A comprehensive model for the prediction and analysis of internal potato tuber damage in postharvest processes

在从收获到最终消费者的农业加工链中，马铃薯块茎经历了无数的机械载荷，这些载荷经常引起内部结构和生理损伤。与外部损伤相反，内部损伤特别令人担忧，因为它在分级阶段不容易检测到。通常，内部组织损伤会激发生化过程，随着时间的推移，会导致黑色素黑色素的产生。这个过程通常被称为黑点瘀伤。在整个马铃薯块茎的规模上，已经进行了广泛的研究，主要是为了评估可调节的工艺参数，如施肥，收获温度，品种和块茎成熟度对黑斑病的易感性的影响。虽然许多研究人员强调了块茎组织的机械特性和瘀伤易感性之间的联系，但对于申请人的意识，在组织尺度上将应力-应变响应与黑点瘀伤相关联的详细生理力学模型还没有。一种多场建模方法，综合了马铃薯块茎组织的非弹性本构关系和反应动力学，出现黑点瘀伤。基于组织规模实验确定应力-应变响应和变色动力学的本构参数，重要的是，包含/吸收马铃薯块茎批次的预测试历史。实验活动包括压缩测试，呼吸和变色测量以及量化的气体扩散率在块茎组织。从概念上讲，所得到的连续介质力学模型可以用来模拟和分析马铃薯块茎组织对不同的负载模式的响应，并预测随着时间的推移的生理瘀伤responses. To量化的负载集体，马铃薯块茎受到在一个典型的采后过程中，一个离散元模型（DEM）的块茎块茎和块茎机械相互作用。农产品DEM的主要持续挑战与可靠的接触力-渗透法的构建和具有代表性的块茎形状的识别有关。此外，在块茎的表面上，冲击力被整理成负载集体根据黑点，他们contributingt.By加入这两个分支的发展，一个前所未有的预测方法，用于量化内部损坏的马铃薯块茎的分数和时间变化的损坏程度为一个给定的马铃薯块茎批次和处理设备提供。在一系列专门的实验中验证了投影连续模型和DEM的预测能力。

In the agricultural process chain leading from the harvest to the final consumer, potato tubers undergo a myriad of mechanical loads which frequently entail internal structural and physiological damage. Contrary to external damage, internal damage is particularly worrisome as it is not easily detectable in grading stages. Typically, internal tissue damage elicits biochemical processes which, over time, entail the inception of the black pigment melanin. This process is commonly referred to as blackspot bruising. On the scale of a whole potato tuber, it has been extensively investigated, mainly in order to assess the influence of adjustable process parameters such as fertilization, harvest temperature, cultivar and tuber maturity on the susceptibility to blackspot bruising. While many researchers have emphasized the connection between mechanical characteristics of tuber tissue and bruising susceptibility, a detailed physio-mechanical model relating the stress-strain response to blackspot bruising on the tissue scale is as yet absent, to the awareness of the applicants.In this project, a multifield modeling approach synthesizing inelastic constitutive relations for potato tuber tissue and reaction kinetics for the intensity and progress of blackspot bruising is developed. The constitutive parameters for the stress-strain response and the discoloration kinetics are determined based on tissue scale experiments and, importantly, encompass/absorb the pre-testing history of a potato tuber batch. The experimental campaign involves compression tests, respirometric and discoloration measurements as well as a quantification of gas diffusion rates in tuber tissue. Conceptually, the resulting continuum mechanical model can be used to emulate and analyze the response of potato tuber tissue to different load patterns and to forecast the physiological bruising response over time.In order to quantify the load collectives that potato tubers are subjected to in the course of a typical postharvest process, a discrete element model (DEM) for the tuber-tuber and tuber-machinery interaction is advanced. The main persisting challenges for DEM of agricultural produce are related to the construction of reliable contact force-penetration laws and the identification of a representative tuber shape. On a tuber's surface, moreover, impact forces are collated into load collectives according to the blackspots which they contribute to.By joining these two branches of development, an unprecedented predictive approach for quantifying the fraction of internally damaged potato tubers and the temporal change in damage extent for a given potato tuber batch and handling equipment is provided. Both the projected continuum model and the predictive capabilities of the DEM are validated in a series of dedicated experiments.