Innovative Approaches to Enhance Activity of Endogenous Olive Enzymes-A Model System Experiment: Part II-Non-Thermal Technique

The aim of this study was to determine the optimal parameters of pulsed electric field treatment to increase the activity of beta-glucosidase and lipoxygenase, crucial enzymes that improve the nutritional quality and sensory properties of virgin olive oils. The activity of the enzymes was determined spectrophotometrically immediately after treatment of model systems (commercial enzymes and their substrates) with pulsed electric fields and after simulation of the malaxation process for 30 min at 25 degrees C. Pulsed electric field treatments were performed with electric field strengths of 2.67 and 13.33 kV/cm at frequencies of 25 and 125 Hz for 1, 2, and 5 min. The results showed a positive correlation of beta-glucosidase activity with the electric field strength and time, with the first of the two factors having the greatest influence. Lipoxygenase activity was affected only by the duration of treatment: positively immediately after treatment and negatively after simulation of the malaxation process. Based on these results, pretreatment with a moderate pulsed electric field for 2 min before the malaxation process could be proposed to increase the activity of beta-glucosidase and lipoxygenase, e.g., for the production of virgin olive oils with higher concentrations of polyphenols and desirable volatile compounds.