Effect of the addition of polysaccharides extracted for grape pomace and must on sensory and chemical composition of white wines

Abstract

AIM: The objective of this work is to study the effect of the addition of polysaccharides extracted for grape pomace by-products and musts on sensory and chemical composition of white wines. Much of the waste obtained in the wine sector is not used, and they can have some valuable compounds, such as the polysaccharides (PS). Then, we decide to extract them from grape pomace and musts and incorporate them into wines to improve their quality, in a circular economy process.

METHODS: Four white wines from Verdejo and Albillo grape varieties were elaborated and five experiments were carried out with each wine: control wines (without the addition of any product); wines with the addition of PS extracted from white grape pomace (1); wines with the addition of PS extracted from white must (2); wines with the addition of rhamnogalacturonans type II (RG-II) of 80% purity; and wines with the addition of commercial PS (inactivated yeast). These products were maintained in contact with the wines for two months, and then they were filtered and bottled. Total polysaccharides, volatile and phenolic compounds were analysed after two months in bottle (2,3), and a sensory analysis was also carried out.

RESULTS: No significant differences were found in the total phenolic compounds by the effect of the addition of the different PS added. In general, the addition of the different PS extracts increased the total PS content, mainly in the wines treated with PS extracted from grape pomace and must. The differences observed in the volatile composition depended on the wine and the family group. The ethyl esters and alcohol acetates slightly increased in some of the wines treated with PS extracted from grape pomace and must, and decreased in wines treated with RG-II. The treatment with the PS extracts reduced the acidity excess of some of the wines studied and increased their mouth-feel and global valuation.

CONCLUSIONS

The use of grape PS extracted from grape pomace or must improve some wine characteristics, such as polysaccharide and volatile composition, and the acidity and mouth-feel attributes. However, these are preliminary results since these wines will be analysed after six months in bottle in order to know if these changes will maintain.

ACKNOWLEDGEMENTS

The authors would like to thank the Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) for the funding provided for this study through the project RTA2017-00005-C02-01.