Effects Of Salinity And Density On Meat Quality And Flavor Of Penaeus Monodon

In this study,Penaeus Monodon stocked with different salinities(0‰,15‰,25‰)or densities(100tail/m2,200tail/m2,300tail/m2)was used as the research object.New food analysis techniques,such as electronic nose,electronic tongue,scanning electron microscope,transmission electron microscope and transcriptome sequencing were used to studied the differences in nutritional composition,water holding capacity,texture,odor and so on,and analyzed the specific manifestations of these differences from the perspective of genes combined with transcriptome sequencing technology.It provides data support for the selection of suitable stocking salinity and density for the Penaeus Monodon,and it also provides the theoretical basis for the improvement of meat quality and flavor of Penaeus Monodon.The main findings are as follows:1.The basic nutrient composition,water holding capacity,sensory evaluation and texture characteristics were compared and the odor was analyzed by electronic nose and tongue.The results showed that when the stocking salinity was 25‰,all the indexes were superior to those of the other two kinds of salinities and the 25‰ salinity was conducive to improve the quality of Penaeus Monodon.When the stocking density was 100 tails/m2,the muscle quality of Penaeus Monodon was the best,but when the stocking density was 200 tails/m2,the quality of Penaeus Monodon could be guaranteed and also could improve its production and bring greater economic benefits.2.The determination of flavor amino acids,flavor nucleotides and volatile flavor compounds showed that the flavor and nutritional value of Penaeus Monodon muscle could be improved by increasing the stocking salinity appropriately.With the increased of the stocking density,it was not conducive to improve the muscle flavor of Penaeus Monodon,and its nutritional value also decreased gradually.With the increased of stocking salinity,the contents of total free amino acids,umami amino acids,sweet amino acids and essential amino acids,as well as the contents of AMP,IMP and GMP of Penaeus Monodon increased.A total of 37 volatile flavor substances were detected from three species of salinized prawns,including 15 alkanes and aromatic,10 alcohols,4 aldehydes,4 ketones,3 esters and 1 ether.The contents of total free amino acids,sweet amino acids,umami amino acids,essential amino acids,AMP,IMP and GMP showed the same trend with the increased of the stocking density what there was no significant change between M1 and M2,M3 was significantly lower than M1 and M2.A total of 45 volatile flavor substances were detected,including 23 alkanes and aromatic,8 alcohols,5 aldehydes,3 ketones,3 esters,2 phenols and1 ether.3.The microstructure of muscle was observed by scanning electron microscope and transmission electron microscope.It was found that with the increased of the stocking salinity,the muscle fiber bundles of Penaeus Monodon were arranged closer,the gap between the muscle fiber bundles were more less and smaller,the diameter of the muscle fiber bundles were more larger and the length of the sarcomere was more longer;With the increased of the stocking density,the compactness of muscle fiber bundle decreased,the gap increased and enlarged,and the diameter and length of sarcomere decreased.The change of the above indexes can explain the variation of water holding capacity and texture characteristics.4.By transcriptome sequencing,1298 differentially expressed genes were found in Y1 vs Y3 and 778 differentially expressed genes in M1 vs M3.All the differentially expressed genes were mapped to KEGG database,and the metabolic pathways related to this study were found to have amino acid metabolic pathways,energy metabolism pathway,osmotic regulation pathway,flavor substance metabolic pathway and nucleotide metabolism pathway and so on.It explained the gene regulation mechanism of the effects on meat quality and flavor of Penaeus Monodon of stocking salinity and density.