Invited review: The application of alkaline phosphatase assays for the validation of milk product pasteurization

Abstract

Standard practices for indirectly assessing the pasteurization status of milk products are primarily based on the thermal inactivation kinetics of the endogenous milk enzyme, alkaline phosphatase (ALP). This assessment provides an invaluable, if not required, tool for both regulatory and in-house process control and validation. Endogenous milk ALP manifests a slightly higher heat resistance than the pathogenic microflora upon which pasteurization time and temperature requirements are based. Hence, ALP activity is recognized and accepted as the method of choice for the rapid validation of milk product pasteurization. However, ALP assays have notable limitations that must be understood if they are to be administered and interpreted correctly and the results are to be applied judiciously. Issues such as the reactivation of heat-denatured ALP and the presence of both heat-stable and -labile microbial ALP are addressed. A discussion of ALP in the milk of nonbovine species is presented based on the limited literature available. Some discussion of research involving alternative pasteurization indicators also is presented. This article is intended to summarize the pertinent details of the ALP assay for dairy products (noting the basis and limitations of various methods) and the processing, handling, and known compositional factors that influence the assay results.

Biochemical Markers of In Vivo Hepatotoxicity

“…Alkaline phosphatase [AP, ALP] (membrane): Alkaline phosphatase is a membrane-bound enzyme that catalyzes specific chemical reactions within the body especially the hydrolysis of a phosphate group from an organic molecule at an alkaline pH [12]. However, if it is present in serum in large amounts, it is diagnostic of bone or liver disease or a tumor in these organs [13].…”

Stability Improvement of Immobilized Alkaline Phosphatase Using Chitosan Nanoparticles

“…ALP can be used in different fields such as immunoassays and electrochemical immunosensors as a labeling enzyme in the dairy industry as an indicator of successful pasteurization, in molecular biology laboratories for preserving DNA molecules, etc. (Muginova et al, 2007;Kreuzer et al, 1999;Rankin et al, 2010;Rittie and Perbal, 2008). Therefore, the improvement of the enzymatic functional stability is important.…”

Lactation Responses toward Milk Indigenous Enzymes

“…It became recognizable when it was confirmed that the requirement for timetemperature relationships to inactivate the ALP required slightly higher as compared to kill Mycobacterium tuberculosis [56,57]. Almost 40% activity of ALP in raw cow milk is declared to be linked with the milk fat globule membrane (MFGM) in the cream phase, though the rest is soluble or dispersed in whey membrane particles (WMP) in skim milk [58].…”