Quick and Cheap Colorimetric Quantification of Proteins Using 96-Well-Plate Images

Students quantified the protein content in beer, milk, powdered milk, and whey protein using the Bradford assay. The assay was carried out using absorbance measured at 595 nm (standard method) and 96-well-plate images (proposed method). They built analytical curves using bovine serum albumin (BSA) and casein and determined that protein type affected the Bradford assay. They also determined figures of merit such as the limit of detection (LOD), the limit of quantification (LOQ), linear working range, sensitivity, precision (standard deviation, F-test), and accuracy (percent error, t test). In addition, an interference test was carried out using nitrogen-rich compounds, organic bases, and amino acids, and it was shown that the Bradford assay was not affected by these compounds. Student learning outcomes were assessed by a final test using Microsoft Forms. As a learning model, students can determine the protein content in various food samples using just sample dilution, without the need for intricate sample preparation procedures.