Antioxidant and antimicrobial active packaging systems

The shelf life of foods is mostly limited by microbial growth and oxidation reactions. Reducing both these mechanisms by active packaging is an attractive concept to enhance the shelf life. Antimicrobial packages recently developed combine natural antimicrobial compounds like carvacrol and isothiocyanates with biobased polylactic acid (PLA) films. Antioxidant packaging can be used to further improve product quality and extend the shelf life of food by free radical scavenging. As an example, a radical scavenger and singlet oxygen quencher, b-carotene, was incorporated into PLA to develop an antioxidant film. The usage of sunflower oil based oleogel as lipid food model was chosen to focus on the lipid oxidation process. We studied the antioxidant activity and color/thermal properties of the antioxidant loaded PLA film. Preliminary results show that the thermal stability of films was not affected by b-carotene addition. b-carotene significantly improved the antioxidant properties of the films in both DPPH and ABTS radical-scavenging activity tests. We evaluated the oxidation stability of sunflower oil based oleogels as a model food product prepared with different proportions of stearic acid (SA) and hydroxypropyl methylcellulose (HPMC). The difference between direct and indirect contact between the product and the film was determined. Preliminary results show that b-carotene-loaded PLA film was able to inhibit lipid oxidation, reducing the formation of lipid hydroperoxides and TBARS of the resulting oleogels. Further research will be on combining the antioxidant and antimicrobial activity of packaging films to further enhance the shelf life of products vulnerable to oxidation and microbial spoilage.