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