Chemical-nutritional quality and oxidative stability of milk and dairy products obtained from Friesian cows fed with a dietary supplementation of dried grape pomace

Background: The aim of the present study was to evaluate the nutritional properties of milk and cheese obtained from Friesian cows fed with a diet supplemented with dried grape pomace, a by-product of the oenological industry, that is very rich in polyphenols. This approach is inspired by the increasing interest on foods containing functional ingredients that may have beneficial effects on human health. During the testing period, analysis of the chemical and nutritional properties of milk and dairy products derived from it were performed; particular attention was given to the effect of cheese ripening on the oxidative stability and fermentation process, evaluating respectively the presence of malondialdehyde and γ-aminobutyric acid. Results: Dietary enrichment with grape pomace did not affect the milk composition but induced modifications on the fatty acid profiles in both milk and cheese with an increase in concentration of linoleic acid, trans-vaccenic acid, rumenic acid and total n-6 fatty acids. Moreover, after 30 days of cheese ripening, an increased oxidative stability and an increased concentration of γ-aminobutyric acid were found. Conclusion: Our results led to a general improvement in nutritional parameters of milk and related cheese obtained from Friesian cows that received the feeding enrichment with dried grape pomace. Further analysis should be performed to improve the knowledge on the chemical and microbiological mechanisms at the source of these findings.