Research On The Influencing Factors And Pork Quality Of Thawing Process

Freezing is one of the most effective methods of preserving meat.Freezing processing can control the ambient temperature and inhibit the growth of bacteria,thereby extending the shelf life of frozen meat and ensuring the quality of meat.At the same time,the thawing process is considered an essential process of frozen meat before further processing or consumption.If the thawing method is not selected properly,it will have a significant impact on the quality of thawed meat,which will affect meat quality.This article studied that radio frequency thawing and traditional thawing(air thawing and water thawing)of frozen lean pork and explored the differences between the new technology(radio frequency thawing)and traditional thawing(air thawing and water thawing).Then researched the effects of pork sample sizes and sample placement distances on the temperature distribution of pork samples which were thawed by radio frequency.Lastly,the thawing factors affecting pork quality were investigated.Firstly,this chapter explored the effects of different thawing methods(radio frequency thawing,water thawing,air thawing)and end-thawing temperature(-1?,-4?)on pork ham quality,frozen lean pork samples(14×14×5 cm~3)in cuboid shapes were treated under radio frequency thawing(27.12 MHz),water thawing,and air thawing,respectively.The power of the radio frequency was 3 k W and electrode gap was 11 cm.Thawing time,temperature distribution,drip loss,cook loss,p H,color,thiobarbituric acid reactive substances(TBARS)value,total volatile base nitrogen(TVBN)value of tempered samples were evaluated for comparison.The results showed that:(1)When thawed to-4?,the highest temperatures of radio frequency,water and air thawed lean pork samples were 14?,15?and 13?(p>0.05).When thawed to-1?,the highest temperature of radio frequency,water and air thawed samples were 25?,17?and 14?(p<0.05).(2)When thawed to-4?,the qualities of lean pork of radio frequency,water and air thawing were not significantly different from fresh pork samples(p>0.05).When thawing to-1?,from the thawing method point of view,air thawing retains the most physiochemical properties of fresh pork samples except for a higher cook loss,lower p H thawing to-1?(p<0.05).The cook loss,TVBN and b~*values were significantly higher,p H and L~*values were lower than fresh samples(p<0.05)in water thawing to-1?.Meanwhile,the cook loss,TVBN and b~*was higher,and p H was lower than those of fresh values(p<0.05)after radio frequency thawing to-1?.(3)As the end-thawing temperature increased,the quality of thawed meat decreased.Therefore,-4?was selected as the suitable end-thawing temperature.When the end-thawing temperature was-4?and the thawing temperature was 18?,the quality of pork samples thawed by water thawing was the worst.The quality of pork samples thawed by air thawing was the best,but had the longest thawing time.The temperature distribution of pork samples of radio frequency thawing was more uniform,and the thawing time was fast.Secondly,this chapter explored the effects of different pork sample sizes and sample placement distances on pork quality,the whole meat(20×10×4 cm~3),equally divided into two blocks(10×10×4 cm~3),equally divided into four blocks(10×5×4 cm~3),and the two pieces placed at different placement distances(1,2,4 cm)were treated under radio frequency thawing.The power of the radio frequency was 1 k W and electrode gap 9 cm.Thawing time and temperature distribution were evaluated for comparison.Results showed that:(1)the whole pieces and dividing them into pieces(divided into two pieces and four pieces equally)had no significant effects on thawing rate and thawing time(p>0.05).When the whole piece was divided into two and four pieces evenly,the maximum temperature value of the upper surface increased from 5.0?to 13.4?.However,there was no significant difference(p>0.05).(2)The maximum temperature values of the adjacent area of the whole pieces,two and four pieces were 0.6,4.9 and5.0?,respectively(p<0.05).When thawing the pork samples with different placement distances by radio frequency,the maximum temperature value of the upper surface increased from 5.0?to 20.5?(p<0.05)and the maximum temperature values of the adjacent area with different placement distances(0,1,2,4 cm)were 0.6,13.5,13.4 and19.5?(p<0.05).When the placement distances were 1 and 2 cm,there had no significant effects on the temperature distribution of pork samples thawed by radio frequency(p>0.05).When the placement distances were increased to 4 cm,the sample placement distances had a significant effect on the temperature distribution of pork(p<0.05).(3)When thawing pork samples by radio frequency,the sample sizes need to be controlled within a reasonable range.With the same volume,the smaller the sample size,the temperature distribution was more uneven.When the samples were thawed by radio frequency,the overall temperature distribution without a gap is more uniform.The smaller the gap(1-2 cm),temperature distribution was more even.Lastly,the effects of thawing temperature(18,40?),methods(natural air thawing,forced air thawing,static water thawing and fluid water thawing)and freezing time(0,5months)on the moisture and color of pork lion(6×8×4 cm~3)were studied.The results showed that:(1)During 5 months of freezing storage,there was no significant difference in the thawing rate,thawing time,thawing loss,and b*value of pork(p>0.05)and the cooking loss,L*value,and a*value had significant difference(p<0.05).(2)When the thawing temperature was 18?,the thawing method had a significant effect on the thawing loss,cooking loss and color of the meat(p<0.05).The quality of lean pork lion samples thawed by water thawing was better than that of air thawed meat.(3)Under the same thawing method,the thawing temperature had a significant effect on the thawing loss,cooking loss,and L*and a*values of meat(p<0.05),and there was no significant difference in b*value(p>0.05).The increase of the thawing temperature resulted in increased thawing loss and cooking loss.(4)When the end-thawing temperature was10?and the thawing temperature was 18?,the static water thawing was better than the natural air thawing,and the thawing loss and cooking loss of pork samples thawed by water thawing are lower than air thawing.There was no significant difference in pork quality of static water thawing and fluid water thawing.However,the water consumption of fluid water thawing was more than the static water thawing.The higher the thawing temperature,the higher the thawing loss and cooking loss of the sample,and it is not beneficial to keep pork quality.