Chapter 4 Fiber

Question 1

Dietary Fiber

Answer 1

non-digestible carbohydrates and lignin that are intact and intrinsic in plants

Question 2

Functional Fiber

Answer 2

non-digestible carbohydrates that have been isolated, extracted, or manufactured and have been shown to have beneficial physiological effects in humans.

Question 3

What percentage of the primary and secondary cell wall contains dietary fibers?

Answer 3

95% +

Question 4

What cell wall has the most cellulose?

Answer 4

The secondary wall

Question 5

How much does hemicelluose content makes up a cell wall?

Answer 5

20-30%

Question 6

Cellulose

Answer 6

(Dietary and functional fiber); B(1,4) linkages; held by hydrogen bonds; water insoluble; poorly fermented

Question 7

Hemicellulose

Answer 7

dietary fiber; components of cell walls XMG (xylose, mannose, and galactose provide sugar backbone); AGG (arabinose, galactose, and glucuronic acid in side chains)

Question 8

Pectins

Answer 8

Dietary and functional fiber; galacturonic acid is the primary constituent; unbranched a(1,4) acid units; water soluble; stable at low pH values; (sources; apples, strawberries, and citrus fruits); added to jellies and jams to promote gelling.

Question 9

Lignin

Answer 9

phenol units; strong intramolecular bonding; insoluble; poorly fermented; dietary and functional fiber;

Question 10

Gums

Answer 10

hydrocolloids; secreted at the site of injury by plants; can be exuded from plants; soluble; gels; pH stability;

Question 11

B-glucans

Answer 11

homopolymers of glucopyranose units; water-soluble; fermentable; dietary fiber; high amounts in cereal brans (oats, barley, and mushrooms)

Question 12

What are the three classes of fructans?

Answer 12

Inulin, oligofructose, fructooligosaccharides.

Question 13

What fiber acts as a prebiotic for bifidobacteria?

Answer 13

Fructooligosaccharides; class of fructans.

Question 14

Most common food sources of inulin and other fructans

Answer 14

chicory, asparagus, leeks, onions, garlic, jerusalem artichokes, tomatoes, and bananas.

Question 15

Resistant Starch

Answer 15

Starch that cannot be or is not easily enzymatically digested, and thus absorbed by humans. (four types 1-4)

Question 16

RS 1

Answer 16

Found in plant cells walls; resists digestion to amylase activity; located within plant’s cellulose cell wall. (milled grains and seeds are sources) (Americans consume 10g/day; 20g/day recommended )

Question 17

RS 2

Answer 17

Resists digestion, because it is located within tightly packed granules within plant cells. (unripe green bananas, some legumes, raw potatoes, and maize)

Question 18

RS 3

Answer 18

Retrograde starch. Moist-heat cooking and cooling extrusion of starchy foods typically generates RS3

Question 19

Insoluble non-viscous fibers

Answer 19

cellulose, lignin, hemicellulose (some insoluble, some soluble)

Question 20

resistant dextrins

Answer 20

a.k.a resistant maltodextrins; generated by treating cornstarch with heat and acid, then with the enzyme amylase. Functional fiber

Question 21

Why is the water binding of fiber of physiological importance?

Answer 21

Slow down movement of substances; enable increased absorption of nutrients; delayed (slowed) emptying of food from the stomach; reduced enzyme function; reduced mixing of gastrointestinal contents with digestive enzymes; decreased nutrient diffusion rates, which attenuates blood glucose response; altered small intestine transit time.

Question 22

Intestinal fibers adsorption physiological effects within the G.I tract

Answer 22

diminished absorption of lipids; increased bile acid excretion; lowered serum cholesterol concentrations; altered mineral, carotenoid, and phytochemical absorption.

Question 23

Prebiotics stimulate the growth of which two health promoting bacteria

Answer 23

lactobacilli and bifidobacilli

Question 24

Primary short chain fatty acids

Answer 24

acetic, butyric, and propionic acids.