Abstract Hops are a key ingredient for beer brewing due to their role in preservation, the creation of foam characteristics, the bitterness and aroma of the beers. Drying significantly impacts on the composition of hops which directly affects the brewing quality of beers. Therefore, it is pivotal to understand the changes during the drying process to optimize the process with the central aim of improving product quality and process performance. Hops of the variety Mandarina Bavaria were dried at 65 °C and 70 °C with an air velocity of 0.35 m/s. Bulk weights investigated were 12, 20 and 40 kg/m2 respectively. Drying times were 105, 135, and 195 and 215 min, respectively. Drying characteristics showed a unique development, very likely due to the distinct physiology of hop cones (spindle, bracteole, bract, lupilin glands). Color changes depended strongly on the bulk weight and resulting bulk thickness (ΔE 9.5 (12 kg), 13 (20 kg), 18 (40 kg)) whilst α and s acid contents were not affected by the drying conditions (full retention in all cases). The research demonstrated that specific air mass flow is critical for the quality of the final product, as well as the processing time required. Three types of visual sensors were integrated into the system, namely Vis-VNIR hyperspectral and RGB camera, as well as a pyrometer, to facilitate continuous in-process measurement. This enabled the dynamic characterization of the drying behavior of hops. Chemometric investigations into the prediction of moisture and chromatic information, as well as selected chemical components with full and a reduced wavelength set, were conducted. Moisture content prediction was shown to be feasible (r2 = 0.94, RMSE = 0.2) for the test set using 8 wavelengths. CIELAB a* prediction was also seen to be feasible (r2 = 0.75, RMSE = 3.75), alongside CIELAB b* prediction (r2 = 0.52 and RMSE = 2.66). Future work will involve possible ways to improve the current predictive models.

中文翻译：

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使用视觉和环境传感器结合化学计量学对啤酒花干燥行为和质量发展的动态进行过程研究

摘要 啤酒花是啤酒酿造的关键原料，因为它们在保存、产生泡沫特征、啤酒的苦味和香气方面发挥着重要作用。干燥对啤酒花的成分有显着影响，直接影响啤酒的酿造质量。因此，了解干燥过程中的变化以优化过程以提高产品质量和过程性能为核心目标至关重要。品种Mandarina Bavaria 的啤酒花在65 °C 和70 °C 下以0.35 m/s 的空气速度干燥。调查的体积重量分别为 12、20 和 40 kg/m2。干燥时间分别为 105、135、195 和 215 分钟。干燥特性显示出独特的发展，很可能是由于酒花球果（纺锤体、小苞片、苞片、羽扇豆腺）的独特生理学。颜色变化很大程度上取决于堆积重量和最终堆积厚度（ΔE 9.5 (12 kg)、13 (20 kg)、18 (40 kg)），而 α 和 s 酸含量不受干燥条件的影响（在所有案例）。研究表明，特定的空气质量流量对于最终产品的质量以及所需的处理时间至关重要。该系统集成了三种类型的视觉传感器，即 Vis-VNIR 高光谱和 RGB 相机，以及高温计，以促进连续的过程中测量。这使得能够动态表征啤酒花的干燥行为。对水分和色度信息的预测以及具有完整和减少波长集的选定化学成分进行了化学计量学研究。对于使用 8 个波长的测试集，水分含量预测被证明是可行的（r2 = 0.94，RMSE = 0.2）。CIELAB a* 预测也被认为是可行的（r2 = 0.75，RMSE = 3.75），以及 CIELAB b* 预测（r2 = 0.52 和 RMSE = 2.66）。未来的工作将涉及改进当前预测模型的可能方法。