Abstract:

This study was designed to explore the effects of freeze-thaw cycles (0, 1, 3, 5 and 7 cycles) on quality
characteristics of pork longissimus muscle (LM). The changes in eating quality, full textural properties, fat oxidation
(thiobarbituric acid-reactive substances, TBARS), and sarcoplasmic protein and total protein contents of repeatedly frozenthawed
pork were analyzed. The results showed that with an increase in the number of freeze-thaw cycles, thawing loss (TL),
pressurized water loss rate (WL) and cooking loss (CL) increased significantly. TL, WL and CL increased to 13.24%, 36.77%
and 31.77%, respectively after the seventh freeze-thaw cycle; L* and b* values increased to 58.46, 13.25, respectively, and
a* value decreased to 11.68. pH and shear force (SF) increased at the initial stage and then decreased. TBARS significantly
increased with increasing number of freeze-thaw cycles. The contents of sarcoplasmic protein and total protein decreased
during freeze-thaw cycles. All these results demonstrated that freeze-thaw cycles decreased the meat quality of pork muscle
significantly and this effect was positively related to the number of freeze-thaw cycles.

Key words: freeze-thaw cycle, pork, meat quality