Importance of Inactivation Methodology in Enzymatic Processing of Raw Potato Starch: NaOCl as Efficient α-Amylase Inactivation Agent

Efficient inactivation of microbial a-amylases (EC 3.2.1.1) can be a challenge in starch systems as the presence of starch has been shown to enhance the stability of the enzymes. In this study, commonly used inactivation methods, including multistep washing and pH adjustment, were assessed for their efficiency in inactivating different a-amylases in presence of raw potato starch. Furthermore, an effective approach for irreversible a-amylase inactivation using sodium hypochlorite (NaOCl) is demonstrated. Regarding inactivation by extreme pH, the activity of five different a-amylases was either eliminated or significantly reduced at pH 1.5 and 12. However, treatment at extreme pH for 5 min, followed by incubation at pH 6.5, resulted in hydrolysis yields of 42-816% relative to controls that had not been subjected to extreme pH. Inactivation by multistep washing with water, ethanol, and acetone followed by gelatinization as preparation for analysis gave significant starch hydrolysis compared to samples inactivated with NaOCl before the wash. This indicates that the further starch degradation observed in samples subjected to washing only took place during the subsequent gelatinization. The current study demonstrates the importance of inactivation methodology in a-amylase-mediated raw starch depolymerization and provides a method for efficient a-amylase inactivation in starch systems.

Automated summary

In this study, the efficiency of commonly used inactivation methods, such as multistep washing and pH adjustment, in inactivating a-amylases in the presence of raw potato starch were evaluated. An effective approach using sodium hypochlorite (NaOCl) for irreversible a-amylase inactivation was demonstrated. Treatment at extreme pH followed by a neutral pH resulted in significant starch hydrolysis, and inactivation by multistep washing followed by gelatinization gave significant starch degradation compared to samples inactivated with NaOCl before the wash.