Alberto DE ISEPPI1; Andrea CURIONI1,2; Matteo MARANGON1; Giovanna LOMOLINO1; Simone VINCENZI1,2; Benoit DIVOL3
1Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padova, Italy
2Centre for Research in Viticulture and Enology (CIRVE), Conegliano, Italy
3 South African Grape and Wine Research Institute, Stellenbosch University, South Africa
Email contact: alberto.deiseppi[@]unipd.it
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 . Recently, some valorisation 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 , 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 stabilisers, 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 characterised by SEC-HPLC, SDS-PAGE or CI-ELLSA . The functionalities of the MPs’ extracts were tested in wine by assessing their as 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 stabilising wine against protein haze formation . 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 analogue 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 .
CONCLUSIONS: The extraction of MPs from wine lees with a simple and food grade autoclave-based method can represent an effective valorisation 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.
1. Devesa-Rey, R.; Vecino, X.; Varela-Alende, J.L.; Barral, M.T.; Cruz, J.M.; Moldes, A.B. Valorization of winery waste vs. the costs of not recycling. Waste Manag. 2011, 31, 2327–2335,
2. De Iseppi, A.; Lomolino, G.; Marangon, M.; Curioni, A. Current and future strategies for wine yeast lees valorization. Food Res. Int. 2020, 137, 109352.
3. Marangon, M.; Vegro, M.; Vincenzi, S.; Lomolino, G.; De Iseppi, A.; Curioni, A. A novel method for the quantification of white wine mannoproteins by a Competitive Indirect Enzyme-Linked Lectin Sorbent Assay (CI-ELLSA). Molecules 2018, 23, 3070.
4. De Iseppi, A.; Marangon, M.; Vincenzi, S.; Lomolino, G.; Curioni, A.; Divol, B. A novel approach for the valorization of wine lees as a source of compounds able to modify wine properties. LWT 2021, 136, 110274.
5. De Iseppi, A.; Marangon, M.; Lomolino, G.; Crapisi, A.; Curioni, A. Red and white wine lees as a novel source of emulsifiers and foaming agents. LWT 2021, under review.