New by-products rich in bioactive substances from the olive oil mill processing.

BACKGROUND: Olive oil extraction generates a large amount of residue consisting mainly of the pomace and leaves when using a two-phase centrifugation system. The aim of this study was to assess the content of phenolic and triterpene compounds in the by-products produced in Spanish olive oil mills.

RESULTS: Olive pomace had concentrations of phenolic and triterpene substances lower than 2 and 3 g kg-1 , respectively. The leaves contained a high concentration of these substances, although those collected from ground-picked olives had lost most of their phenolic compounds. Moreover, the sediment from the bottom of the olive oil storage tanks did not have a significant amount of these substances. By contrast, a new by-product called olive pomace skin has been revealed as a very rich source of triterpenic acids, the content of which can reach up to 120 g kg-1 in this waste product, maslinic acid comprising around 70% of total triterpenics.

CONCLUSION: Among the by-products generated during extraction of olive oil, olive pomace skin has been discovered to be a very rich source of triterpenic acids, which can reach up to 120 g kg-1 of the waste. These results will contribute to the valorization of olive oil by-products. © 2017 Society of Chemical Industry.