Water and WHC Flashcards

1
Q

% of water in lean red meat muscle

A

75%

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2
Q

ration of water to protein

A

relatively constant
3.6-3.7: 1

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3
Q

what does retained water contribute to in meat

A

juiciness and palatability
economic factor in processed meat

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4
Q

three ways water is found in meat

A

free
immooblised
bound

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5
Q

describe bound water

A

4-5%
tightly bound to charged groups on protein chains

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6
Q

describe immobilised water

A

bound closely to the bound water molecules, bound to protein structure/ static
10%

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7
Q

describe free water

A

80-85%
free to move

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8
Q

where is free water held

A

in the myofibrillar protein matrix

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9
Q

what does the I band of muscle consist of

A

actin only

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10
Q

what does the A band of muscle consist of

A

overlapping actin/myosin

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11
Q

what is the M-line in muscle

A

bulge in centre of myosin filaments

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12
Q

What is the H zone of muscle

A

light zone in the center of the sarcomere that actin can slide into

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13
Q

factors that influence WHC

A

-shrinkage/swelling of a myofibrillar protein matrix
-pH
-salt
-phosphate

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14
Q

how does shrinkage and swelling affect WHC

A

contraction results in limited space for water

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15
Q

what is the isoelectric point of actomyosin

A

pH 5

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16
Q

when does maximum shrinkage occur

A

at isoelectric point due to maximum shrinkage

17
Q

describe what happens as pH increases

A

more negative charges repel = swelling = increased WHC

18
Q

describe what happens as pH decreases

A

negative charges repel = swelling = increased WHC

19
Q

describe the effect of low pH and salt on WHC

A

Cl- in salt cancels out the positive charges and shrinkage occurs = decreased WHC

20
Q

describe the effect of high pH and salt on WHC

A

Cl- cant interact with the negative charges so no shrinkage occurs = increased WHC

21
Q

why are phosphate added to meat

A

improve WHC, control drip + improve yeild

22
Q

how do phosphate act in meat

A

to dissociate actomyosin and solubilise myosin
-physically prevents leakage
-like jello that entraps water

23
Q

what does solubilised myosin do to the viscosity

A

increases

24
Q

what do phosphate do to pH

A

increase it
-negative charegs increase which increases swelling

25
Q

what do short chain (ortho and pyro) phophates act as

A

buffers
-resists change in pH

26
Q

what can long chain phosphates be

A

good antioxidants