Whey Protein Analysis Using the Lowry Assay and 96-Well-Plate Digital Images Acquired Using Smartphones

Here, students determine the total protein content in whey protein samples using the Lowry assay. Quantitative analysis was carried out using absorbance measured at 750 nm (standard method) and 96-well-plate digital images obtained using smartphones (proposed method). The proposed method was carried out using two smartphones (1 and 2). Smartphone 1 had a higher resolution than smartphone 2. The statistical evaluation of the data set produced by the students was carried out using JASP (Jeffreys's Amazing Statistics Program), and it was a valuable tool to teach descriptive statistics and hypothesis tests. We chose JASP because it is free and open-source software with a graphical user interface. The protein percentage found in five whey protein samples using the standard method during three lab classes was compared using one-way and two-way ANOVA. Five whey protein samples were analyzed using the standard method and the proposed methods (smartphones 1 and 2). The results were compared using one-way repeated measure ANOVA (RMANOVA) and mixed-factor ANOVA. During the statistical analysis of the data set, students identified outlier results using boxplots and checked data normality using the Shapiro–Wilk test, histograms, and boxplots. They learned the difference between dependent and independent variables and compared variances using Levene's test (dependent variables) and Mauchly's test (independent variables). The interpretation of statistical tests was also carried out using descriptives plots, boxplots, and raincloud plots.