AIM: Biosurfactants can be used as emulsifier agents to improve the taste, flavour, and quality of food-products with minimal health hazards . They are surface-active compounds with antioxidant and solubilizing properties . In this study, a biosurfactant has been evaluated during red winemaking for its effect on fermentation dynamics, phenolic compounds extraction, and colour stabilization. METHODS: The biosurfactant used was obtained from a fermented residual stream of corn-milling industry, named corn steep liquor (CSL). The harvested mass from Merlot winegrapes was distributed in 12 fermentation flaks with the same proportion of grape juice and solid parts. Six of them were added with CSL biosurfactant (1 g/L) whereas the other six were not added (control). Two fermentation protocols were assessed (spontaneous and Saccharomyces cerevisiae inoculated). Fermentation dynamics and kinetics, standard chemical parameters, colour characteristics, and phenolic composition were determined during maceration and at the end of malolactic fermentation.RESULTS: During inoculated maceration, the biosurfactant-added samples showed significantly higher values of total polyphenols and colour intensity when compared to control, and lower ones of the three colour CIEL*a*b* coordinates (lightness, red/green, and yellow/blue). At the end of alcoholic fermentation, a higher percentage of more stable polymerized pigments was also observed. The final wine resulted to be richer in total polyphenols and anthocyanins, as well as in high molecular weight flavanols for the biosurfactant-added samples. CONCLUSIONS: The biosurfactant addition did not affect negatively on inoculated fermentation dynamics and influenced positively the colour stability after malolactic fermentation resulting in darker and bluish wines. No significant changes on colour properties and related compounds were observed when spontaneous fermentation was performed. ACKNOWLEDGMENTS: This study was supported by the Spanish Ministry of Economy and Competitiveness (MINECO project RTI2018-093610-B-100).
Authors: Susana Río Segade – University of Torino, Italy,Susana RÍO SEGADE, University of Torino, Italy Vasileios ENGLEZOS, University of Torino, Italy Alejandro LÓPEZ-PRIETO, University of Vigo, Spain Maria Alessandra PAISSONI, University of Torino, Italy Simone GIACOSA, University of Torino, Italy Kalliopi RANTSIOU, University of Torino, Italy Luca ROLLE, University of Torino, Italy Benita PÉREZ CID, University of Vigo, Spain Ana Belén MOLDES, University of Vigo, Spain Jose Manuel CRUZ, University of Vigo, Spain
Keywords: red grapes; winemaking; biosurfactant; fermentation dynamics; colour characteristics; phenolic compounds; polymeric pigments