Analysis of Metabolite Diversity in Apple Processing Based on High Temperature and High Humidity Conditions
By analyzing the intrinsic mechanisms of how fermentation affects apple quality,this study provides a scientific basis for the functional components and metabolic regulation mechanisms of apples,supporting the in-depth development of the apple industry.In this research,non-targeted metabolomics technology was utilized to analyze the diverse differential metabolic compounds generated during the processing of apples under high temperature and high humidity conditions.Various methods such as principal component analysis(PCA),cluster heat maps,partial least squares discriminant analysis(PLS-DA),and KEGG pathway enrichment were utilized to evaluate the metabolomic data.PCA revealed significant stage-wise changes in the metabolic composition of apples during different fermentation processes.Metabolite identification indicated the presence of 314 metabolites,with lipids and lipid-like molecules accounting for the largest proportion,reaching 44.61%.Utilizing cluster dendrograms and orthogonal partial least squares discriminant analysis(OPLS-DA),it was revealed that the metabolite levels in the apple samples at the end of fermentation were significantly higher than those in the unfermented samples,effectively distinguishing apple samples at different fermentation stages.Further,KEGG pathway analysis pointed out that the biosynthesis of phenylpropanoids and the metabolism of phenylalanine in apples were very active during fermentation,and specific pathways for the biosynthesis of cornoside and sphingolipid metabolism were activated under high temperature conditions,which have an important impact on the high-temperature adaptability and flavor formation of apples.