## 9 Metabolic Features and By-Products from _Candida stellata_ Activity
### Production of Sophorolipids Biosurfactants by Candida
In a study using Malvar white grape [87], an autochthonous grape variety from Madrid (Spain), different inoculation strategies were applied with _C. stellata_ CLI 920 (Cs) and _S. cerevisiae_ CLI 889 (Sc). Mixed and sequential were significantly different with regard to their volatile composition and the control of _S. cerevisiae_. These wines were characterized by increased esters concentration and \(\beta\)-phenylethyll alcohol (Figure 3). After sensory analysis, the sequential inoculation was well appreciated by tasters for its pleasant fruity (green apple, grapefruit) and floral aroma and its freshness and full-bodied on the palate. These results were corroborated by pilot scale fermentations [26]. Figure 3: Relevant volatile compounds (mg/L) of pure (p), mixed (m), and sequential (s) fermentations made with _C. stellata_ CLI 920 (Cs) and _S. cerevisiae_ CLI 889 (Sc) native strains (adapted from [PERSON] et al. [87]). In agreement with above, [PERSON] et al. [10] described the aroma of banana, flowers, and lime in wines conducted by sequential inoculation in comparison with the control of _S. cerevisiae_. Other works have also shown the fruity and flowery aroma in cocultures between _C. stellata_ and _S. cerevisiae_, which is the result of greater concentration of desirable aromatic compounds including some higher alcohols; \(\beta\)-phenylethyl alcohol and ethyl esters correlated well with its medium-chain fatty acids [26; 64; 105; 116; 129]. In recent years, multiples studies have focused on polysaccharides content in wines, giving special attention to the mannoproteins. These molecules are one of the major polysaccharide groups in wines from yeast cell walls [130], and they are secreted into wine during alcoholic fermentation and yeast autolysis during ageing on lees [131]. Mannoproteins composition consists mainly of mannose (80 to 90%) and small amounts of glucose, associated with 10-20% of protein. Numerous investigations have clearly confirmed that these macromolecules are related to technological and sensorial properties in wines, such as prevention of protein haze in white wines [132], protection against crystallization of tartrate salts [133], interaction with aroma compounds [134], improvement of foam stability and flocculation in sparkling wines [135], reduction of astringency and increased body and mouthfeel [136], and increase of the growth of malolactic bacteria [137]. Moreover, it has been noted that the utilization of _Saccharomyces_/non-_Saccharomyces_ co-fermentations results in increased release of polysaccharides into the wine, since the high capacity of non-_Saccharomyces_ wine yeasts to release polysaccharides (including mannoproteins) has been verified [143; 138; 139; 140]. [PERSON] et al. [139] characterized the monosaccharide composition of mannoproteins produced by _S. bombicola_ 3827; they noted that the polysaccharides produced by _S. bombicola_ were essentially mannoproteins with 73-74% of mannose residues. In the previously mentioned study [87] (Figure 3), the polysaccharides' content and structure were studied in Malvar wines elaborated with _C. stellata_ CLI 920 and _S. cerevisiae_ CLI 889. The greater content of arabinose, galactose, and mannose in the total colloids means that mannoproteins from yeast cell walls and Polysaccharides Rich in Arabinose and Galactose (PRAGs) were the main macromolecules in Malvar wines regardless of the inoculation strategy used (Figure 4a). The high content of galactose observed, especially in _C. stellata_ pure culture (p-Cs), could also be explained by the presence of this monosaccharide-like galactomannan in yeast cell walls, as in _Schizosaccharomyces pombe_. However, a phylogenetic study with 33 species of _Candida_ carried out by [PERSON] et al. [141] determined that the cell wall of _C. stellata_ lacked galactose. Mannose residues are larger in _C. stellata_/_S.