Effects of Microwave Heating on the Quality of Crayfish

To reveal the potential application of microwave in the thermal processing of crayfish,the effects of microwave heating with different power densities on the qualities(color,texture,shelling integrity,mass loss,etc.) of crayfish were investigaled by the thermal imaging analysis,photographic image analysis,texture and shelling integrity analysis and sensory analysis,etc.. The results showed that the temperature and shell color of crayfish were non-uniform during microwave heating,but the uniformity could be improved by increasing the heating time or microwave power. There was no significant difference between the appearance scores of crayfish heated for 4.5 and 5.5 min at 5 W/g and those boiled with water for 4.5 and 5.5 min. However,the mass loss and moisture loss of crawfish increased with the power density and time of microwave heating,and thus affected the texture,shear properties,expressible moisture and taste of crayfish tail. There were different correlations between the taste of crayfish tail and the texture or shear properties for the microwave heating with different power density. Among them,the taste of crayfish tail was positively related to the surface hardness,compactness,moisture content and expressible moisture of crayfish tail,and negatively related to the shear force and shear energy of crayfish tail. Furthermore,the crayfish tail heated for 3.5 min at 3 W/g had the highest taste score and no significant difference with the crayfish boiled for 3.5 min,but it was more difficult for the crayfish heated by microwave in non-aqueous environment to shuck and keep moisture than boiled crayfish,and thus the tail shape and skin color of the former were worse than the latter. Although the value of L^* and b^* of crayfish tail increased with the increasing of microwave heating time or power density,the value of a^* of the crayfish tail decreased and the ratio of intact tail did not improve significantly. In a word,microwave had potential application in the thermal processing of crayfish,but it also exposed some shortcomings.