Preservation of Food with High Oil Content by Supercritical Impregnation Techniques

Nuts are very important foods for human nutrition due to their high content of mono- and polyunsaturated fatty acids. However, they are substrates very sensitive to oxidation, appearing rancidity that affects both the taste and the smell, that led to the consumer’s rejection. To avoid this, the food industry uses some strategies that sometimes substantially alter the composition and nutritional value of nuts. A promising possibility for the conservation and stability against its oxidation is to impregnate a natural antioxidant such as methyl gallate using CO2 in supercritical conditions. This technology is being used recently for the impregnation of different natural substances on polymers for its use in the food and biomedicine field. However, the direct supercritical impregnation of compounds into food has been scarcely investigated.In the present work, it is studied the effect of pressure and temperature in the impregnation process of methyl gallate on peeled peanuts. Additionally, the effect of the depressurization rate and impregnation time was studied at the most convenient conditions. The results obtained indicate the best conditions for impregnation were reached at 150 bar and 45 oC. These conditions improved the antioxidant capacity of the nuts while preserving the quality by avoiding breakages during the process.