Indigenous yeasts: emerging trends and challenges in winemaking
Graphical abstract
Introduction
Wine has long been characterized as a product that conveys significant socio-economic impact. Its production involves complicated biochemical reactions, carried out in the presence of complex microbial entities. Wine chemistry is the result of the entire microbiota contribution; however, significant attention is addressed on yeasts, since ‘modern’ winemaking is mostly carried out by selected Saccharomyces cerevisiae strains [1].All yeasts are potentially capable to convert sugars into ethanol, carbon dioxide, and other metabolic products. However, the broad use of commercial starter cultures results in wines lacking authenticity, defined by contiguous sensorial profiles. Yeasts exhibit a fundamental role in the development of the organoleptic characteristics of wine (e.g. flavor, aroma), contributing to distinctive wine character often associated with specific vinicultural regions [2]. Notably, non-conventional indigenous microflora communities in wineries are equally able to shape flavor profile of wines [3]. Hence, many researchers support the idea to preserve the autochthonous microflora, which can be associated with a distinct terroir. Likewise, the “microbial terroir” concept is considered emerging as a principal element in modern winemaking. Primarily, the “microbial terroir” designates a microbial wine character that indicates the origin of a specific wine, dependent on grape varieties, vineyard climate or even the winery environment [4]. More specifically, the “microbial terroir” comprises the microbial fingerprint of a given area, consisting of indigenous yeasts, lactic acid and acetic acid bacteria that can also denote the signature of a specific wine within an authenticity concept. Evolutionary approaches for indications of microbial terroirs are currently flourishing, since native microflora entails a pivotal role in winemaking authentication.
Following the hypothesis of the suggested link between microbial colonization patterns and the environmental conditions in vineyards, biodiversity studies have attempted to widely characterize the native microflora in diverse agricultural ecosystems aiming to perceive the dynamic interactions between plant, soil, and microbes [5,6]. Metabolic interaction within a spontaneous fermentation constitutes another resource to create a new microbial terroir. This new guideline is targeting to merge spontaneous fermentations with industrial safety. Newly introduced approaches employ multicultural fermentation processes in an attempt to express microbiome specificities on the resulting wines [7]. On top of that, an important aspect relates to the observation that yeasts generate a distinctive aromatic profile, that is attributed to intraspecific levels [8••]. Therefore, biodiversity identification emerges to be of great importance as it highly reflects the specific phenotypes of a certain area.
Consumers’ demand and recognition for regionally distinguished wine products are increasing; thereby, it is imperative to exploit indigenous yeasts and their beneficial impact to meet the current trends in wine fermentation. The understanding and the interpretation of the aforementioned mechanisms demonstrate a necessity particularly for local wineries with small scale production that struggle to compete with industrial manufacturers. The economic feasibility of the former will only be secured and sustained through the production of premium quality wines presenting distinctive sensory characteristics from a specific region. Retrospectively, wine tasting, vineyard visits, and familiarization with wine making process could be all combined under the constantly emerging scheme of agricultural tourism to further promote premium quality products, and boost the economy of rural areas.
The aim of the present review is to consolidate the current insights of indigenous yeasts isolation as biotechnological tools to enhance wine quality through an update of the most recent studies in this field. It is envisaged that, a detailed understanding of the elusive mechanisms that contribute in specific sensory characteristics will enable the controlled manufacture of premium quality products and the preservation of their regional character.
Section snippets
Native S. cerevisiae strains
Grape must constitute a highly complex environment, affected by several intrinsic and extrinsic factors that ultimately (among others) determine the quality of wine. Typically, these variables are prevailed by microbial entities that elaborate to form the final product. Among these, S. cerevisiae is the most widely studied yeast strain, involved in industrial-scale fermentations in the form of specific commercial starters. Nevertheless, recent oenological practices endorse the manufacture of
Mixed fermentation and sequential inoculations
A prominent and emerging approach to exploit the distinctive sensory characteristics of the spontaneous fermentation by indigenous yeasts, reckons the controlled application of mixed yeasts as co-starters in winemaking [54•,55]. The concept is to exploit the biodiversity of native phenotypic traits via controlled inoculation to generate distinct metabolites that will attribute premium quality regional wines. Generally, when a specific strain of S. cerevisiae is employed as the starter culture,
Perspectives
Large scale industrial winemaking and the need to conform with standardized quality via a uniform process has compromised and overruled authenticity of wines. There is a tangible commercial need to manufacture regionally distinctive wines that meet the consumers demand for premium quality. Thus, the exploitation of indigenous yeast has been on the spotlight to establish regional starter culture collections with peculiar phenotypes, in an attempt to preserve complex aroma and flavor
Conclusions
The implementation of indigenous yeast, for the development of local starter cultures with specific characteristics has emerged as a strategy to overcome the lack of wine authenticity. Complex sensory characteristics will be evidently sustained and related to distinctive regions and commensal yeast biota. Yeast combinations demonstrate a crucial factor, thus indigenous microbiota simulations are essential to highlight the interacting mechanisms associated with regional wine character. On top of
Conflict of interest statement
Nothing declared.
References and recommended reading
Papers of particular interest, published within the period of review, have been highlighted as:
• of special interest
•• of outstanding interest
Acknowledgements
This manuscript is part of the project ‘Producing higher quality local wines of the Ionian Islands via the use of indigenous wild type yeast strains’ (MIS 5006342) which is implemented under the Action ‘Targeted Actions to Promote Research and Technology in Areas of Regional Specialization and New Competitive Areas in International Level’ funded by the Operational Programme ‘Ionian Islands 2014–2020’ and co-financed by Greece and the European Union (European Regional Development Fund).
References (83)
- et al.
Microbial terroir and food innovation: the case of yeast biodiversity in wine
Microbiol Res
(2015) - et al.
Volatile profile of reduced alcohol wines fermented with selected non-Saccharomyces yeasts under different aeration conditions
Food Microbiol
(2019) - et al.
The use of indigenous Saccharomyces cerevisiae and Starmerella bacillaris strains as a tool to create chemical complexity in local wines
Food Res Int
(2018) - et al.
Saccharomyces cerevisiae-Starmerella bacillaris strains interaction modulates chemical and volatile profile in red wine mixed fermentations
Food Res Int
(2019) - et al.
Isolation of Saccharomyces cerevisiae yeast strains from Macedonian “Tikveš” wine-growing region and their impact on the organoleptic characteristics of Vranec and Cabernet Sauvignon wines
Res J Biotechnol
(2019) - et al.
Selection of non-Saccharomyces yeasts to be used in grape musts with high alcoholic potential: a strategy to obtain wines with reduced ethanol content
FEMS Yeast Res
(2017) - et al.
Growth and metabolism of non-Saccharomyces yeasts isolated from Washington state vineyards in media and high sugar grape musts
Food Microbiol
(2019) - et al.
Assessment of chemical composition and sensorial properties of ciders fermented with different non-Saccharomyces yeasts in pure and mixed fermentations
Int J Food Microbiol
(2020) - et al.
Wine aroma evolution throughout alcoholic fermentation sequentially inoculated with non- Saccharomyces/Saccharomyces yeasts
Food Res Int
(2018) - et al.
Non-Saccharomyces yeasts: an enzymatic unexplored world to be exploited