Study of the influence of technological coadjuvants on enzyme activities and phenolic and volatile compounds in virgin olive oil by a response surface methodology approach

Although the use of technological coadjuvants during virgin olive oil extraction helps in maximising the process efficiency, it could influence the characteristics of the final product. So far, why this happens is still not understood. In this context, an influence on the biochemical activities occurring during the malaxation step was supposed, and this hypothesis was verified by a response surface methodology approach. The effect of two independent variables, namely malaxation temperature and amount of coadjuvant, on polyphenol oxidase, peroxidase and lipoxygenase activities as well as on the corresponding phenolic and volatile compounds of the oils was studied. Calcium carbonate enhanced the activities of oxidases leading to a reduction of phenolic compounds, which were negatively correlated with the coadjuvant usage. Micronized natural talc behaved the opposite but had a general weaker influence, often overcome by that of mixing temperature. A significant shift of the olive paste pH toward that optimal for oxidases enzymes was highlighted under the use of calcium carbonate. The findings evidenced a “side effect” of the use of technological coadjuvants in the context of virgin olive oil extraction.