Carbohydrates

Question 1

Define carbohydrates

Answer 1

“polyhydroxy aldehydes or
polyhydroxy ketones, or substances that
yield such compounds on hydrolysis”

Question 2

Formula for starch

Answer 2

(C6H10O5)n

Question 3

Glucose converted to starch for storage

Answer 3

C6H12O6 => (C6H10O5)n + nH20

Question 4

What does colonic fermentation of fibre produce

Answer 4

Colonic fermentation of fibre produces butyrate which is beneficial for gut health

Question 5

Two types of simple sugars:

Answer 5

Monosaccharides and disaccharides

Question 6

Types of monosaccharides

Answer 6

Glucose, fructose, galactose

Question 7

Types of disaccharides

Answer 7

Lactose, maltose, sucrose

Question 8

Two types of complex carbs

Answer 8

polysaccharides (starch)
non-starch polysaccharides (dietary fibre)

Question 9

Monosaccharides

Answer 9

(2-6 carbon units)
– Biose, triose, tetrose, pentose, hexose (# of C)
– Glucose, fructose, galactose

Question 10

Disaccharides

Answer 10

(2 monosaccharides)
– Sucrose (glucose + fructose)
– Maltose (glucose + glucose)
– Lactose (glucose + galactose)

Question 11

Oligosaccharides

Answer 11

(3-10 monosaccharides)
– Not as common in food; pulses
– Inulin (fructan - chain of fructose; extracted from chicory)

Question 12

Polysaccharides

Answer 12

(10+ monosaccharides)
– Complex carbohydrates
– Dextrin, starch, cellulose, pectin, gums

Question 13

Hydrolysis of sucrose produces

Answer 13

Glucose, Fructose
Beet & cane (table) sugars, molasses/treacle, maple syrup

Question 14

Hydrolysis of lactose produces

Answer 14

Glucose, Galactose
Milk & milk products

Question 15

Hydrolysis of starch produces

Answer 15

Glucose
Branched/linear, contributes to
viscosity & gel formation

Question 16

Hydrolyis of dextrin produces

Answer 16

Glucose
Hydrolysis product of starch

Question 17

Hydrolysis of glycogen produces

Answer 17

Glucose
Meat products and seafood

Question 18

Hydrolysis of cellulose produces

Answer 18

glucose
skeletal structure of plant cell (indigestible)

Question 19

Simple sugars functions

Answer 19

Sweetness
* Other taste/aroma
* Colour
* Volume (e.g. fermentation in bread)
* Texture (e.g. crystallisation vs gelling in jams)
* ↓ freezing point
* Binds water (shelf-life)

Question 20

Starch

Answer 20

• Complex carbohydrate (polysaccharide)
• Long chains of glucose (C6H10O5)n
  n=400-4000
  – Amylose (linear) (gel) 25% of starch
  – Amylopectin (branched) (waxy) 75% of starch
• Found in granules (small packets)
  Derived from various plants:
  – Roots (e.g. potato, tapioca)
  – Cereal (e.g. corn, wheat, rice)

Question 21

Caramelisation

Answer 21

• Browning of sugar (>100°C)
• Dry & moist heat
• e.g. crème caramel

Question 22

Dextrinisation

Answer 22

Browning of starchy food
* Dry heat
* Breaks down starch > dextrins
* e.g. toasting bread

Question 23

Gelatinisation

Answer 23

Thickening
* Starch heated with water
* Forms a suspension
* 60°C = swell
* 80°C = burst

Question 24

Maillard reaction

Answer 24

sugar + protein

Question 25

Enzymatic browning reaction

Answer 25

polyphenol oxidase > melanin

Question 26

Unmodified starch uses in foods

Answer 26

Refined wheat flour - Thickening sauces/soups (roux)
Potato starch - Thicken soups (++ viscosity)
High amylose starch -Edible film for wrapping candies

Question 27

Uses for modified starch in foods

Answer 27

Pre-gelatinised starch - instant puddings and soup mixes

Question 28

uses for other polysaccharides in foods

Answer 28

Cellulose - Powered form- bulk in weight-reducing foods
Dextrins - In coffee extracts
Gums - Thickening & gelling agent

Question 29

Uses for sugars in foods

Answer 29

Glucose - Humectant in confectionery
Caramel - Colouring & flavouring

Question 30

How much total dietary energy should come from carbs?

Answer 30

50%