Department of Agricultural and Food Science, Alma Mater Studiorum, University of Bologna, 40127 Bologna, Italy.
Interdepartmental Center for Industrial Agri-Food Research, University of Bologna, 47521 Cesena, Italy.
Sensors (Basel). 2022 Jul 14;22(14):5277. doi: 10.3390/s22145277.
A cheap technique based on an open-ended coaxial probe together with a vector network analyzer was set up. The vector network analyzer , a very tiny handheld device, is the affordable component that gives the instrumental chain a cost-effective perspective. The open-ended coaxial probe is a cable with an SMA gold-plated termination. User-friendly programs can be used to calibrate the instrument, carry out the measurements, and save data on PC. Simple liquid solutions (sodium chloride, citric acids, and saccharose) and more complex liquid food (milk, egg products, and fruit juice) were investigated. In addition, the temperature on the electric measurement of milk was measured to evaluate a possible influence for refrigerated storage products. The reflection parameters, such as the real and imaginary parts of S11, were used to build univariate and multivariate models. The best results in terms of coefficient of determination and related error were 0.997 (RMSE 0.05%) for sodium chloride and 0.965 (RMSE 0.71 °Brix) for fruit juice considering the univariate model, and 0.997 (RMSE 0.04%) for sodium chloride and 0.981 (RMSE 4.44%) for yolk using multivariate analysis. The proposed solution is non-destructive, cheap, rapid, and very attractive for potential lab and industrial applications.
建立了一种基于开口同轴探头和矢量网络分析仪的廉价技术。矢量网络分析仪是一种非常小巧的手持设备，是赋予仪器链具有成本效益的可承受组件。开口同轴探头是带有 SMA 镀金端的电缆。可以使用用户友好的程序来校准仪器、进行测量并将数据保存到 PC 上。研究了简单的液体溶液（氯化钠、柠檬酸和蔗糖）和更复杂的液体食品（牛奶、蛋制品和果汁）。此外，还测量了牛奶电测量的温度，以评估冷藏储存产品的可能影响。使用反射参数，例如 S11 的实部和虚部，构建了单变量和多变量模型。考虑到单变量模型，氯化钠的最佳决定系数和相关误差结果为 0.997（RMSE 0.05%），果汁的最佳结果为 0.965（RMSE 0.71 °Brix）；而对于多变量分析，氯化钠的最佳结果为 0.997（RMSE 0.04%），蛋黄的最佳结果为 0.981（RMSE 4.44%）。该解决方案是非破坏性的、廉价的、快速的，对于潜在的实验室和工业应用具有很大吸引力。
