Different lipolysis in winter cheese compared to summer

This study shows results on the content of individual free fatty acids in six different ripened winter and summer Swiss cheeses. The sum of the content of free fatty acids formed by lipolysis was always higher in winter cheeses than in summer ones, the one in Emmental being 4 to 5 times higher than in Gruyère, Sbrinz, Tilsit, Appenzell and Vacherin fribourgeois. The high value in Emmental is due to the highest lipolytic activity of the propionic acid bacteria. Lowest values were found in the Vacherin fribourgeois cheese because of the use of mesophilic bacteria. In the other cheeses, the values were similar due to the use of a mixture of meso- and thermophilic bacteria. The concentration of the individual bound fatty acids in cheese fat was also determined and that of free fatty acids expressed as a percentage of the fatty acids in fat. The number of significantly different fatty acids between the seasons was considerably reduced when compared to that obtained when the free fatty acids alone was determined. Among the many factors which influenced the lipolytic activity, the different feeding modes during the seasons were therefore very important. The remaining significant differences between the percentage of free fatty acids, independent of fodder, concerned two short chain free fatty acids for Emmental cheese and C18 long chain free fatty acids for the other cheese types.