Dietary Grape Pomace Supplementation in Dairy Cows: Effect on Nutritional Quality of Milk and Its Derived Dairy Products.

Grape pomace (GP) is the main solid by-product of winemaking and represents a rich source of potent bioactive compounds which could display a wide range of beneficial effects in human health for their association with reduced risk of several chronic diseases. Several studies have proposed the use of GP as a macro-ingredient to obtain economically worthwhile animal feedstuffs naturally enriched by polyphenols and dietary fibers. Moreover, the research carried out in this field in the last two decades evidences the ability of GP to induce beneficial effects in cow milk and its derived dairy products. First of all, a general increase in concentration of polyunsaturated fatty acids (PUFA) was observed, and this could be considered the reflection of the high content of these compounds in the by-product. Furthermore, an improvement in the oxidative stability of dairy products was observed, presumably as a direct consequence of the high content of bioactive compounds in GP that are credited with high and well-characterized antioxidant functions. Last but not least, particularly in ripened cheeses, volatile compounds (VOCs) were identified, arising both from lipolytic and proteolytic processes and commonly associated with pleasant aromatic notes. In conclusion, the GP introduction in the diet of lactating cows made it possible to obtain dairy products characterized by improved nutritional properties and high health functionality. Furthermore, the presumable improvement of organoleptic properties seems to be effective in contributing to an increase in the consumer acceptability of the novel products. This review aims to evaluate the effect of the dietary GP supplementation on the quality of milk and dairy products deriving from lactating dairy cows.