Study On The Key Technology Of Quality Control For The Muscle Of Crisped Grass Carp

There are four domestic Chinese carps,and the grass carp(Ctenopharyngodon idellus)is one of them.After only fed the certain weight of the grass carp with broad beans of a period of time such as 120 days,its muscle properties will change a lot,and the texture will be different from grass carp with tight and crisp,and very popular with consumers.In this experiment,the grass carp cultured in Nanchang was used as the research object,analysis the quality change of grass carp during brittle breeding process.And the effects of the the quality of fish for different processing methods.The key research findings as fallows:(1)Crisping of grass carp were collected on a regular basis,of muscle nutrition composition,edible quality,microstructure,structure characteristics and the changing rule of the flavor compounds were determined,to analyze its meat quality changes after feeding beans.From the results,we found is that after 175 days,water holdup and cooked meat percentage of the fishes was dropped 5.62% and 8.27% with one of in 0 days,there was significant difference between them(P<0.05).The total sugar content increased 5.3%,fat content dropped 0.63%,other nutrients also have certain movements trend.The hardness,adhesiveness,elasticity,gumminess,chewiness of grass carp in 175 days was significantly higher than that in 0 days(P<0.05).After the crisping breeding,the spacing between muscle bundle were increased,diameter coarsed,flavor components also have obvious changes.In the crisping breeding,the contents of nutrients and hardness all have different degrees of changes and these changes caused the brittle change of crisp grass carp.(2)Crisp grass carp were farmed in clean-water reservoir during 7-day short term starvation.The muscle nutrition composition,edible quality,color changes,structure characteristics and the changing rule of the flavor compounds were determined,to analyze its meat quality changes after 7-day short term starvation.The results showed that the moisture content and pH-value were significantly increasing(P<0.05).The ash content,total sugar and crude fat content were significantly decreasing(P<0.05),water holding capacity,cooked meat rate and crud protein content also has increasing and decreasing from 0 to 7 days.The whiteness was significantly increasing(P<0.05),and the hardness,resilience,gumminess and chewiness were significantly decreasing(P<0.05),the viscous has not changed obviously.The flavor change in the flesh of crisp grass carp during different short term starvation periods was evaluated by electronic nose.The results was analysised using principal component analysis(PCA)discriminant factor analysis(DFA)and its total contribution rate were more than 90%.So that the flavors of crisp grass carp who were farmed during short term starvation could be distinguished by electronic nose.So 7-day short term starvation has a greater influence on the muscle nutrition composition,edible quality and the structure characteristics of crisp grass carp,also could affect fishy smell of it.(3)In order to get a better killing method to improve the quality of fish death,we studying the effects of different killing methods on the quality of crisped grass carp.In the experiment,four kinds of killing methods were used to killing crisped grass carp.The pH,chromatic aberration,texture change,tissue fiber structure and flavor difference of each group were determined.The results showed that the pH value of the fish who was killed by locomotory bloodletting was the lowest compered with the other three ways(P <0.05),and the whiteness of the fish was the best.But the hardness was lower than that of the static bloodletting.The fish muscle fibers were the most regular by killed in locomotory bloodletting.The analysis of PCA and DFA can well distinguish the differences between several killing ways,especially the flavor components are no overlap of locomotory bloodletting with three other ways.There is that to say killing methods affect the smell of fish.It can be seen from the results that the locomotory bloodletting is a better way to killing crisped grass carp.(4)The technology used crisped grass carp as the research object,and studied the changes of sensory scores,total bacteria counts,TVB-N and TBA during chilled storage,and establish the shelf life prediction model.The experimental results show that the drip loss,TVB-N value and TBA value were all positively with the storage time,and the pH presents in a tend of increase after the rise,and the sensory scores were in the tends of increasing,and the total bacteria counts showed a rising trend after gently during chilled storage.When the TVB-N was used as the final point,the end of the shelf life is 8,14,16 days.At the same time,the shelf life prediction model can be used to predict the shelf life of 0-8 ? under the condition of TVB-N.(5)In order to study the spoilage-related microbiota of crisped grass carp fillets under refrigerated conditions,a combination of bacteria flora analysis and high-throughput sequencing techniques were used to analyze the crisped grass carp fillets stored at 4 °C.We extracted it's total bacterial DNA which be saved in 4? for 0 days and 14 days.And the V4 region of 16 S rDNA was amplified and the products were sequenced by high-throughput sequencing techniques to compare the structure and diversity of the flora.The results indicated that the total number of colonies increased gradually with the time of cold storage,and gradually became smooth after 6 days.And the trends of other selective microbial with the total number's trends in the same colony.The dominant bacteria on 0 days were Acinetobacter,Pseudomonas and Citrobacter.And the dominant spoilage bacteria on the 14 th days were Citrobacter,Lactobacillus and Serratia.