Studies On The Change Of Main Nutrients Contents In Maturity And Storage Period Of Fresh Walnut

Fresh walnut were received by consumers because it tastes excellent in recent years,and consumption of fresh walnut also increased year by year. Although rich nutrients offresh walnut, but the moldy, germination and water loss problems easily occurred duringstorage and fresh walnut varieties selection in China is still blank, these greatly restrictedthe development of fresh walnut. In this paper, four walnut cultivars were chosen asmaterials and the variety of fresh walnut had been selected and the suitable time for harvesthad determined through the changes of main nutritional content of kernel in mature period.The best storage conditions had determined by detecting the changes of main nutritionalcontent of kernel during storage period. Those can provide the basic data and theoreticalbasis for the storage and processing of fresh walnut. The main results were as follows:1. The water content of kernel showed a downward trend in mature period. Themoisture content of fresh walnut decreased sharply in early storage, the overall showeddownward trend.2. Walnut fruits during ripening, the soluble sugar content of Qingxiang and Zanmeiwalnut kernel had the trend of decline, while the content of soluble sugar of Qingcui andZhenzhuxiang walnut kernel showed overall upward trend. The protein content of Zanmeiwalnut kernel showed a downtrend and the protein content of Qingcui, Qingxiang andZhenzhuxiang walnut kernel has the trend of upward in the mature period.3. The flavonoids and polyphenols content of Qingcui, Qingxiang walnut kernel hadthe ’M’ type trend, but the changes of flavonoids and polyphenols content of Zanmei andZhenzhuxiang showed the downward trend.4. The fat content of walnut kernel had upward trend in mature period. The linoleicacid content decreased in mature period and the change of other fatty acids content werevaries by species.5. The mature period, the soluble sugar, protein, fat, polyphenols, flavonoids contenthad significant difference during the same period of different varieties; The soluble sugar,protein, flavonoids, polyphenols content of Qingcui walnut kenerl were significantlyhigher than other varieties, while the fat content was the lowest among the four varieties.6. Qingcui was suitable for fresh food through the comparison of kernel color, seedcoat color, kernel crispness, kernel flavor and kernel plumpness.7. The content of protein and soluble sugar of Qingcui kernel reached maximum in August24th, respectively10.73%,2.2%, and the fat content was38%. The polyphenolsand flavonoids content of Qingcui kernel reached the highest value in August19th.Ombined with the tasting results, the best harvest period of fresh walnut was late August.8. The soluble sugar, polyphenols, flavonoids content of fresh walnut kernel decreasedduring storage, protein and fat content increased, oleic acid, linoleic acid and linolenic acidcontent decreased, palmitic acid and stearic acid content increased in storage period.9. The quality guarantee period of Fresh walnut were short at0℃storage conditions,but the shelf life were longer at the temperature of-10℃,-20℃storage conditionslonger. It can better prevent the oxidation of unsaturated fatty acid at-20℃storageconditions.