Determination of Neutral Lactase Activity in Industrial Enzyme Preparations by a Colorimetric Enzymatic Method: Collaborative Study

Abstract

Thirteen laboratories participated in a collaborative study to validate a colorimetric assay for determining neutral lactase activity in industrial enzyme preparations. Each laboratory received 5 duplicate samples with activity levels of 2000 and 5000 neutral lactase units provided by 4 commercial suppliers. Two laboratories did not return results. Method performance was calculated according to AOAC guidelines. From the 11 remaining laboratories, 3 were excluded from statistical analysis because of invalid data determined during initial review by Youden pair, value versus laboratory. Repeatability relative standard deviation (RSDr) values ranged from 3.20 to 8.62%, and reproducibility relative standard deviation (RSDR) values ranged from 8.77 to 16.35%. With outliers excluded, RSDr values ranged from 2.94 to 5.01%, and RSDRvalues ranged from 7.50 to 13.84%. The colorimetric enzymatic method for determining neutral lactase activity in industrial enzyme preparations has been adopted first action by AOAC INTERNATIONAL.

Effect of Storage on Lactase-Treated β-Casein and β-Lactoglobulin with Respect to Bitter Peptide Formation and Subsequent in Vitro Digestibility

“…Commercial lactase preparations A and B, which were purified from Kluyveromyces lactis using both ultra filtration and chromatography, were obtained from the DSM Co. (Heerlen, Netherland). The activities of lactase A and B were identified as 5574 and 5149 NLU/mL, respectively, according to the method of Engelen and Randsdorp . Prior to use, each lactase enzyme preparation was filtered with a sterile filter (0.2 μm; Sarstedt, Germany).…”

“…The activities of lactase A and B were identified as 5574 and 5149 NLU/mL, respectively, according to the method of Engelen and Randsdorp. 14 Prior to use, each lactase enzyme preparation was filtered with a sterile filter (0.2 μm; Sarstedt, Germany). Fluorescamine, leucine, pepsin, and pancreatin were purchased from Sigma-Aldrich (Steinheim, Germany).…”