A highly sensitive, accurate, and stable method for measuring pectin depolymerase activity

Pectin depolymerase is widely utilized in various industrial sectors. However, the traditional methods for determining its enzymatic activity have limitations, such as cumbersome operations and a significant impact of enzyme solution dilution ratios on activity. The 3-methyl-2-benzothiazolinone hydrazone (MBTH) method can be employed to address these issues, but pectin precipitation and strong background commonly arise in this method. We have successfully overcome these challenges by employing a low-temperature and high-alkaline environment, and further optimized the reagent compositions and detection wavelength to improve the method. Consequently, enzyme hydrolysis follows a zero-order reaction within 60 min, which is helpful for the endpoint measurement of pectinase activity. The developed calibration curve for pectinase concentration and hydrolysis rate demonstrates linearity (R 2  = 0.9945) within the range of 2.5–15.8 mU/mL of pectinase. This method exhibits high sensitivity, accuracy, and stability, making it suitable for routine determination of pectin depolymerase activity in research and applications.