| Microplastic is particle which is smaller than 5mm in size.With the development of breeding mode,there are many problems at the sametime.The safety detection method of freshwater products has been done very well now,but there is no detection method which is suitable for microplastics in freshwater fish.Meanwhile,microplastic pollution of freshwater products has affected the quality and safety of food seriously.Therefore,the study takes different kinds of freshwater fish under different freshwater breeding modes as the research object.On the basis of previous research about microplastic in water field,we explored the method which is suitable for freshwater fish and other products in abundance,particle size,shape,color and other physical characteristics and chemical composition,which is the microplastic separation method of KOH digestion,and tested the freshwater aquaculture mode in different species of freshwater fish quality and flavor.It is expected to provide some basis for the pollution characteristics of microplastics in fresh water fish,fresh water aquaculture and quality and safety detection of fresh water products.The contents and conclusions of this study as follows:(1)In this paper,the method about KOH digestion was used to digest and extract of microplastics of freshwater fish,we found that there was no significant difference in microplastic abundance of grass carp.Carp and Aristichthys nobilis in breeding mode difference are remarkable.The abundance of microplastics of bighead was from low to high in order of reservoir,lake and pond.The abundance of microplastics of crucian carp from low to high in order which is lake,reservoir and pond.The results indicated that the microplastic pollution of pond mode of freshwater fish was the most serious and bighead carp and crucian carp were the suitable for indicator species of microplastic pollution.The results indicated that the pond mode of freshwater fish was the most serious in microplastic pollution and bighead carp and crucian carp were suitable for indicator species for microplastic pollution,the microplastics abundance of freshwater fish was form 6.89 to 12.2 grains every piece in lake,form 7.5 to 1.57 grains every piece in reservoir and form 6.33 to 36.00 grains every piece in pond.The results indicated that the microplastic pollution was the lowest in reservoir modes.The particle size of microplastic pollution in the bigheads and grass carps under the lake mode,the reservoir mode and the artificial intensive culture pond mainly concentrated in the range of form 100 to 500?m.Crucian carp prefers to feed on microplastics with small particle size,while bighead carp and grass carp prefer to feed on microplastics with larger particle size.Besides,in freshwater fish,fibrous microplastics are the main form,and colored and black microplastics are the most of all,The main ingredients are polycarbonate and phenolic resin.About the comparison of the microplastics abundance of different species of freshwater fish,the microplastics abundance of lakes from low to high were carp,grass carp and bighead carp respectively.The abundance of microplastics in the reservoir from low to high were carp,bighead carp and grass carp respectively and the bighead carp was similar to grass carp.The abundance of microplastics in the pond from low to high were carp,grass carp and bighead carp.It can be seen that among the three modes,bighead carp has the highest abundance of microplastics and the most serious pollution.(2)In order to explore the difference in flesh texture of different species of freshwater fish,the flesh texture of four species freshwater fish in breeding modes was measured by texture apparatus.It was found that the elasticity and masticability of bighead carp,grass carp,crucian carp and silver carp of four kinds of freshwater fish in lake were different significantly.The elasticity of bighead and grass carp was better than silver carp.Elasticity gradually decrease in order which is Bighead carp,Grass carp,Silver carp and Crucian.Masticability gradually decrease in order Bighead carp,Grass carp,Silver carp and Crucian.The elasticity and chewability of bighead carp were the best of all kinds of freshwater fish in junshan lake.There were significant differences in cohesion and adhesion of freshwater fish in reservoirs.The results indicated that the cohesion and adhesion of bighead carp and grass carp were the greatest in the reservoir aquaculture mode.The cohesion of silver carp was the lowest and the adhesion was the least.However,in the Julongwan pond mode,there was no significant difference in flesh texture characteristics among the four freshwater fish species.(3)To explore the difference of flesh texture of fresh water fish with different breeding modes,the flesh texture of four kinds of fresh water fish with three breeding modes was measured by texture apparatus.By comparing the three culture modes of silver carp,it was found that there were significant differences in cohesion and elasticity,and pond culture mode could improve the cohesion of grass carp and silver carp.Lake and pond culture mode can improve the chewability,elasticity and viscosity of bighead fish.The fish quality of cultured pond crucian carp was better than that of the other two modes.Lakes and artificial cultured ponds greatly improved the elasticity and cohesion of silver carp,and the cohesion and elasticity of reservoir were the worst.The cohesion of grass carp was the greatest in pond culture,but the cohesion was the least in reservoir culture.The fish of lake culture mode greatly improved the chewability,elasticity and viscosity of bighead fish,and the quality of fish of the other two modes was better,while the fish of the reservoir mode was the worst in these aspects.The abundance of microplastics in bighead fish will affect the hardness of fish.The chewability and elasticity of bighead fish are negatively correlated with the abundance of microplastics,the viscosity of bighead fish is positively correlated with the abundance of microplastics and the hardness of crucian carp is positively correlated with the abundance of microplastics.(4)In order to explore the difference of physical and chemical components of different species of freshwater fish,the physical and chemical indexes of four species of freshwater fish under three breeding modes were compared.The physicochemical components of four kinds of freshwater fish in three breeding modes were determined by the national standard method.It was found aristichthys bighead is a higher protein species than grass carp,Silver carp is a high fat variety and Carp is a high moisture species.Freshwater fish in Junshan Lake were significantly different in fat content,ash content and p H.Fat content gradually decrease in order which is crucian,Bighead carpand,Grass carp.Ash content gradually decrease in order Bighead carp,Silver carp,crucian and Grass carp.And p H gradually decrease in order Grass carp,Crucianand Bighead carp.The difference of content of water and fat between silver carp and crucian carp was significant.Water content gradually decrease in order Crucian carpand Silver carp.Fat content gradually decrease in order Silver carp and Crucian carp.In the pond aquaculture mode of Julongwan,there were significant differences in fat,moisture content and p H of different freshwater fish species.Fat content gradually decrease in order which is Silver carp,Crucian and Bighead carp.Moisture content gradually decrease in order which is crucian,silver carp and Bighead carp.And p H gradually decrease in order which is Bighead carp,Crucian,Silver carp,Cruciancarp and Bigheadcarp.Besides,Moisture content gradually decrease in order crucian,silvercarp and Bighead carp.And p H gradually decrease in order Bighead carp,Crucianand Silver carp.In order to explore the difference of flesh texture of different types of freshwater fish,the physical and chemical indexes of all kinds of freshwater fish under three breeding modes were compared.The physical and chemical components of four kinds of freshwater fish in three breeding modes were determined by national standard method.The comparison between basic physical and chemical indexes of crucian carp in breeding modes showed significant difference in fat content.Fat content gradually decrease in order which is lake fish,pond fish and servoir fish.Pond crucian carp compared with reservoir crucian carp is high protein and low fat variety.Reservoir carp is high in water content and low in advantage of fat content.There were significant differences in ash content,fat content,moisture content and p H value between the two breeding modes.Ash content gradually decrease in order which is Julongwan,reservoir.Moisture content gradually decrease in order which is reservoir fish and pond fish,fat content gradually decrease in order which is pond fish and servoir fish,p H gradually decrease in order which is reservoir fish and pond fish.The hardness of crucian carp was negatively correlated with the abundance of microplastics.(5)To study the difference of flavor substances of different kinds freshwater fish,the solid phase microextraction(SPE)and gas chromatography mass spectrometry(GC-MS)were used to detect the flavor substances of four kinds of freshwater fish in three kinds of freshwater aquaculture modes at the same time.It was found that alcohols,aldehydes and alkanes were the main flavor components of fish.The flavor of silver carp was the most abundant in the four kinds of freshwater fish,and the flavor of bighead carp was the least abundant in the four kinds of freshwater fish.The flavours of grass carp,bighead carp and crucian carp were the most abundant of the three breeding modes,and the flavours of silver carp were the most abundant of three aquaculture modes.(6)To understand different flavour compounds of freshwater fish in three breeding modes and using solid-phase microextraction and gas chromatography mass spectrometry instrument detected three kinds of flavour compounds of four kinds of freshwater fish in fresh water aquaculture model,through comparing the differences of freshwater fish flavor substances in different modes,the various types of compound breeding pattern detected a number of comparisons gradually decrease in order which is lake,reservoir and pond.The flavor substanceof fish in reservoir was the most abundant of these aquaculture modes,while the fish flavor substance in pond was the least abundant of aquaculture modes.Higher the abundance of microplastics in the freshwater fish,the fewer flavors the fish had.For grass carp,aldehydes,alcohols,alkanes gradually decrease in order which is pond,reservoir and lake.The alkane content of grass carp of three models was significantly different and the degree of reservoir and pond was significantly different compared with that of lake.Compared with the content of various flavor substances in crucian carp,aldehydes gradually decrease in order which is lake,reservoir and pond.Alcohol,alkane,acid gradually decrease in order which is reservoir,lake and pond.Ethers gradually decrease in order which is reservoir,pond and lake.Salts,esters gradually decrease in order which is pond,reservoir and lake.In the three modes,the aldehydes,alcohols,alkanes and acids are the most in the pond,while salts,esters and ethers are the most in the lake.For bighead,aldehydes gradually decrease in order which is lake,reservoir and pond mode.Alcohols and alkanes gradually decrease in order which is pond fish,reservoir fish and lake fish,and there was no significant difference in the content of flavor substances of various patterns bighead fish.Compared with reservoir,the difference of lake was significant,but the difference of pond was not significant.Compared with ponds,the difference of lakes was significant,but the difference of reservoirs was not significant.For silver carp,aldehydes,alcohols,olefins gradually decrease in order which is reservoir,lake and pond.Alkanes gradually decrease in order which is lake,pond and reservoir. |
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