Impact of coadjuvants on enzymes activity during VOO extraction

Maximizing oil yield during the extraction process is a primary goal of virgin olive oil producers. According to this scope, a great deal of innovation is oriented toward the process. Innovative machines have been tested such as ultrasounds, microwaves, pulsed electric field and different combinations of those. However, the implementation of these systems is not so straightforward. Another strategy, well known since long time, is the usage of technological coadjuvants. Coadjuvants have some practical advantages: i) their use could be simply implemented in the industrial context; ii) no or minor changes at the industrial lines are required; iii) the product could be labelled as extra virgin. Literature provide numerous references about the use and misuse of different processing aids. Side effects of their application have been observed too, also regarding the phenolic compounds. In particular, calcium carbonate seems to decrease the phenolic content while talc seems behave the opposite. Nonetheless, no clear explanation have been furnished about these evidences. In this context, we tested the hypothesis that coadjuvants could affect enzymatic activities during extraction. A central composite design of experiment was build considering two independent variables (malaxation temperature and % coadjuvant addition) having as a response the enzymatic activities of PPO, POD, LOX and related metabolites (phenolic and volatile compounds). The results showed an effect of coadjuvants on enzymatic activities. More in detail, calcium carbonate increased the oxidases activity leading to a consequent reduction of phenolic compounds. On the opposite, talc reduces the oxidases activities. Significant modifications of the olive paste pH were considered responsible of the obtained results.