Comparative study of coadjuvants for extraction of olive oil

Abstract

Three complete 23 factorial designs were developed in order to evaluate the effect of three physical acting coadjuvants on the extraction of virgin olive oil: talc, calcium carbonate and silica. Ranges of operating conditions were 0–2 % (w/w) for dosage of the coadjuvant, 20–60 °C for temperature and 20–60 min for time. Mathematical models and statistical analysis (ANOVA) were performed to evaluate the effects of these coadjuvants on oil yield, quality of virgin olive oil (acidity, peroxide index and UV absorption at 270 and 232 nm), natural pigments (chlorophylls and carotenoids) and natural antioxidants. In all cases, the oils obtained with coadjuvants were the same quality of those from non-treated olive paste. Therefore, all of them are producing a physical action. While improved oil extraction yields were achieved by using talc and calcium carbonate (1.1 and 1.0 kg oil per 100 kg olives), the use of silica resulted in an oil yield reduction (1.3 kg/100 kg olives). Concerning natural pigments and antioxidants, none of the studied coadjuvants modified the pigment content while that of the antioxidants increased slightly. All oils obtained with coadjuvants showed higher contents of polyphenols and tocopherols, which indicates increasing quality and nutraceutical level.