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Nutritional Biochem 2 > Fiber > Flashcards

Fiber Flashcards

1
Q

Dietary fiber refers to what?

A

nondigestible carbs and lignin that are intact and intrinsic in plants

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2
Q

functional fiber consists of what?

A

nondigestible carbs that have been isolated/extracted/manufactured

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3
Q

Cellulos is made of what?

A

long linear polymers of B-(1/4) linked glucose units
(plant cell walls)
- water insoluble

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4
Q

Hemicellulose consits of what?

A

a heterogenous group of polysaccharide substances

  • branched polymer
  • 20-30 % cell wall
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5
Q

sugar monomers in hemicellulose can include what?

A

xylose, mannose, galactose, rhamnose, and arabinose

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6
Q

Hemicellulose that contain acids in their side chains are what?

A

slightly charged and water soluble

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7
Q

What components of Hemicellulose are accessible to bacteria?

A

hexose and uronic acid

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8
Q

Pectins are referred to as?

A

galacturonoglycans

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9
Q

What is the primary constituent of pectin?

A

galacturonic acid

- backbone of unbranched chains of alpha-(1-4) linked D-galacturonic acid units

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10
Q

Why are pectins used in food as a gelling agent?

A

water soluble and gel-forming

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11
Q

Pectins have a high what?

A

ion-binding potential

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12
Q

Pectins are completely fermented by what?

A

colonic bacteria

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13
Q

What is the only non-polysaccharide constituent of fiber?

A

lignin

- branched polymer made of phenol units with strong intramolecular bonding

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14
Q

Lignin is comprised of three monolignol monomers…

A

coniferyl alcohol, sinapyl alcohol, and p-coumaryl alcohol

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15
Q

Intestinal microflora can convert some lignins into what?

A

enterolactone and enterodiol which can protect against hormone-related cancers, diabetes, and HD

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16
Q

Gums are are tree exudates secreted where?

A

at the site of plant injury

- highly fermenteds

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17
Q

Gums as food additives

A

Gum arabic, guar gum, and xanthan gum

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18
Q

Gums are composed of what?

A

GALACTOSE, mannose, glucuronic acid…

19
Q

Guar gum is comprised of what?

A

galactomannans –> linear chains of mannose with B-(1-4) linkage to which galactose units are attached with a-(1-6) linkages

20
Q

Xanthan gum is comprised of what?

A

B-(1-4) glucose linkages but every second glucose unit is attached to a trisaccharide of mannose and glucuronic acid

21
Q

Xanthan gum can be synthesized by what?

A

microorganisms

22
Q

What are homopolymers of glucopyranose units?

A

B-glucans

- water soluble and highly fermentable in colon

23
Q

B-glucans are similar in structure to?

A

cellulose (every 3rd glucosidic bond is a B(1-3) bond

24
Q

B-glucans are found in?

A

oats and barley

25
Q

B-glucans are effective in reducing what?

A

serum cholesterol and posprandial blood glucose

26
Q

Fructose residues are bonded together using?

A

B(1-2) glycosidic bonds

27
Q

Fructans can be divided into what 3 groups?

A
  1. inulin –> fat replacement
  2. oligofructose
  3. fructooligosaccharides
28
Q

Which fructan contains 9-60 units of fructose with a glucose molecule linked at the C-2 position of the terminal fructofuranose unit?

A

inulin

29
Q

Which fructan is formed by the partial hydrolysis of inulin?

A

oligofructose

- 5-8 fructose units

30
Q

Which fructan contains 2-4 fructose units?

A

fructooligosaccharides (FOS)

31
Q

Fructooligosaccharides (FOS) can promote the growth of what?

A

bifidobacteria

FOS = prebiotic

32
Q

A straight chain amino-polysaccharde containing B(1-4) linked glucose units?

A

chitin

33
Q

Chitin is similar in structure to?

A

cellulose

34
Q

Chitin is found where?

A

insect exoskeleton and shells of arthropods

35
Q

Deacetylated form of chitin?

A

chitosan (soluble in water)

36
Q

What can reduce serum cholesterol?

A

chitosan

- binds with (-) charged unesterfied fatty acids and cholesterol for excretion

37
Q

Are chitin and chitosan fermentable?

A

NO

38
Q

Provides viscosity in solutions.

A

psyllium (similar to gums)

39
Q

What seeds contain mucilage?

A

psyllium seeds

40
Q

What is found in the laxative metamucil?

A

psyllium (not fermentable)

41
Q

Fibe may induce the secretion of what satiating hormones?

A

glucagon-like peptide 1 (GLP-1) and Peptide YY (PYY)

42
Q

What has shown to reduce gastric emptying?

A

GLP-1

43
Q

What are the 6 roles that fiber has against colon cancer?

A
  1. absorb primary bile acids
  2. fiber fermentation to short-shain fatty acids which decreases luminal pH
  3. fermentation may release fiber-bound calcium
  4. butyrate inhibits histone deacetylases
  5. increase fecal bulk
  6. insoluble fibers bind to carcinogens
44
Q

Avg U.S. fiber consumption?

A

15 g/day

Nutritional Biochem 2 (6 decks)

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