Identification and characterization of polyphenols in different varieties of Camellia oleifera seed cakes by UPLC-QTOF-MS

Although camellia seed cakes are by-products of extracting oil from the seeds, they contain an abundant level of polyphenols, which are desirable compounds in human foods due to their antioxidant capacity. The object of this study was to detect polyphenols from three varieties of camellia seed cake by UPLC-QTOF-MS. In total, 73 unequivocal or tentative individual phenolic compounds were identified from methanol extracts of camellia seed cake, and the majority of phenolic compounds were in free form. Compared with other two varieties, more individual phenolic compounds were identified and characterized in Shucheng01 camellia seed cakes. In addition to flavonoid glycosides, numerous other polyphenols were identified in camellia seed cake, including phenolic acid and its derivatives, anthocyanins, and flavanones, the majority of which were first reported in the study of camellia seed cakes. Significant variations in individual polyphenol concentrations were found. The p-coumaric acid was the predominant free polyphenol in Shucheng01, while Luohan03 had the highest content of protocatechuic and 4-hydroxybenzoic acids. All results confirmed that camellia seed cakes are a rich source of various polyphenols, and their inclusion in the diet might provide health benefits.