枣在干制过程中糖代谢和糖苷键合态香气释放机制研究

Sugars and aroma composition were important factors to the quality of dried jujube, which were influenced by dried condition. Research showed that the change of sugars, aroma and texture indexes were related to the dried process, hydrolytic of glycosidic aroma precursors release can be significantly enhanced fruit and the overall quality aroma of its processed products. Taking xinjiang hami jujube as the research object, the processes of natural dried and 40-45℃ hot-air dried were applied, studying on the correlation between dynamic changes of the sugar and related enzyme by modern separation and detection technology, synchroniz-carrying out between the change rule of content of glycosidic bond aroma and activity of glycosidic enzyme. We analyze the influence factors of release of glycosidic bond aroma in the process of dried, reveal change mechanism of sugars and glycosidic bond aroma, in order to make clear sugars and glycosidic bond aroma's contribution to the quality of dried jujube in the process of dried, for provide theoretical basis for dried jujube quality control.

糖类和香气成分是影响干枣品质的重要因素，干制条件对其影响极大。已有研究表明枣在干制过程中糖类、香气和质构等指标的变化与干制工艺密切相关，糖苷类香气前体的水解释放可以显著地增强水果及其加工制品的整体香气品质。本研究以新疆哈密大枣为研究材料，采用自然晒制和40-45℃热风干制两种方式干燥处理，应用现代分离及检测技术研究干制过程中糖（单糖、蔗糖、多糖和可溶性总糖）的动态变化与相关酶（蔗糖合成酶、蔗糖转化酶、果胶酶等）的相关性，同步开展糖苷键合态香气成分的含量及糖苷水解酶活性变化规律，分析红枣在干制过程中糖苷键合态香气释放微平衡的影响因素，揭示影响哈密大枣干制过程中糖类和糖苷键合态香气变化机制，以明确红枣干制过程中糖类和糖苷键合态香气对干枣品质的贡献，为干制红枣品质调控提供理论依据。

糖类和香气成分是影响干枣品质的重要因素，干制条件对其影响极大。已有研究表明枣在干制过程中糖类、香气和质构等指标的变化与干制工艺密切相关，糖苷类香气前体的水解释放可以显著地增强水果及其加工制品的整体香气品质。本研究以新疆哈密大枣为研究材料，采用自然晒干和40-45℃热风干制两种方式干燥处理，哈密大枣脆熟全红期枣果可溶性总糖主要由蔗糖与果糖和葡萄糖等还原糖组成，其中蔗糖含量最高29.23g/100g，而果糖和葡萄糖含量相当，分别为12.96g/100g和12.53g/100g。干制处理后，可溶性总糖含量降低，还原糖含量增加，干枣糖类含量由蔗糖转换为果糖和葡萄糖的积累。干制时间和呼吸强度极显著影响可溶性总糖和蔗糖含量，果糖和葡萄糖呈极显著正相关，而分别与蔗糖呈极显著负相关，说明果糖和葡萄糖的积累是蔗糖分解所致。40-45℃热风干制处理比自然晒干处理有效的促进了蔗糖向果糖和葡萄糖的转化，多糖含量变化趋势一致。40-45℃干制处理枣果中FRK呈现先增加后下降的趋势，而自然晒干处理枣果FRK呈持续降低的趋势。枣果中糖分的变化趋势受分解酶（NI、SSc、AI）和合成酶（SPS和SSs）共同作用的影响，在干制过程中SPS和SSs是影响可溶性糖变化的关键酶。不同干制温度处理多糖和对应酶的活性相关性差异较大，提高干制温度促进原果胶的转化，而对可溶性果胶和纤维素的含量影响不大。40-45℃热风干制在短期内刺激β-D-葡萄糖苷酶酶活（8 h），且比自然晒干更快达到酶失活点（36 h）。自然晒干游离态香气成分63种，主要为醛类，键合态香气成分83种，其中较多的组分为酯类（十二酸甲酯）。40-45℃热风干制游离态香气成分74种，主要为酸类，键合态香气成分100种，主要为酯类（肉豆蔻酸甲酯）。两种干制方式β-D-葡萄糖苷酶酶活与键合态酯类香气成分呈极显著正相关，40-45℃热风干制可释放出更多香气物质种类以及含量。本研究揭示了影响哈密大枣干制过程中糖类和糖苷键合态香气变化机制，明确糖类和糖苷键合态香气对干枣品质的贡献，为干制红枣品质调控提供理论依据。