Assessing available phytochemicals from commercial blackcurrant and raspberry pomaces

BACKGROUND: Berry pomaces obtained after commercial juice production contain phytochemicals which may find use as antioxidants, food additives and biomedical products. Oil extraction from seeds provides additional value but the availability of phytochemicals before and after oil extraction is not well established. OBJECTIVE: This pilot study defines the content and composition of phytochemicals from raspberry and black currant pomaces after extraction with water-ethanol mixes, but also before and after milling/ oil extraction. METHODS: The total phenol (TPC), total anthocyanin (TAC) and antioxidant content of extracts was assessed. Their phytochemical composition was studied using liquid chromatography-mass spectrometry (LC-MSn). RESULTS: TPC and TAC increased with increasing % ethanol. Anthocyanins were major components in blackcurrant pomace and were more readily extracted than total phenols. Total oil content and composition was not influenced by solvent pre-extraction. Milling/ oil extraction markedly increased TPC from raspberry but not from blackcurrant pomace. LC-MSn confirmed characteristic phytochemical compositions and that increasing % ethanol increased yield of certain components. Milling increased specific ellagitannins, proanthocyanins and triterpenoids from raspberry. CONCLUSIONS: Milling/ oil extraction increased the yield and phytochemical diversity of extracts from raspberry but not from blackcurrant pomace which suggests that the phytochemicals from blackcurrant pomace are largely available on the pomace surfaces.