Natural antioxidants in mitigation of vegetable oils oxidation

Oxidation reactions in vegetable oils are one of the main causes of deterioration, being responsible for the loss of quality and safety of the oil itself, but also of the foods that use the oil. On the other hand, nowadays we are facing a sustainability challenge concerning natural sources of edible oils, as well as the increased quantities of food industry by-products, for which fruit and vegetables account with 45% of the food losses. Therefore, it is of utmost importance to increase the shelf-life of vegetable oils, and one of the appointed strategies is to use natural antioxidants obtained from herbs, spices and food industry by-products. Also, consumers acceptance of synthetic antioxidants is decreasing because they are usually perceived has detrimental for human health. The present review focuses on the different natural antioxidants already applied to prone oxidation in vegetable oils, as well as future trends and needs regarding this subject. Up to now, natural antioxidants from olive leaves, rosemary, coriander, green/black tea leaves, oregano, garlic, onion skin, sage, lavender and thymus, have been experimented to decrease oils oxidation, namely during storage and frying. Those have been effective, nonetheless some difficulties have emerged when laboratory scale technology is transferred to industry, such as possible variations in the quantities of antioxidants (climatic and geographical variations), as well as lower price of synthetic antioxidants, and probable changes in the flavour, colour and sensory attributes of the frying oils and foods. There is no doubt, that this is a promising research field, but it is necessary to increase the number of studies regarding the safety of these natural antioxidants, as well as consumers’ acceptance.This work was funded by INSA, I.P., under the project “PTranSALT (2012DAN828)”. T. G. Albuquerque is grateful for PhD fellowship (SFRH/BD/99718/2014) funded by FCT, FSE and MEC.N/