To cope with these stressful conditions, which can cause nitrogen shortages, yeasts consume and metabolize these compounds as efficiently as possible during fermentation. The preferred compound for yeast is glutamate, which is stored for _de novo_ amino acid biosynthesis. This is particularly relevant when the ethanol content increases, which inhibits amino acid absorption [9]. _S. cerevisiae_ uses amino acids differentially; preferred nitrogen sources are alanine, arginine, asparagine, aspartate, glutamate, glutamine, and serine [7]. The amino acids present in sparkling wines have different origins: (i) they can come directly from the grape, without being metabolized by yeast during its growth, (ii) they can excrete at the end of fermentation, (iii) and they can also originate during the autolysis process. Generally, these amino acids are used by yeast for the formation of proteins or as a source of nitrogen by oxidative deamination; alternatively, an amino acid can be broken down and thus liberate nitrogen. During fermentation, yeast incorporates and metabolizes amino acids to grow and produce biomass. In this process, a series of volatile aromatic compounds are produced (esters, higher alcohols, volatile fatty acids, carbonyls, and sulfur compounds), which have a great impact on the organoleptic properties of wines. In addition, the nitrogen released can also be used for the biosynthesis of other nitrogenous cellular constituents, and its carbon structure can be excreted in wine or used as a carbon source for the biosynthesis of other compounds, such as higher alcohols [10,11], which constitute the main group of aromatic compounds in wine [7]. Nitrogen metabolism is very complex because its intermediaries are also shared among other metabolic pathways. Because of this, there is not yet a complete understanding of the impact of amino acids on the formation of different aromatic compounds. Therefore, it is important to establish a fundamental dataset in order to build solid knowledge. This new study, along with the rest of the work carried out by our research group, seeks to address the lack of information that exists in multi-omics analysis by integrating the proteomics and metabolomics of _S. cerevisiae_ during the second fermentation in the production of sparkling wines (cava). For this reason, in previous works, our research group has focused on the study of ester metabolism [12] and the autophagy process [13], as well as the effect of CO\({}_{2}\) overpressure on the aroma [14,15] during the second fermentation in the production of sparkling wines (cava). In addition, the novelty of using an unconventional yeast for the production of this type of wine was introduced. It is a flor yeast that, due to properties such as its high tolerance to ethanol and its flocculation capacity, could be a good candidate for use in the production of sparkling wine. In this way, the diversity, uniqueness, and typicality of sparkling wine yeasts could be improved. The main objective of this study was to compare the differential proteomic response of amino acid metabolism, specifically their proteins and their interactions in the G1 strain (unconventional yeast) during sparkling wine production _versus_ the conventional P29 strain. This relationship never been investigated before in sparkling wines, hence the difficulty of this study and the relevance of its results. This knowledge is intended to serve as a guide for future research and ultimately to improve the quality of the wine.