Determination of triterpenic acids in natural and alkaline-treated Greek table olives throughout the fermentation process

•Maslinic and oleanolic acids are found in abundance in olive fruits.•Both acids were quantified in naturally processed Conservolea and Kalamon olives.•The natural process did not influence their concentration in the final product.•Lower concentrations were determined in alkaline-treated Conservolea olives.•The alkaline process affects adversely their concentration in the final product.

Maslinic and oleanolic acids are among the most abundant triterpenic acids found in olive fruits. Both acids are considered to be important bioactive compounds which can confer multiple beneficial health effects to the consumer. In the present work, we have monitored and quantified maslinic and oleanolic acids throughout processing in alkaline-treated green olives (Spanish-style) and in natural green olives of the Conservolea variety that is particularly popular in Greece. Our findings clearly demonstrate that the fast de-bittering process with NaOH treatment in Spanish-style olives has a profound negative effect on the concentration of both acids. This decrease of concentration was more prominent regarding maslinic acid when compared to oleanolic acid. In contrast, the slow de-bittering during natural fermentation of green olives had no effect on the content of maslinic or oleanolic acid. To verify the broad applicability of our observation we have also looked into the natural processing of the Kalamon variety (Greek-style). Our findings were consistent, since once again, natural fermentation did not influence the concentration of both acids.