Publication details

Phytoestrogens in milk: Overestimations caused by contamination of the hydrolytic enzyme used during sample extraction

Authors

BLÁHOVÁ Lucie KOHOUTEK Jiří PROCHÁZKOVÁ Tereza PRUDÍKOVÁ Michaela BLÁHA Luděk

Year of publication 2016
Type Article in Periodical
Magazine / Source Journal of Dairy Science
MU Faculty or unit

Faculty of Science

Citation
Web http://www.sciencedirect.com/science/article/pii/S0022030216304143
Doi http://dx.doi.org/10.3168/jds.2016-10926
Field Food production
Keywords bovine milk; phytoestrogen; mass spectrometry; equol
Description Isoflavones are natural phytoestrogens with antioxidant and endocrine-disrupting potencies. Monitoring of their levels is important to ensure the high quality and safety of food, milk, and dairy products. The efficiency and accuracy of phytoestrogen analyses in complex matrices such as milk depend on the extraction procedure, which often uses hydrolysis by means of the beta-glucuronidase/sulfatase enzyme originating from Helix pomatia. The present study reveals that the commercially available hydrolytic enzyme is contaminated by several phytoestrogen isoflavones (genistein, daidzein, formononetin, and biochanin A) and their metabolite equol, as well as flavones (naringenin and apigenin) and coumestrol. We show that the concentrations of daidzein and genistein in the enzyme could have impaired the results of analyses of the main isoflavones in several previously published studies. Of 8 analyzed compounds, only equol was confirmed in the present study and it serves as a reliable marker of phytoestrogens originating from cow feed. Critical reassessment of phytoestrogen concentrations in milk is needed because several previously published studies might have overestimated the concentrations depending on the extraction procedure used.
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