Study On Frozen Storage Conditions And Heating Methods On The Color,astaxanthin Content And In Vitro Antioxidant Activity Of Litopenaeus Vannamei

Color is one of the most important quality attributes of shrimp products,which will have a significant impact on the market value of the product.The color of shrimp depends largely on the content of astaxanthin in the external tissues.Astaxanthin not only provides bright color,but also has strong antioxidant activity.Therefore,this article discusses the changes in color,astaxanthin and in vitro antioxidant activity of different parts of Litopenaeus vannamei under different storage conditions,thawing methods and heating methods,and provides a theoretical basis for the development and quality control of prawn products.The main research contents and analysis results are as follows:(1)The distribution of astaxanthin in Litopenaeus vannamei was determined,and the freezing storage temperature of-20,-40 and-70?was studied for 0,14,28,60,90 and 120 d.Changes in indicators such as the color and astaxanthin content of Litopenaeus vannamei after thawing by different methods such as low temperature or ultrasound.The results showed that the astaxanthin content of shrimp meat,shrimp shell,shrimp head and shrimp tail in Litopenaeus vannamei was 12.69±0.83?g/g,55.85±1.84?g/g,62.62±0.56?g/g,117.31±3.22?g/g in order.When the freezing temperature is-70?,it has little effect on the dry consumption rate,color difference value and astaxanthin content of Litopenaeus vannamei.The L~*value of Litopenaeus vannamei under different frozen storage temperatures showed a downward trend,the a~*value showed an upward trend,and the b~*value did not change significantly;the astaxanthin content of each part of Litopenaeus vannamei showed a tendency to increase with the extension of the frozen storage time.Downtrend.Low-temperature thawing has the least effect on the thawing loss rate of Litopenaeus vannamei;it has a greater impact on the color;flow thawing has the least effect on the color difference and astaxanthin content of Litopenaeus vannamei,while ultrasonic thawing has the greatest effect.The results showed that Litopenaeus vannamei was frozen and stored at-70°C and thawed by the flow thawing method,which had little effect on its color and astaxanthin content.(2)To explore the effects of color,astaxanthin and in vitro antioxidant activity of Litopenaeus vannamei during boiling.The parameters of CVS were determined by measuring the standard color card using computer vision system(CVS)and colorimeter.During the heating process the color was continuously measured.The astaxanthin content and DPPH free radical scavenging rate,ABTS free radical scavenging rate and hydroxyl free radical scavenging rate during boiling were determined,and then the correlation was analyzed.The results showed that CVS could replace the colorimeter to determine the color change of continuous heating.During the heating,the values of L~*,a~*and b~*increased in the first 300 s and then after 360 s,the values of a~*,b~*had non-significantly change.L~*values decreased.At300 s,the content of astaxanthin reached the highest level,and then decreased.With the extension of heating time,the ability of Litopenaeus vannamei to scavenge DPPH free radicals increased.The hydroxyl radical scavenging rate and ABTS free radical scavenging rate increased first and then stabilized.In the 300 s,the values of L~*,a~*,and b~*were highly correlated with astaxanthin content and free radical scavenging rate,and the correlation coefficient was greater than 0.7.CVS could replace the colorimeter to continuously measure the color of the shrimp during the heating process,and the color value was highly correlated with the astaxanthin content and free radical scavenging rate.(3)Frying,air fryer and microwave heating were used to study the moisture content,color,astaxanthin and its antioxidant activity of various parts of Litopenaeus vannamei.The results showed that under different heating methods,with the extension of heating time,the moisture content of shrimp tails lost the most serious.During the microwave heating process,with the extension of the heating time,the L~*value of the shrimp first increased and then stabilized,the a~*value and b~*value first increased and then decreased.During the frying heating process,the L~*value and a~*value first increase and then decrease,and the b~*value increases and then stabilizes.In the air-cooking process,with the extension of heating time,the value of L~*first increased and then decreased,while the values??of a~*and b~*first increased and then stabilized.Before the heating time is 150 s,microwave heating can significantly enhance the antioxidant activity of astaxanthin in Litopenaeus vannamei.In the air-cooking process,the antioxidant activity of astaxanthin in shrimp meat showed an upward trend,and the antioxidant activity of shrimp shells and shrimp tails was the highest at 240 s.During frying and heating,the antioxidant activity of astaxanthin gradually decreases.Comprehensive analysis shows that when the microwave heating time is controlled within 150 s and the air cooking time is controlled within 240 s,the astaxanthin content and antioxidant activity of Litopenaeus vannamei are the best.