A Sensitive and Robust Method for Direct Determination of Lipolytic Activity in Natural Milk Environment

Publikations-Art

Zeitschriftenbeitrag (peer-reviewed)

Autoren

Krewinkel, M.; Baur, B.; Kranz, B.; von Neubeck, M.; Wenning, M.; Scherer, S.; Stoeckel, M.; Hinrichs, J.; Fischer, L.

Erscheinungsjahr

2016

Veröffentlicht in

Food Anal. Methods

DOI

10.1007/s12161-015-0233-4

Seite (von - bis)

646-655

Microbial lipases may be produced during milkstorage and processing. This can lead to organoleptic changesin the corresponding dairy products. Thus, monitoring of lipase activity in milk is desirable. Turbidity of milk prevents adirect photometric measurement of lipase activity using chromophore- or fluorophore-based assays. Laborious pretreatments or alternative analytical methods normally have to be used. With the method for the determination of lipolyticactivity (MeDeLi) proposed here, it is possible to measure lipase activity directly in the natural milk utilizing tailored fluorometric substrates. Only a defatting step is carried outinitially for the MeDeLi. Then, the conversion of added lipase substrate is carried out in the unmodified milk without addition of any solutions or any enzyme extraction procedure which may influence the enzyme activity. Thereafter, the milksample is treated with two solutions to remove the turbidity of milk by dissolution. A valid and sensitive fluorometric measurement is then possible. The applicability of the MeDeLiwas demonstrated in comparison with tests published previously: The limit of detection for lipolytic activity measured by MeDeLi was the lowest, with 41 pkat/mL. Raw milk, milkproducts, and spoiled milk samples were also investigated with the MeDeLi.