## 1 Introduction  
In the past few years, radical changes in global wine exports have occurred, creating a new era in production and consumption of wine [1]. Targeting national competitive advances, producers have focused on the production of terrori wines, using indigenous grape varieties and autochthonous yeast strains [2]. In the industrial wine sector, selected yeast and bacterial strains are employed for fermentation, targeting high yields of productivity, stress tolerance, unique aromatic characteristics and positive sensory attributes [3, 4].  
Growth and fermentation kinetics of yeasts are influenced by their nutritional requirements and are highly strain-dependent [5]. Nitrogen availability in grape must is a key parameter for the wine fermentation process, since N- is a substantial nutrient element for yeast growth. It affects the formation of yeast biomass, which, in turn, regulates fermentation duration and kinetics [5]. Grape must contains several different nitrogen sourcesincluding amino acids, ammonium, and small peptides, although not all of these forms can be metabolized by yeasts. The ammonium and the \(\alpha\)-amino acid nitrogen forms are described as the preferential forms, while utilization of small peptides in different environments is possible under specific conditions [6]. A minimum of 140 mg/L of assimilable nitrogen has been established as essential for yeast growth in must under anaerobic fermentation conditions [5; 7]. The assimilation rate of nitrogen is strictly strain-dependent, and as a result, the selected strain plays a major role in alcoholic fermentation kinetics [8]. Different _S. cerevisiae_ strains are characterized by unique nitrogen uptake requirements resulting in variable fermentation behaviors and unique wine organoleptic profiles [9]. Previous studies revealed that different yeast strains can show sufficient fermentation capacity even with limited amounts of nitrogen, while other strains require higher amounts and may result in stuck fermentations in case of nitrogen deficiency [5; 10]. In order to avoid nitrogen deficiency during wine fermentation, it is a common practice to supplement munsts with inorganic nitrogen mainly in the form of diammonium phosphate (DAP). This nitrogen source has been linked with significant effects on wine flavor [11; 12; 13]. More specifically, the type of nitrogen source directly affects the production of wine volatiles (esters, alcohols, and volatile fatty acids) as well as glycerol and organic acid composition [12; 13; 14]. Likewise, nitrogen-containing compounds are considered as important precursors of wines' volatile compounds, and as a result, the origin and availability of nitrogen significantly affects the final quality of wine [11].  
The aim of the current study was to investigate the potential of two _S. cerevisiae_ strains (previously isolated from Santorini Island), to produce wine with unique organoleptic characteristics. For this purpose, must from the Assyrtiko grape variety (indigenous to Santorini Island), were fermented with the autochthonous yeasts. Aiming to produce wines of high quality, the fermentation performance of the yeasts under two YAN contents (high and low) was evaluated, and their impact on wine sensory character was assessed.