Effect of freezing as pre-treatment prior to pulsed electric field processing on quality traits of beef muscles

Abstract

The purpose of this research was to study the effects of freezing as pre-treatment prior to pulsed electric field (PEF) on the quality of beef semitendinosus muscles. Fresh and frozen-thawed samples were treated using square -wave bipolar pulses at electric field strength 1.4 kV/cm, pulse width 20 μs, frequency 50 Hz and total specific energy 250 kJ/kg. PEF caused significant microstructural changes of meat tissue compared to freezing. Combined freezing–thawing and PEF resulted in improved tenderness indicated by reduced shear force, but not PEF alone. PEF significantly increased purge loss but not cooking loss. A two log-unit increase in aerobic microbial counts during log phase of frozen-thawed PEF-treated samples was positively associated with increased purge loss. PEF itself did not affect the ratios of polyunsaturated/saturated fatty acids and omega 6/omega 3 nor the free fatty acid profiles. Freezing with and without PEF greatly affected the volatile profile of meat. PEF treatment provides an alternative to mechanical, thermal and enzymatic cell disintegration of animal raw materials, providing a short duration (milliseconds) and energy efficient treatment. In this study, the possible relationship between freezing prior to PEF and changes in beef tissue microstructure that influence storage stability and safety was investigated. The results of this study contribute toward understanding how PEF induced changes in beef microstructure influence the important quality attributes of beef. • PEF treatment resulted in microstructural changes in meat tissue. • PEF had a positive effect on shear force of frozen–thawed samples after storage. • PEF treatment had no effect on PUFA/SFA or on n6/n3 ratios. • Free fatty acid profile of beef samples was unaffected by PEF treatment. • PEF treatment decreases oxidative stability of frozen–thawed meat.