Studies On Quality Assessment And Protein Indicators Of Freshness Of Coregonus Peled During Storage

Tianshan glaciers and permanent snow cover in Xinjiang area of 164 square kilometers,glacial water reserves of about 2 trillion cubic meters,accounting for 50%of the total glacier reserves,enjoy the"natural solid reservoir,"said.It is because of the special geographical environment in which Xinjiang is located that the aquatic products mainly based on the cultivation of cold-water fish have become an important breakthrough point for farmers to increase their income.Cold-water fish are rich in amino acids,unsaturated fatty acids,minerals and vitamins,especially the content of DHA and EPA,which are several times higher than other fish species,so the cold-water fish has been favored by consumers.The coregonus peled is one of the largest output varieties of cold-water fish farming in Xinjiang.For now,cold-water fish in Xingjiang have a good market.In order to improve the production efficiency,must expand the sales market,so the transportation is a vital link of cold water fish.Transportation is the key factor that decides the determination of the freshness of fish,for the determination of the freshness of aquatic products inspection in China mainly depends on the determination of physical and chemical indicators,inspection methods generally divided into sensory evaluation,physical inspection,chemical and microbiological examination,and the evaluation of the combination between the above methods.However,fish is rich in protein,and protein is also the most important factor in the corruption of fish and other aquatic products.In this study,the freshness of fish was determined by the change of fish protein.The difference of muscle protein during storage was searched by two-dimensional gel electrophoresis and the freshness indicator protein of fish was screened by proteomics.The aim of this study is to provide a new method for the detection of the freshness of cold-water fish,and to fully understand the correlation between the quality change mechanism of cold-water fish and the freshness quality.At the same time,this study is of great value for the rapid and objective evaluation of the freshness of cold-water fish and the processing of aquatic products.The main results are showed as follows:1.Through the evaluation method of freshness of aquatic products,the changing rule of fish quality during the storage of the coregonus peled was determined.TVB-N value,TMA-N value and total number of colonies can be used as an important index to judge the freshness of high white salmon during storage;PH value,TBA value,water holding capacity and sensory score can be used as reference indexes.The change of the freshness quality of the coregonus peled stored at different temperatures was analyzed.It is suggested that the shelving period of the coregonus peled at 4?is 7 days,and the shelf life at 0?is 10days.2.Muscle protein of the coregonus peled changed during storage,the content of myofibrillar protein,sarcoplasmic protein and muscle matrix protein decreased with the increase of storage time,but the content of alkali soluble protein showed an upward trend;The activity of myofibrin Ca²⁺-atpase activity and total sulfhydryl content decreased gradually with the extension of storage time.The surface hydrophobicity and carbonyl content of myofibrin were increasing with the increase of storage time.Comparison of different indicators of changes in temperature available,low temperature can effectively inhibit the oxidative degeneration of muscle protein.3.A two-dimensional electrophoresis system suitable for the coregonus peled muscle protein was established and optimized.The protein samples were prepared by acetone precipitation method,24 cm pH4⁷ IPG strips were used,the amount of sample was 1200?g,the amount of silver stain was 100?g,setting the focusing time to 400 v 16 h+1000 v 2 h and the equilibration time to 15 min.The coagulant dosage was 0.05 m L of ammonium persulfate and 2?L of TEMED.The concentration of 12.5%and silver nitrate staining.The establishment of this system can be used for the research of muscle proteomics research of the coregonus peled.4.The differential protein points were screened by using the optimized muscle two-dimensional electrophoresis system,and the spots were analyzed by MALDI-TOF-TOF mass spectrometry.Three protein spots were identified from 15 differentially expressed protein spots,which could be used as indicator of the freshness of the coregonus peled.After database searching,they were predicted to be L-lactate dehydrogenase,adenylate kinase family isozyme subtype,myosin heavy chain.