starch properties

flavour

white powder not sweet in flavour

base ingredient used to carry other flavours

bread

Solubility

insoluble in cold wtaer

must be blended well before using as a thickening agent

roux sauces

Hygroscopic

starch absorbs moisture in the air eg biscuits soften when not kept airtight

starch in cake help keep texture moist

hydrolysis

chemical breakdown of a molecule by adding water to produce a smaller molecule

polysaccharides breakdown to disaccharides which breakdown into monosaccharides

occurs during digestion

dextrinisation

starch heated under dry heat break down into shorter chains dextrins

further heating, dextrins form longer chains and become a brown coloured substance called pyrodextrins, give food an attractive brown colour and a sweet ‘toasted’ flavour

toast

gelatinisation

starch heated in the presence of water, starch grains swell, burst and absorb liquid resulting in thickening of liquid

as temperature rises, mixture becomes even more viscous, forming a sol ( contains particles that are not fully dissolved but evenly dispered throughout the liquid)

on cooling, becomes gel as water molecules are trapped

roux sauce