Variability of volatile profiles in milk from the PDO Ragusano cheese production zone

Abstract

Native pasture has been shown to have a strong influence on the sensory characteristics of dairy products. However, few studies have been carried out on milk flavor profiles. The aim of the present study was to evaluate the influence of cows’ pasture-based feeding on milk volatile profile. Four Sicilian dairy farms, with three different breeds and located in the Ragusano PDO cheese production area, were selected and bulk milk samples were collected during three seasons (two pasture seasons and one non-pasture season). Pasture was available in spring and autumn time but not in summer because of the climatic conditions. A total of 72 milk samples were collected. All 72 samples were analyzed by SMart Nose®; and taking into account SMart Nose results, only 48 of spring and summer milk samples were selected for gas chromatography/olfactometry (GC/O) coupled with gas chromatography/mass spectrometry (GC/MS) systems. By applying a principal component analysis on standardized means value, results by SMart Nose showed that if native pasture was present in cows’ diet, milk samples were similar in volatile fingerprint (spring and autumn time) but it strongly differed when cows’ diet lacked native pasture (summer time). However, spring milk samples showed a higher variability than milk samples collected in autumn. Using GC/O, 179 odor-active compounds were detected in milk extracts; 87% of which were chemically identified by GC/MS. Milk samples collected in spring presented 26% more compounds than non-pasture milk samples collected in summer, thus implying a pasture effect on milk aroma profile.