Abstract:

Impact of refrigerating failure during frozen logistics on the quality and texture of yak meat was simulated using
refrigerating failure test for yak M. Longissimus dorsi muscle at various time points. Thawing loss percentage, cooking
loss percentage, pH value, thiobarbituric acid (TBA) value, chromaticity parameters, elasticity and chewiness of the tested
samples were measured and the microstructure of muscle fibers was observed with microscope. With the extension of
refrigerating failure time, extremely significant increases in thawing loss percentage, cooking loss percentage, L* value and
b* value (P < 0.01) were found, while extremely significant decreases in a* value and elasticity (P < 0.01) existed. The pH
value and chewiness significantly decreased (P < 0.05). TBA value significantly increased (P < 0.05). In addition, muscle
fibers displayed larger gaps and they were broken down to a larger extent. The distribution of muscle bundles and the space
left by ice crystals tended to be more irregular and larger, respectively. Furthermore, high correlation between refrigerating
failure time and indices relevant to the quality and texture of meat was observed. Therefore, it was indicated that the time of
refrigerating failure played a very important role in affecting the quality of yak meat and the harmful effect of temperature
fluctuation induced by refrigerating failure on meat quality should be avoided.

Key words: yak meat, refrigerating failure, quality, frozen logistics