Oxidative Stability Analysis of Selected Oils from Unconventional Raw Materials Using Rancimat Apparatus

Abstract

This study aimed to evaluate the quality of selected oils from the seeds of herbs and vegetables (basil, fenugreek, coriander, tomato, garden cress, parsley, and dill), especially their oxidative stability. The oils were tested for oxidation degree (acid value, peroxide value, p-anisidine value, TOTOX indicator, and specific extinction under ultraviolet light), colours, content of carotenoid and chlorophyll pigments, fatty acid composition, indicators of lipid nutritional quality, oxidative stability, and oxidation kinetics parameters (Rancimat). Principal component analysis was applied to identify a correlation between the oils’ quality parameters. The results of the fatty acid compositions show that basil oil was a good source of omega-3 fatty acids. Coriander seed oil was found to be the most resistant to oxidation, containing mainly monounsaturated fatty acids. The highest value of activation energy was calculated for fenugreek oil (94.18 kJ/mol), and the lowest was for dill seed oil (72.61 kJ/mol). However, basil oil was characterised by the highest constant reaction rate at 120 °C—3.0679 h−1. The colour determined by the L* parameter and the calculated oxidizability value had the most significant influence on the oxidation stability of the oils, and the correlation coefficients were r = −0.88 and 0.87, respectively.

Keywords

• activation energy
• cold-pressed oils
• constant rate of oxidation
• kinetic parameters
• oxidative stability
• Rancimat