Development of a modified malaxer reel: Influence on mechanical characteristic and virgin olive oil quality and composition

Malaxation represents a critical and deeply studied step of the virgin olive oil extraction process due to its influence on yield and quality. Nonetheless, few experimental works have been focused on the mechanical aspects of the malaxer machine itself, with the aim of increasing its performance. In this framework, we investigated the effects of design changes of the rotating parts of the malaxer machine on the oil yield and on the virgin olive oil quality, antioxidants and volatile compounds. The modified reel determined a significant increase in extraction yield, respect to the traditional one, as a consequence of the decrease in consistency index of the olive paste. By the qualitative point of view the extracted oil could be categorized as extra virgin. However, malaxer modification brought to a decrease of the antioxidants and an increase of the oxidative phenomenon, as showed by volatiles originated from oxidative degradation and by the enzymatic activities in olive paste. Nonetheless, the outcomes suggested that a possible reduction of malaxation time by the modified reel could be useful to increase the work capacity and to possibly preserve oil quality.