Residual olive paste as a source of phenolic compounds and triterpenic acids

Abstract

The two-phase centrifugation system of olive oil extraction produces huge amounts of olive pomace called alperujo that could be a good source of bioactive substances. However, alperujo is currently stored in open air ponds before it is dried and submitted for extraction of the residual oil. The aim of this work was to study the evolution of phenolic and triterpenic acids in alperujo during its storage and extraction processes on an industrial scale. Alperujo was stored in large open air ponds, dried and the residual oil was extracted with hexane over a course of a year for two consecutive olive seasons.The storage of alperujo did not cause great changes in the content of these substances in the paste although the pomace olive oil was enriched in triterpenic compounds, mainly oleanolic acid . By contrast, the drying and extraction steps gave rise to a great reduction in the concentration of phenolic compounds. Likewise, triterpenic acids were very stable during the extraction process, and an enrichment of them was detected in the extracted alperujo that could reach up to 7-8 g/kg in these substances, particularly maslinic acid.

Practical applications: There are many studies, methods and patents to extract bioactive substances from olive by-products, particularly from the fresh olive pomace called alperujo. However, this study is the first to explore the stored and extracted alperujo as a good source of phenolic and triterpenic substances. Specifically, triterpenic acids were very stable during the storage and drying steps and extracted alperujo was highly enriched in them. This research will contribute to the valorization of olive by-products.

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