Effects Of Different Freezing Methods And Complex Cryoprotectants On The Quality Of Conditioned Steaks

Nowadays,conditioned steaks are popular among consumers and have a good development prospect due to its advantages of convenient consumption and balanced nutrition.In the market,conditioned steaks are mainly sold by direct freezing.However,at present,the meat products in our country are faced with many problems,such as high juice loss rate,short shelf life,restricted circulation and sales in different regions,and so on.In order to solve the problems of juice loss and protein denaturation caused by long-term storage,conditioned steaks were taken as the research object to further optimize the ketone recipe of quick freezing liquid,explore the influence of different freezing methods on the quality of them and optimize the formulation of anti-freezing agent.At the same time,the effects of combined technology of quick freezing and cryoprotectants on the quality of conditioned steaks were deeply discussed to provide some theoretical data for the freezing of conditioned steaks.The main research contents are as follows:1.The effects of different freezing methods on the quality of conditioned steaks during storage were studied.The effects of refrigerator freezing,immersion freezing(20%ethanol,21%propylene glycol,4%sodium chloride)and plate freezing on the quality of conditioned steaks at-30?were evaluated in this paper.In this study,conditioned steaks were divided into three groups and frozen in three different freezing methods before measuring the freezing curve and freezing rates of the samples.Water retention(juice loss,thaw loss,cooking loss),color difference,pH,TBARS,TPA,shear force and the micro-structures of samples were measured and observed.The results showed that the color,tenderness,shear force and water-holding capacity of conditioned steaks after immersion freezing treatment were significantly better than those in the refrigerator freezing group and plate freezing group(P<0.05).The freezing rate of immersion freezing group was the highest while the TBARS values of the immersion freezing group were the lowest in the three groups(P<0.05).2.The study was designed to obtain the optimal immersion solution formulation for conditioned steaks.In this project,ethanol,betaine,propanediol and sodium chloride were used.The L9(3~4)orthogonal experiment was conducted on the basis of single factor experiment,and the freezing point,viscosity ratio and juice loss rate of the conditioned steaks were measured before obtaining the best immersion solution formulation.In the meantime,color values,juice loss rate,TBARS values and shear force of conditioned steaks were measured.The results showed that the optimal immersion solution formulation was a multi-variable freezing fluid system consisting of 28%ethanol,10%betaine,8%propanediol,4%sodium chloride and water.The absolute value of freezing point divided by the viscosity value reached 0.88,so it can be seen that the freezing effect was significant and the juice loss was low.Adopting immersion freezing,compared with refrigerator freezing and plate freezing,which has the best freezing rate.The processed steaks had significant advantages in colors,TBARS value,juice loss and shear force.3.The study was designed to develop new functional cryoprotectants suitable for conditioned steaks and trehalose,polydextrose and xanthan gum were selected as the main ingredients of cryprotectants.On the basis of single factor,the formulation of cryoprotectants was optimized by orthogonal test and the juice loss rate and hardness of conditioned steaks were taken as comprehensive evaluation indexes.The optimum cryoprotectants formulation was determined as follows:1.8%trehalose,3.3%polydextrose and 0.5%xanthan gum.Results showed that adding cryprotectants could reduce the freezing point of conditioned steaks significantly.Moreover,the water retention,texture and color of the conditioned steaks with the new antifreeze agent group were better than those with the traditional antifreeze agent group(4%sorbitol+4%sucrose)and the control group.This indicates that the addition of new antifreeze agent is helpful to maintain the quality of conditioned steaks during long-term storage,which is beneficial to the industrial production of conditioned steaks.4.The effects of control group,new antifreeze agent group,immersion freezing group,new antifreeze agent combined with immersion freezing group on the quality of conditioned steaks during 3 months'storage were studied.The results showed that the conditioned steaks treated by antifreeze agent and immersion freezing had significant advantages in color,TBARS value,water holding capacity and shear force.The brightness and redness of conditioned steaks were significantly affected by four different treatments(P<0.05).The muscle fibers of the conditioned steaks in the new antifreeze agent combined with immersion freezing were tightly arranged.Therefore,in order to improve the quality of conditioned steaks,manufacturers can use immersion freezing combined with antifreeze agent to treat the conditioned steaks,which can help conditioned steaks maintain better quality in the later freezing process.