Evaluation of Shelf Life of Walnut Kernels Treated by Antioxidants and Different Packaging under Two Temperatures

Abstract

In this study, the effects of coatings made of chitosan (Chi) incorporating thyme essential oil (TEO) on lipid oxidation and changing color indexes of walnut kernels were investigated. Chi: pure, in accompany with TEO at concentrations of 500 and 1000 microliter per liter, in an aqueous coating solution, with different packaging methods: Gunny sack, polypropylene and active packaging, compared with control walnut, were used and stored at 4ºC and 25ºC. The study was performed as factorial experiment based on a complete randomized design. The results showed that amounts of color indexes in treated samples decreased. The samples stored at 4°C contained minimum moisture fluctuations in all packaging methods. The peroxide values and conjugated diene values at 4°C were lower than those at 25°C. Treatments did not have positive effect on free fatty acids of walnut kernels. During the storage, shelf life of walnut kernels prolonged with active packaging and chitosan coating at 4ºC.