Food Science

to make it safe to eat, improve its shelf life, develop flavours and improve texture

conduction, convection and radiation

the transfer of heat energy through vibration of particles

transfer of heat energy through gases or liquids

transfer of heat energy through waves of radiation

boiling, steaming, blanching, simmering and poaching

stir-frying, deep-frying, sweating and shallow frying

baking, grilling, roasting and dry frying

proteins denature (the chemical bonds holding their structure break down and the protein unravels); this can happen from physical agitation, interacting with an acid or heat

they coagulate; water is trapped between the protein molecules and the appearance and texture change (this happens when cooking eggs)

when liquids containing proteins become agitated the proteins denature and stretch; they trap air when they coagulate, creating a foam

molecules are coiled which allow them to stretch and bend; kneading a dough allows the gluten to get longer, stronger and more elastic

thickening of foods that have starch; when starch granules are heated with water, the bonds are broken and water enters, which increases their size and they soften: between 62-80 degrees the molecules burst and release their starch into the water, which causes the liquid to thicken

when starch molecules are broken down from exposure to dry heat; the starch molecules break down into small molecules called dextrins, which gives food a crisper and more brown appearance

where sugar molecules break down and turn brown with a change in flavour

incorporating air (e.g. creaming sugar and butter together for a sponge cake makes it fluffy and lighter in colour; this gives the cake a light texture)

when long gluten strands are prevented from forming (e.g. when fat is rubbed into flour, the flour particles are made waterproof and can’t stretch: this is done for piecrust, tarts and shortbread)

ability to stretch and be manipulated; this is possible because fats have different triglycerides that melt at different temperatures, so fat gradually melts over a range of temperatures (e.g. used for decorating cakes with buttercream and rubbing fat into flour)

when oily and watery liquids are shaken together; this is done in margarine as the water molecules bond to the hydrophillic (water attracted) side and the oil molecules bond to the hydrophobic (water repellent) side, which hold the water and oil in a stable emulsion

Chemical: bicarbonate of soda breaks down to produce carbon dioxide and baking soda is used to neutralise the soapy taste of bicarbonate
Biological: yeast is a microorganism that ferments and releases alcohol and carbon dioxide when left to prove

Steam: if a mixture contains a lot of liquid, water leaves the mixture as steam and allows the mixture to rise
Mechanical: air can be folded into mixtures or beat, whisked, sieved and creamed into a mixture