Major compounds- non-starch polysaccharides

Question 1

What are non-starch polysaccharides (NSPs)? provide examples.

Answer 1

Non-starch, carbohydrate polymers that are not digestible by human enzymes (include soluble and insoluble fibers = dietary fiber)
-Pectin, beta-glucan, arabinoxylan, inulin/fructan, cellulose, hemicellulose, galactomannan, glucomannan

Question 2

What is the primary focus of carbohydrates in grains?

Answer 2

Subdivided into digestible (starch) and indigestible (dietary fiber)
-indigestible =remaining indigestible carbs that are not classified as fibre

Question 3

What is cellulose? where is found? what bonds does it have?

Answer 3

A major plant cell wall component, β-D glucose polymer linked by β-1,4 glycosidic bonds
-also found in crop residues (biomass)

Question 4

What is the structural significance of cellulose?

Answer 4

Highly packed structure = resistance to water penetration and enzyme hydrolysis.

Question 5

What are cellulose derivatives used for in food?

Answer 5

• Micro crystalline cellulose (texturizer, anti-caking agent, fat sub, emulsifer)
• cellulose nanocrystal
  *carboxy methyl cellulose
  *cellulose nitrate

Question 6

Define hemicellulose.

Answer 6

All plant cell wall polysaccharides excluding cellulose, can be soluble or insoluble
-include arabinoxylan and galactomannan
-found in wood tissues, grain husk and bran

Question 7

What is Arabinoxylan (AX)? what is it made of? where is it found? what linkage does it have?

Answer 7

A pentosan (polymer of pentose sugars) made of arabinose and xylose, major hemicellulose in wheat (beta-1-4 linked xylan backbone)
-mainly insoluble, but slighlty soluble in wheat endosperm
-major component of cell wall

Question 8

How does Arabinoxylan interact with gluten in bread making?

Answer 8

Improves loaf volume, water binding, and delays staling.

Question 9

what is xylanase?

Answer 9

An eznyme that hydrolyzes the xylan backbone of hemicellolse
-targets xylan in AX

Question 10

What is ferulic acid? what is its impact on Arabinoxylan? what treatment is used?

Answer 10

AX esterified to a phenolic acid to make ferulic acid which inhibits xylanase preventing hydrolysis of AX
-ferulic acid esterase /alkaline treatment works in conjuction with xylanase to increase hydrolysis-lowers solubility

Question 11

What is the impact of phytic acid? what is its impact on Arabinoxylan? what treatment is used?

Answer 11

AX cross linked by phytic acid reduces solubility and impedes xylanase activity
-Phytase treatment can enhance AX degradation when used with xylanase

Question 12

What is the impact of diferulate? what is its impact on Arabinoxylan? what treatment is used?

Answer 12

AX esterified to diferulate is less soluble and impedes xylanase action
-ferulic acid esterase /alkaline treatment works in conjuction with xylanase to increase hydrolysis

Question 13

What is the significance of β-glucans? what are major sources?

Answer 13

Soluble dietary fibers that help reduce cholesterol and improve heart health

• Barley: 3–10%
• Oats: 2–6%
• Wheat: 0.5–1.5%

Question 14

Describe the molecular structure of β-glucans.

Answer 14

linear, kinked polymer of β-D-glucose units with mixed linkages of (1→3) and (1→4) glycosidic
-40-80% arabinoxylan and cellulose

Question 15

how is beta glucan distrubted in barley vs oats?

Answer 15

barley: uniform distrubtion
oats: thicker beta-glucan in bran/surface layer

Question 16

What is pectin? what is its function? where is it found?

Answer 16

A polygalacturonic acid found in fruits and vegetables, used as a gelling agent
-cementing material in cell walls
-used as a geling agent

Question 17

What is inulin? what is its function? where is it found?

Answer 17

A soluble dietary fiber that acts as a prebiotic and increase Ca2+ absorption
-found in onion, chicory roots, artichoke

Question 18

What are hydrocolloids? what portions of the grain are considered hydrocolloids? what is an animal source?

Answer 18

powerful water binding agents that increase viscosity
-soluble AX
-Beta-glucan
-Starch

animal source = gelatin
plant soucre = xanthan gum

Question 19

What are all grain carbohydrates other than starch called? what is it comprised of?

Answer 19

Dietary Fiber
-total dietary fiber
-soluble dietary fiber
-insoluble dietary fiber

Dietary fiber consists of non-starch polysaccharides (NSPs) that resist digestion in the human small intestine.

Question 20

what are its characteristics of SDF? provide examples.

Answer 20

Soluble Dietary Fiber; it dissolves in water, is fermentable, and slows digestion.

Examples include β-glucan, pectin, and inulin.

Question 21

What are the characteristics of IDF? provide examples.

Answer 21

Insoluble Dietary Fiber; it does not dissolve, adds bulk, and promotes bowel movement.

Examples include cellulose, lignin, and hemicellulose.

Question 22

What was the first gold standard definition of dietary fiber according to Trowell et al. (1976)?

Answer 22

Plant polysaccharides + lignin, resistant to digestion.

This definition laid the groundwork for future dietary fiber classifications.

Question 23

What is the Health Canada (2012) definition of dietary fiber?

Answer 23

Includes naturally occurring carbohydrates (DP ≥ 3) from plant foods not digested in the small intestine and accepted novel fibers that resist digestion and have at least one proven health benefit.

Novel fibers must demonstrate proof of safety and physiological efficacy.

Question 24

Fill in the blank: The current average fiber intake in North America is approximately _____ g/day.

Answer 24

18 g

Low intake is associated with increased health risks.

Question 25

What are the energy values for dietary fiber listed on nutrition labels?

Answer 25

2 kcal/g ## Footnote This value is mandatory for fiber content on nutrition facts tables.

Question 26

What constitutes a 'High source of fiber' claim on food labels? what about "source of fiber" and "very high source of fiber"?

Answer 26

"high source of fiber" ≥ 4 g/serving 'Source of fiber' (≥ 2 g) 'Very high source of fiber' (≥ 6 g).

Question 27

What is the implication of processing traditional fiber into a fine powder?

Answer 27

It may be classified as a novel fiber and must show efficacy to be included in dietary fiber counts. ## Footnote Processing alters the physiological behavior of the fiber.

Question 28

What is a novel fiber?

Answer 28

manufactured to be a source of dietary fibre, and: a) has not traditionally been significantly used for human consumption b) has been chemically/physically processed or c) been highly concentrated from its plant source

Question 29

What is a traditional fiber?

Answer 29

components of plant material in the diet which are resistant to digestion by enzymes produced by humans