Water and WHC Flashcards
% of water in lean red meat muscle
75%
ration of water to protein
relatively constant
3.6-3.7: 1
what does retained water contribute to in meat
juiciness and palatability
economic factor in processed meat
three ways water is found in meat
free
immooblised
bound
describe bound water
4-5%
tightly bound to charged groups on protein chains
describe immobilised water
bound closely to the bound water molecules, bound to protein structure/ static
10%
describe free water
80-85%
free to move
where is free water held
in the myofibrillar protein matrix
what does the I band of muscle consist of
actin only
what does the A band of muscle consist of
overlapping actin/myosin
what is the M-line in muscle
bulge in centre of myosin filaments
What is the H zone of muscle
light zone in the center of the sarcomere that actin can slide into
factors that influence WHC
-shrinkage/swelling of a myofibrillar protein matrix
-pH
-salt
-phosphate
how does shrinkage and swelling affect WHC
contraction results in limited space for water
what is the isoelectric point of actomyosin
pH 5
when does maximum shrinkage occur
at isoelectric point due to maximum shrinkage
describe what happens as pH increases
more negative charges repel = swelling = increased WHC
describe what happens as pH decreases
negative charges repel = swelling = increased WHC
describe the effect of low pH and salt on WHC
Cl- in salt cancels out the positive charges and shrinkage occurs = decreased WHC
describe the effect of high pH and salt on WHC
Cl- cant interact with the negative charges so no shrinkage occurs = increased WHC
why are phosphate added to meat
improve WHC, control drip + improve yeild
how do phosphate act in meat
to dissociate actomyosin and solubilise myosin
-physically prevents leakage
-like jello that entraps water
what does solubilised myosin do to the viscosity
increases
what do phosphate do to pH
increase it
-negative charegs increase which increases swelling
what do short chain (ortho and pyro) phophates act as
buffers
-resists change in pH
what can long chain phosphates be
good antioxidants
