Use Of non-Saccharomyces Yeasts Research Articles

β-glycosidase activity associated with the formation of aroma compounds in native non-Saccharomyces yeasts isolated from cocoa bean fermentation

Description of the subject. The use of non-Saccharomyces yeast for improving fine cocoa flavor perception has been poorly explored. Objectives. In this study, we investigated the contribution of the non-Saccharomyces yeasts producing β-glycosidase isolated from the spontaneous fermentation of cocoa to the quality and production of aromas during the alcoholic fermentation of a medium based on cocoa pulp. Method. The screening for β-glycosidase activity and molecular identification of non-Saccharomyces yeast isolates from Amazonian cocoa bean fermentations were performed on agar plates with esculin as a substrate and by 5.8S ITS rDNA sequence analysis, respectively. The yeasts producing β-glycosidases were used as a starter culture for alcoholic micro-fermentations of a medium based on cocoa pulp, incubated at 30 °C for 48 h. The quantification of organic acids, ethanol, and sugars was obtained by HPLC, and aroma compounds after cocoa pulp fermentation were identified by GC-FID and GC-MS. Results. Twenty-six non-Saccharomyces yeast isolates were selected by β-glycosidase activity, comprising species such as Pichia kudriavzevii (n = 15), Pichia sp. (n = 2), Pichia sporocuriosa (n = 1), Candida orthopsilosis (n = 3), Issatchenkia sp. (n = 1), I. orientalis (n = 1), and P. kudriavzevii/I. orientalis (n = 3). All yeast strains exhibited rapid growth in cocoa pulp medium, low ethanol production, high organic acid production, and higher glucose consume than fructose. These yeasts produced thirty different volatile compounds. The main groups included alcohols (3), esters (19), terpenes (4), phenols (2), organic acids (2), and aldehydes (3), with 67% of these having fruity and floral aromas. Pichia sp., P. kudriavzevii/I. orientalis and Issatchenckia sp. were the largest producers of volatile compounds. Notably, this study identified volatile compounds with fruity aromas previously unassociated with cocoa fermentations for the first time. Conclusions. These data demonstrate the potential of β-glycosidase-producing non-Saccharomyces yeasts to improve floral and fruity aromas, suggesting their promising use as a starter culture for cocoa fermentation.

Use of Non-Saccharomyces Yeast to Enhance the Acidity of Wines Produced in a Warm Climate Region: Effect on Wine Composition

One of the most notable effects of climate change, especially in warm regions, is the decrease in acidity (i.e., increase in pH) of wines and a reduction in their aromatic profile. To address this issue, must from a white grape variety with low acidity were inoculated with two non-Saccharomyces yeasts (Lachancea thermotolerans and Torulaspora delbrueckii) to enhance the acidity of the resulting wines. Basic oenological variables and major volatile compounds and polyols of the wines were analyzed, and the results were compared with those obtained through a Saccharomyces cerevisiae strain. Through multiple regression analysis, we found relations between the production of lactic acid to compounds involved in yeast metabolism and redox balance, including glycerol, acetic acid, isobutanol, isoamyl alcohols, and 2-phenylethanol. By means of principal component analysis, we obtained three components that explain more than 89% of the observed variability. The first component differentiates wines produced by L. thermotolerans; the second differentiates wines obtained by S. cerevisiae from those obtained by T. delbrueckii; and the third component is related to the temperature of fermentation. Organoleptic wines produced with S. cerevisiae were the best valuated, but taste was a highlight of the wines produced with L. thermotolerans due to possessing the best acidity.

Optimizing growth and biomass production of non-Saccharomyces wine yeast starters by overcoming sucrose consumption deficiency.

The use of non-Saccharomyces yeasts as starters in winemaking has increased exponentially in the last years. For instance, non-conventional yeasts have proven useful for the improvement of the organoleptic profile and biocontrol. Active dry yeast starter production has been optimized for Saccharomyces cerevisiae, which may entail problems for the propagation of non-Saccharomyces yeasts. This work shows that the poor growth of Hanseniaspora vineae and Metschnikowia pulcherrima in molasses is related to a deficient sucrose consumption, linked to their low invertase activity. In order to address this issue, simple modifications to the cultivation media based hydrolysis and the reduction of sucrose concentration were performed. We performed biomass propagation simulations at a bench-top and bioreactor scale. The results show that cultivation in a hexose-based media improved biomass production in both species, as it solves their low invertase activity. The reduction in sugar concentration promoted a metabolic shift to a respiratory metabolism, which allowed a higher biomass yield, but did not improve total biomass production, due to the lower sugar availability. To evaluate the technological performance of these adaptations, we performed mixed grape juice fermentations with biomass produced in such conditions of M. pulcherrima and S. cerevisiae. The analysis of wines produced revealed that the different treatments we have tested did not have any negative impact on wine quality, further proving their applicability at an industrial level for the improvement of biomass production.

Importance of micronutrients and organic nitrogen in fermentations with Torulaspora delbrueckii and Saccharomyces cerevisiae

The current use of non-Saccharomyces yeasts in mixed fermentations increases the relevance of the interactions between yeast species. In this work, the interactions between Saccharomyces cerevisiae and Torulaspora delbrueckii were analyzed. For this purpose, fermentations with and without contact between strains of those yeast species were performed in synthetic must. Fermentation kinetics, yeast growth and dynamics were measured over time. Additionally, the effects of nitrogen and other nutrient supplementations on the mixed fermentations were determined. Our results showed that S. cerevisiae did not always dominate the sequential fermentations, and experiments without yeast contact (in which T. delbrueckii cells were removed from the medium before inoculating S. cerevisiae at 48 h) resulted in stuck fermentations except when the inoculum size was increased (from 2 × 106 to 108 cells/mL) or there was a supplementation of thiamine, zinc and amino acids at the same concentration as initially found in the synthetic must. Our findings highlight the importance of inoculum size and ensuring the availability of enough micronutrients for all yeast species, especially in sequential fermentations.

Co-inoculations of Lachancea thermotolerans with different Hanseniaspora spp.: Acidification, aroma, biocompatibility, and effects of nutrients in wine

The use of non-Saccharomyces yeast in the winemaking industry and even more their co-inoculations to maximize their growth and to express phenotypic characteristic is gaining more and more relevance. This study aimed to shed light on the biocompatibilities between Lachancea thermotolerans and Hanseniaspora spp., using different types of nutrients and considering the effect on Yeast Assimilable Nitrogen (YAN), at low temperature (16 °C) and medium SO2 (50 mg/L), in white must. L. thermotolerans has been used for its positive effect on pH reduction and Hanseniaspora spp. for improving the sensory profile. The behaviour of these yeasts was evaluated in co-inoculation, always finishing the fermentation with the sequential inoculation of S. cerevisiae. Significant results were obtained on the population count (CFU/mL) in CHROMagar™, with higher populations of Hanseniaspora spp. with respect to L. thermotolerans. Fermentations with L. thermotolerans/H. vineae, showed inhibition of acidification, generating up to 0.41 g/L of lactic acid. On the contrary, a synergistic effect when L. thermotolerans/H. opuntiae was used, achieved 2.44 g/L of lactic acid and a pH reduction of up to 0.16 and always more significant with Nutrient Vit BlancTM. At the same time ethanol concentration decreased by 3.4 % and volatile acidity never exceeded 0.5 g/L. Aromatic composition was analysed and it was found that all fermentations retained more aromatic esters and that on day 7 the amount of 2-phenylethyl acetate was at least 3 times higher in all fermentations compared to the control (Sc + Nutrient Vit BlancTM) which had 5.96 mg/L. Less yellow intensity (-17.3 %) typical of oxidation were observed in all fermentations in which Nutrient Vit BlancTM had been used and in the sensory analysis the co-inoculations with H. vineae generated better scores.

Assessment of Spontaneous Fermentation and Non-Saccharomyces Sequential Fermentation in Verdicchio Wine at Winery Scale

The use of non-Saccharomyces yeasts in sequential fermentation is a suitable biotechnological process to provide specific oenological characteristics and to increase the complexity of wines. In this work, selected strains of Lachancea thermotolerans and Starmerella bombicola were used in sequential fermentations with Saccharomyces cerevisiae and compared with spontaneous and pure S. cerevisiae fermentation trials in Verdicchio grape juice. Torulaspora delbrueckii together with the other two non-Saccharomyces strains (L. thermotolerans, S. bombicola) in multi-sequential fermentations was also evaluated. Wines, obtained under winery vinification conditions, were evaluated for their analytical and sensorial profile. The results indicated that each fermentation gave peculiar analytical and aromatic features of the final wine. L. thermotolerans trials are characterized by an increase of total acidity, higher alcohols and monoterpenes as well as citric and herbal notes. S. bombicola trials showed a general significantly high concentration of phenylethyl acetate and hexyl acetate and a softness sensation while multi-sequential fermentations showed a balanced profile. Spontaneous fermentation was characterized by the production of acetate esters (ethyl acetate and isoamyl acetate), citrus and herbal notes, and tannicity. The overall results indicate that multi-starter fermentations could be a promising tool tailored to the desired features of different Verdicchio wine styles.

Effect of non‐Saccharomycesyeast strains on 3‐isobutyl‐2‐methoxypyrazine concentration and aroma properties in Sauvignon Blanc wines during fermentation

Background and Aims 3-Isobutyl-2-methoxypyrazine (IBMP) is a compound whose aroma is reminiscent of green capsicum and is found in many winegrape cultivars, such as Cabernet Sauvignon and Sauvignon Blanc. A high concentration in grapes can lead to excessive greenness in the resulting wine products, thus reducing quality. This study sought to determine the impact of using non-Saccharomyces yeast during fermentation on the concentration and perception of IBMP in wines. Methods and Results As a potential postharvest remediation strategy, 11 strains of non-Saccharomyces were evaluated through fermentation of juices containing IBMP. Wines fermented with Kazachstania servazzii, Metschnikowia pulcherrima, K. aerobia, Hanseniaspora uvarum, Meyerozyma guillermondii and Candida krusei were rated with a higher level of fruitiness and less greenness in sensory analysis, even though no significant difference was observed amongst yeast treatments for IBMP concentration. Conclusions In mixed fermentation, in which Saccharomyces cerevisiae yeast strain EC1118 was sequentially inoculated, several non-Saccharomyces yeast strains differentially masked the perception of IBMP. Significance of the Study The selective use of non-Saccharomyces yeast may be a strategy for modulating the excessive perception of greenness in wines derived from grapes containing a high concentration of IBMP.

Metabolomics of Non-Saccharomyces Yeasts in Fermented Beverages

Fermented beverages have been consumed for millennia and today support a global industry producing diverse products. Saccharomyces yeasts currently dominate the fermented beverage industry, but consumer demands for alternative products with a variety of sensory profiles and actual or perceived health benefits are driving the diversification and use of non-Saccharomyces yeasts. The diversity of flavours, aromas, and other sensory characteristics that can be obtained by using non-Saccharomyces yeasts in fermentation is, in large part, due to the diverse secondary metabolites they produce compared to conventional Saccharomyces yeast. Here, we review the use of metabolomic analyses of non-Saccharomyces yeasts to explore their impact on the sensory characteristics of fermented beverages. We highlight several key species currently used in the industry, including Brettanomyces, Torulaspora, Lachancea, and Saccharomycodes, and emphasize the future potential for the use of non-Saccharomyces yeasts in the production of diverse fermented beverages.

Impact of Non-Saccharomyces Wine Yeast Strains on Improving Healthy Characteristics and the Sensory Profile of Beer in Sequential Fermentation.

The use of non-Saccharomyces yeasts in brewing is a useful tool for developing new products to meet the growing consumer demand for innovative products. Non-Saccharomyces yeasts can be used both in single and in mixed fermentations with Saccharomyces cerevisiae, as they are able to improve the sensory profile of beers, and they can be used to obtain functional beers (with a low ethanol content and melatonin production). The aim of this study was to evaluate this capacity in eight non-Saccharomyces strains isolated from Madrid agriculture. For this purpose, single fermentations were carried out with non-Saccharomyces strains and sequential fermentations with non-Saccharomyces and the commercial strain SafAle S-04. The Wickerhamomyces anomalus strain CLI 1028 was selected in pure culture for brewing beer with a low ethanol content (1.25% (v/v)) for its fruity and phenolic flavours and the absence of wort flavours. The best-evaluated strains in sequential fermentation were CLI 3 (Hanseniaspora vineae) and CLI 457 (Metschnikowia pulcherrima), due to their fruity notes as well as their superior bitterness, body, and balance. Volatile compounds and melatonin production were analysed by GC and HPLC, respectively. The beers were sensory-analysed by a trained panel. The results of the study show the potential of non-Saccharomyces strains in the production of low-alcohol beers, and as a flavour enhancement in sequential fermentation.

With Advantages and Disadvantages The Role of Non-Saccharomyces Yeast In The Wine Industry

This article aims to describe non-Saccharomyces yeast and their effects on wine composition, fermentation, chemistry and organoleptic characters. The use of non-Saccharomyces yeast is on the rise in the wine industry despite the negative perception from previous research. It is known that higher levels of non-Saccharomyces yeast could cause implications during winemaking practices. On the contrary, non-Saccharomyces yeast provides complexity, richer aroma and flavour and decreases ethanol content. If the main goal is using indigenous yeast and having a starter culture, use of non-Saccharomyces yeast collected from winery environment could be an option, yet again a risky option. However, previous studies indicated the relation between acetic acid production and the use of non-Saccharomyces yeast. In brief, it is important to increase sanitation in the winery environment and personal awareness to maximize cleanliness and to reduce any unwanted yeast activity. More importantly, in the recent years, the use of non-Saccharomyces yeast is attracting winemakers to achieve unique wine styles, and it is an important topic that should be taken under consideration, particularly on a research basis, specifically for targeting consumer liking-perceptions of the wine. In addition to their positive effect on sensory characters on wines, non-Saccharomyces yeasts as bio-control agents (BCAs) is also charming researchers around the globe.

Effect of ‘loss of function’ mutation in <i> SER1 </i> in wine yeast: fermentation outcomes in co-inoculation with non-<i>Saccharomyces </i>

In wine fermentation, improved wine complexity and sensorial properties can arise from the use of non-Saccharomyces yeast. Generally less alcohol tolerant, such strains often do not finish fermentation, therefore requiring a second inoculation with the more robust Saccharomyces cerevisiae, usually added on Day 3. This sequential approach affords non-Saccharomyces time to make an impact before being overtaken by S. cerevisiae. However, two inoculations are inconvenient; therefore the identification of a slow growing S. cerevisiae strain that can be used in a single co-inoculation with the non-Saccharomyces yeast is highly attractive. In this study we investigated the use of the naturally occurring ‘loss of function’ SER1 variant, identified in a Sake yeast, for the purposes of carrying out co-inoculated wine fermentations. The SER1-232(G > C; G78R) change was introduced into the commonly used wine strain, EC1118, via CRISPR/Cas9 editing. In a chemically defined grape juice medium, the SER1(G78R) mutant grew and fermented more slowly and increased acetic acid, succinic acid and glycerol concentrations. Simultaneous inoculation with the slower-growing mutant with a Metschnikowia pulcherrima or Lachancea thermotolerans strain in sterile Sauvignon blanc juice resulted in differences in sensorial compounds, most likely derived from the presence of non-Saccharomyces yeasts. The EC1118 SER1 (G78R) mutant completed fermentation with M. pulcherrima, MP2, and in fact improved the viability of MP2 compared to when it was used as a monoculture. The SER1 (G78R) mutant also promoted both the growth of the SO2-sensitive L. thermotolerans strain, Viniflora® Concerto™, in a juice high in SO2 and its subsequent dominance during fermentation. In co-fermentations with wild-type EC1118, the Concerto™ population was substantially reduced with no significant changes in wine properties. This research adds to our understanding of the use of a novel slow-growing S. cerevisiae yeast in wine fermentations co-inoculated with non-Saccharomyces strains.

Exploring the phenotypic diversity of oenological traits in Kluyveromyces marxianus strains.

The use of non-Saccharomyces yeasts in the winemaking process may have several positive outcomes. Kluyveromyces marxianus has recently been revealed as a promising species for this industry. While the majority of studies mention the use of K. marxianus in various industries including food production (e.g. dairy and cocoa), recent studies have also shown that its aroma and pectinase production make it a suitable yeast for the wine industry. Nevertheless, only particular strain, IWBT Y885, was investigated. In this study, five different K. marxianus strains as well as one protoplast fusant (BF2020) were compared to strain Y885. These comparisons focused on various oenological traits such as fermentation performance, fermentation metabolites, hydrogen sulfide, and pectinase production. Throughout the study, variations were found between the K. marxianus strains investigated. Indeed, although common traits such as high pectinase activity appeared conserved among K. marxianus strains, a fairly large phenotypic diversity was also evident. Using cluster analysis, strain groupings emerged with strains L01, L05, Y885, and BF2020 grouping together. Similarly, strains L02 and L04 grouped together while strain L03 appearing to show the most variation between the strains investigated. Variation between strains was observed regardless of the original source of isolation.

Use of Non-Saccharomyces Yeasts in Berry Wine Production: Inspiration from Their Applications in Winemaking

Although berries (nongrape) are rich in health-promoting bioactive compounds, and their consumption is associated with a lower risk of diverse chronic diseases, only a fraction of the annual yield of berries is exploited and consumed. Development of berry wines presents an approach to increase the utilization of berries. Alcoholic fermentation is a complex process driven by yeasts, which influence key properties of wine diversification and quality. In winemaking, non-Saccharomyces yeasts were traditionally considered as undesired microorganisms because of their high production of metabolites with negative connotations. However, there has been a recent and growing interest in the application of non-Saccharomyces yeast in many innovative wineries. Numerous studies have demonstrated the potential of these yeasts to improve properties of wine as an alternative or complement to Saccharomyces cerevisiae. The broad use of non-Saccharomyces yeasts in winemaking provides a promising picture of these unconventional yeasts in berry wine production, which can be considered as a novel biotechnological approach for creating value-added berry products for the global market. This review provides an overview of the current use of non-Saccharomyces yeasts in winemaking and their applicative perspective in berry wine production.

Selection Process of a Mixed Inoculum of Non-Saccharomyces Yeasts Isolated in the D.O.Ca. Rioja

The use of non-Saccharomyces yeasts in sequential fermentations with S. cerevisiae has been proposed to improve the organoleptic characteristics involved in the quality of wine. The present study set out to select a non-Saccharomyces inoculum from the D.O.Ca. Rioja for use in winemaking. Strains included in the study belonged to Torulaspora delbrueckii, Lachancea thermotolerans, Metschnikowia pulcherrima, Zygosaccharomyces bailii, Williopsis pratensis, Debaryomyces hansenii, Pichia kluyveri, Sporidiobolus salmonicolor, Candida spp., Cryptococcus spp. and two mixed inocula of Lachancea thermotolerans-Torulaspora delbrueckii in a 30/70 ratio. In the first stage of the process, SO2 resistance and presence of enzymatic activities related to wine aroma and wine color and fining (esterase, esterase-lipase, lipase, leucine arylamidase, valine arylamidase, cystine arylamidase, β-glucosidase, pectinase, cellulose, xylanase and glucanase) were studied. In the later stages, selection criteria such as fermentative behavior, aroma compound production or influence on phenolic compounds were studied in laboratory scale vinifications. Taking into account the results obtained in the different stages of the process, a mixed inoculum of Lachancea thermotolerans-Torulaspora delbrueckii in a 30/70 ratio was finally selected. This inoculum stood out for its high implantation capacity, the production of compounds of interest such as glycerol and lactic acid and the consequent modulation of wine acidity. Given these characteristics, the selected inoculum is suitable for the production of quality wines.

Non-Saccharomyces as Biotools to Control the Production of Off-Flavors in Wines.

Off-flavors produced by undesirable microbial spoilage are a major concern in wineries, as they affect wine quality. This situation is worse in warm areas affected by global warming because of the resulting higher pHs in wines. Natural biotechnologies can aid in effectively controlling these processes, while reducing the use of chemical preservatives such as SO2. Bioacidification reduces the development of spoilage yeasts and bacteria, but also increases the amount of molecular SO2, which allows for lower total levels. The use of non-Saccharomyces yeasts, such as Lachancea thermotolerans, results in effective acidification through the production of lactic acid from sugars. Furthermore, high lactic acid contents (>4 g/L) inhibit lactic acid bacteria and have some effect on Brettanomyces. Additionally, the use of yeasts with hydroxycinnamate decarboxylase (HCDC) activity can be useful to promote the fermentative formation of stable vinylphenolic pyranoanthocyanins, reducing the amount of ethylphenol precursors. This biotechnology increases the amount of stable pigments and simultaneously prevents the formation of high contents of ethylphenols, even when the wine is contaminated by Brettanomyces.

Influence of Non-Saccharomyces Strains on Chemical Characteristics and Sensory Quality of Fruit Spirit.

The use of non-Saccharomyces yeasts for alcoholic beverage improvement and diversification has gained considerable attention in recent years. The effect of pure and mixed inocula (of Torulaspora delbrueckii, Lachancea thermotolerans, and Saccharomyces cerevisiae) on apple mash fermentation has been determined for the production of Hungarian fruit spirit (Pálinka), with a special emphasis on the chemical, volatile, and sensory attributes. The enological parameters were followed during the fermentation process. Sugar consumption and organic acid production were determined by HPLC, whereas the aromatic profile of the distillates was characterized by GC-FID. According to the results, single and mixed cultures showed similar characteristics during mash fermentation. The identified volatile compounds included aldehydes, esters, and higher alcohols. Mixed culture fermentation trials revealed a significantly higher concentration of volatile compounds and better sensorial attributes compared to those exhibited by the pure culture of S. cerevisiae.

Non-Saccharomyces yeasts as bioprotection in the composition of red wine and in the reduction of sulfur dioxide

Non-Saccharomyces yeasts have been used for many years due to their technological potential, particularly as a “booster” of wine fruity aroma in mixed fermentations with Saccharomyces cerevisiae. Recently, a new application has emerged, bioprotection, which consists in colonizing the environment in the context of sulfite reduction in wines. The chemical and sensory impact of non-Saccharomyces yeast according to different modes of application in a context of fermentation without addition of SO2 was evaluated through trial with Merlot N. (Vitis vinifera L.). An effective niche occupation by non-Saccharomyces yeasts was highlighted during the prefermentary stages by Quantitative-PCR and MALDI-TOF MS identification. Chemical analysis (GC-MS and GC MS/MS) of finish wine showed the significant impact of the dose applications, with bioprotection characterized by linear esters and sequential application by acetates of higher alcohol contents. Moreover, a separation according to the species used in bioprotection was revealed. Finally, using a panel trained, the sensory analysis confirmed that the use of non-Saccharomyces yeast was a fruity booster in sequential inoculation and, to a less extent, when used as bioprotection. This study shows for the first time that the use of non-Saccharomyces yeast as a bioprotection has a significant impact on the aromatic profile of wines.

Simulated lees of different yeast species modify the performance of malolactic fermentation by Oenococcus oeni in wine-like medium

The use of non-Saccharomyces yeast together with S. cerevisiae in winemaking is a current trend. Apart from the organoleptic modulation of the wine, the composition of the resulting yeast lees is different and may thus impact malolactic fermentation (MLF). Yeasts of Saccharomyces cerevisiae, Torulaspora delbrueckii and Metschnikowia pulcherrima were inactivated and added to a synthetic wine. Three different strains of Oenococcus oeni were inoculated and MLF was monitored. Non-Saccharomyces lees, especially from some strains of T. delbrueckii, showed higher compatibility with some O. oeni strains, with a shorter MLF and a maintained bacterial cell viability. The supplementation of lees increased nitrogen compounds available by O. oeni. A lower mannoprotein consumption was related with longer MLF. Amino acid assimilation by O. oeni was strain specific. There may be many other compounds regulating these yeast lees-O. oeni interactions apart from the well-known mannoproteins and amino acids. This is the first study of MLF with different O. oeni strains in the presence of S. cerevisiae and non-Saccharomyces yeast lees to report a strain-specific interaction between them.

Starmerella bombicola and Saccharomyces cerevisiae in Wine Sequential Fermentation in Aeration Condition: Evaluation of Ethanol Reduction and Analytical Profile.

In the last few decades, the increase of ethanol in wine, due to global climate change and consumers’ choice is one of the main concerns in winemaking. One of the most promising approaches in reducing the ethanol content in wine is the use of non-Saccharomyces yeasts in co-fermentation or sequential fermentation with Saccharomyces cerevisiae. In this work, we evaluate the use of Starmerella bombicola and S. cerevisiae in sequential fermentation under aeration condition with the aim of reducing the ethanol content with valuable analytical profile. After a preliminary screening in synthetic grape juice, bench-top fermentation trials were conducted in natural grape juice by evaluating the aeration condition (20 mL/L/min during the first 72 h) on ethanol reduction and on the analytical profile of wines. The results showed that S. bombicola/S. cerevisiae sequential fermentation under aeration condition determined an ethanol reduction of 1.46% (v/v) compared with S. cerevisiae pure fermentation. Aeration condition did not negatively affect the analytical profile of sequential fermentation S. bombicola/S. cerevisiae particularly an overproduction of volatile acidity and ethyl acetate. On the other hand, these conditions strongly improved the production of glycerol and succinic acid that positively affect the structure and body of wine.

The Use of Yeast Mixed Cultures for Deacidification and Improvement of the Composition of Cold Climate Grape Wines.

Interest in the use of non-Saccharomyces yeast in mixed cultures is increasing due to the perceived improvement in the quality and complexity of the resulting wines. The aim of the study was to determine the ability of monocultures and mixed yeast cultures for deacidification and improvement of the composition of cold climate grape wines. Fermentation of grape musts with increased total acidity was carried out with the use of monocultures of Saccharomyces cerevisiae MH020215 (Sc), Zygosaccharomyces bailii 749 (Zb) and Metschnikowia pulcherrima MG970690 (Mp), and their mixed cultures, inoculated simultaneously and sequentially. Oenological parameters, organic acids and volatile compounds profiles of obtained wines were characterized. The fermentation kinetics and analytical profiles of the obtained wines showed that the use of mixed yeast cultures contributed to the reduction of volatile acidity and acetic acid content in the wines, as well as obtaining a favorable aromatic profile of the wines. The dominant higher alcohols in all wines were 2-methyl-1-propanol, 3-methyl-1-butanol and 2-methyl-1-butanol. Significantly higher amounts of the first two compounds were found in wines obtained with M. pulcherrima MG070690, both in monoculture and in mixed cultures. The monocultures of M. pulcherrima MG070690 (Mp) compared with Z. bailli 749 (Zb) synthesized higher levels of esters in wines, including ethyl acetate, ethyl propionate, isobutyl acetate, ethyl pyroracemate and isoamyl acetate.