Macrowine 2021
IVES 9 IVES Conference Series 9 Optimised extraction and preliminary characterisation of mannoproteins from non-Saccharomyces wine yeasts

Optimised extraction and preliminary characterisation of mannoproteins from non-Saccharomyces wine yeasts

Abstract

The use of non-Saccharomyces yeast species for the improvement of wine technological and oenological properties is a topic that has gained much interest in recent years [1]. Their application as co-starter cultures sequential to the inoculation of Saccharomyces cerevisiae and in aging on the lees has been shown to improve aspects such as protein stability and mouthfeel [2]. These contributions have frequently been associated with higher levels of polysaccharides, specifically the cell wall-derived mannoprotein [3]. Furthermore, mannoprotein structure and composition has been shown to vary between yeast strains, which in turn may influence their behaviour in the wine matrix [4-6]. However, non-Saccharomyces yeasts are typically weak fermentors and are frequently out-competed in the fermentation medium. An alternative strategy to their use as co-starter cultures is the isolation of the compound of interest for exogenous application to wine [7]. Indeed, the addition of exogenous mannoprotein-containing products derived from the cell wall of the wine yeast S. cerevisiae is a fairly common winemaking practice [8]. Nevertheless, the extraction of mannoproteins from non-Saccharomyces yeasts has not yet been well described. AIM: This study aimed to optimise the extraction of mannoproteins from four non-Saccharomyces strains, and to perform a preliminary investigation into the compositional differences of the mannoproteins obtained from the different species.

METHODS: Four non-Saccharomyces wine strains, Saccharomyces cerevisiaeSaccharomyces boulardiiMetschnikowia fructicola and Torulaspora delbrueckii, were exposed to combined methods with varied parameters of ultrasound and enzymatic extraction with β-glucanase to optimise mannoprotein yield. Colorimetric assays were used to quantify protein and carbohydrate concentrations in the extracts.

RESULTS: Yeast cells subjected to 4 min of ultrasound treatment applied at 80% of the maximum amplitude with a 50% duty cycle, followed by an enzymatic treatment of 4000 U lyticase per g dry cells weight, showed the highest yield of mannoproteins from all species. Furthermore, preliminary evaluation of the obtained extracts revealed differences in carbohydrate/protein ratios between species and with increased enzyme incubation time, as demonstrated by the higher ratios obtained for T. Delbrueckii and S. cerevisiae after almost all treatments, in comparison to M. fructicola and S. boulardii.

CONCLUSIONS: The results obtained in this study form an important step towards further characterisation of extraction treatment impact and yeast species effect on the extracted mannoproteins. Their impact on the carbohydrate/protein ratio in particular is an important factor to consider for applications such as wine protein haze reduction and tartrate stabilisation, and requires more in-depth investigation of isolated mannoproteins.

DOI:

Publication date: September 3, 2021

Issue: Macrowine 2021

Type: Article

Authors

Carla Snyman, Benoit DIVOL, Matteo MARANGON, Julie MEKOUE NGUELA, Nathalie SCIECZKOWSKI

South African Grape and Wine Research Institute, Department of Viticulture and Oenology, Private Bag X1, Matieland 7602, South Africa, South African Grape and Wine Research Institute, Department of Viticulture and Oenology, Private Bag X1, Matieland 7602, South Africa, Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padova, Viale Dell’Università, 16, 35020, Legnaro, Padova, Italy, Lallemand SAS, 19 rue des briquetiers, BP 59, 31702 Blagnac, France, Lallemand SAS, 19 rue des briquetiers, BP 59, 31702 Blagnac, France

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Keywords

mannoprotein; yeast; non-saccharomyces; extraction; wine; ultrasound; β-glucanase

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Climate change impacts on Douro Region viticulture and adaptation measures

Climate has a significant impact in the success of any agricultural system, with a direct influence on the crops suitability to a given region, interfering on yield and quality and also with the economic sustainability of the productive activity. In the Douro Demarcated Region (RDD), as in most regions of the Mediterranean climate, the scarce precipitation (33% has less than 600 mm per year), and your high variability, associated with high rates of evapotranspiration during the summer, is usually one of the fundamental factors that limit the grapevine development, as well as the production and quality of the harvest. Thus, facing the scenario in temperature changes for the next decades (1.5-2.5°C) and confirming the predictions of precipitation decreases and/or great variability in the occurrence of heat waves and intense rainfall, the consequences for slope stability in mountain viticulture and sustainability of all operations involved, are risks to be taken into account. In this way, a deepest and sustained knowledge regarding the adaptation measures to adverse environmental conditions is of a crucial importance, enabling a more efficient adaptation of plant growth conditions and the optimization of production and quality of the grapevines. The development of this work, carried out in two commercial vineyards, one located in Soutelo do Douro, São João da Pesqueira, Cima Corgo sub-region, and another located in Numão, Vila Nova de Foz Côa, Douro Superior sub-region, it seeks to establish a relationship between climatic elements and physiological, productive and qualitative parameters, as well as to evaluate the effectiveness of adaptation measures, including different types of deficit irrigation (2002-2019) and the application of shading nets (2019-2020) in the physiological, viticultural and oenological behavior in the Touriga Nacional and Moscatel Galego Branco varieties, respectively. The results showed that the application of deficit irrigation allowed to significantly reduce the impact of the adverse weather conditions at key moments in the development of the grapevine, particularly in the period immediately before veráison and maturation, reducing the negative effects on the physiological processes and productivity, without compromise the must quality parameters. On the other hand, the application of shading nets significantly reduced de leaves temperature, allowing to increase the water potential, stomatal conductance and photosynthetic rate of grapes, which was reflected in the yield increase in the 2nd year of the study. For the maturation indicators, higher levels of total acidity, malic acid and assimilable nitrogen were obtained. The last measure presents a huge potential, being essential to carry out more years of trials to obtain stronger conclusions in terms of production parameters, but also in characteristics as important as the grape ripening components and the organoleptic characteristics of wines.

The use of rootstock as a lever in the face of climate change and dieback of vineyard

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Macrowine 2021
IVES 9 IVES Conference Series 9 Optimised extraction and preliminary characterisation of mannoproteins from non-Saccharomyces wine yeasts

Optimised extraction and preliminary characterisation of mannoproteins from non-Saccharomyces wine yeasts

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