Monitoring Acidity, Cl– and NO2– in Pickles Using Microfluidic Paper-Based Analytical Devices

We describe a project-based learning activity using microfluidic, paper-based analytical devices (μPADs). Students used fresh mustards as raw materials to make pickles and monitored acidity, nitrite, and chlorides in pickles during the processing of pickles using μPADs. This activity is provided to train students to understand the principles and develop the experimental skills of three quantitative analysis methods on μPADs, including titration, colorimetric analysis, and distance-based detection. Moreover, this activity is helpful for students to develop a consciousness of food security and to facilitate their deep understanding of the mechanisms of food processing. 84 undergraduates majoring in culinary and nutritional education participated in this activity. Positive feedback from these students indicated that the learning objectives were met.