carbohydrates

Question 1

outline the difference between alpha bonds and glycosidic bonds

Answer 1

. Beta bonds form long, straight, parallel chains
. Alpha bonds form helical structure
. Alpha bonds can be broken by human enzymes
. Beta bonds cannot be broken, insoluble starch, fibre pass form digestive tract.

Question 2

outline difference between starch polymers amylose and amylopectin

Answer 2

. amylose 1-4 glycosidic bonds, 20% starch, less branched
. amylopectin 1-6 glycosidic bonds, 880% starch, more branched

Question 3

outline the difference between non starch polymers pectin and cellulose

Answer 3

. Pectin is formed from alpha and beta bonds
. Cellulose is straight, linearly formed from beta-glucose bonds, so undigestible for humans.

Question 4

how do carbs act in food

Answer 4

Help with colour change
Sweetness
Chewiness and texture
Thickener or gelBulk and volume

Question 5

describe gelatinisation in relation to starch and water

Answer 5

When starch is mixed with water
and heated at 60 degrees.
. starch swells and thickens mixture
. gelatinisation is complete at 98 degrees and begins to set at 38 degrees.

Question 6

describe why carbs turn brown when heated

Answer 6

. mallard reaction
. amino acids and sugars (e.g.
glucose, fructose) react with each other when heat is at 140
. melanoidins

Question 7

how are sugars caramelised

Answer 7

When sucrose is heated above its melting point, it produces caramel.
* Sugar at high temperature
causes loss of water and react with
each other producing
many different types of
compounds.

Question 8

describe dextrinsation

Answer 8

. Dextrinisation is when starch is broken down into dextrins when exposed to dry heat. This causes the food to brown and develop a toasty, nutty flavor.