Study On The Effect Of Low-temperature Vacuum Storage Packaging On The Nutritional Quality Of Aquatic Products

Aquatic products arc an indispensable category in the diet structure of residents.They have high nutritional value and contain a wide variety of amino acids,fatty acids and vitamins,which can protect the human cardiovascular system.Because aquatic products are rich in watcr,protein,etc.,they arc easily to get spoilage for affecting by microorganisms or endogenous enzymes during transportation and storage,so the use of appropriate packaging methods is of great significance to protect the nutritional quality of aquatic products.At present,the quality of aquatic products is mainly evaluated by measuring protein,fat.content and total volatile base nitrogen,2-thiobarbituric acid,total colony and other physical and chemical indicators,but no effective evaluation technology has been established for functional ingredients.Therefore,it is of great significance to carry out research on the evaluation technology of small-molecule nutritional components,especially to analyze the changes of small-molccule nutritional substances under different packaging conditions,to protect the nutritional quality of aquatic products and improve economic efficiency.In this paper,salmon was selected as the research object,based on ultra performance liquid chromatography/tandem mass spectrometry(UPLC-MS/MS).the simultaneous analysis technology for 22 amino acids such as arginine and methionine,6 viamins such as folic acid and vitamin B1,and other 11 nutrients such as taurine acid in salmon muscle was established.The nutrients of salmon under three vacuum packaging conditions of-90 kPa,-45 kPa,0 kPa,and three different temperatures 0?,4?,and-20? were clarified.The main research and results are as follows.(1)A liquid chromatography tandem mass spectrometry method for 39 nutrients was established.The Declustering Potential(DP).Collision energy(CE),precursor ions and product ions of 22 kinds of amino acids,6 kinds of vitamins and 11 kinds of metabolic nutrients are defined.A Waters XBrige C18(3.5?m4.6×50 mm)column was selected.Acetonitrile(0.1%formic acid)/water(0.1%formic acid)was used as the mobile phase system.The analysis was completed in 18 min.(2)A pretreatment method for the extraction of 39 nutrients in fish samples was established.First,the extraction solvent was optimized,comparing the four extraction solvents of acetonitrile,methanol,water(containing 1%formic acid),methanol:water=1:1,the results showed that when methanol:water=1:1 was used as the extraction solvent,the extraction efficiency of most nutrient composition is the highest.Secondly,through the Plackett Burman(PB)test design,the five parameters of extraction solvent volume,vortex time,ultrasonic temperature,time and intensity are optimized,and finally the vortex time is determined as 3 min,ultrasonic temperature time and power are 20?,10 min and 60 W respectively.Finally,the extraction solvent volume(V)of the significant influence factor determined during the PB test was optimized by single factor,and the optimal extraction solvent volume was determined to be 2 mL.(3)Method evaluation of the built method was carried out in three aspects,range of linear,precision and accuracy.The 39 nutrients have a good linear relationship in the range of 5,10,20,50,100 and 200?g/L,and the linear correlation coefficients R2 are all greater than 0.99.The detection limit(MDL)of the method is 0.01?10?g/kg,and the limit of quantitation(MQL)is 0.05?20?g/kg,and the relative standard deviation is 0.42%?18.03%.The coverage,accuracy and precision of the method are better than most reported literature recently.(4)The nutrient content of salmon meat under different packaging and storage conditions was determined by the established method,and the concentrations of nutrients in salmon samples under different storage temperatures and different packaging conditions were obtained.Through the principal component analysis and orthogonal partial least squares analysis,the effects of different storage temperatures,degrees of vacuum packaging and storage time on the nutritional composition of fish were studied.The results showed that,when the packing condition was 0? and 90 kPa,the nutritional contents of salmon muscles decreased rapidly within 0-4 days,and the contents of inosine,histidine,and glutamic acid decreased significantly.On the 4th day,the concentrations of 7 nutrients,cysteine,alanine,astaxanthin,2'-deoxyuridine,adenine,guanosine,and L-iditol decreased below the detection limit.4-8 days,folic acid,vitamin B2,cytosine,vitamin B3,inosine,serine,aspartic acid,?-aminobutyric acid,histidine,arginine,2-hydroxyadenine,11 nutrients changed obviously.On day 8,the concentrations of 1-methyladenosine and cytidine fell below the detection limit.8-12 days,inosine,?-aminobutyric acid,vitamin B2,glutamic acid,arginine,pyroglutamic acid,2-hydroxyadenine,histidine,serine,aspartic acid 10 kinds of nutrition contents changed significantly.Low temperature storage combined with vacuum packaging is beneficial to the maintenance of nutrients.When the storage time is the same,as the temperature decreases and the vacuum increases,the loss of nutrients also gradually decreases.However,-20? freezing storage will destroy two nutrients,cytosine and ?-aminobutyric acid.Since the most common fresh-keeping period for salmon is 8 days,the nutritional analysis was carried out when 8 days of storage was selected.The results showed that under the packaging condition of-20? and 90 kPa,vitamin B2,4-guanidinobutyric acid,lysine,asparagine,and isoleucine in salmon these 5 nutrients have the highest content,which is most beneficial to the maintenance of nutrients.