 IVES 9 IVES Conference Series 9 The valorization of wine lees as a source of mannoproteins for food and wine applications

The valorization of wine lees as a source of mannoproteins for food and wine applications

Abstract

AIM. Wine yeast lees constitute a winemaking by-product that, unlike grape skins and seeds, are not sufficiently exploited to add value to the winemaking sector, as their treatment and disposal generally represents a cost for wineries [1]. Recently, some valorization strategies proposed the integrated extraction of ethanol, polyphenols, and tartaric acid, while only a few studies investigated ways to exploit the remaining wine lees’ yeast biomass. In particular, no studies attempted the extraction of mannoproteins (MPs), yeast cell wall polysaccharides with known foaming, emulsifying and wine-stabilizing activities [2], from the wine lees’ yeast biomass. To fill this gap, this research aims at developing an efficient and food-grade method for the extraction of yeast MPs from commercial wine lees, and to test the obtained extracts as wine stabilizers, foaming agents, and food emulsifiers.

METHODS. Several protocols were studied to extract MPs from wine lees. Ultimately, commercial wine yeast lees were extracted at pH 3.4 using an autoclave-based treatment (121°C, 20 min). The obtained MPs extracts were characterized by SEC-HPLC, SDS-PAGE or CI-ELLSA [3]. The functionalities of the MPs’ extracts were tested in wine by assessing their foam-promoting ability and their stabilizing potential against protein and tartrate instabilities. Additionally, MPs extracts were tested as emulsifying and foaming agents in model food matrices. The results were compared to those obtained using commercial MPs-based products and/or MPs extracts from pure cultures of the same yeast strains.

RESULTS. Among the extraction protocols tested, the autoclave emerged as the best performing in terms of extract’s effectiveness and, therefore, it was selected for the subsequent extractions. Firstly, MPs obtained from white winemaking lees positively impacted both wine’s foaming properties (+260% height; +360% stability) and tartrate stability (-11%) compared to untreated wine samples. Conversely, the extracts were ineffective in stabilizing wine against protein haze formation [4]. Subsequently, MPs extracts obtained autoclaving red and white wine lees and tested in model food matrices showed encouraging emulsifying activity (≃55% emulsion stability) and foaming properties (stability >3h). In this case, the extract from red wine lees performed better than its analog derived from the same yeast strain grown in the laboratory, thus suggesting a possible impact of wine polyphenols in enhancing the surfactant action of MPs [5].

CONCLUSIONS

The extraction of MPs from wine lees with a simple and food-grade autoclave-based method can represent an effective valorization strategy that, if integrated with the already available techniques to recover ethanol, tartaric acid, and polyphenols, would result in a better exploitation of this by-product with a consequent improvement of the environmental and economic sustainability of the wine industry.

DOI:

Publication date: September 7, 2021

Issue: Macrowine 2021

Type: Article

Authors

Alberto De Iseppi

Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padova, Italy, Andrea CURIONI1,2; Matteo MARANGON1; Giovanna LOMOLINO1; Simone VINCENZI1,2; Benoit DIVOL3

¹ Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padova, Italy
² Centre for Research in Viticulture and Enology (CIRVE), Conegliano, Italy
³ South African Grape and Wine Research Institute, Stellenbosch University, South Africa

Contact the author

Keywords

wine yeast lees, by-product valorisation, mannoproteins, stability, foam, emulsion

Citation

Terroir and climate: the role of homoclime matching

Climate is an important component or determinant of terroir, especially at the regional level. One can define three levels of terroir. These are the macro– or regional scale, which applies over tens of kilometres of the landscape. The second level is the meso- scale, which applies over kilometres or hundreds of meters, at the individual vineyard scale.

Plant nitrogen assimilation and partitioning as a function of crop load

Aims: The optimization of nitrogen use efficiency (NUE, i.e. uptake, assimilation and partitioning) is a solution towards the sustainable production of premium wines, while reducing fertilization and environmental impact. The influence of crop load on the accumulation of N compounds in fruits is still poorly understood. The present study assesses the impacts of bunch thinning on NUE and the consequences on the free amino N (FAN) profile in fruits.

Kinetic study of browning caused by laccase activity using different substrates

To our knowledge all the studies about laccase kinetics and its inhibition have been performed with substrates and conditions very different from those of real grape juice. Moreover, none of these researches really measure enzymatic browning, since they have not taken into account what happens after the oxidation of o-diphenols in o-diquinones and their subsequent polymerization to form melanins1. For that reason, the aim of this research was to develop a new model to measure the kinetics of browning caused by Botrytis cinerea laccase under conditions much closer to those of grape juice and using the substrates naturally present in it.

Vertical temperature gradient in the canopy provides opportunities to adapt training system in a climate change context

Aims: The aims of this study were (1) to measure the vertical temperature gradient in the vine canopy in parcels with different vineyard floor management practices and (2) to analyze the factors influencing this gradient. The objective was to investigate whether the increase of trunk height could be an adaptation strategy to reduce air temperature in the bunch zone in a context of climate change.

Assessment of wine non-Saccharomyces yeast strains as promising producers of glutathione

AIM: Glutathione (GSH) is a non-protein thiol naturally present in grape berries and produced by yeasts during fermentation. It has a strong antioxidant activity, thus can be added during winemaking to limit the oxidative phenomena of wine, preserving sensory characteristics and stability, ultimately promoting a healthier product by reducing the need for SO2 addition.