Hanseniaspora vineae and the Concept of Friendly Yeasts to Increase Autochthonous Wine Flavor Diversity

Yeast-insect interactions in southern Africa: Tapping the diversity of yeasts for modern bioprocessing

Yeast-insect interactions are one of the most interesting long-standing relationships whose research has contributed to our understanding of yeast biodiversity and their industrial applications. Although insect-derived yeast strains are exploited for industrial fermentations, only a limited number of such applications has been documented. The search for novel yeasts from insects is attractive to augment the currently domesticated and commercialized production strains. More specifically, there is potential in tapping the insects native to southern Africa. Southern Africa is home to a disproportionately high fraction of global biodiversity with a cluster of biomes and a broad climate range. This review presents arguments on the roles of the mutualistic relationship between yeasts and insects, the presence of diverse pristine environments and a long history of spontaneous food and beverage fermentations as the potential source of novelty. The review further discusses the recent advances in novelty of industrial strains of insect origin, as well as various ancient and modern-day industries that could be improved by use yeasts from insect origin. The major focus of the review is on the relationship between insects and yeasts in southern African ecosystems as a potential source of novel industrial yeast strains for modern bioprocesses.

Exploring future applications of the apiculate yeast Hanseniaspora

As a metaphor, lemons get a bad rap; however the proverb 'if life gives you lemons, make lemonade' is often used in a motivational context. The same could be said of Hanseniaspora in winemaking. Despite its predominance in vineyards and grape must, this lemon-shaped yeast is underappreciated in terms of its contribution to the overall sensory profile of fine wine. Species belonging to this apiculate yeast are known for being common isolates not just on grape berries, but on many other fruits. They play a critical role in the early stages of a fermentation and can influence the quality of the final product. Their deliberate addition within mixed-culture fermentations shows promise in adding to the complexity of a wine and thus provide sensorial benefits. Hanseniaspora species are also key participants in the fermentations of a variety of other foodstuffs ranging from chocolate to apple cider. Outside of their role in fermentation, Hanseniaspora species have attractive biotechnological possibilities as revealed through studies on biocontrol potential, use as a whole-cell biocatalyst and important interactions with Drosophila flies. The growing amount of 'omics data on Hanseniaspora is revealing interesting features of the genus that sets it apart from the other Ascomycetes. This review collates the fields of research conducted on this apiculate yeast genus.

The use of Torulaspora delbrueckii to improve malolactic fermentation

The potential use of Torulaspora delbrueckii as a starter culture for wine alcoholic fermentation has become a subject of interest in oenological research. The use of this non-Saccharomyces yeast can modulate different wine attributes, such as aromatic substances, organic acids and phenolic compound compositions. Thus, the obtained wines are different from those fermented with Saccharomyces cerevisiae as the sole starter. Nevertheless, information about the possible effects of T. delbrueckii chemical modulation on subsequent malolactic fermentation is still not fully explained. In general, T. delbrueckii is related to a decrease in toxic compounds that negatively affect Oenococcus oeni and an increase in others that are described as stimulating compounds. In this work, we aimed to compile the changes described in studies using T. delbrueckii in wine that can have a potential effect on O. oeni and highlight those works that directly evaluated O. oeni performance in T. delbrueckii fermented wines.

Emerging biotechnologies and non-thermal technologies for winemaking in a context of global warming

In the current situation, wine areas are affected by several problems in a context of global warming: asymmetric maturities, pH increasing, high alcohol degree and flat wines with low freshness and poor aroma profile. The use of emerging biotechnologies allows to control or manage such problems. Emerging non-Saccharomyces as Lachancea thermotolerans are very useful for controlling pH by the formation of stable lactic acid from sugars with a slight concomitant alcohol reduction. Lower pH improves freshness increasing simultaneously microbiological stability. The use of Hanseniaspora spp. (specially H. vineae and H. opuntiae) or Metschnikowia pulcherrima promotes a better aroma complexity and improves wine sensory profile by the expression of a more complex metabolic pattern and the release of extracellular enzymes. Some of them are also compatible or synergic with the acidification by L. thermotolerans, and M. pulcherrima is an interesting biotool for reductive winemaking and bioprotection. The use of bioprotection is a powerful tool in this context, allowing oxidation control by oxygen depletion, the inhibition of some wild microorganisms, improving the implantation of some starters and limiting SO2. This can be complemented with the use of reductive yeast derivatives with high contents of reducing peptides and relevant compounds such as glutathione that also are interesting to reduce SO2. Finally, the use of emerging non-thermal technologies as Ultra High-Pressure Homogenization (UHPH) and Pulsed Light (PL) increases wine stability by microbial control and inactivation of oxidative enzymes, improving the implantation of emerging non-Saccharomyces and lowering SO2 additions. GRAPHICAL ABSTRACT.

Screening of Saccharomyces cerevisiae and Torulaspora delbrueckii strains in relation to their effect on malolactic fermentation

The use of Torulaspora delbrueckii in the alcoholic fermentation (AF) of grape must is increasingly studied and used in the wine industry. In addition to the organoleptic improvement of wines, the synergy of this yeast species with the lactic acid bacterium Oenococcus oeni is an interesting field of study. In this work, 60 strain combinations were compared: 3 strains of Saccharomyces cerevisiae (Sc) and 4 strains of Torulaspora delbrueckii (Td) in sequential AF, and four strains of O. oeni (Oo) in malolactic fermentation (MLF). The objective was to describe the positive or negative relationships of these strains with the aim of finding the combination that ensures better MLF performance. In addition, a new synthetic grape must has been developed that allows the success of AF and subsequent MLF. Under these conditions, the Sc-K1 strain would be unsuitable for carrying out MLF unless there is prior inoculation with Td-Prelude, Td-Viniferm or Td-Zymaflore always with the Oo-VP41 combination. However, from all the trials performed, it appears that the combinations of sequential AF with Td-Prelude and Sc-QA23 or Sc-CLOS, followed by MLF with Oo-VP41, reflected a positive effect of T. delbrueckii compared to inoculation of Sc alone, such as a reduction in L-malic consumption time. In conclusion, the obtained results highlight the relevance of strain selection and yeast-LAB strain compatibility in wine fermentations. The study also reveals the positive effect on MLF of some T. delbrueckii strains.

Aroma Profiles of Vitis vinifera L. cv. Gewürztraminer Must Fermented with Co-Cultures of Saccharomyces cerevisiae and Seven Hanseniaspora spp

In this study, the aroma-production profiles of seven different Hanseniaspora strains, namely H. guilliermondii, H. meyeri, H. nectarophila, H. occidentalis, H. opuntiae, H. osmophila and H. uvarum were determined in a simultaneous co-inoculation with the wine yeast Saccharomyces cerevisiae Champagne Epernay Geisenheim (Uvaferm CEG). All co-inoculated fermentations with Hanseniaspora showed a dramatic increase in ethyl acetate levels except the two (H. occidentalis and H. osmophila) that belong to the so-called slow-evolving clade, which had no meaningful difference, compared to the S. cerevisiae control. Other striking observations were the almost complete depletion of lactic acid in mixed-culture fermentations with H. osmophila, the more than 3.7 mg/L production of isoamyl acetate with H. guilliermondii, the significantly lower levels of glycerol with H. occidentalis and the increase in certain terpenols, such as citronellol with H. opuntiae. This work allows for the direct comparison of wines made with different Hanseniapora spp. showcasing their oenological potential, including two (H. meyeri and H. nectarophila) previously unexplored in winemaking experiments.

Proteolytic activity under white wine fermentation by Hanseniaspora vineae yeast strains

Apiculate yeasts from Hanseniaspora genus are predominant on the native flora of grapevines, while Hanseniaspora uvarum is well known for its abundant presence in grapes, it results generally, in detrimental quality effects on wine due to high production of acetic acid. By contrast, Hanseniaspora vineae is better adapted to fermentation, increasing flavor complexity in wines as it has been demonstrated in winemaking practices during the last decade. We obtained a collection of more than 22 different Hanseniaspora vineae strains from which we could detect, by a plating screening method, high and moderate protease activity. In this study, we tested these strains under real winemaking conditions on a Sauvignon blanc white wine must. Results obtained demonstrated that there is an interesting protease active diversity in all H. vineae strains when compared to conventional fermentations conducted by Saccharomyces cerevisiae. Four H. vineae strains showed a decrease in wine protein turbidity, up to three times lower than that observed in S. cerevisiae, which imply a significant decrease in the demand for bentonite before bottling. This attribute of some H. vineaestrains should be very attractive at the commercial level to reduce manipulations and flavor removal in the production of delicate white wines such as Sauvignon blanc.

Wine Aroma Characterization of the Two Main Fermentation Yeast Species of the Apiculate Genus Hanseniaspora

Hanseniaspora species are the main yeasts isolated from grapes and grape musts. Regarding genetic and phenotypical characterization, especially fermentative behavior, they can be classified in two technological clusters: the fruit group and the fermentation group. Among the species belonging to the last group, Hanseniaspora osmophila and Hanseniaspora vineae have been previously isolated in spontaneous fermentations of grape must. In this work, the oenological aptitudes of the two species of the fermentation group were compared with Saccharomyces cerevisiae and the main species of the fruit group, Hanseniaspora uvarum. Both H. osmophila and H. vineae conferred a positive aroma to final wines and no sensory defects were detected. Wines fermented with H. vineae presented significantly higher concentrations of 2-phenylethyl, tryptophol and tyrosol acetates, acetoin, mevalonolactone, and benzyl alcohol compared to H. osmophila. Sensorial analysis showed increased intensity of fruity and flowery notes in wines vinificated with H. vineae. In an evolutionary context, the detoxification of alcohols through a highly acetylation capacity might explain an adaption to fermentative environments. It was concluded that, although H. vineae show close alcohol fermentation adaptations to H. osmophila, the increased activation of phenylpropanoid metabolic pathway is a particular characteristic of H. vineae within this important apiculate genus.