Grains - Minor Components Flashcards
where are the minor components of grains located
minor grain components of cereals are mostly concentrated in the bran or outer layers
Phytic acid
- mainly in bran
- makes up 70-75% of phosphorous
- anti-nutrient
- chelating agent; binds to minerals and makes them bio-unavailable
- affects digestion of nutrients
- causes nutrient deficiencies in animals
- phytase can convert phytic acid into vitamin and phosphorous
How is phytic acid an anti-nutritional compound?
anti nutrient due to it’s chelating functionality
- mitigates digestion of starch and proteins
- mitigates absorption of minerals calcium, zinc, iron)
- cross-links proteins ↓ digestibility
- cross-links fiber (aribinoxylans) ↓ solubility
how does phytic acid bind to dietary fibre (aribinoxylan)? how can the antinutritional effects be minimized?
- aribinoxylan is cross-linked by phytic acid, making it less soluble and affects xylanase activity
- introducing both xylanse and phytase will chelate and make the vit/min more bioavailable
xylanase - creates oligomers from aribinoxylan
phytase - cleaves phytic acid cross links
what is sprouting, malting & germination - how does it improve the bioavailability of minerals?
germination: process of speeding up the sprouting process (soaking/wetting seeds)
sprouting: natural process by which seeds/spores germinateand put out shoots or other structures to experience further growth
malting: grain is made to germinate then stopped from further germinating by drying with hot air
- increases activities of hydrolytic enzymes, improvement in the contents amino acids, total sugars, and B vitamins, and a decrease in dry matter, starch, and antinutrients.
- Partial hydrolysis improves the digestibility of storage proteins and starch
purpose of phytase treatmeant
- commonly used in animal feed to minimize anti nutritional effects of phytic acid
- can cleave the cross-links b/w phytic acid and molecules
phenolic acids - 3 common types, and presence in grains
1.Coumaric acid
2.Cinnamic Acid
3.Ferulic Acid
- usually present in association with fiber (ferulic acid+AX) and protein (tannins+protein)
- loss of fiber solubility
- ferulic acid esterase can enhance xylanase hydrolysis
benefits of phenolic acids, bioavailability
- antioxidants; anticancer properties
- better absorbed as free circulating phenolics (not bound to fiber)
- eating whole grains is promoted = phenolic compounds
- pearling abrasively removes outer bran layer where majority of pehnolics are found which depletes antioxidant properties of flour
common vitamins and minerals found in cereal grains
vitamins: thiamin, riboflavin, niacin, pantothenic acid, pyridoxine
minerals: phosphorous, potassium, calcium, magnesium, iron, copper, manganese
what vitamin(s) is abundant in oilseeds?
vitamin E (tocols)
* good antioxidants
* soybean - mainsourse
* fat soluble - extracted from oil + sold independantly
sugars and lipids as minor grain components
sugars (2-3%): glucose, galactose, fructose, sucrose…
lipids (up to 5% in cereals):
- various types
- free or bound to grain components
- starch surface + internal lipids
- bound: lipid-amylose comples
two notable cereal grains high in lipid
- rice bran
- corn germ
lowest to highest bounded -antioxidant grains
- triticale
- wheat
- corn
- barley
7 enzymes present in grains + their actions
1. endo/exo amylases - hydrolyse starch
2. endo/exo xylanases - hydrolyse xylan/pentosans
3. endo/exo proteases - hydrolyse proteins/peptides
4. lipase - de-estirify lipids
5. lipoxygenase - peroxidation of polyunsaturated fats
6. phytase - hydrolyse phytic acid
7. phenolic acid esterase - de-esterify phenolic acids
explain how endo/exo enzymes work
endo: makes cuts within the molecule
exo: releases 1 monomer by 1 monomer down the tip
