Abstract: The preservation of fresh walnut kernels during low temperature shelf was studied using fresh walnut kernels of ‘Xiangling’ as raw material. Four modified atmosphere packaging (MAP) treatments and four dosages of short-wave ultraviolet radiation C (UVC) were adopted to treat the fresh shelled kernels with food wrapping film (CK1), vacuum packaging (CK2), and scatter light treatment (CK) was used as control. According to results of the changes of O2 and CO2 concentration in each treatment, texture parameters, sensory quality and microorganism number of kernels from each treatment, 0.03 mm polyethylene 30(PE30) and 1 kJ/m2 UVC was selected as the best parameters respectively for packaging and sterilization. Then, walnuts were treated with MAP and UVC, separately, and in combination under each best parameter, stored at (5±0.5) ℃ to observe the changes of related physiology, quality and microorganisms during shelf life at a low temperature. The results showed that there were no significant differences on the tribute between these treatments with control on 21th day, and no mold was detected. Moreover, on 56th day, the compound treatment acted priorly to each separate one, which significantly reduced both the content of malondialdehyde (MDA) and acid value (P<0.05) than control. However, the content of total phenol, oil and protein was not affected by the treatment, and the soluble sugar was decreased (P<0.05). Furthermore, the visible mold appeared till on the 70th day, which 10 days later than control. The compound treatments also inhibited the activities of phospholipase D (PLD) and lipoxygenase (LOX) stronger than the other two treatments, providing the physiological basis of combined MAP and UVC maintained the quality of fresh kernels through the inhibition of membrane degradation.
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