Carbohydrates

Question 1

What are carbohydrates

Answer 1

Diverse class of compounds in all cells

Question 2

What is the typical formula for monosaccharides

Answer 2

CnH2nOn

Question 3

What is the typical formula for larger carbohydrates

Answer 3

CnH2n-2xOn-x where x is the number of glycosidic bonds present

Question 4

What three elements are carbohydrates composed of

Answer 4

Carbon, hydrogen and oxygen

Question 5

What technical roles can carbohydrates play in food manufacture and processing

Answer 5

Texture, viscosity, flavour, colour formation and bulking

Question 6

What three ways can carbohydrates be classified

Answer 6

Chain length, number of carbons per monomer and digestible vs non-digestible

Question 7

What is the chain length of the carbohydrates responsible for/determine

Answer 7

Behaviour of carbohydrate

Question 8

What does the number of carbons determine

Answer 8

Application of sugar in biological source

Question 9

How many kcal/g are in digestible carbohydrates

Answer 9

3.75-4kcal/g

Question 10

What is the difference in metabolism between glucose and fructose

Answer 10

Glucose is used in most cells and is insulin mediated while fructose is metabolised by the liver and bypasses some glycolysis steps

Question 11

What us fructose associated with in the body

Answer 11

Increased VLDL cholesterol and reduced insulin response

Question 12

How are digestible carbohydrates absorbed

Answer 12

Larger carbohydrates e.g oligo and polysaccharides are enzymically degraded into sugar monomers

Question 13

What is the Glycaemic index

Answer 13

The rate at which sugar is absorbed from food

Question 14

What is the difference between High GI and low GI foods

Answer 14

High are rapidly absorbed and result in a sugar spike while low GI require greater digestion before sugars are absorbed

Question 15

What are high GI foods associated with

Answer 15

Snacking behaviour, high blood sugar and increased insulin response

Question 16

What are nutrition claims

Answer 16

Claims that relate to the specific composition of a food

Question 17

What is the low sugar nutrition claim in the UK

Answer 17

No more than 5g/100g in solid and no more than 2.5g/100gmL in liquid foods

Question 18

What is the sugar free nutrition claim in the UK

Answer 18

No more than 0.5g/100g in solids and no more than 0.5g/100mL in liquid foods

Question 19

What is the no added sugars nutrition claim in the UK

Answer 19

Does not contain any added mono or disaccharides or any other food used for its sweetening properties

Question 20

What should naturally present sugars be labelled with

Answer 20

Contains naturally occurring sugars

Question 21

What is the nutrition claim for sources of fibre

Answer 21

At least 3g/100g or 1.5g/100kcal

Question 22

What is the nutrition claim for high fibre

Answer 22

At least 6g/100g or 3g/100kcal

Question 23

Why is it beneficial for manufacturers to receive a nutrition claim

Answer 23

Demonstrates improved nutrition vs competitors

Question 24

What two forms can monosaccharides exist in

Answer 24

Cyclic and linear

Question 25

What projection are cyclic monosaccharides depicted as

Answer 25

Haworth projection

Question 26

When do sugars transition between the linear and cyclic form

Answer 26

In solution

Question 27

When do sugars contain an aldehyde or ketone group

Answer 27

When in linear form

Question 28

What projection are linear monosaccharides depicted as

Answer 28

Fischer projection

Question 29

Why do polar sugars have a high solubility

Answer 29

Hydroxyl group forms H bonds between molecules of water keeping them in solution

Question 30

What type of bond are glycosidic bonds

Answer 30

Covalent bonds

Question 31

Where do glycosidic bonds form

Answer 31

Between a sugar and another organic compound

Question 32

What is a condensation reaction

Answer 32

A reaction that liberates one molecule of water

Question 33

What does bond labelling tell us

Answer 33

What atoms in a molecule are involved in the bond

Question 34

What do alpha and beta bonds refer to

Answer 34

The position of the hydroxyl on C1

Question 35

Where has an alpha-1-4 bond formed

Answer 35

On carbon 1 and the 4th carbon of another sugar

Question 36

Where does an alpha-1-6 bond form and what does it produce

Answer 36

Between C1 and C6 producing branching between sugars

Question 37

Why can sugars not be simply substituted for eachother by manufacturers

Answer 37

Variable in intensity, profile of sweetness and properties

Question 38

What are Advanced glycation end-products (AGEs) are what are they associated with

Answer 38

Reactive sugar-protein or sugar-lipid complexes that form during high temperature food processing and are associated with loss of cellular function, reduced elasticity and cardiovascular stress

Question 39

What are oligosaccharides

Answer 39

3-10 unit carbohydrates

Question 40

What are polysaccharides

Answer 40

11+ unit polysaccharides

Question 41

What are linear form carbohydrates

Answer 41

Single chain of monomers with the same glycosidic bond linking them

Question 42

What are branched chain carbohydrates

Answer 42

Several branches due to multiple different bonds

Question 43

What is amylose

Answer 43

Helical component of starch that is long chains of alpha 1-4 bonded glucose monomers

Question 44

What is amylopectin

Answer 44

Branched shorter chain component of starch with alpha 1-4 glycosidic bonds and frequent alpha 1-6 branching

Question 45

What are the crystalline regions of starch

Answer 45

Long unbranched chains where separate chains can self-associate decreasing hydrogen bonding opportunities and therefore interact with water less

Question 46

What are amorphous regions of starch

Answer 46

Regions with a high degrees of branching and limited self-association so increased hydrogen bonding availability for interaction with water molecules

Question 47

What are starch granules

Answer 47

A long term energy store found in storage organs (tubers, roots) and seeds, grains and some legumes

Question 48

Why does starch need to be gelatinised to be digested

Answer 48

In granule form it is poorly soluble as the outermost region is crystalline

Question 49

What is starch gelatinisation

Answer 49

Mixing starch into water to suspend the granules and then heating to break the hydrogen bonds involved in self association to hydrate the amorphous regions, leading to irreversible breakdown of the granule and increasing viscosity

Question 50

What is starch retrogradation

Answer 50

Starch reassociation by releasing bound water and recrystallising without returning to a granule structure resulting in hardness/ unpalatable texture modification

Question 51

Why can fibre not be digested

Answer 51

Primarily composed of beta glycosidic bonds which humans do not synthesise the enzymes to break down beta bonds so the oligo- or polysaccharides remain intact until the colon

Question 52

What are insoluble fibres

Answer 52

Fibres that are not fermented and pass through the colon intact contributing to stool frequency, bulk and bind to harmful components (bile acids, toxins)

Question 53

What are soluble fibres

Answer 53

Fibres that can be fermented by saccharolytic colonic bacteria which liberates short chain fatty acids for use by the body as energy or in gluconeogenesis (passively providing energy)

Question 54

What is dietary fibre

Answer 54

Carbohydrates polymers with 3 or more units which are not hydrolysed by endogenous enzymes in the small intestine

Question 55

What is the carbohydrate recommendations by the eatwell guide

Answer 55

1/3 of diet, higher fibre and whole grain varieties are recommended

Question 56

What are the daily recommendations for fibre for over 16s

Answer 56

30g a day

Question 57

What is the daily recommended intake for free sugars

Answer 57

No more than 5% of total energy

Question 58

What is the daily recommendations for carbohydrates

Answer 58

50% of total energy intake

Question 59

What does free sugars not include

Answer 59

Naturally occurring sugars in dairy or fresh/cooked/dried fruit and veg