Effect of malolactic fermentation by Pediococcus damnosus on the composition and sensory profile of Albariño and Caiño white wines.

AIM: This study was aimed to investigate the influence of malolactic fermentation (MLF) on sensory profile and organoleptic characteristics of Albariño and Caiño white wines. METHODS AND RESULTS: Autochthonous bacteria were isolated from wines after alcoholic fermentation (AF) and further identified as Pediococcus damnosus by 16S rRNA gene sequence analysis. When a commercial Oenococcus oeni starter was inoculated into Albariño and Caiño white wines to perform MLF, which was checked by HPLC quantification of malic and lactic acids, it was shown that autochthonous Ped. damnosus strains were able to predominate over the commercial O. oeni starter and perform MLF in Caiño wine. By contrast, neither commercial strain nor indigenous Pediococcus carried out MLF in Albariño wine. However, MLF was achieved when autochthonous strains that predominated in Caiño were inoculated into Albariño. Sensory analysis showed that after the MLF Albariño increased its body and softness, while Caiño result a more mature wine. CONCLUSIONS: MLF can positively affect Albariño and Caiño wines giving them new attributes. Pediococci isolated and characterized in this work can successfully perform MLF without negative effects on the wine, because no production of biogenic amines or exopolysaccharides by the selected pediococcus strains was detected. SIGNIFICANCE AND IMPACT OF THE STUDY: The effect of MLF in the sensory profile of Albariño and Caiño wines has never been studied before. Results obtained in this work showed that Ped. damnosus strains can be considered as a new topic of investigation on malolactic starter.

Chemical evaluation of white wines elaborated with a recombinant Saccharomyces cerevisiae strain overproducing mannoproteins.

In this study, a recombinant Saccharomyces cerevisiae strain EKD13 overproducing mannoproteins has been used to obtain Albariño white wines. The inoculated strain prevailed and produced complete fermentation of the must, as also occurred in the case of spontaneous (non-inoculated) fermentation and in the must inoculated with the S. cerevisiae EC1118 strain. The analytical study of the wines obtained showed that the most important chemical differences among the wines produced with EKD-13, corresponded to the high concentration of mannoproteins, 2-phenyl ethanol and tyrosol. These differences were attributed to the expression, during must fermentation, of genes modified in the recombinant EKD-13 strain. The results obtained imply that this strain could be potentially useful to produce wines rich in mannoproteins that have distinctive characteristics compared to other similar wines, modifying the sensorial and technological parameters of the wines obtained.

Influence of yeast mannoproteins in the aroma improvement of white wines.

UNLABELLED: In the present work, 3 different yeast strains (1, 2, and 3) were used to elaborate white wines using Albariño must. The concentration of polymeric mannose was determined using a method based on the mannoprotein precipitation, hydrolysis and analysis of sylylated mannose derivatives by gas chromatography. Wines elaborated with the strain 1 (W1) presented a higher mannoprotein concentration than the other wines. The analysis of the volatile composition of wines showed significant differences (P < 0.05) among them, being W1 which presented the highest concentration of aroma compounds, mainly terpens and norisoprenoids. The sensorial analysis of wines also showed that W1 had the best quality. The results obtained from this work demonstrate that mannoproteins could be involved in the behavior observed. Some evidences were obtained using a model wine, where 2 major terpens in W1 were preferentially retained by the colloids rich in mannoproteins released by strain 1. PRACTICAL APPLICATION: White wines elaborated with yeast strains overproducing mannoproteins could have better quality than others. Mannoproteins could contribute to aroma enhancement of Albariño white wines.