不同采收期对温185和新新2核桃品质的影响

针对新疆阿克苏地区温宿县核桃产区普遍存在采收时间过早、过晚,造成核桃品质参差不齐现象。本文以核桃青果开裂率为标准研究不同采收时期温185和新新2核桃外在品质和内在变化,确定不同青果开裂率下其较适宜的采收期。温185于2020年8月16日至9月5日,新新2于2020年9月15日至10月5日,每隔5 d进行采样,每次采样以青果开裂率为准(温185:0%、5%、20%、50%、95%;新新2:0%、5%、50%、70%、90%),并测定两种样品的鲜果三径、干果三径、鲜果重、干果重、壳厚、出仁率、含水率、黑斑率、脂肪含量、蛋白质含量、总糖含量、单宁含量、矿质元素含量。结果表明,随着采收期的延后,温185和新新2的鲜果三径、干果三径、鲜果重、干果重、出仁率均呈增加趋势,壳厚、含水率和果壳黑斑率均呈下降趋势。温185的坚果外观品质于8月31日至9月5日达到较高水平,新新2的坚果外观品质于9月30日至10月5日达到较高水平。随着采收期延后,温185脂肪含量、蛋白质含量呈上升状态,单宁和总糖含量呈下降趋势,这4项指标于9月5日达到较高水平。矿质元素含量P、Ca、Zn、Na、K、Fe总体呈上升趋势,Cu呈下降状态,且峰值均在9月5日。新新2脂肪含量、蛋白质含量、矿质元素含量(除Cu)呈增加趋势,单宁含量和总糖含量呈下降趋势,峰值均在9月25日至10月5日。核桃过早采收会显著降低核桃坚果的外观品质和内在品质。所以当温185青果开裂率达到50%至95%(8月31日至9月5日),新新2青果开裂率达到70%至90%(9月30日至10月5日),为两种核桃的适宜采收期。

Effects of different harvest time on quality of walnut varieties Wen 185 and Xinxin 2

Considering the premature and late harvesting time in walnut producing areas of Wensu County, Aksu, Xinjiang, the uneven quality of walnuts is caused. In this paper, the cracking rate of walnut green peel was taken as the standard to study different harvest periods and measure external quality and internal change of walnut varieties Wen 185 and Xinxin 2, for determining suitable harvest time of walnut under different cracking rates. Samples were taken every 5 days, Wen 185 was taken from August 16th to September 5th, 2020, Xinxin 2 was from September 15th to October 5th, 2020, and each sampling was based on cracking rate (Wen 185: 0%, 5%, 20%, 50%, 95%; Xinxin 2: 0%, 5%, 50%, 70%, 90%), and the three diameters of fresh fruit and dry fruit, fresh fruit weight, dry fruit weight, shell thickness, kernel rate, moisture content, black spot rate, the contents of fat, protein, total sugar, tannin and trace elements of the two samples were determined. The results showed with the harvest time delay, Wen 185’s and Xinxin 2’s three diameters of fresh fruit and dry fruit, fresh fruit weight, dry fruit weight and kernel rates all increased, while shell thickness, moisture contents and shell black spot rates decreased. The appearance quality of Wen 185 nuts reached a high level from August 31st to September 5th, while the appearance quality of Xinxin 2 reached a high level from September 30th to October 5th. With the harvest time delay, fat and protein contents of Wen185 increased, while tannin and total sugar contents decreased. On September 5th, they reached the higher levels. Mineral element contents such as P, Ca, Zn, Na, K and Fe was on an upward trend, Cu was descending, and the peaks were on September 5th. Fat content, protein content, mineral element content (except Cu) from Xinxin 2 were on the upward trend. The content of tannin and total sugar decreased, and the peak values were from September 25th to October 5th. Early harvesting of walnuts will significantly reduce the appearance and internal qualities of nuts. Therefore, when cracking rate of Wen 185 green fruit reached 50%-95%, from August 31st to September 5th, and Xinxin 2 green fruit reached 70%-90%, from September 30th to October 5th were the suitable harvest times for the two kinds of walnuts.