A novel electrochemical assay for chymosin determination using a label-free peptide as a substrate

Chymosin is a predominant enzyme in rennet and is used in cheese production because of its excellent milk-clotting activity. Herein, we proposed a facile and label-free electrochemical method for determining chymosin activity based on a peptide-based enzyme substrate. The synthesized substrate peptide for chymosin was assembled onto the surface of the Au-deposited grassy carbon electrode. The current was proportional to chymosin activity, and thus chymosin activity could be determined. The detection ranges of chymosin activity were 2.5 to 25 U mL(-1). The detection limit of chymosin activity was 0.8 U mL(-1). The sensing platform was used to quantify chymosin activity in commercial rennet with high selectivity, excellent stability, and satisfactory reproducibility. We developed a facile, fast, and effective electrochemical assay for detecting chymosin activity, which has potential applications in cheesemaking.

Automated summary

A label-free electrochemical method was developed to determine chymosin activity in cheese production, with a synthesized peptide substrate assembled on an Au-deposited carbon electrode. The method showed high selectivity, stability, and a low detection limit. This fast and effective assay has potential applications in the quantification of chymosin activity in commercial rennet.