Lecture 10 - Fibre

Question 1

what is dietary fiber?

what kind of fermentation can occur?

Answer 1

• edible parts of plants that are resistant to digestion and absorption in human SI
• can have complete or partial fermentation in large intestine
• promotes beneficial physiological effects (ie laxation, blood cholesterol attenuation, blood glucose attenuation)

Question 2

nutrition importance of fiber?

Answer 2

-reduces cholesterol levels, normalizes sugar levels, maintains colon integrity, reduces obesity risk, reduces intestinal ulcers, reduces colon cancer risk

Question 3

what are major dietary fiber components?

Answer 3

cellulose
hemicelluloses
pectins
hydrocolloids and food gums
resistant starch
lignin

Question 4

ways for classification of DF?

Answer 4

1. based on role in plant
2. based on type of polysaccharide
3. based on digestion and physiological classification

Question 5

what is the most widely accepted classification for DF?

Answer 5

based on solubility in a buffer

Question 6

2 ways that DF is classified based on solubility

Answer 6

1. soluble DF: pectins, gums and mucilages

2. insoluble DF: cellulose, hemicellulose and legnin

Question 7

6 ways of determining fiber content?

Answer 7

1. crude fiber method
2. total DF method
3. insoluble DF method (IDF)
4. soluble DF method (SDF)
5. neutral detergent fiber method (NDF)
6. acid detergent fiber mthod (ADF)

Question 8

what is crude fiber

Answer 8

the loss in weight as a result of residue obtained after extraction of a dried and defatted sample with H2SO4 and NaOH

Question 9

equation to calculated crude fiber %?

Answer 9

crude fiber % = (W1-W2)/wt of sample x 100

Question 10

what are the 2 solvents used in crude fiber method?

Answer 10

H2SO4 and NaOH

Question 11

dietary fiber is an _____ method

Answer 11

enzymatic

Question 12

what enzymes are used in the dietary fiber method?

Answer 12

1. amylase
2. protease
3. amyloglucosidase

Question 13

what is NDF?

what does it consist of?

Answer 13

neutral detergent fiber

residue after extraction with boiling neutral detergent

consists of lignin, cellulose and hemicellulose

Question 14

what solutions does NDF method use?

Answer 14

involves use of boiling neutral solution of sodium dodecyl sulfate and EDTA

Question 15

what is ADF?

what does it consist of?

Answer 15

acid detergent fiber

residue after extraction with boiling acid detergent

consists of lignin and cellulose

Question 16

what solutions are used in ADF?

Answer 16

H2SO4 and acetyl trimethyl ammonium bromide

Question 17

what does ADF not determine?

Answer 17

does not determine hemicellulose (which is part of crude fiber and dietary fiber)