Interactions of α-Amylase and Calcium Chelator during Neutral Detergent Fiber Analysis

Amylase and calcium chelators, such as disodium ethylene diaminotetraacetate (EDTA), are used in analysis of neutral detergent fiber (NDF) to dissolve starch and pectin, respectively. However, these reagents may interfere with each other's activity. Six combinations of α-amylase and EDTA were examined for determining NDF values of beet pulp (Beta vulgaris), ground corn (Zea mays L.), timothy hay (Phleum pratense), and soybean meal (Glycine max L). For treatment A, 2.5 mL of α-amylase was added 5 min after boiling. Other treatments differed as follows:  (B) 4.5 mL of α-amylase, (C) 4.5 mL of α-amylase added 30 min after boiling, (D) delayed addition of EDTA to 30 min after boiling, (E) no EDTA, and (F) no α-amylase. Inclusion of EDTA interfered with amylase activity in corn grain samples, and addition of amylase to beet pulp and soybean meal samples reduced the effectiveness of EDTA and increased ash in the NDF residue. Amylase should not be used for samples that do not contain starch. Calculating NDF on an ash-free basis minimized the negative effects of amylase on EDTA activity.

Keywords: Neutral detergent fiber analysis; amylase