Presentation on theme: "Functional properties of food Food designers need to understand the properties of foods when they are designing new dishes, to make sure they match the."— Presentation transcript:
Functional properties of food Food designers need to understand the properties of foods when they are designing new dishes, to make sure they match the product profile.
Solutions Examples of a solution are Fruit juices Sugar and water syrups Salt and water brine A solution is formed when A liquid is dissolved in another liquid, for example fruit squash in water A solid is dissolved in a liquid like sugar in a cup of tea. Solutions will not separate when left to stand.
Suspensions A suspension forms when solid particles are added to liquid but do not dissolve Starch particles such as flour do not dissolve in a liquid but they form a suspension. If the suspension is not agitated the solid particles fall to the bottom. One example is when a sauce pan is not stirred when heated and lumps form at the bottom of the pan.
Gels A gel is a solid jelly-like substance. Gels are mostly liquid but behave like a solid due to the gelling agent holding the liquid in place. Gels form when starch is heated in a liquid and cooled(gelatinisation). Examples include White sauce Lemon meringue pie filling Jam Flan glaze
Smart starches Manufacturers use a large number of starches which have been altered to change their working properties. These are known a modified starches or smart starches. Some modified starches are pre- gelatinised. This allows them to thicken instantly such as cup a soups or pot noodles Some modified starches allow sauces to be reheated with no synerisis Some modified starches are not affected by acidity so can be used to thicken salad dressings.
Emulsions Liquids that will not mix together are immiscible such as oils and water. When shaken together they form an unstable emulsion which separates if left standing. A mixture only remains stable if an emulsifier is used. Lecithin in egg yolk is an emulsifier. Egg yolk is used in the preparation of mayonnaise where it holds oil and vinegar together. It helps the fat in the cake mix with the egg white.
Foams Foams are gas mixed into a liquid giving a light texture like in ice cream. Meringues are a foam made by whisking air (gas) into egg white (liquid). When you bake then the air expands and the egg white coagulates to give a solid structure.
Elasticity Wheat contains two proteins glutenin and gliadin. When water is added to wheat flour they form gluten. Gluten is very stretchy or elastic it allows food made from wheat flour such as bread and cakes to rise.
Plasticity Plasticity describes how fats change shape under pressure such as rubbing in or spreading You can easily rub in Soft margarine Butter Lard Oil cannot be easily rubbed in Plasticity allows fat to coat each flour particle in rubbed in products like short crust pastry or shortbread.
Shortening Fats make cakes and biscuits crumbly and melt in the mouth by forming a coating around the starch and protein molecules in the flour. This stops the liquid coming into contact with the flour and helps stop gluten forming. Any gluten that does form is in short lengths not the long elastic strands found in bread. These short gluten strands give us the term shortening.