi, bacteria and other microorganisms. Sugaring - the process of desiccating a food by first dehydrating it, then packing it with pure sugar. This

creates an environment hostile to microbial life and prevents food spoilage. Sugaring is commonly used to preserve fruits as well as vegetables such as ginger. A risk in sugaring is that sugar itself attracts moisture. Once a sufficient moisture level is reached, native yeast in the environment will come out of dormancy and begin to ferment the sugars into alcohol and carbon dioxide. Pickling - preserving food by anaerobic fermentation in brine to produce lactic acid, or marinating and storing it in an acid solution, usually vinegar (acetic acid). Salt

Question Use the keywords above to describe the properties of the ingredients in the following – a) Flapjacks made from oat flakes, sugar, golden syrup and butter. b) Dhal made from lentils, spices, garlic, onion and oil. c) Fruit bread made from flour, yeast, sugar, butter, dried fruits, eggs. d) Samosa made from flour, oil, spices, peas, potato, onion 1. Add to these examples by creating your own chart and describing the function of ingredients in your own practical work. 1.