Improvement of a method for the measurement of lactoperoxidase activity inmilk

Lactoperoxidase (LPO) is one of the two most used indigenous enzymes to eva luate milk heat treatment, alkaline phosphatase being the other. In the pre sent work, LPO activity, was measured using Clarifying Reagent (R) to facil itate spectrophotometric measurement in milk. Satisfying repeatability was obtained with a CV of 5.2% (n = 33). Results obtained by this method correl ated well with the classic Rothenfusser method (R-2 = 0.97; n = 20) and als o with another method using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphon ate diammonium salt) (R-2 = 0.98; n = 21). This very easy rapid colorimetri c method avoided preliminary casein precipitation and filtration steps. It has been shown to be suitable for routine characterisation of heat treatmen t of milk. (C) 2001 Elsevier Science Ltd. All rights reserved.