Anotace:
Cheese was in the past, and still is today, one of the leading commodities. The production of “bryndza” has been preserved over the years, and today it is represented by the Protected Geographical Indication “Slovenská bryndza” (Slovenská bryndza). There are two types of “Slovenská bryndza”, mixed or 100% sheep. However, the name 'traditional' belongs only to sheep's bryndza. The high demand for a particular foodstuff also brings risks associated with its quality and fairness. The same is true of the national heritage product, sheep's bryndza. Identifying the originality or authenticity of various animal food products has received considerable attention recently. Our work has focused on the control of adulteration of 100% sheep's bryndza. Purchased samples from different parts of Slovakia were analyzed with a focus on the addition of cow's milk to sheep's bryndza. The reference method for determining the presence of cow's milk in sheep's cheese is based on detecting cow's γ2- and γ3-caseins from cheese after electrophoretic separation on urea-polyacrylamide gels. This method has proven to be reliable and sensitive. We tested sheep's bryndza made from both raw milk and heat-treated milk. The method of checking for adulteration of the cheese proved successful and in one sample we found the presence of cow casein in smaller amounts, probably due to accidental contamination. Isoelectric focusing of γ-caseins after plasmolysis is suitable for qualitatively determining sheep and cow proteins in traditional Slovak bryndza.