Effect of active packaging with Satureja thymbra extracts on the oxidative stability of fried potato chips

Satureja thymbra extracts, rich in phenolic acids and flavonoids, were obtained through successive extractions with ethyl acetate and ethanol, and tested as natural antioxidants to prolong the shelf life of fried potato chips. The extracts were more effective when coated on a laminated film used as active packaging for the chips, compared to spraying them on the surface of the fried product or adding to the frying oil. The increased incorporation of the ethanol extract, as coating, from 100 to 300 mg total phenols (expressed as gallic acid equivalents, GAE)/m(2) resulted in increased protection, as evidenced through peroxide values, volatile products, and oxygen consumption inside the packaging that remained stable for 55 days. Ethyl acetate extract was very effective up to a concentration of 200 mg GAE/m(2), but demonstrated prooxidant activity at higher concentration. Partial migration of the natural polyphenols to the product was observed.