Study Of Different Thawing Methods And Storage Temperature On The Quality Of Squid

In this experiment,the basic nutrients and comparative analysis and nutritional value of different squids were studied.At the same time,the effects of different freezing temperatures(-18?,-28?and-60?)on the freezing and denaturation of muscles of three species of squids were studied.Variation of physical and chemical indicators on the quality of squid muscles as an effect of freezing for 150 days were determined,and select the suitable frozen storage temperature for squid preservation.Furthermore,the indices of three squids were determined under four different thawing methods,such as: low temperature thawing,ultrasonic thawing,flow thawing and hydrostatic thawing.physical and chemical indicators such as thawing loss,cooking loss,texture characteristics,pH value,TVB-N value,SSP value and other parameters were determined,also,comparison on effects of different thawing methods on the quality of squids muscles,and choose the best way to thaw the squids.Finally,studying the effects of different phosphorus and non-phosphorus water-retention agent on the squid.The research results were as follows:1.Squid is a seafood with low fat and rich in protein content.The protein is between 16.97% and 19.80%,and the fat is only about 1.01%-1.12%.Amino acid composition is balanced and reasonable with glutamic acid content in higher quantity in squids.The DAA/TAA% were 43.693%,43.192% and 43.763%,respectively,especially the glutamic acid content were 0.395%,0.481% and 0.446%,respectively.The content of polyunsaturated fatty acids in the three squids was the highest,especially the EPA+DHA content was 47.41%,56.71%,and 48.85%,respectively.The most abundant inorganic elements in the muscles of three species of squids are K,Na,Mg,Ca and Zn,which can be used as a good food source for human to supplement inorganic elements.2.Sensory indices,pH value and salt-soluble protein content of the three species of squids are showed different decreasing trends against freeze storage temperature,while the TVB-N value,TBARS value and K value showed different increasing trend with freeze storage temperature.In the early stage of storage,the fat oxidation in the muscle of the squids is more obvious,and the other indicators changed more slowly.But at the later stage of storage,the sensory indices and nutritional value of the squids changed significantly.Theorder of quality during storage is: Todarodes pacificus>Illex argentinus>Dosidicus gigas.The lower the temperature of frozen storage,the less obvious on quality change of squids and the better on storage effect.The quality of squids at-60? is better than-28? and-18?.Therefore,in the three different frozen temperature freezing processes,the quality order of the squid is:-18 ?<-28 ?<-60 ?.3.Different thawing methods have significant effects on squid muscles.Ultrasonic thawing was found to have a great influence on squid muscles,the thawing time is shorter,the thawing loss rate is high,and the TBARS value is low.Although low temperature thawing can maintain good quality,the thawing time is longer.There were no significant difference in time between hydrostatic thawing and flow thawing.In terms of the chewiness,flow hydrolysis method is better,and the thawing loss rate is relatively smaller,the TBARS value and TVB-N value also appeared to be the best for flow thawing method.Therefore,the flow thawing method can be used as the most suitable thawing method for squids.4.Different water retention agents have different effects on the water retention of squid.The addition of 0.2% sodium pyrophosphate and 0.3% sodium alginate resulted to higher moisture content,79.18% and 79.32% respectively.and the addition of 0.1%compound phosphorus water retention agent resulted to lower cooking loss rate,it is 1.79%.the centrifugal loss rate of adding 0.1% complex phosphate,0.2% sodium hexametaphosphate and 0.3% sodium tripolyphosphate(3.2%?3.0%? 2.8%)is lower than that of the control group(4.32%).The centrifugation loss rates of 0.1%,0.2%,and 0.3%sodium citrate and sodium chloride lower than the blank group are in the range of 3.5%-4.3%,respectively;and the weight loss rate after freezing by addition of 0.3% compound phosphorus water retention agent is 2.6%,the minimum is reached,and when the addition amount is 0.1% sodium citrate,the weight loss rate after freezing is 4.7%,and the effect is the best.In summary,0.1% sodium citrate can be used as a suitable phosphorus-free water retention agent for squid.However,studies have shown that sodium alginate has poor water retention effect on squids and it is not suitable for use in squids.