Meat Preservation by Dehydration Processes

a b i l i t y of water in the food t o a l e v e l at which there is no &nger
from mi c robi e l growth and, i n sor doing, t o lower t h e w ~ t e rem t e n t with
a view t o mfnimiaing r a t e s of biological, chemical and physical processes
which l e ad t o meat d e t e r i o r a t i o n and subeequent a p o i l a ~ eo r rejection.
The a v a i l a b i l i t y of water f o r microbial growth and chsmiaal deter5arntion
is determined not only by the t o t a l water content but also by the nntnre
of its binding t o s p e c i f i c polar and non-polar s i t e a and t o ione in ~nd
around meat piecee, and through capillary condensation end oemotic
pressure of diesolved s o l u t e s l i k e s a l t , The more strongly bound. the
meat-water is, the less available it i a t o p a r t i c i p a t e in chemical
reactions or support the growth of micro-organisms. The proportion of
total meat-water available for theae d e t e r i o r a t i v e reactions fa
indicated by the water a c t i v i t y , uaually abbreviated as a . w It is nn
inverae measure of how strongly water is bound, and hence of the
r e l a t i v e biochemical a o t i v i t y of water i n the meat. The quality and
s t a b i l i t y of dehydrated meats are thus related t o the reduction af nv
%
in these products, showing t h a t dehydration is, indeed, preservntion
by' aw reduction.
Water a c t i v i t y (a ) is defined ae the r a t i o of vapour presanre of w
water i n the meat(^ ) to the vapour prasaure of pure water (P 1 nd the
m W
Chapter If,