Tracing Technology Of Laminaria Japonica Based On Fatty Acid Composition And Stable Isotope Ratio

Laminaria japonica is a large perennial edible algae,which is currently the largest marine economic algae in China in terms of both production and cultivation area.With the increasing popularity of food safety,after food safety accidents occur,tracing technology is used to investigate the origin,processing,transportation,and circulation of food,identify potential links that may cause accidents,and thus ensure the increasing demand for food safety among the people.Due to the advantages and disadvantages of each traceability technology,multiple analysis techniques and parameters can be combined to provide more accurate and reliable information and data,achieving better and more accurate traceability effects.In this study,the extraction of total fat in Laminaria japonica and the determination method of fatty acid methyl ester were evaluated and optimized.Through comparative experiments,Folch improved method was selected as the extraction method of total fat in Laminaria japonica.Under the condition of satisfying the separation effect and having reasonable analysis time,SP-2560（100 m×0.25 mm×0.2μm）The capillary column is used as the analytical column for fatty acid methyl ester in Laminaria japonica,and the acetyl chloride methanol esterification method is selected as the method for fatty acid methyl ester in Laminaria japonica.This study selected Laminaria japonica from four production areas,namely Xiapu in Fujian,Rongcheng in Shandong,Changdao in Shandong,and Dalian in Liaoning as analysis samples.The composition of fatty acids and carbon and nitrogen stable isotope ratios were measured,and the differences and correlation between data results were analyzed and discussed.The feasibility of the above indicators for tracing and discriminative analysis of Laminaria japonica from different origins was explored.Based on the above analysis and research,the main results obtained are as follows:（1）Using the fatty acid data,a discriminative model for the traceability of Laminaria japonica origin based on 16 fatty acid compositions（C14:0,C14:1,C15:0,C16:0,C16:1,C17:0,C18:0,C18:1n9c,C18:2n6c,C20:0,C18:3n6,C18:3n3,C20:3n6,C22:1n9,C20:3n3,C22:2n6）was constructed.The cross validation results showed that the classification of original Laminaria japonica samples from four origins achieved a correct discrimination rate of 99.2%,and the cross validation achieved a correct discrimination rate of 95.8%.The overall discriminant classification effect is good,and the overall discriminant classification model based on 16 fatty acids runs effectively.Using the overall discriminant classification function constructed from eight kinds of fatty acids（C14:0,C15:0,C17:0,C18:0,C20:0,C18:3n3,C22:2n6,C20:5n3）optimized by data analysis,the cross validation results show that the classification discrimination of original Laminaria japonica samples from four origins achieved 95.8%of the correct discrimination rate,and the cross validation discrimination achieved 95.0%of the correct discrimination rate,indicating that this study is effective in reducing the dimension of fatty acid variables.The optimized overall discriminant classification model based on 8 fatty acids has good performance and can meet the classification and discrimination of Laminaria japonica samples from four origins.（2）The application of carbon and nitrogen stable isotope data has been constructed based on the carbon and nitrogen stable isotope ratio(δ¹³C,δ¹⁵N).The cross validation results show that the classification of the original Laminaria japonica samples from the four origins has achieved a correct discrimination rate of 70.8%,and the cross validation has achieved a correct discrimination rate of 70.0%.This shows that the success rate of the identification of Laminaria japonica origins through carbon and nitrogen stable isotopes with only two variables has no obvious advantage.（3）A combination of fatty acid composition and carbon and nitrogen stable isotope ratios was constructed based on 16 fatty acids and carbon and nitrogen stable isotopes(C14:0,C14:1,C15:0,C16:0,C16:1,C17:0,C18:0,C18:1n9c,C18:2n6c,C20:0,C18:3n6,C18:3n3,C20:3n6,C22:1n9,C20:3n3,C22:2n6,δ¹³C,δ¹⁵N).The cross validation results show that the original Laminaria japonica samples from four origins achieve 100%correct discrimination rate,and the cross validation achieves 97.5%correct discrimination rate,indicating that the overall discrimination classification effect is good.The overall discrimination classification model based on 16 fatty acids and carbon and nitrogen stable isotopes is good,and can trace the Laminaria japonica samples from different origins.Combining optimized 7 fatty acids with nitrogen stable isotopes(C14:1,C15:0,C16:1,C18:3n6,C22:1n9,C20:3n3,C20:5n3,δ¹⁵N).The cross validation results show that the classification and discrimination of the original Laminaria japonica samples from four origins has achieved a correct discrimination rate of 97.5%,and the cross validation and discrimination has achieved a correct discrimination rate of 95.0%.The overall discrimination and classification model based on the combination of seven fatty acids and nitrogen stable isotopes is effective in reducing the workload of data analysis and still meeting the requirements of Laminaria japonica origin discrimination,it is possible to trace Laminaria japonica samples from different origins.（4）The traceability effects of several discriminative model are compared and the key points are screened.By comparing five discriminative model based on 16 fatty acid compositions,8 optimized fatty acids,carbon nitrogen stable isotope ratio,combination of16 fatty acids and carbon nitrogen stable isotopes,and combination of 7 optimized fatty acids and nitrogen stable isotopes,it is found that the number of variables in the model,multiple measurement methods The combination of multiple data sources has a positive effect and impact on the identification of origin traceability.