Carbohydrates Flashcards
Monosaccharides
chemical formula
examples
source
C6H12O6
Fructose, glucose
Honey, fruit
Disaccharides
Chemical formula
examples
sources
C12H22O11
Lactose, sucrose
Milk, table sugar
Polysaccharides
Chemical formula
Examples
Sources
(C6H10O5)n
Starch, cellulose
Cereals, skins of fruit and vegetables
Effects of heat
Moist heat dissolves sugar, creating syrup
Dry heat causes sugar to caramelise
Maillard reaction
Hydrolysis
Disaccharides reacts with water
Broken down into simpler sugar
Enzymes can speed up reaction
Inversion
When sucrose reacts with water in the presence of an acid or enzyme it produces glucose and fructose
Crystallisation
When a liquid has dissolved as much sugar as it can and more is added
Reducing sugar
Sugar can remove oxygen from other substances
Assists aeration
Sugar denatures egg protein
Properties of sugar
Effects of heat Hydrolysis Inversion Crystallisation Reducing sugar Assists aeration
Properties of starch
Insoluble in cold water Uncooked is indigestible Hygroscopic Dextrinisation Gelatinisation Dry heat Gel formation Pectin extraction
Hygroscopic
The ability to absorb moisture from the air
Dextrinisation
Some foods containing starch also contain short chains of polysaccharides called dextrins
When heat is applied a brown compound called pyrodextrin is formed
Gelatinisation
When starch is combined with water and heated it swells, bursts and absorbs moisture
The mixture thickens
A temperature over 85C will create a sol, which can be used to thicken soups and sauces
Dry heat
Starch grains burst and absorb any fat
Gel formation
Pectin contains long chains of polysaccharides
When heated they form a 3D arrangement in which water becomes trapped
When the mixture cools down a gel is formed
Pectin extraction
Pectin in underripe fruit is called protopectin
It cannot absorb water
If an acid is added the protopectin is converted to pectin
Culinary uses of sugar
Sweetener Preservative Caramelisation Fermentation Gel formation Prevents discolouration of fruit
Culinary uses of starch
Thickener
Hygroscopic
Dextrinisation
Culinary uses of Non-starch polysaccharides
Gel formation
Cellulose gives a feeling of fullness
Functions of carbohydrates
Heat and energy Stored as an energy reserve Excess converted to fat Cellulose prevents bowel disorders Cellulose gives a feeling of fullness
Digestion in mouth
Salivary amylase
Starch
Maltose
Digestion by pancreas
Amylase
Starch
Maltose
Digestion by small intestine
Maltase>maltose>glucose
Sucrase>sucrose> glucose, fructose
Lactase>lactose> glucose, galactose