Effects Of Low Voltage Electrostatic Field On The Quality Characteristics In Prepared Beef Steak During Freezing Process And Mechanism Analysis

Prepared beef steak is a kind of prefabricated meat product that is usually stored and transported at-18 ?.It is favored by more consumers as its convenience,high added value,and balanced nutrition.However,the traditional freezing method will make the texture and juiciness of the product deteriorate after thawing.In order to improve the quality deterioration,this research applies the new physical technology of Low Voltage Electrostatic Field(LVEF)to the frozen steak.Firstly,the effects of Low Voltage Electrostatic Field-assisted Freezing(LVEFF)on the water hold capacity and texture characteristics of the steak under different layer spacing conditions were explored;then,the effects on the muscle microstructure and myofibrillary protein were analyzed.The changes were studied to clarify the potential mechanism of LVEFF to improve the quality deterioration of steak;finally,LVEF was combined with commercial antifreeze(4%sucrose + 4% sorbitol)to influence the quality of steak to get a better improvement effect.This research will provide a theoretical basis for the application of LVEF in frozen storage and transportation of steaks.(1)This chapter aims to explore the influence of LVEFF on the water retention and texture characteristics of the prepared steak under different layer spacing(10 cm,20 cm,30 cm,40 cm).The freezing curve results show that: LVEF treatment can significantly reduce the freezing time of steaks(P < 0.05),and the LVEF treatment with a layer spacing of 30 cm(LVEFF-30)has the best effect,and the improvement efficiency is 29.8%.And compared with the air freezing(AF)group,the pressure loss and thawing loss of the steak were significantly reduced(P < 0.05),which were 7.99% and 1.45%,respectively.The results of this chapter show that compared with AF,LVEFF can effectively reduce the juiciness and texture loss of steak during freezing.(2)This chapter aims to explore the effect of LVEFF on the microstructure and myofibril protein structure of steak muscles,and to clarify its potential mechanism for improving the quality deterioration of steak.Scanning electron microscopy(SEM)and transmission electron microscopy(TEM)results show that: LVEFF can improve the compactness of muscle fibers and maintain the complete structure of the sarcomere;in addition,the content of carbonyl and total sulfhydryl groups,raman spectra,and fluorescence spectra analysis shows that: LVEFF can significantly reduce the changes in the primary,secondary and tertiary structure of myofibrillar protein.The results of this chapter show that LVEFF can alleviate the microstructure damage and the structural changes of myofibril protein during the freezing process of steak.(3)This chapter aims to explore the effect of LVEFF and commercial antifreeze on the quality of conditioned steak.Observation of the morphology of ice crystals in muscles found that compared with AF,LVEFF synergizes with antifreeze to promote the formation of smaller and uniform ice crystals.It also prevented the conversion of difficult-flowing water to free water to the greatest extent,and significantly reduced the pressure loss,thawing loss,and cooking loss of the prepared steak(P < 0.05),which were 8.83%,1.69%,and 7.61%,respectively.The research results in this chapter show that LVEFF and commercial antifreeze can effectively improve the quality deterioration of cooked steak.