Chapter 12: Food proteins and enzymes Flashcards Preview

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Flashcards in Chapter 12: Food proteins and enzymes Deck (33):
1

What is a protein good for?

Amino acids, source of calories (energy)

2

Calories:

amount of heat required to raise 1 g of water 1 degree
1 Calorie=1 kcal=1000 calories

3

Where is energy stored?

Polysaccharides (glycogen) or fat (triglycerides

4

Proteins

amino acids
20 amino acids
differ on R structure

5

Fibrous Protein

insoluble in water
ex: muscle, connective tissue and hair

6

Globular proteins

soluble in water
ex: eggs, dairy, enzymes, myoglobin

7

Membrane proteins

not water soluble
transporters, receptors

8

Primary 1ᵒ structure

the amino acid sequence

9

Secondary 2ᵒ

local structure
-coils: alpha-helix, "random" coil
-extended: beta-strands (sheets)
-turns

10

Tertiary 3ᵒ

overall 3-D structure
2 and 3ᵒ fold to produce 3D structure

11

Quaternary 4ᵒ

multiple protein chains
-proteins can associate with other proteins

12

Hydrolysis of protiens

- we reverse synthesis by chemically insert a water molecule, break apart the aa's
we are able to absorb and digest the individual amino acids

13

Connective tissue

-triple helices of proline-rich peptides
-covalently cross-linked
-assembled into fibers

14

How is gelatin formed?

collagen structure is "unwound" by heating in hot water
-the backbone forms a sol or gel of gelatin

15

Red meat

red part is muscle protein + myoglobin

16

In red meat fat between muscle is called?

seam fat
fat is held by connective tissue

17

Within the muscle it is called

marbling (often prized)

18

What is the contractile protein?

actomyosin: composed of several proteins, notably actin and myosin

19

Myosin

is assembles in muscle fibers

20

Seed Proteins

bran
germ
aleuron
starchy endosperm

21

Starchy endosperm

85% of kernel
10-15% is protein
remains in white flour

22

Prolamins

wheat proteins: storage proteins
gluten
-gliadin (mixture of proteins)

23

Glutelins

wheat proteins
gluten
storage proteins
-glutenin (also a mixture)

24

Albumins and globulins

wheat protein
`15% of seed protein
-cellular proteins
-enzymes

25

Gluten proteins and flour types

high molecular weight glutenins form (S-S) crosslinks during kneading- "visco-elastic" dough

26

Hard wheat

strong flour
bread flour (10-13% protein)
high gluten protein concentration

27

Soft wheat

cake flour (8-10% protein)
lower gluten concentration
used for quick breads
minimally kneaded

28

All-purpose flour

a blend of soft and hard wheat (9-12%)

29

Enzymes

proteins
-ase
catalyze nearly all the reactions of life

30

What do enzymes catalyze?

digestion
energy metabolism
biosynthesis
everything

31

essential amino acids

body can not metabolize or make on its own in sufficient quantities
-must be in diets
9 of them

32

Limiting amino acids

when a protein is low in one essential amino acid necessary for synthesis, that EAA is the limiting factor

33

Protein quality

3.9 hens egg
3.1 Cows milk
3.5 fish
2.3 beef
2.3 Soybeans
1.5 Dry beans
1.1 Corn