Study On The Migration Law Of Tilapia Fillets Under Different Processing Methods

Tilapia has become a favorite aquatic product trade object in the international market due to its characteristics of non-muscle spines,low breeding cost and suitable for processing.However,the development of domestic fishery further processing technology is relatively slow,and there have always been various technical problems,which greatly affected the competitiveness of China's tilapia products in the market.Therefore,it is necessary to strengthen the res earch on the further processing technology of tilapia,develop more high value-added products and realize product diversification,and at the same time pay attention to the research of tilapia processing and cooking technology and the development of leisure food,to strengthen the development of tilapia consumption market at home and abroad.In this study,ultra high performance liquid chromatography-tandem Orbitrap mass spectrometry combined with Lipid Search software was used to study the effects of fish salt mass ratio and curing time on free fatty acids and compound lipids in muscle of dry-cured tilapia fillets,and the effects of different heat treatment methods on muscle free fatty acids in dry-cured tilapia fillets.At the same time,the effect of using spices to eliminate nitrite in dry-cured tilapia was studied.In general,the migration rules of substances(free fatty acids,compound lipids,nitrite)in tilapia fillets under different processing methods were studied.The results show that:(1)Dry salting has important effects on food lipids.In this work,the reliability of Lipid Search software identification and its application to assess the effect of dry salting on the long-chain fatty acid profile of tilapia fleshes were studied by ultra-high-performance liquid chromatography-Q-Extractive Orbitrap mass spectrometry and Lipid Search software.Compared with the standard reference identification method,the Lipid Search software identification method was suggested to be a reliable identification method for long-chain fatty acid identification.During the dry salting process,tilapia fleshes with low flesh-to-salt mass ratios of 3-8 might have stable and similar fatty acid profile changes,and the lipid fatty acid amounts decreased and then increased with time.This work could provide useful information to evaluate the development and application of Lipid Search software as well as a way to analyze the effect of dry salting on the lipid fatty acids change of aquatic products.(2)Lipidomics is a useful tool to analyze lipid profiles in tissues.In this work,a lipidomics-based manual comparative analysis method was built to analyze the effects of thermal processing methods on fatty acid species in Tilapia muscles.About 66 fatty acid species were present in the raw,steamed,boiled,and roasted Tilapia muscles and only five fatty acid species had higher sensitivity in positive ionization mode than negative ionization mode of mass spectrometry.Thermal processing mainly had no obvious effects on the amounts of about 60% fatty acid species.Two,two,five,and twelve fatty acid species could be the best biomarkers for differentiation of raw,steamed,boiled,and roasted,respectively,Tilapia muscles in our experiments.This work could provide a correct workflow of lipidomics analysis and basic information on the effect of thermal processing on the fatty acid profile of foods.(3)Dry curing has an important effect on food lipids.In this study,the effects of fish-salt ratio and dry curing time on compound lipids in tilapia meat were studied by ultra high performance liquid chromatography-tandem Orbitrap mass spectrometry and Lipid Search software.The results showed that under different curing time,240-467 lipids containing 22-27 subclasses were detected in negative ionization mode,and 400-779 lipids containing 24-27 subclasses were detected in positive ionization mode.Nine lipid subclasses were identified by positive and negative ionization patterns,such as Cer,LPC,LPE,PC,PE,PG,PI,PS,SM and so on.The main compound lipid subclasses in dry-cured fish are TG,PC and PE,which play an important role in human health.With the increase of curing time,the content of lipid subclasses increases or decreases.This work can provide useful information for evaluating the development and application of Lipid Search liposome engineering software.This work provides a way to analyze the effect of processing on the changes of compound lipids in food,provides basic knowledge for understanding the composition of compound lipids in food,and improves the relevant information of mass spectrometry of compound lipids in tilapia.(4)The development of nitrite scavenging agents for application in curing products has attracted much attention.In this work,we developed eight types of spice microparticles(myrcia,aniseed,cinnamon,chili,Sichuan pepper,nutmeg,clove,and cumin)using a high-speed disintegrator method and explored their potential application as nitrite scavenging agents.The results demonstrate spice microparticles can efficiently reduce nitrite in sodium nitrite solutions(nitrite scavenging percentages: 36–100%)and high nitrite Tilapia muscle models(nitrite scavenging percentages: 11–42%).Moreover,the nitrite scavenging ability is dependent on spice types and spice microparticle sizes.These results suggest spice microparticles have another potential role(nitrite scavenging)besides flavor adding when they are applied in the curing process of fish and meat.This work can potentially expand the application of spice microparticles in food industry and provide useful information to understand the role of spice microparticles in cured fish,seafood and meats.Conclusion: Lipid Search software identification method is a reliable method for the identification of long-chain fatty acids.The results of the study on the law of matter migration in tilapia fillets under different processing methods showed that: The meat of tilapia with low salt mass ratio(3-8)may have stable and similar fatty acid spectrum changes in dry-curing process,the content of fatty acids decreased at first and then increased with the curing time of tilapia fillets;Heat treatment mainly had no obvious effect on 42.3%-53.8% fatty acid types in tilapia muscle,but increased 17.3%-44.2% fatty acid species,2,2,5 and 12 fatty acids could be used as the best biomarkers to distinguish raw,steamed,boiled and roasted tilapia muscle,respectively;Under different curing time,240-467 lipid molecules containing 22-27 subclasses were detected in negative ionization mode,and 240-779 lipids containing 24-27 subclasses were detected in positive ionization mode.N ine lipid subclasses were identified in both positive and negative ionization mode: Cer,LPC,LPE,PC,PE,PG,PI,PS,SM,the main compound lipid subclasses in dry pickled fish were TG,PC,PE and so on,they play an important role in human health.With the increase of curing time,the content of lipid subclasses increases or decreases;Then,studies have shown that micron spice particles can effectively reduce the content of nitrite in sodium nitrite solution(nitrite clearance rate of 36%-100%)and high nitrite tilapia muscle model(nitrite scavenging rate of 11%-42%).In summary,the research shows that the processing of tilapia has good nutritional value,which provides a favorable direction for the development of tilapia industry in the future.