Stabilisation of edible oils with natural antioxidants

Abstract

Natural antioxidants have recently gained increased interest because of the belief that natural food ingredients are better and safer than synthetic ones. The review presents the results on stabilisation of the main edible oils with different types of natural antioxidants. Sources of natural antioxidants are spices, herbs, teas, oils, seeds, cereals, cocoa shell, grains, fruits, vegetables, enzymes, proteins. Researchers concentrate on ascorbic acid, tocopherols and carotenoids as well as on plant extracts containing various individual antioxidants such as flavonoids (quercetin, kaemferol, myricetin), catechins or phenols (carnosol, rosmanol, rosamaridiphenol) and phenolic acids (carnosic acid, rosmarinic acid). Ascorbyl palmitate is regarded as a 'natural' antioxidant because it is hydrolysed in the body to ascorbic and palmitic acids. Among the herbs of the Lamiaceae family, rosemary has been more extensively studied and its extracts are the first marketed natural antioxidants. Oregano, which belongs to the same family, has gained the interest of many research groups as a potent antioxidant in lipid systems. The review concerns the following main topics: stabilisation of oil with individual natural antioxidants, interaction of antioxidants with synergists, stabilisation of oil with extracts or dry materials from different plant sources (e.g. herbs and spices), stabilisation at frying temperatures and in emulsions.