Study On Quality Improvement Of Typical Raw Meat Based On Surface Humidity Control And Physical Field Synergistic Quick Freezing/thawing

Freezing has been a common method for preserving raw meat and has been used on a commercial scale to extend its shelf life for over 140 years.Despite the convenience offered by freezing,it still has many drawbacks,such as excessive juice loss,severe wrinkling,nutrient degradation,and color change.Frequent thawing can also lead to permanent structural damage,loss of nutritional value,and color change.Therefore,this study investigates the effects of a novel infrared meat surface humidity regulation technique,magnetic field synergistic freezing technique,electrostatic field thawing technique,and alternate infrared microwave thawing technique on the quality of raw meat throughout the freezing/thawing process.Beef shank,pork tenderloin,chicken breast,and hairtail were used as research subjects.Finally,the processing conditions of each process were optimized to obtain the best freezing/thawing parameters to improve the product quality.The study further clarifies the influence of each freezing/thawing process on the quality of different types of frozen fresh meat to provide theoretical and data references for the relevant industries.The main findings and conclusions of the study are as follows:(1)To mitigate the losses incurred during the thawing process of frozen raw meat,a novel infrared meat surface humidity regulation technique was employed as a pre-treatment for fresh meat.This study investigated the impact of different IR surface humidity control treatment times on various quality parameters of raw meat,including thawing losses,cooking losses,moisture content,low field NMR,color,p H,texture and TBARS.Results indicated that the thawing juice losses of frozen beef,pork and chicken were reduced by 51.48%,63.50% and77.22% respectively when compared to unregulated frozen products,while no significant differences were observed for hairtail.Although all thawed frozen raw meat samples exhibited reduced hardness compared to fresh samples,the textural properties of IR-treated raw meat were found to be more similar to those of fresh meat samples.The color of the infrared treated samples after thawing was closer to that of the fresh samples,except for hairtail,and the TBARS values of the IR-treated meat were lower than those of regular frozen meat products.Based on a comprehensive assessment of raw meat color,texture,thawing loss and TBARS,it was determined that infrared heating at 40°C for 150 s,120 s and 120 s resulted in the best quality frozen beef,pork and chicken products,respectively,while no significant changes were observed in the quality of surface humidity regulated frozen hairtail.(2)To further enhance the quality of frozen meat,the static magnetic field freezing technology was employed during the freezing process of fresh meat under the optimal surface humidity control conditions obtained in content(1).The effects of magnetic fields with different strengths(0,2,4,6,and 8 m T)on the freezing rate,ice crystal size,ice crystal distribution,and product quality after thawing were investigated.The results revealed that the freezing time of beef shank(6 m T),pork tenderloin(2 m T),and chicken breast(6 m T)decreased by 37.81%,35.27%,and 41.16%,respectively.Moreover,beef shank(6 m T),pork tenderloin(2 m T),and chicken breast(6 m T)had 77.00%,57.62%,and 54.00% lower thawing losses,respectively,compared to untreated frozen products.The low-field NMR analysis of the thawed samples indicated that,except for scallops,the static magnetic field-assisted freezing method was superior in maintaining the moisture state of the samples.The microstructure analysis also demonstrated that static magnetic field freezing reduced the degree of tissue damage in the frozen products.Notably,magnetic field freezing did not significantly affect the freezing rate and product quality of the hairtail.(3)Under the optimal conditions of surface humidity regulation obtained in content(1),this study investigated the effects of electrostatic fields on the thawing process of frozen fresh meat and the quality of thawed products.Results revealed that electrostatic field-assisted thawing significantly accelerated the thawing process,with thawing times of frozen beef,pork,chicken,and striped bass being reduced by 29.84%,46.93%,23.06%,and 38.31%,respectively,under a 30 k V/m electric field.Moreover,electrostatic field-assisted thawing effectively reduced the juice loss of the products during thawing,with defrosting losses of beef,pork,chicken,and fish under a 30 k V/m electrostatic field being reduced by 67.17%,48.29%,40.12%,and 36.25%,respectively.Samples thawed under the 30 k V/m electrostatic field exhibited stronger colour stability and colour variation and a more stable moisture state than ordinary thawed products.Additionally,the thermal stability of the proteins of the electrostatic field-assisted thawed products was better than that of the ordinary thawed products.Based on the above indexes,the optimal electrostatic field-assisted thawing electric field strength for different frozen meat products was determined to be 30 k V/m.(4)To address the problem of long thawing time in content(3),the effect of infrared and microwave alternate thawing(IR+MWT)on the thawing process and quality improvement was investigated under the optimal conditions of surface humidity regulation obtained in content(1).Results indicated that IR+MWT significantly improved the thawing speed of frozen raw meat,reducing the defrosting time of beef,pork,chicken,and fish by 83.83%,82.32%,85.57%,and 86.10%,respectively,compared to air thawing.IR+MWT also reduced the loss of juices during thawing of frozen raw meat,preserved the original color and textural properties of the product to some extent,and delayed the oxidation of lipids.However,unlike electrostatic field thawing,this part of the thawing method is not suitable for scale-up pilot production in terms of product quality improvement,despite its improvement in thawing speed.(5)As fish was not suitable for surface humidity regulation freezing in the previous study,this pilot study investigated the effect of surface humidity controlled magnetic field fast freezing and electric field fast thawing on product quality and myofibrillar protein properties using beef,pork,and chicken as raw materials.Results demonstrated that the combined treatment effectively reduced juice loss during freeze-thawing by 56.24%,59.12%,and54.24%,respectively,compared to normal freeze-thawing.The a* value of the combined treatment was closer to that of the fresh samples and had a smaller ΔE value than that of the normal freeze-thawing.The moisture state of the samples was more stable and the moisture distribution was more uniform after the combined treatment,which reduced the damage to the tissues during freezing-thawing.The extraction and characterization of myofibrillar proteins showed that the combined treatment had a higher proportion of α-helix and β-sheet,which better maintained the structure and properties of the protein.These pilot test results demonstrate that the synergistic optimization of multiple physical fields based on surface humidity regulation of meat can maximize the quality of typical raw meat quick-freezing/thawing.