Significance of the nonvolatile minor compounds of the neutral lipid fraction as markers of the origin of dairy products.

In the past few years several researchers have approached the problem of traceability of dairy products mainly by examining the volatile compounds that could be transferred from forage into milk and cheese. Our research focused on the study of the composition of the nonvolatile minor components of the neutral lipid fraction in mountain dairy products, obtained from animals feeding on pasture, and in milk and cheese samples produced from cows under intensive breeding, fed with concentrates and silages. Hydrocarbons were separated by silica gel column chromatography from the whole lipid matrix and analyzed by GC/MS. Among all the compounds detected, 1-phytene, 2-phytene, neophytadiene, and to a lesser extent the esters of phytol with C16 and C18 fatty acids seem to be promising tools for the recognition of the feeding system. The value of the sum of isoprenoid hydrocarbons (summation operator-hyd) of mountain dairy products (12.3-34.0 mg/kg) was always higher than that obtained from plain samples (1.3-6.4 mg/kg).