Differences in quality changes of fresh walnuts in different states during cold storage
To explore the physiological and quality changes of fresh walnuts in different states during storage,'Qingxiang'fresh wal-nuts were stored at(0±0.5)℃ in three different states,including in-shell nuts,whole kernels,and crushed kernels,then the dynamic changes of physiological and quality indicators were measured.Results showed that the mould index of fresh walnuts in different states in-creased with the storage time,while those of whole and crushed kernels decreased significantly.There was no significant change in the com-position of fatty acids,and the saturated fatty acids content decreased while the unsaturated fatty acids content increased.The crude fat con-tent declined overall,with the average content being the highest in the crushed kernels.During 30 days of storage,the polyphenol oxidase ac-tivity was lower while the peroxidase activity significantly increased in crushed kernels compared with other states,but thereafter the contents of soluble sugar and soluble protein were lower than those of nuts and whole kernels.The acid value and peroxide value both meet the forestry standards.Overall,the whole kernels maintained better quality and the oil quality was relatively stable for the crushed kernels,while the nuts kept the higher nutritional quality and oleic acid content with the greater potential for application in maintaining oxidative stability during storage.However,due to the higher degree of fragmentation and nutritional loss,the crushed kernels lost commercial value earlier.
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