Abstract: Walnut kernels were sealed in polyethylene (PE) or KNY17//CPE80 (a composite material) bags for low-oxygen, high-carbon dioxide modified atmosphere packaging (MAP) and then stored at (2 ± 1) ℃ for 180 days. The control samples were packaged in PE bags under normal atmospheric conditions. Meanwhile, non-MAP nano-material packaging was also studied. Relevant quality indicators were measured periodically during the storage period to investigate the effect of different modified atmosphere packaging on the quality of walnut kernels. The results showed that nano-material packaging and low-oxygen, high-carbon dioxide PE MAP had the best preservative effect on walnut kernels, significantly inhibited the increase of peroxide value (POV) and acid value (AV) in walnut kernels and maintained the good appearance of walnut kernels. Moreover, the POV, AV and carbonyl group value of amber walnuts from raw walnut kernels with both pre-storage treatments were significantly lower than those from the control group as demonstrated by high temperature accelerated storage tests.

Key words: walnut kernels, modified atmosphere storage, packaging material, storage quality, amber walnuts