Oxidation kinetics of rapeseed oil pressed from microwave pre-treated seeds during long-term storage

In this study oxidation kinetics of the rapeseed oils prepared from microwave (MV) pre-treated seeds (2-10 min, 800 W) and stored for 12 months was examined. As a result of seeds MV pre-treatment, degradation of monounsaturated and polyunsaturated fatty acids up to 16-17% and 30-42% was noticed. At the same time, induction period of the oils prepared from seeds microwaved for 10 min was 1.5- and 1.7-times higher than that of the control oil. During storage, the increase of oil oxidative indices displayed first-order reaction kinetic. Oils obtained from MV pre-treated seeds showed significantly lower progress of oxidation, as the values of oxidation rate constant (k) for oxidation indices decreased with longer seeds exposure to MVs. Following 12 months of storage, the rate of the principal unsaturated fatty acids decrease ranged from 4.2 mg/100 g in the control oils to 4.1-2.3 mg/100 g in the oil samples pressed from MV pre-treated seeds. Practical applicationsOver the last few years, thermal oilseeds pre-treatment prior to further processing has gained a substantial interest. Oxidation is one of the major causes of edible oil quality deterioration. Although favorable effect of rapeseed MV pre-treatment on the phytochemicals content has been confirmed in several studies, the impact of this pre-processing method on the oxidative stability of the oil has not yet been fully examined. Thus, the accurate knowledge of the oxidation kinetics is essential to predict the quality changes that occur during storage.