Abstract In industrial yoghurt production, continuous process monitoring using pH meters is a cumbersome and non-appropriate technique. The objective of this study was to evaluate the suitability of an optical sensor as a new method for the inline control of yoghurt fermentation. Tests were conducted with three fat and three inulin concentrations and fermentation was monitored simultaneously using an inline light backscatter sensor, pH-meters and a rheometer. A mathematical model that correlates the near infrared light backscatter ratio with the pH, at real time during milk fermentation, was developed. The model was calibrated and successfully validated at the different experimental conditions, predicting the evolution of pH from 5.2 to 4.6 with determination coefficient values higher than 0.993 and standard error of prediction values between 0.02 and 0.11 pH units. The results demonstrated that this is a promising method for the inline control of pH in industrial yoghurt production.

中文翻译：

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使用近红外光背向散射传感器在线控制酸奶发酵过程

摘要 在工业酸奶生产中，使用 pH 计进行连续过程监控是一项繁琐且不合适的技术。本研究的目的是评估光学传感器作为酸奶发酵在线控制新方法的适用性。使用三种脂肪和三种菊粉浓度进行测试，并使用在线光反向散射传感器、pH 计和流变仪同时监测发酵。开发了一种数学模型，该模型将牛奶发酵过程中的近红外光反向散射率与 pH 值实时关联起来。该模型在不同的实验条件下进行了校准和成功验证，预测了 pH 从 5.2 到 4.6 的演变，决定系数值高于 0.993，预测值的标准误差在 0 之间。02 和 0.11 pH 单位。结果表明，这是在工业酸奶生产中在线控制 pH 值的一种很有前景的方法。