Computer programs to design and control the malaxation step of extra virgin olive oil processing under low oxidative operating conditions

Malaxation is essential in the extra virgin olive oil (EVOO) processing to induce several phenomena, but algorithms based on kinetic approach for predicting the effect of malaxation operating conditions on both oil process yield and EVOO quality are lacking. The kinetics phenolic compounds (PC) and positive volatile organic compounds (i.e., ( E )-2-hexenal) were studied in lab scale at different time-temperature malaxation treatments under low oxidative operating conditions. The kinetics were also linked with the literature kinetics data of both negative volatile organic compounds (i.e., 2+3-methylbutanal) formation and oil process yield indices. A first computer program ( MalaxAction 2.1 ) was set up to design malaxation by planning time-temperature conditions to maximize or select combined levels of ( E )-2-hexenal content, PC total content and apparent extraction yield, without exceeding threshold value of 2+3-methylbutanal contents. A second computer program ( MalaxAction 2.2 ) was set up to control malaxation by determining effects of both every time-temperature condition and unsteady heat transfer on the above EVOO quality characteristics and oil process yield. An opposite effect on increase of both phenolic compounds and pleasant volatile organic compounds was predicted without oil sensory defect by the MalaxAction 2.1 . A maximization of extraction yield can be also consistently reached increasing PC total content, but not increasing the ( E )-2-hexenal content. However, the designed time-temperature conditions have less applicability if the heat transfer resistance of malaxers are not considered. MalaxAction 2.2 program was able to both check feasibility of actual malaxation temperature profile and, if necessary, adjust it to reach the designed goal.