Olive mill wastewater polyphenol‐based extract as a vegetable oil shelf life extending additive

Abstract

Olive mill wastewater (OMW) was used as a source to extract radical scavenging compounds, in order to study their possible valorization as natural antioxidants. Their antioxidant activity (IC50 0.32 µg/ml) was found to be more potent than that of a commercial antioxidant: Ascorbic acid (AA) (IC50 1.91 µg/ml). The olive mill wastewater extract (OMWE) and AA were separately added to two vegetable oils, sunflower oil and rapeseed oil. These oils were then put under simulated storage conditions (accelerated test at 60°C) for 4 weeks. The physicochemical parameters, analysis of fatty acids, phytosterols, and tocopherols were the key parameters used to monitor the evolution of the oxidation state. The results obtained showed that the oils treated with the OMWE underwent oxidative deterioration slower than that of the control (without additives), and that phytosterols and tocopherols content decreased as a function of storage time following first-order kinetics. The use of the OMWE helped reduce the loss of both phytosterols and tocopherols in 4 weeks by half compared to the control samples, with the exception of total phytosterols in rapeseed oil where the loss reduction was not as important (about 2% loss reduction). Practical application Antioxidants are widely used in the food industry, as they prevent the development of rancid aromas that lead to harmful consequences during storage and cooking. The practical implication of the study is that natural radical scavenging compounds extracted from OMW can be efficiently used to enhance the quality and safety of refined oils stored at high temperature conditions.