枣干制过程中无氧呼吸代谢对品质形成机理的研究

Currently,the processing of jujube was dried mainly in Xinjiang, including naturally dried and hot air drying system.Due to the long drying cycle, dry jujube easy to have a bitter taste, dehiscent fruit , pulp color was brown, nutrient loss and other serious issues affected the quality during the naturally ; Hot air drying cycles was shorter, but also caused serious dry-shrinkage of jujube, the flavor was not strong, acid taste quality issues; Earlier research founded that drying technology and drying process of anaerobic respiration metabolism was essential for formation of quality dry jujube. This project for jujube in the drying process of quality problems caused by anaerobic respiration metabolism study. Using different concentrations of CO2 induced by inflatable packaging of fresh jujube anaerobic respiration.By analyzing the relationships of the different processing stages major products of anaerobic respiration metabolism,such as pyruvic acid, acetaldehyde,ethanol accumulation, related enzyme activities and quality indicators of jujube,such as flavor components,textural properties,soluble sugar,the formation of micro-structure. Reveal dry jujube on quality formation of anaerobic respiration metabolism mechanism,explore induced by anaerobic respiration in the best conditions and control measures.For the development of new drying technology to provide theoretical basis of science,improve quality and inhance market competitiveness of jujube,Results of the study on improving the development level of jujube industry throughout the region,promoting rural economic development, promote peasants is of important significance.

新疆目前红枣加工主要以干制为主，方法有自然干制和热风干制。自然干制由于周期长，干枣易产生苦味、裂果、果肉色泽褐变、营养成分损失等严重影响品质的问题；采用热风干制虽然周期短，又会造成干枣收缩严重、香味不浓郁、口感偏酸等品质问题；前期研究发现干制工艺及干制过程中的无氧呼吸代谢对干枣品质的形成至关重要，本项目针对栆干制过程中由无氧呼吸代谢引起的品质问题进行研究，采用不同浓度的二氧化碳充气包装诱导鲜枣产生无氧呼吸，通过分析不同处理阶段无氧呼吸代谢的主要产物丙酮酸、乙醛、乙醇的积累量及相关的酶活性与干栆的风味成分、质构特性、可溶性糖、微观结构等品质指标形成的关系，揭示出无氧呼吸代谢对干枣品质形成的作用机理，探索出无氧呼吸诱导的最佳时期及调控机制，为制定干制新工艺提供科学的理论依据，提升干枣的品质及市场竞争力，研究结果对提升全区红枣产业发展水平，促进农村经济的发展、带动农民脱贫致富具有重要意义。

新疆目前红枣加工主要以干制为主，方法有自然干制和热风干制。自然干制由于周期长，干枣易产生苦味、裂果、果肉色泽褐变、营养成分损失等严重影响品质的问题；采用热风干制虽然周期短，又会造成干枣收缩严重、香味不浓郁、口感偏酸等品质问题。项目针对枣干制条件、干制过程中由无氧呼吸代谢引起的品质问题进行了系统研究，研究了经CO2诱导鲜枣产生无氧呼吸在不同阶段其代谢的主要产物丙酮酸、乙醛、乙醇的积累规律及相关的酶活性与干枣的风味成分、质构特性、可溶性糖、微观结构等品质指标形成的相关性得出的主要结论如下：.1、无氧呼吸代谢对哈密大枣风味品质有较大的影响，鲜枣经不同浓度CO2及O2预处理干制后会使干枣的香气成分构成发生变化，5%CO2处理明显促进了果实中乙酯类化合物的合成，干枣中酯类、醛类相对百分含量的明显高于对照样品，干制前样品中乙醛含量与的干枣的香气成分有很高的相关性，在0.017～0.019%范围内干枣的香气品质较好。.2、不同浓度的CO2、O2处理对哈密大枣干制前后还原糖、总糖、葡萄糖、果糖、蔗糖含量及糖酸比的影响较大；5%CO2、10%O2处理样品的糖酸比在第2d时达到最大值，此时比对照样品高出49.9、35.5。新疆主栽品种哈密大枣、骏枣、灰枣在不同干制条件下的干制过程中均有无氧呼吸代谢产生，丙酮酸脱羧酶和乙醇脱氢酶酶活性大小依次为哈密大枣＞骏枣＞灰枣，干制后枣果中积累了一定量的乙醇、乙醛、杂醇油、糠醛等影响风味的物质。. 3、CO2诱导无氧呼吸处理加速了哈密大枣的衰老进程，PG、PME、CX活性高峰的出现较对照早，CO2诱导处理及干制条件对枣果的组织结构、质构特性、收缩特性、枣表皮脂溶性成分、色泽、干制速率及干制过程都有一定的影响。 .研究结果表明无论是自然干制还是热风干制，工艺中适度的后熟过程是保证干枣品质形成的关键工艺过程，采用CO2诱导鲜枣产生无氧呼吸代谢能够加速枣果后熟对热风干制工艺中干枣品质的形成具有重要的作用，为以鲜枣为原料制定热风干制新工艺提供了科学依据。