| Penaeus vannamei Boone is a kind of aquatic products which is delicious, richnutrition and high economic value. However, the general testing method to the quality ofshrimp is unable to meet the requirements of our fast-paced life. The test methods of specialcan achieve rapid and non-destructive purpose, so it has become a new direction ofdetection technology. Therefore, this topic researched the shrimp from physical, chemicaland sensory properties, compared the quality changes during different storage, and analyzedthe model of freshness. The main content was as follows:1The stress relaxation of shrimp was tested by TA-XT2i texture analyzer, thecompressive deformation was30%, and testing probe was P50cylindrical probe. the speedof probe dropping, testing, and returning was1mm/s and testing time held100s, dataacquisition rate was500Hz. Based on quasi-static compression characteristics of shrimp,the Burgers model was presented on its non-linear viscoelasticity character, the Burgersmodel was better fit to the testing results, determination coefficient was greater than0.99;the stress relaxation time τ1, τ2of shrimp obviously changed in different temperaturestorage, they indirectly indicated the change of structure and quality of shrimp. Therefore,the theoretical basis was provided for the nondestructive testing quality of shrimp.2Based on sensory evaluation and TVBN of shrimp, combined with its texture, color,water-hold capacity detection, the quality change of shrimp was researched under4℃,﹣3℃and﹣26℃storage. The results showed that the sensory score of the3groups weregradually decreased. The TVBN values were on the rise with the extension of storage time,the samples of4℃deteriorated on the fifth day, and the samples of﹣3℃deteriorated onthe thirtieth day, however, the samples of﹣26℃were not beyond the second standard atthe end of the experiment; Under the three storage temperature, the water-hold capacity ofshrimps declined, the4℃samples lost more water and the﹣26℃lost the least. Thetexture properties of hardness, elasticity, chewiness, plastic viscosity and shear force weredropped at the end of the experiment. The value of L*, a*, ΔE*and C changed obviously,b*and h was not significant. The gloss of the samples obviously decreased in4℃,﹣3℃storage, however,﹣26℃samples was not significant, compared with the original within60days.3The samples were packed under vacuum, stored at different temperature (4℃,﹣3℃and﹣26℃), and the changes of physical index, TVBN value and sensory characteristicswere analyzed. The results showed that the vacuum packaging improved sensory qualitycompared with the control group; and vacuum packing obviously inhibited the growth of the TVBN, extended the quality of the shrimp. But some anaerobic bacteria could grow andproduce lactic acid in vacuum condition, lactic acid could lead to shrimp meat nutrition lostand water-hold capacity decreased. Compared with vacuum group and control group, onlychewiness, L*, a*, b*,ΔE*and C value were significant difference (P<0.05) under4℃storage. The hardness, adhesive viscosity, elasticity, chewiness, a*, ΔE*and C wassignificant difference (P<0.05) between vacuum group and control group under﹣3℃storage. However, the texture and color properties were not significant change under﹣26℃.4The correlation of texture, color and TVBN was analyzed, and the multipleregression method was used to establish different model to predict the shrimp quality. Thedetermination coefficient of texture prediction model was0.903, the result was good. Onlya little samples’ relative error reached10%or more; the determination coefficient of colorprediction model was0.831, the relative error of the other group of samples was bigger,most under20%; combined with texture and color to establish prediction model, thedetermination coefficient was0.825. All of the three models can evaluate shrimp quality,and the method was quick, easy. So the texture and color properties of shrimp could beused to predict the freshness changes during storage. |
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