Effects of malaxation time on the quality of extra virgin olive oil from the Ascolana tenera olive variety

Malaxation (kneading) exerts a crucial influence on the final phenolic profile of extra virgin olive oil (EVOO) and thus on the nutritive and sensory quality, on the resistance towards lipid oxidation and thus on the date of minimum durability of the EVOOs. The effect of two different malaxation times (10 min and 30 min) were evaluated on the EVOO produced by using 100% olives of the Ascolana tenera variety at an industrial scale (about 750 kg). The phenolic profile, oxidative stability and legal (both chemical and sensory) quality parameters were monitored in the fresh EVOO and during a one-year storage of the oil in sealed bottles stored in the dark at room temperature. The increasing bitter taste perceived during the storage of the oils is due to the increasing content of the low molecular weight phenolics resulting from the degradation of secoiridoids. The oils from Ascolana tenera obtained with a short kneading time had a slightly higher quantity of phenols and a higher oxidative stability, compared to the samples produced with a more prolonged kneading; the oxidative stability was statistically different after a storage of six months and up to 12 months. Thus, the production of EVOO from Ascolana tenera olives can be advantageously improved (shorter processing time and lower energetic costs) in a small/medium olive mill by reducing the kneading time during malaxation from 30 to 10 min without any substantial difference in terms of both sensory and chemical quality parameters.