## 1 Introduction  
Nowadays, natural antioxidants extracted from plant by-products represent a useful source of active compounds to produce healthy and functional foods more and more requested by consumers [1]. In order to face this increasing demand, in the last years, the food industries also focused the attention toward dairy products. Thus, several efforts are being made to enrich dairy products such as cheeses with functional and antioxidant components [2] because these foods are basically poor in bioactive compounds [3].  
The most interesting natural antioxidants belong to the chemical classes of phenols [4]. They are particularly present in some fruits such as red grape [5]. Thus, winemaking industry by-products constitute an interesting source of bioactive phenolic compounds [6]. The main by-products generated during the winemaking process are composed by a mix of grape seeds and skins [7], namely grape pomace, which represents approximately 20-25% of the grapes at harvest [8]. The wine industry produces millions of tons of grape pomace with several environmental and economic implications [9]. These by-products are characterized by high contents of antioxidant polyphenols and dietary fiber with potential beneficial effects on human health, including antioxidant activity and antimicrobial, anti-inflammatory, anticancer, and cardiovascular properties [10].  
Grape pomace in powder (GPP) has been added to several food formulations including cereal-based foods [11], meat [12], and fish [13] products as well as cheeses [7; 14] in order to increase their antioxidant activity and dietary fiber content. Regarding GPP addition to cheese, so far, this application has only been performed for bovine milk derived cheeses.  
In Italy, dairy sheep farming is particularly located in the islands of Sardinia and Sicily and in central regions. Sheep milk produced in Sicily derives mainly from ewes of Valle del Belice and Comisana local breeds fed pasture-based diets and is processed to manufacture dairy products at industrial or farm level. Sicily region valorized some of its dairy productions by means of the recognition of quality status like Protected Designation of Origin (PDO), but due to their scarce reputation in terms of healthy properties, cheeses, especially those processed from ewe's milk, are considered as unsuitable for a valuable nutrition by the majority of people. For this reason, in the last years, several breeders and cheese producers pushed research institutes to develop dairy functional foods in order to contribute to the rural development. This issue is particularly relevant for the Mediterranean area because the production of cheeses is important for the environmental sustainability, makes advantageous the maintenance of native breeds, allows the survival of handicraft techniques, limits the land abandonment phenomenon, and a renewed interest for high-quality, safe products can increase the employment for livestock raising and milk transformation and have an appreciable impact on the local economy.  
With this in mind, in this work a novel fresh-stretched ewes' milk cheese was produced with the addition of GPP using four lactic acid bacteria (LAB) strains individually. These LAB were previously selected for their resistance in presence of the main grape polyphenols [15]. The final cheeses were subjected to the evaluation of the microbiological, physicochemical, sensory, and functional aspects.