Malaxing temperature affects volatile and phenol composition as well as other analytical features of virgin olive oil

Three Italian olive varieties (Caroleo, Leccino and Dritta) were processed by centrifugation in the oil mill. The olive paste was kneaded at 20, 25, 3 0 and 35 degreesC. The results achieved revealed that the oil content in gr een volatiles from lipoxygenase pathway (including C-5 and C-6 compounds an d especially unsaturated C-6 aldehydes) decreased progressively as the knea ding temperature increased, dropping markedly at 35 degreesC. The content o f phenols, o-diphenols and secoiridoids showed an opposite trend, but the t emperature of 35 degreesC was critical also for them, as it was for the maj ority of the other components, analytical parameters and indices related to quality, typicality and genuineness. In general, an increasing kneading te mperatures increased the release of oil constituents from the vegetable tis sue. This factor also affected the oil extraction yields. The best overall results were achieved by malaxing the olive paste at 30 degreesC. In fact, this temperature level fed to achieving both pleasant green virgin olive oi ls and satisfactory oil extraction outputs.