基于细胞ATP含量光谱无损检测的蔬菜新鲜度新型评价方法研究及其仪器系统研制

Current indicators for assessing the freshness of fruits and vegetables include the rate of weight loss, the change of bacteria in prodcut slices observed using optical microscopy, the effecacy of ethylene gas decomposition, the changes in the contents of vitamin C, chlorophyll and other nutrients, etc. The above indicators exthibit significant differences among different types of fruits and vegetables, thus the importance of each indicator varies in the freshness assessment of different fruit and vegetable species. Adenosine triphosphate (ATP), which is a high-energy compound in living organisms, was found to be closely associated with the vitality of living cells. Numerous previous studies have shown that the reduction of high-energy compounds, particularly the ATP content in agroproduct cells, was one of the main reasons that might lead to the loss of freshness and quality deterioration. Therefore, the intracellular ATP content can be used as a potential indicator for freshness and quality evaluation of agricultural products. The traditional method relies on the destructive sampling to determine the ATP content using the bioluminescence reaction. It follows a complicated series of test procedures, and is therefore costly and time-consuming. This research intends to propose a fast non-destructive method for measuring intracellular ATP content in vegetables using a spectroscopic approach. This novel method would provide a rapid, accurate, versatile and easy-to-use indicator for evaluating the freshness of vegetables. Attempts will also be made to design a prototype system with the embedded ARM core microprocessor for measuring the intracellular ATP content in vegetables. Expected outcomes from this research will have a broad prospect in application in the field of vegetable storage, management and classification in large-scaled vegetable distribution and sales companies.

对果蔬新鲜度的评价，目前主要选择失重率、光学显微镜观察细菌切片变化、乙烯气体分解效果、维生素C、叶绿素及其它营养素的含量变化等指标。上述指标在不同果蔬种类中差异显著，对评价不同果蔬种类新鲜度的重要性不尽相同。三磷酸腺苷(ATP)是生物体内的高能化合物，研究表明农产品细胞内以ATP为代表的高能量出现短缺是导致其新鲜度丧失和品质劣化的主要原因。因此，细胞ATP含量可以作为一个潜在的农产品新鲜度和品质的评价指标。确定ATP含量的传统方法主要依靠破坏性的生物发光反应原理，其测试程序复杂、代价昂贵且耗时费力。本项目拟提出一种基于光谱技术的蔬菜细胞ATP含量的快速无损检测方法，为蔬菜新鲜度评价提供一种准确性高、通用性好的新型评价指标，并试图自行设计基于ARM微处理器的滤光片型蔬菜细胞ATP含量的光谱快速无损检测仪器系统。研究预期成果在大型蔬菜流通销售企业的蔬菜贮藏、管理与分级等领域具有广阔的应用前景。

本项目以研究蔬菜贮藏过程中细胞ATP含量的变化与其光谱特征之间的关系为主线，提出基于光谱的细胞ATP含量无损检测的蔬菜新鲜度的新型评价方法，并自行设计了蔬菜细胞ATP含量的光谱快速无损检测装置的原型系统。具体研究内容主要分为：贮藏期间蔬菜光谱特征和细胞ATP含量变化动态研究; 基于光谱数据的蔬菜细胞ATP含量无损检测研究; 蔬菜细胞ATP含量的光谱快速无损检测装置原型系统的设计三个方面。在研究过程中，我们首先以菠菜为主要的研究对象，研究表明：菠菜光谱数据与贮藏时间相关，菠菜细胞原生质体ATP含量与贮藏时间呈显著相关。选取298nm紫外光和730nm近红外光两个特征波长，建立基于叶片光谱数据的细胞原生质体ATP含量的预测模型，并用验证集数据进行验证。结果显示，基于298nm紫外光和730nm近红外光两个特征波长菠菜叶片光谱反射率建立的细胞原生质体ATP含量的预测模型均具有较好的预测效果，其模型的决定系数分别达到了0.8029和0.901。.项目执行后期，在前两年的研究基础上，对ATP含量测量实验过程进行了再次的梳理，对不同品种的蔬菜展开基于ATP的蔬菜新鲜度评价。以青菜，毛毛菜，番茄为研究对象，分别建立了模型。并在前述光谱模型的基础上，研制了蔬菜ATP含量快速测量装置。该装置主要包括：放置蔬菜叶片的样品室、外设的海洋光学HL-2000光源、内置的海洋光学QE65000型光谱仪、内置的树莓派3代B型作为数据处理平台、以及可触摸的屏幕作为输入输出接口。在得到光谱仪所测得的蔬菜叶片在特定波段的光谱数据后，通过调用三种不同品种下的多元线性回归模型来计算叶片的ATP含量。而该ATP含量可代入该种蔬菜在4度或0度的ATP与天数模型，得到被测蔬菜相当于在4度或0度下面，存放了几天，以此作为新鲜度的判断。.本项目的研究利用ATP光谱模型判断蔬菜的新鲜度问题，解决了原理、模型、检测方法到快速检测原型机研发的全过程，为开发研制基于细胞ATP含量光谱无损检测的蔬菜新鲜度的新型评价方法及其设备提供理论和技术基础。