Impregnation of oil containing fruits

Fruits of oil plants, like nuts, are widely used in food industry and regarded as healthy due to their content of unsaturated fatty acids. Handling, processing and storage of products containing nuts are challenging, because oxidation has to be avoided. The consumer is able to taste rancidity, the consequence of oxidation, in an early stage. Therefore suitable precautions have to be considered. A promising possibility to enhance the oxidation stability was investigated – high pressure impregnation with antioxidants. A two steps procedure and the use of a CO2-rosemary extract, containing carnosic acid, gave the best result in terms of homogeneous impregnation. The effect on prolonging the shelf life was successfully observed using three different analytical methods – peroxide value, rancidity test and DPPH method. The oxygen stability and hence the shelf life of nuts was increasing with an increasing concentration of carnosic acid.