Cereals and Grains Flashcards
What parts of the seed is edible?
Grain, kernel, berry
What are the most common grains?
1) Corn
2) Rice
3) Wheat
4) Barley
What is the function of the husk?
protective covering; usually not consumed
What is the function of bran? What is it a good source of?
protects the endosperm; excellent source of fiber and minerals
What is the underneath bran called? What is it a good source of?
- Aleurone layer: less fibrous coating
- contains protein, phosphorus, B vitamins (thiamin), some fat, antioxidants
Which layers are removed during processing of white flour?
Bran and aleurone
Husk and germ
Which part of the grain is the largest and is the basis of all flours?
Endosperm
What does the endosperm contain?
contains mostly carbohydrates, some protein and small amounts of vitamins, minerals and fiber
Which part of the grain is the smallest?
Germ (embryo)
What does the germ (embryo) contain?
rich in fat and contains some incomplete protein, vitamins (B vitamins, vitamin E) and minerals
Protein is generally higher in which grain?
Wheat
Grains are an incomplete protein. What are they lacking? Why should you pair with legumes?
- Lack in lysine, adequate methionine
- Legumes lack methionine, have sufficient lysine
= complete protein
The majority of lipids in grains are what?
Omega-6 PUFA
Which vitamins are contained in grains?
B vitamins: thiamin (B1), riboflavin (B2), niacin (B3), vitamin B6, pantothenic acid (B5), folate (B9); Vitamin E
Which minerals are contained in grains?
◦ Varies by type of grain
◦ Fe,Mg,P,K,Cu,Mn,Se
Where is fiber found in grains?
Bran and endosperm
What kinds of fibers are contained in grains?
cellulose, hemicellulose, lignin, inulin, resistant starch
Name some notable phytochemicals in grains.
phenolic compounds, carotenoids, vitamin E compounds, lignans, β- glucan, inulin and phytosterols
Where are the highest levels of phytochemicals in grains?
Bran and aleurone = highest
germ too
How does processing affect the phytochemicals in grains?
Decreases content but may increase bioavailibility
What is white refined flour composed of?
- Endosperm
- Husk bran and germ are REMOVED
Which nutrients are added to fortify white flour?
Thiamin (B1), Riboflavin (B2), Niacin (B3), Iron, Folate
They are enriched to a level equal or higher than that found in whole grains
Define enrichment.
replacement of nutrients to levels that existed before processing of the whole grains
Define fortification.
addition of nutrient to levels higher than those which existed before processing
What are Canada’s Food Guide recommendations for grains?
- 1/2 grains = whole
- Eat a variety of grains
- Choose products that are lower in fat, sugar and salt
What is not removed to make a product whole grain?
Bran is NOT removed
What is the chemical structure of a starch?
Complex CHO
Polymer of alpha-D-glucose
How is starch used in plants? Where is it stored?
Used for energy or stored in seeds, roots, stems or tubers
What do we use starches for?
◦ Thickeners, stabilizers, texturizers, bind water or fat
◦ Fat substitutes, emulsifiers
◦ Contribute to texture, taste and appearance!
What are the two distinct types of starches?
Amylose and amylopectin
What grains contain higher amount of amylose?
Corn and wheat flour
How is amylose in its natural state?
Coiled up into helix (H-bonding)
What is amylose?
A linear chain (500-2000) of alpha-D-glucose molecules linked by glycosidic bond between carbon 1(aldehyde group) and 4 (hydroxyl group)
What is amylopectin?
A highly branched molecule that consists of relatively short chains of alpha- D-glucose units linked 1-4
Where does the branching structure of amylopectin chains join together?
Through carbon atoms 1 and 6
Compare the shape of amylopectin and amylose.
amylopectin is larger than amylose but amylopectin is more bushy and compact in shape
Which grain contains 100% amylopectin?
Waxy maize
Define gelatinization.
happens when starch granules are heated in the presence of a liquid
How does gelatinization happen?
- Heat causes H-bonds to weaken – ↑ solubility •Water infiltrate the starch granule
- Granule swells to peak thickness
- Volume, viscosity and translucency increases
Define gelation?
occurs after gelatinization; aka: gelation