Targeted Metabolomics Combined with OPLS-DA to Elucidate Phenolic Differences in Eight Cashew Apples

Phenolic compounds were separated and identified using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and analyzed with OPLS-DA and metabolomics in eight cashew apples. The results showed that the phenolic compound content in Bra4 was the highest, while Gua had the lowest levels. The content of 39 phenolic compounds (nine types) showed significant variability across the 8 cashew apples. Sixteen phenolic compounds with significant differences were excavated and could be used to differentiate and identify cashew apple varieties. The 18 differentially significant phenolic compounds present in Bra4 and Gua were mainly distributed in 6 metabolic pathways, and the metabolic pathways of flavonoid biosynthesis and phenylpropanoid biosynthesis were elucidated to regulate the synthesis of luteolin and syringin, respectively. These studies provide a scientific basis for selecting and breeding cashew varieties and developing products.