The effect of freezing rate, frozen storage time and thawing methods on the concentration of thymosin proteins in pork meat
Proteins are the most important ingredients in meat. They are found in meat
in different forms and with different functions. Thymosins are small proteins
present in many animal tissues, with molecular weights of 1000–15000 Da. The
technological processing of meat causes changes in the amount and shape of
the basic ingredients. During the freezing of meat and its storage in the frozen
state, various chemical reactions take place causing changes in the proteins. The
aim of this paper was to examine the influence of the freezing rate and thawing
methods on the changes and behaviour of thymosin proteins in pork meat (M.
longissimus thoracis et lumborum) during storage. Protein analyses were performed
using capillary gel electrophoresis (CGE) and the SDS-MW Analysis Kit (Beckman
Coulter). The meat samples were frozen at 10 different rates (from 0.23 cm/h
to 1.43 cm/h). The samples were tested at different times during 60 days of
storage at -20oC (after 1, 15, 30, 45, 60 days). Before the analysis, the samples
were thawed in the refrigerator, at room temperature and in the microwave.
After one day of storing frozen meat samples, the relative concentration of
thymosin was less than 1% in all tested samples. During 60 days of storage,
most samples had a slight increase in the relative concentration of thymosin. The
highest relative concentration of thymosin after 60 days of storage (1.67%) was
recorded in a meat sample that was frozen at a rate of 1.10 cm/h and thawed in
a microwave oven.