Macrowine 2021
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

Related articles…

Variety and climatic effects on quality scores in the Western US winegrowing regions

Wine quality is strongly linked to climate. Quality scores are often driven by climate variation across different winegrowing regions and years, but also influenced by other aspects of terroir, including variety. While recent work has looked at the relationship between quality scores and climate across many European regions, less work has examined New World winegrowing regions. Here we used scores from three major rating systems (Wine Advocate, Wine Enthusiast and Wine Spectator) combined with daily climate and phenology data to understand what drives variation across wine quality scores in major regions of the Western US, including regions in California, Oregon and Washington. We examined effects of variety, region, and in what phenological period climate was most predictive of quality. As in other studies, we found climate, based mainly on growing degree day (GDD) models, was generally associated with quality—with higher GDD associated with higher scores—but variety and region also had strong effects. Effects of region were generally stronger than variety. Certain varieties received the highest scores in only some areas, while other varieties (e.g., Merlot) generally scored lower across regions. Across phenological stages, GDD during budbreak was often most strongly associated with quality. Our results support other studies that warmer periods generally drive high quality wines, but highlight how much region and variety drive variation in scores outside of climate.

Assessing the climate change vulnerability of European winegrowing regions by combining exposure, sensitivity and adaptive capacity indicators

Winegrowing regions recognized as protected designations of origin (PDOs) are closely tied to well defined geographic locations with a specific set of pedoclimatic attributes and strictly regulated by legal specifications. However, climate change is increasingly threatening these regions by changing local conditions and altering winegrowing processes. The vulnerability to these changes is largely heterogenous across different winegrowing regions because it is determined by individual characteristics of each region, including the capacity to adapt to new climatic conditions and the sensitivity to climate change, which depend not only on natural, but also socioeconomic and legal factors. Accurate vulnerability assessments therefore need to combine information about adaptive capacity and climate change sensitivity with projected exposure to new climatic conditions. However, most existing studies focus on specific impacts neglecting important interactions between the different factors that determine climate change vulnerability. Here, we present the first comprehensive vulnerability assessment of European wine PDOs that spatially combines multiple indicators of adaptive capacity and climate change sensitivity with high-resolution climate projections. We found that the climate change vulnerability of PDO areas largely depends on the complex interactions between physical and socioeconomic factors. Homogenous topographic conditions and a narrow varietal spectrum increase climate change vulnerability, while the skills and education of farmers, together with a good economic situation, decrease their vulnerability. Assessments of climate change consequences therefore need to consider multiple variables as well as their interrelations to provide a comprehensive understanding of the expected impacts of climate change on European PDOs. Our results provide the first vulnerability assessment for European winegrowing regions at high spatiotemporal resolution that includes multiple factors related to climate exposure, sensitivity, and adaptive capacity on the level of single winegrowing regions. They will therefore help to identify hot spots of climate change vulnerability among European PDOs and efficiently direct adaptation strategies.

How can historical cultivars mitigate the effects of climate change?

IFV, INRAe and the national network “Partenaires de la Sélection Vigne” representing 37 organizations from the different wine regions, have been working increasingly closely over the last 2 decades towards the preservation of the French varietal patrimony. There are approximately 600 patrimonial varieties according to INRAe and SupAgro Montpellier experts, including ancient cultivars (400) and intravarietal crossbreeds obtained since the 19th century. In the context of a drastic reduction in such varieties from the mid 1980’s in favor of mainstream varieties, it was essential to carry out an inventory of old vines and vineyards. INRAe Vassal collection plays a key role here as it holds the largest diversity available, along with a rich bibliography and herbariums, offering us the opportunity to document and double check the identity of a cultivar, consolidating the expertise of ampelographers. The work is carried out in several stages, from verifying the existence of a variety in a small region, through to rehabilitation. During this session, the authors present the process that leads to the official registration of a variety. After this, IFV selection center takes over to initiate the process of selection and propagation. A specific focus within regions such as the Alps, Champagne and the South-West will provide details of the full procedure. Bia, Bouysselet, Chardonnay rose, Mecle and the aptly named Tardif, are some of the cultivars that have followed this procedure. Furthermore, a recent regulation established by INAO on “varieties of interest for adaptation purposes” might boost uptake by growers. Since 2006, 36 historical cultivars have been registered. Most of these have been neglected in the past due to late maturity, lack of sugar and high titratable acidity at harvest time. Such characteristics are today considered as positive qualities, not only in mitigation of the effects of climate change, but also as an opportunity for restoring diversity…

Teasing apart terroir: the influence of management style on native yeast communities within Oregon wineries and vineyards

Newer sequencing technologies have allowed for the addition of microbes to the story of terroir. The same environmental factors that influence the phenotypic expression of a crop also shape the composition of the microbial communities found on that crop. For fermented goods, such as wine, that microbial community ultimately influences the organoleptic properties of the final product that is delivered to customers. Recent studies have begun to study the biogeography of wine-associated microbes within different growing regions, finding that communities are distinct across landscapes. Despite this new knowledge, there are still many questions about what factors drive these differences. Our goal was to quantify differences in yeast communities due to management style between seven pairs of conventional and biodynamic vineyards (14 in total) throughout Oregon, USA. We wanted to answer the following questions: 1) are yeast communities distinct between biodynamic vineyards and conventional vineyards? 2) are these differences consistent across a large geographic region? 3) can differences in yeast communities be tied to differences in metabolite profiles of the bottled wine? To collect our data we took soil, bark, leaf, and grape samples from within each vineyard from five different vines of pinot noir. We also collected must and a 10º brix sample from each winery. Using these samples, we performed 18S amplicon sequencing to identify the yeast present. We then used metabolomics to characterize the organoleptic compounds present in the bottled wine from the blocks the year that we sampled. We are actively in the process of analysing our data from this study.

Understanding graft union formation by using metabolomic and transcriptomic approaches during the first days after grafting in grapevine

Since the arrival of Phyloxera (Daktulosphaira vitifolia) in Europe at the end of the 19th century, grafting has become essential to cultivate Vitis vinifera. Today, grafting provides not only resistance to this aphid, but it used to adapt the cultivars according to the type of soil, environment, or grape production requirements by using a panel of rootstocks. As part of vineyard decline, it is often mentioned the importance of producing quality grafted grapevine to improve vineyard longevity, but, to our knowledge, no study has been able to demonstrate that grafting has a role in this context. However, some scion/rootstock combinations are considered as incompatible due to poor graft union formation and subsequently high plant mortality soon after grafting. In a context of climate change where the creation of new cultivars and rootstocks is at the centre of research, the ability of new cultivars to be grafted is therefore essential. The early identification of graft incompatibility could allow the selection of non-viable plants before planting and would have a beneficial impact on research and development in the nursery sector. For this reason, our studies have focused on the identification of metabolic and transcriptomic markers of poor grafting success during the first days/week after grafting; we have identified some correlations between some specialized metabolites, especially stilbenes, and grafting success, as well as an accumulation of some amino acids in the incompatible combination. The study of the metabolome and the transcriptome allowed us to understand and characterise the processes involved during graft union formation.