采前钙处理对冬枣贮藏品质、钙形态及亚细胞分布的影响

研究了离子钙、熬合钙和纳米钙处理对冬枣贮藏后的品质及钙形态的影响，采用焦锑酸钾沉淀- 透射电子显微镜观察方法，研究了冬枣果实细胞中钙的亚细胞分布特点。结果表明，同对照(CK)相比，三种钙处理均有效的抑制了冬枣贮藏期间的褐变及硬度的变化，各喷钙处理对冬枣果实采摘时VC 的含量影响不显著，但有效的抑制了贮藏后VC 的消耗，Che-Ca(熬合钙)处理效果最佳。各处理间冬枣可溶性糖、可溶性固形物的含量差异很小，采摘时可滴定酸差异也不大，但当贮藏至第60d 时，CK 酸度的下降要高于其他喷钙处理。与CK 相比，喷钙处理冬枣的全钙、水提取钙、NaCl 溶液提取钙及醋酸提取钙的含量均有增加。冬枣果实中的钙主要以80%乙提取钙(ALc-Ca)的形式存在，贮藏至60d 时，NaCl 溶液提取钙和醋酸提取钙含量下降，ALc-Ca 的含量有所上升。各处理中细胞壁、细胞膜、液泡、液泡膜上锑酸钙颗粒分布较多；细胞之间、细胞膜和细胞壁的间隙中也有一定量的钙累积；CK 处理的细胞质中有大量钙累积，Che-Ca 处理有效地抑制了钙向细胞质的流动，细胞质中累积较少。

Effects of Preharvest Calcium Treatment on Storage Property, Calcium Fractions, and Subcellular Distribution in Zizyphus jujube Mill. cv. Dongzao Fruits

Three different calcium solutions and water (CK) were sprayed three times to the surfaces of the young Zizyphus jujube Mill. cv. Dongzao fruits during the early stage of fruit growth. Effects of different calcium solutions on the quality of young Zizyphus jujube Mill were studied. Forms of calcium during the storage were fractionated by sequent extraction in this paper. Besides, location and distribution of calcium were observed by transmission electron microscopy combined with in situ precipitation of calcium with an improved method of potassium pyroantimonate technique. Results showed that the three different calcium treatments could remarkably retard the increase in browning index and prolong the shelf-life with higher fruit firmness. Although the calcium treatments have no effect on the content of vitamin C (VC), they could prevent the VC consumption during storage effectively. The effects of different calcium treatments show no obvious difference on the content of total soluble solids, sugar and titratable acidity. Compared to the calcium treatment, the titratable acidity in fruits treated by CK is lower at 60th day after storage. Calcium treatment significantly increases the content of total calcium, H2O-Ca, NaCl-Ca and HAc-Ca. The content of ALc-Ca is the highest in fruit, which is about 37.9% to 55.1%. The content of NaCl-Ca and HAc- Ca declines, but the ALc-Ca content increases at 60th day after storage. Calcium containing antimonite precipitates are mainly distributed in cell wall tonoplast, nuclear membrance,and nucleoplasm. There are much more calcium containing antimonite precipitates in fruit cytoplast treated by CK than those of calcium treatments.