Grains - Major components

Question 1

3 major components of grains

Answer 1

Carbohydrates
Protein
Fat

Question 2

Grain carbohydrates

Answer 2

1. Starch/resistant starch
2. Cellulose
3. Hemicellulose/non starch polysaccharides
   - Pectin
   - Beta-glucan
   - Arabinoxylan (& xylan, galactomannan, glucomannan, fructan/inulin)

all indigestible carbs are dietary fiber

starch is the only digestible carbohydrate in humans

Question 3

How does beta glucan differ in yeast and cereals

Answer 3

cereals (oats, barley): (1,3), (1,4) linkage, good for heart health

yeasts/mushrooms: increase immunity

Question 4

What are FODMAPS

Answer 4

fermentable oligo-, di-, mono- saccharides and polyols.

Question 5

cellulose - role of ligands

Answer 5

• major cell wall component in plants
• linear (1,4) linkage structure - makes hydration difficult
• abundant in hydroxyl groups
• ligands: hydrophobic, surround fiber components to help bind cellulose tightly, resists hydration

Question 6

MCC and CNC

Answer 6

micro crystalline cellulose:
- used as a texturizer, anti-caking agent, fat substitute, emulsifier, extender, bulking agent and in formulation of vitamin supplements/tablets
- comes from wood, bran and husk
- gives good mouthfeel, retains moisture
- grated cheese
- made by partial depolymerization (acid hydrolysis) of cellulose fiber to destruct some of the amorphous regions

cellulose nanocrystals: environmentally friednly ink for 3D printing, makes microstructures with outstanding mechanical properties

Question 7

what is cellulosic biomass

Answer 7

crop residue made up of lignands, cellulose and hemicellulose (mainly xylans)

Question 8

Hemicellulose

Answer 8

• indigestible
• polysaccharide component of cell walls aside from cellulose
• water souble/insoluble (mostly hydrated)
• extractable by dilute basic solutions
• wood tissues (1/3), husk (1/4) bran (1/12)

Question 9

xylan and aribinoxylan

Answer 9

primary hemicelluloses

xylan: found in wood, polymer of xylase

aribinoxylan AX (major): found in grain husks/bran, pentosan; polymer of ribose, main dietary fiber component

Question 10

cell wall of barley contains how much AX?

cell wall of wheat contains?

Answer 10

20%

> 90%

Question 11

aribinoxylan structure and functions

Answer 11

• highly soluble due to branched beta 1-4 linked xylan backbone
• resists staling by retaining water
• important in baking: holds gas
• exists in complex with phytochemicals: influences their solubility
• AX in bran is insoluble (phytochemicals, higher DF)
• AX in endosperm in soluble (lower DF)
• can be hydrolyzed into pentose sugars such as aribinose and xylose

Question 12

aribinoxylan + ferulic acid, deferulate

Answer 12

ferulic acid:
- AX esterifed to ferulic acid
- decreases solubility
- impedes xylanase action - improved by ferulic acid esterase/alkaline treatment

diferulate:
- cross-linked
- less soluble
- impedes xylanase action - improved by ferulic acid esterase/alkaline treatment

phytic acid:
- cross linked
- decreases solubility
- impedes xylanase action - improved by phytase treatment