Lectures 7 & 8

Question 1

Examples of monosaccharides

Answer 1

Glucose, Fructose, Galactose

Question 2

Examples of disaccharides

Answer 2

Maltose, Sucrose, Lactose

Question 3

Which saccharide is not a reducing sugar?

Answer 3

Sucrose because it does not have an anomeric carbon. Involved in the 1(glucose),2(fructose)-glycosidic bond.

Question 4

What is the maillard reaction?

Answer 4

Chemical reaction between a primary amino acid and a reducing sugar to produce maillard reaction products that causes browning and the development of umami flavours.

Amadori rearrangement -> fragment melanoidins polymerization

Question 5

Important characteristics of lactose

Answer 5

1. Synthesized from glucose transported from the blood.
2. 1 molecule of glucose is epimerized to 1 molecule of galactose to form lactose via lactose synthetase.
3. Lactose has 2 anomers - A-lactose crystallizes as a monohydrate while B-lactose crystallizes as an anhydrous. Present in a ratio of 37:63

Question 6

Hydrolysis of lactose

Answer 6

1. via lactase
2. via acid

Question 7

Applications of lactose hydrolysis

Answer 7

1. Circumvent lactose intolerance for some people
2. Increase solubility of lactose
3. Increase the sweetness potential of lactose

Question 8

What is galactosemia

Answer 8

Inability to digest galactose due to an enzyme deficiency of galactokinase or galactose-1-phosphate uridyl transferase

Question 9

Side effects of galactokinase deficiency?

Answer 9

Accumulation of galactose in tissues including the eye - cause serious damage to the nervous system, liver and other organs

Question 10

Side effects of galactose-1-phosphate uridyl transferase deficiency?

Answer 10

abnormalities in brain leading to mental retardation.

Question 11

Uses of oligosaccharides?

Answer 11

Prebiotics

Question 12

Lactose derivatives

Answer 12

1. Lactulose - made by isomerization in alkaline. Can be used as a laxative.
2. Lactitol - made from the hydrogenation of lactose using a catalyst. Used as a non-caloric sweetener.

Question 13

Some applications of lactose

Answer 13

1. Infant formulation
2. Promote browning
3. Anti-caking agent
4. Pharmaceutical excipient

Question 14

Main minerals present in milk

Answer 14

1. Sodium (48 mg/100g) - 95% present in the serum
2. Potassium (143 mg/100g) - 94% present in the serum
3. Calcium (117 mg/100g) - 32% present in the serum
4. Chloride (110 mg/100g) - 100% present in the serum
5. Magnesium (11 mg/100g) - 66% present in the serum
6. Phosphate (203 mg/100g) - 53% present in the serum
7. Citrate (175 mg/100g) - 92% present in the serum

Question 15

Sources of calcium

Answer 15

1. Tofu
2. Sardines
3. Soy milk
4. Salmon

Question 16

Function of citrate in milk?

Answer 16

Acid regulation act as a buffer to resist pH changes

Question 17

Level of membrane processing

Answer 17

1. Microfiltration: filter out bacteria and suspended solids
2. Ultrafiltration: filter out viruses, bacteria and suspended solids
3. Nanofiltration: filter out bivalent ions, viruses, bacteria and suspended solids.

Question 18

Fat soluble vitamins in milk

Answer 18

Vitamins A, D, E & K

Question 19

Water soluble vitamins in milk

Answer 19

Vitamins B1,2,3,5,6,7,11,12 and C

Question 20

Levels of vitamin A in milk

Answer 20

0.2 - 2mg/L (38% RDA/L)

Question 21

Level of vitamin B2 (Riboflavin) in milk

Answer 21

1.8 mg/L (139% RDA/L)

Question 22

Level of vitamin B12 in milk

Answer 22

0.0045mg/L (167% RDA/L)

Question 23

Level of vitamin C in milk

Answer 23

5 - 20mg/L (25% RDA/L)

Question 24

Structure of lactose and sucrose

Answer 24

Sucrose: glucose joined to a fructose molecule via a 1,2-glycosidic bond

Lactose: Galactose joined to a glucose molecule via a 1,4-glycosidic bond