Effects of temperature fluctuations on the meat quality and muscle microstructure of frozen beef

Temperature fluctuation during storage and distribution of frozen foods has been a major concern in the frozen food industry. Recrystallisation of ice due to fluctuations in storage temperature can induce microstructural modifications of meat products, leading to irreversible cell and tissue damage, degrading the quality of frozen meat during storage. To explore the effects of temperature fluctuation on the quality of frozen beef, four experimental groups were used in this study: storage at a constant -18 +/- 0.1 degrees C, and fluctuations between -18 to -17 degrees C, -18 to -15 degrees C, and -18 to -13 degrees C. The parameters analysed were drip loss, colour, muscle fibre morphology, pore distribution, and Pearson correlation coefficients. Experimental results showed that, with an increase in temperature fluctuation, the rate of drip loss increased, redness (a*) decreased, yellowness (b*) increased, while chroma (C*) expressed negative correlation. Computed Tomography scans showed that with the increase in temperature fluctuation, the fibre structure of meat gradually collapsed, porosity increased, and the pore volume increased steadily. The number of pores, however, demonstrated a decreasing trend. Scanning electron microscopy showed that increasing temperature fluctuation damaged the dimensional structure of the fibre and increased the pore diameter. Pearson correlation coefficients showed that porosity, pore volume, and pore diameter were significantly correlated to each other, which were also correlated to drip loss, a*, and b*. The structural changes due to temperature fluctuations affect the colour and final meat quality of frozen beef. (C) 2019 Elsevier Ltd and IIR. All rights reserved.