冷热温度激化抑制果蔬衰变的机理研究

In China, the losses of postharvest fruits and vegetables are heavy. However, the application of chemical preservative methods has become more and more restricted. In the field of fruits and vegetables preservation, scientific and effective physical methods and related basic research have become important subjects. Cold and heat shock treatments have many advantages, such as good storage quality, less investment and simple operation. However, the related researches are still at an initial stage and focus on their biological effects to fruits and vegetables. Many respects, such as heat transfer characteristics during treatments, influence law to physiological and biochemical characteristics of fruits and vegetables and inhibitory mechanism on chilling injury, should also be studied. Combined with physiochemical tests, we intended to use theories of heat transfer, mathematics, and physiology to study the dynamic response characteristics of tissue temperature and its interaction law with life vigor of fruits and vegetables in our subject. Meanwhile, their inhibition mechanism on chilling injury and senescence of fruits and vegetables would be studied. We also want to get a quantitative evaluation method of storage quality and a optimization method of cold and heat shock treatments parameter. It would provide basis scientific theory and data for the application of high-quality physical preservative methods.

我国果蔬采后损失较大，而化学保鲜方法的应用日益受到限制，因此科学有效的果蔬物理保鲜相关基础研究已成为重要课题。果蔬采后温度激化处理具有抗衰老、保鲜效果显著、投资少、操作简便等诸多优势，但相关研究还处于试验摸索阶段且多数侧重于其生物学效应层面，而在果蔬温度激化过程中的生物传热特性、激化过程对果蔬生理指标影响规律、抑制果蔬衰变及冷害机理等方面的研究较少，使得温度激化过程的关键参数缺乏深层次科学依据支持。本项目拟运用非稳态热力学和传热学、与植物生理学等交叉学科理论，结合果蔬生理生化测试，建立果蔬温度激化处理试验系统，探索温度激化过程中果蔬组织温度动态响应特性与果蔬贮藏期间生命活力的相互作用规律，剖析温度激化处理抑制果蔬冷害及品质衰变的作用机理，确定温度激化果蔬保鲜效果量化评价方法及温度激化过程参数优化方法，为实施高品质的果蔬采后物理保鲜技术提供科学依据及基础数据支持。

果蔬温度激化处理是近几年新兴的一种物理保鲜方法，具有绿色安全、高效环保、操作简便、保鲜效果显著等诸多优点。然而针对果蔬温度激化处理的作用机理及如何获取不同果蔬类型最佳处理工艺的研究十分缺乏，为此本项目在以下五点展开了深入研究。1、搭建了分别以水和空气为处理介质的果蔬温度激化处理试验系统以及多功能恒温恒湿系统，为后期开展的试验研究奠定了基础；2、基于CFD仿真软件建立以黄瓜为代表的柱状果蔬和以香瓜为代表的球状果蔬的温度激化过程非稳态传热模型，通过试验证明：建立的果蔬传热模型能够准确预测不同类型果蔬组织温度变化特性，并对比研究了不同处理温度和流速、果蔬尺寸大小对处理过程中果蔬组织温度变化的影响；3、对黄瓜进行不同强度冷激处理，结果显示：在0℃冷水处理条件下，不间断处理40min的失重率与硬度损失最小，POD酶也表现出了较高的活性。在同样的40 min处理条件下，与0℃和4℃冷激处理相比，2℃冷激处理40min对于降低失重率，保持硬度具有较好的作用。针对果蔬热激处理研究，采用38℃热水连续或间歇热处理40min的热处理方式，均起到抑制低温冷害发生的效果，且间歇组表现更好，其冷害指数、相对电导率较连续处理组明显降低，且SOD活性明显升高。4、对不同冷激强度处理的黄瓜贮藏品质进行了模糊综合评价，构建了果蔬贮藏品质模糊评价数学模型，采用模糊集贴近度理论对果蔬保鲜品质进行定量评价。结果显示：3℃冷水处理40min的黄瓜贮藏品质最优，并通过实验验证其预测误差仅为6.3%。5、基于果蔬热激处理实验研究基础，采用响应曲面法，优化果蔬热处理工艺。其结果显示：各响应值回归模型的预测值与其实测值吻合度较高，且均达到了显著水平，“火凤凰”黄瓜热激处理对应的最佳温度-时间组合为：40.1℃热水处理32.2 min。其预测精度高达92.0%以上。本项目获得的果蔬温度激化处理机理性研究成果及最佳工艺研究新方法，为研究采后果蔬高品质的保鲜技术及工艺提供科学依据及宝贵经验。