For students
FTIR spectra libraries
Master collection

Zentralinstitut für Ernährungs- und Lebensmittelforschung (ZIEL)

Abteilung Mikrobiologie
Technische Universität München
Weihenstephaner Berg 3
D-85350 Freising


Food Analytical Methods,
March 2016, Volume 9, Issue 3, pp 646-655, First online: 26 June 2015

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

Manuel Krewinkel, Claudia Baur, Bertolt Kranz, Mario von Neubeck, Mareike Wenning, Siegfried Scherer, Marina Stoeckel, Jörg Hinrichs, Lutz Fischer

Microbial lipases may be produced during milk storage and processing. This can lead to organoleptic changes in the corresponding dairy products. Thus, monitoring of lipase activity in milk is desirable. Turbidity of milk prevents a direct 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 lipolytic activity (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 out initially 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 milk sample 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 MeDeLi was 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, milk products, and spoiled milk samples were also investigated with the MeDeLi.

Milk Lipase Test system Clarification Enzyme activity Milk analysis Biotechnology



Otto-von-Guericke Forschungspreis für Siegfried Scherer

Innovationspreis für Siegfried Scherer

Spoilage of Microfiltered and Pasteurized Extended Shelf Life Milk Is Mainly Induced by Psychrotolerant Spore-Forming Bacteria that often Originate from Recontamination (2017)

Transcriptional and translational regulation by RNA thermometers, riboswitches and the sRNA DsrA in Escherichia coli O157:H7 Sakai under combined cold and osmotic stress adaptation. (2016)

Hysteresis in myo-inositol utilization by Salmonella Typhimurium (2016)

Probiotic Enterococcus faecalis Symbioflor® down regulates virulence genes of EHEC in vitro and decrease pathogenicity in a Caenorhabditis elegans model (2017)

Draft Genome Sequence of Lysinibacillus xylanilyticus SR-86 (Nov. 2016)

Permanent colonization of creek sediments, creek water and limnic water plants by four Listeria species in low population densities (November 2016)

Draft Genome Sequence of the Xanthan Producer Xanthomonas campestris LMG 8031 (Oktober 2016)

Comparative Bioinformatics and Experimental Analysis of the Intergenic Regulatory Regions of Bacillus cereus hbl and nhe Enterotoxin Operons and the Impact of CodY on Virulence Heterogeneity (Mai 2016)

Regulation of fucose and 1,2-propanediol utilization by Salmonella enterica serovar Typhimurium (März 2016)

Acidified nitrite inhibits proliferation of Listeria monocytogenes - Transcriptional analysis of a preservation method (März 2016)

Translatomics combined with transcriptomics and proteomics reveals novel functional, recently evolved orphan genes in Escherichia coli O157:H7 (EHEC)

A sensitive and robust method for direct determination of lipolytic activity in natural milk environment (März 2016, online first)

Evidence for the recent origin of a bacterial protein-coding, overlapping orphan gene by evolutionary overprinting (Dez. 2015)

Massive horizontal gene transfer, strictly vertical inheritance and ancient duplications differentially shape the evolution of Bacillus cereus enterotoxin operons hbl, cytK and nhe (Nov. 2015)

Chemodiversity of cereulide, the emetic Toxin of Bacillus cereus (2015)