Transcript Water Binding in Meat

Unit
Food Science
Problem Area
Processing Animal Products
Lesson
Water Binding in Meat
Student Learning Objectives
 1. Describe the importance of water to the
characteristics of meat products.
 2. Explain how postmortem changes affect
water loss in meat and identify techniques
applied directly after slaughter for reducing
water loss in meat.
 3. Explain the effects of non-meat additives on
the water-binding ability of meat.
Terms
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Actin
Calcium phosphate
Lactic acid
Myosin
pH
Postmortem
Rigor mortis
What is the importance of water to the
characteristics of meat products?
 Water contributes to many of the characteristics
of meat products.
 A. Approximately 65% of the weight of fresh
meat is from water which is directly related to the
protein content of meat. There is a constant
relationship of about 3.7 to 1 between water and
protein content in fresh meat.
 B. In all living animals, water contributes to
cellular integrity, meaning it provides the internal
pressure to keep cells from collapsing on
themselves. Water also provides lubrication for
muscle fibers, allowing smooth contraction and
release of muscle tissue.
 C. Protein binds with water in the cell because of
a polar attraction between water and protein
molecules. When an animal is slaughtered, the
ability of the muscle to retain water is reduced.
How do postmortem changes affect water loss in meat
and what techniques are applied directly after slaughter
for reducing water loss in meat?
 Postmortem changes will affect water loss in
fresh meat. Several techniques are applied after
slaughter to reduce water loss.
 A. Postmortem is a term used to describe the state of
the animal after it has been slaughtered. Once an animal
has been slaughtered, rigor mortis, or the stiffening of
body joints due to contraction of the muscle tissue,
begins after a few hours. Rigor mortis occurs in a dead
body because of the body’s inability to keep calcium ions
out of the muscle cells.
 Calcium ions promote the linking of actin and myosin,
two types of muscle fibers, which begin to contract and
are unable to release. The muscles will stay contracted
until the muscle tissue begins to decompose,
approximately 72 hours after death. Refrigeration and
rapid cooling can delay the onset of rigor mortis, but the
process will occur upon the thawing of the carcass. Meat
is generally considered to be more tender if prepared
after rigor mortis has passed.
 B. Most of the reduction in water holding capacity of
muscle is due to a decrease in the pH of the muscle.
pH is a measurement of the acidity or alkalinity of a
substance. The final water-binding ability depends
on the rate and extent of the pH drop. When the pH
drops rapidly during the conversion of muscle to
meat (slaughtering), a lower water-binding capacity
results.
 C. The lowered pH is due to an accumulation of
lactic acid, a product of glycogen metabolism, in
the muscle of the animal. The lactic acid becomes
concentrated in the muscle because the circulatory
system, inactive after slaughtering, is unable to
remove it.
What effects do non-meat additives have on the water-binding
ability of meat?
 A. The loss of water from the muscle after slaughter can be
reduced by slowing down the production of lactic acid. Lactic
acid production can be reduced by decreasing the
temperature of the carcass and by using an additive to inhibit
water loss.
 Salt and calcium phosphate are two common substances
that are used as meat additives which promote water
retention. Both of these cations (substances with a negative
charge) increase the water-holding capacity of meat by
neutralizing positively-charged ions that compete with water
molecules for protein attachment. By neutralizing the
competing ions, the water is allowed to bind with protein
molecules, resulting in water retention and decreased water
loss.
Review/Summary
 What is the importance of water to the
characteristics of meat products?
 How do postmortem changes affect water loss in
meat and what techniques are applied directly
after slaughter for reducing water loss in meat?
 What effects do non-meat additives have on the
water-binding ability of meat?