Carbohydrates Flashcards
Word equation for photosynthesis
Carbon dioxide + water –> glucose + oxygen
Chemical equation for photosynthesis
6Co2+6H2O–>C6H12O6+6O2
Structure of a monosaccharide
Simple sugar, one unit, smallest carbohydrate
Monosaccharide chemical formula
C6 H12 O6
Example and sources of monosaccharides
Glucose - fruit
Fructose- fruit and honey
Galactose - digested milk
Disaccharide structure
When two monosaccharides join together
Loss of H2O
Chemical formula of a disaccharide
C12 H22 O11
Examples and sources of disaccharides
Maltose(glucose + glucose) = barley
Sucrose ( glucose + fructose) = table sugar
Lactose (glucose + galactose) = milk
Structure of a polysaccharide
2+ monosaccharides join together
Chemical formula of polysaccharide
(C6 H10 O5)n
Examples and sources of polysaccharide
Starch -potatoes Pectin -fruit Glycogen -meat Gums -plants and seaweed Cellulose dietary fibre -nuts
Properties of sugar
Soluble in water Sweetness Assists aeration Maillard reaction Caramelisation Crystallisation Hydrolysis Inversion
Explain solubility of sugar
A syrup is formed when it is dissolved in water
Culinary use : preservative in food e.g. Canned peach
Explain sweetness of sugar
Gives appetising flavour
Culinary use : cupcakes
Name the types of sugar
Fructose
Glucose
Sucrose
Lactose
What is the sweetness in fructose
170%
What is the sweetness in sucrose
100%
What is the sweetness in glucose
75%
What is the sweetness in lactose
15%
Explains assist of sugar in aeration
Sugar helps denature eggs protein causing it to unfold and entrap air bubbles
Culinary use: meringues
Explain caramelisation of sugar
On heating sugar melts and caramelises.
Gradual stages between 104-177 degrees
Normally occurs at 160 degrees
Culinary use : caramel squares.
Explains crystallisation of sugar
When a liquid has dissolved as much sugar and possible it is saturated. Crystals are formed when the solution solidifies when cools
Culinary use : fudge
Explain hydrolysis of sugar
Reverse of condensation reaction.
Water and enzymes splits disaccharides back into monosaccharides
Explain inversion of sugar.
When a liquid sucrose solution is heated in the presence of an acid or enzyme is causes the disaccharide to split into glucose and fructose
Culinary use: jam making
Properties of starch
Solubility Flavour Hygroscopy Gelatinisation Hydrolysis Dextrinisation
Explain hydrolysis of starch
Occurs during digestion
Water and enzymes split starch(poly) into maltose (dis)
Explain dextrinisation of starch
When starch foods are dry heated short chained polysaccharides called dextrins are formed
They combine to form pyrodextrins
This causes colour change.
Culinary use : browning of toast
Explain solubility of starch
Insoluble in water
Explain starch flavour
Non sweet
Explain hygroscopy of starch
Can absorb moisture from air
Explain gelatinisation of starch
Hen starch is co,boned with liquid and heated to 55-70 degrees grains swell burst and absorb liquid around them.
As temperature increases it becomes more viscous and forms a sol
When mixture cools water molecules become trapped resulting in a gel
Properties of non starch polysaccharides
Gums
Cullulose
Pectin
Explain the property cellulose
Cellulose / dietary fibre is insoluble in water.
Cannot be digested by body
passes through intestinal tract and helps stimulate peristalsis
Explain gums
Soluble in water
Can absorb large amounts of water to form a thick gel
Culinary application: ice cream.
Explain pectin
Naturally present in plant cells and cell walls of fruit and veg Used as a Setting agent Absorbs water to form a gel Only present in ripe fruit Over ripe fruit = pectic acid Under ripe fruit = protopectin For pectin extraction it needs heat and acid Culinary application: jam making
Effects of dry beta on carbs
Dextrinisation
Caramelisation
Maillard reaction
Effects of moist heat on carb
Syrup form
Gelatinisation
Cellulose
Pectin extraction
