| Squids,one of the three marine biological species that has yet developed in the world,have great potential for development.Due to the short life cycle and high reproductive capacity,the reproduction of squid is showing a rising trend and accounts for a considerable amount of fishery.With the decline of the traditional fishery resources and the increasing demand of marine,squid has obtained more attention from all over the world as a rich source of animal protein.However,the organization structure of squid along with other factors would cause inconvenience to industrilizing production during the practical production process,which mainly reflected in the following aspects:(1)With the special structure of epidermis,endodermis and the muscle tissue,the skin would shrink and harden with the heat or cooking during the production of squid,which would affect the sensory quality of squid products and cause longitudinal contraction of muscles of dried squid;(2)Chromatophores released upon heating by pigment cell is the prinical part of color and luster of squid products.However color fading and browning of chromatophores can easily take place during the processing and storage,which would affect the sensory quality of aquid products as well as the development of squid processing industry.In this paper,protease enzyme was used to remove the squid skin,and the color stability of squid products during storage can be enhanced by adding color-protecting agents.The results and conclusions are shown as follows:(1)Through prolonging the time of enzymolysis,change rules of physical and chemical indicators of squid were analysed and compared under the function of papain protease and neutral protease.The result showed that papain protease presented high activity just at the early stage of reaction,leading a significant reduction of content of squids muscle protein(P<0.05).However,neutral protease showed a less effect on the characters of squid on the base of removing skin effectively.(2)The optimal conditions were determined by monitored the quality indicators including myofibril protein extraction rate,hydroxyproline content,hardness,a*value and sensory evaluation in hydrolysis process of neutral protease.The results showed that temperature of enzymolysis would significantly affect the quality of muscle including the hardness and redness.With the optimum conditions:a neutral protease dosage of 0.08%,a temperature of 45±2? and a reaction time of 13 min,the skin of the squid could be effectively removed,allowing the squid to present better texture and pink color.(3)The changes in the external appearance and color of squid using color-protecting agents such as erythorbate,chelating agents,pyrophosphate and tea polyphenol were studied.The results showed that the squid products control groups discolored during storage and this phenomenon can be postponed by adding erythorbate and chelating agents.Tea polyphenol could maintain the color stability by preventing the lipid oxidation.(4)The quality changes of squid treated with different color-protecting agents was studied under the effect of light.The results showed that the light could accelerate the decline of quality of the squid,and the b*value,TBA value and pH value increased significantly(P<0.05);a*value and the total pigment content declined significantly(P<0.05).Besides,the addition of antioxidants including erythorbate and tea polyphenol could maintain the quality of squid products to some extent during storage. |
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