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During 3 years, we explored the biodiversity of the indigenous yeast flora in five Greek wine regions by collecting five varietal grape samples, conventionally and biologically cultured. Spontaneous wine fermentations were carried out by the native microbiota of the grape juice, without the inoculation of selected industrially produced yeast. The indigenous yeast flora, isolated at three phases of these fermentations, was purified and characterized using different oenological and technological criteria. The pre-selected Saccharomyces cerevisiae strains, with the most promising oenological characteristics, were evaluated in microvinifications of Malagousia must and the quality of the produced wines was subjected to a sensorial descriptive analysis.

Wine is a product of microbial activities and microbe–microbe interactions. Yeasts are the principal microorganisms responsible for the evolution and fulfillment of alcoholic fermentation. Several species and strains coexist and interact with their environment and with each other during the fermentation course. Yeast–yeast interactions occur even from the early stages of fermentation, determining yeast community structure and dynamics during the process. Different types of microbial interactions (e.g., mutualism and commensalism or competition and amensalism) may exert positive or negative effects, respectively, on yeast populations. Interactions are intimately linked to yeast metabolic activities that influence the wine analytical profile and shape the wine character. In this context, much attention has been given during the last years to the interactions between Saccharomyces cerevisiae (SC) and non-Saccharomyces (NS) yeast species with respect to their metabolic contribution to wine quality. Yet, there is still a significant lack of knowledge on the interaction mechanisms modulating yeast behavior during mixed culture fermentation, while much less is known about the interactions between the various NS species or between SC and Saccharomyces non-cerevisiae (SNC) yeasts. There is still much to learn about their metabolic footprints and the genetic mechanisms that alter yeast community equilibrium in favor of one species or another. Gaining deeper insights on yeast interactions in the grape–wine ecosystem sets the grounds for understanding the rules underlying the function of the wine microbial system and provides means to better control and improve oenological practices.

Oenococcus oeni is the main agent of malolactic fermentation in wine. This fermentation takes place after alcoholic fermentation, in a low nutrient medium where ethanol and other inhibitor compounds are present. In addition, some yeast-derived compounds such as mannoproteins can be stimulatory for O. oeni. The mannoprotein concentration in wine depends on the fermenting yeasts, and non-Saccharomyces in particular can increase it. As a result of the hydrolytic activity of O. oeni, these macromolecules can be degraded, and the released mannose can be taken up and used as an energy source by the bacterium. Here we look at mannoprotein consumption and the expression of four O. oeni genes related to mannose uptake (manA, manB, ptsI, and ptsH) in a wine-like medium supplemented with mannoproteins and in natural wines fermented with different yeasts. We observe a general gene upregulation in response to wine-like conditions and different consumption patterns in the studied media. O. oeni was able to consume mannoproteins in all the wines. This consumption was notably higher in natural wines, especially in T. delbrueckii and S. cerevisiae 3D wines, which presented the highest mannoprotein levels. Regardless of the general upregulation, it seems that mannoprotein degradation is more closely related to the fermenting medium.

The current trend of rising temperatures and sun irradiation associated to climate change is pushing traditional grape-producing areas with a warm climate towards a very accelerated ripening, leading to earlier harvesting dates and grape must with an unbalanced composition. However, this climatic trend could be exploited to produce other types of wine. In this sense, the increase in temperature could be used to produce wines with overripe grapes. In this regard, the aim of this research work is to evaluate the influence of different degrees and techniques of grape over-ripening to produce wines with the presence or absence of its skins during alcoholic fermentation. To this end, a physicochemical characterization of grape musts and wines obtained from overripe grapes and the monitoring of their fermentation has been performed. Over-ripening grapes by sun-drying has been established as a viable technique viability, producing musts and wines with unique physicochemical and sensory characteristics. In view of the above, it is considered that the production of wines from overripe grapes and in the presence or absence of grape skins is a viable approach to make new white wines taking advantage of the conditions imposed by climate change in a warm climate zone and meet the trends and expectations of current wine consumers., This researchwas funded by PALOMINOSWINES research contract, fund number OT2018-093.

The production of fruit vinegars as a way of making use of fruit by-products is an option widely used by the food industry, since surplus or second quality fruit can be used without compromising the quality of the final product. The acetic nature of vinegars and its subsequent impact on the organoleptic properties of the final product allows almost any type of fruit to be used for its elaboration. A growing number of scientific research studies are being carried out on this matrix, and they are revealing the importance of controlling the processes involved in vinegar elaboration. Thus, in this review, we will deal with the incidence of technological and biotechnological processes on the elaboration of fruit vinegars other than grapes. The preparation and production of the juice for the elaboration of the vinegar by means of different procedures is an essential step for the final quality of the product, among which crushing or pressing are the most employed. The different conditions and processing methods of both alcoholic and acetic fermentation also affect significantly the final characteristics of the vinegar produced. For the alcoholic fermentation, the choice between spontaneous or inoculated procedure, together with the microorganisms present in the process, have special relevance. For the acetic fermentation, the type of acetification system employed (surface or submerged) is one of the most influential factors for the final physicochemical properties of fruit vinegars. Some promising research lines regarding fruit vinegar production are the use of commercial initiators to start the acetic fermentation, the use of thermotolerant bacteria that would allow acetic fermentation to be carried out at higher temperatures, or the use of innovative technologies such as high hydrostatic pressure, ultrasound, microwaves, pulsed electric fields, and so on, to obtain high-quality fruit vinegars.

Lack of nutrients in grape may cause problems for a proper alcoholic fermentation process, resulting in an altered aromatic profile of the wines. To avoid this situation, commercial winemakers often use fermentation activators, which are usually combinations of ammonium salts, inactivated yeast and thiamine. In addition, it has been shown that bee pollen addition to the grape can help to improve fermentation, resulting in better volatile compound profile of wines responsible for sensory quality. For this reason, the aim of this research work was to carry out a comparative study using bee pollen versus commercial fermentation activators in white and red winemaking. The same dose of bee pollen and commercial activators (0.25 g/L) were used in all experiments. Volatile compounds were analyzed by gas chromatography–mass spectrometry, odor activity values were determined to assess odorant impact of various volatile compound families, and finally a descriptive sensory analysis was carried out. Then, the triangular test and the ranking assay were used to identify perceptible differences as well as preference among the wines elaborated. Compared to commercial activators, bee pollen wines increased volatile compound formation, mainly higher alcohols, esters, and terpenes, enhancing fruity and floral odorant series. On the other hand, triangular test showed significant differences between wines, and the ranking assay showed a greater preference for bee pollen wines.

Nitrogen composition on grapevines has a direct effect on the quality of wines since it contributes to develop certain volatile compounds and assists in the correct kinetics of alcoholic fermentation. Several strategies can be used to ensure nitrogen content in grapes and one of them could be the use of elicitors such as methyl jasmonate. The use of this elicitor has been proven to be efficient in the production of secondary metabolites which increases the quality of wines, but its use also has some drawbacks such as its low water solubility, high volatility, and its expensive cost. This study observes the impact on the amino acid and ammonium composition of must and wine of Monastrell grapes that have been treated with methyl jasmonate (MeJ) and methyl jasmonate n-doped calcium phosphate nanoparticles (MeJ-ACP). The first objective of this study was to compare the effect of these treatments to determine if the nitrogenous composition of the berries and wines increased. The second aim was to determine if the nanoparticle treatments showed similar effects to conventional treatments so that the ones which are more efficient and sustainable from an agricultural point of view can be selected. The results showed how both treatments increased amino acid composition in grapes and wines during two consecutive seasons and as well as the use of MeJ-ACP showed better results compared to MeJ despite using less quantity (1 mM compared to 10 mM typically). So, this application form of MeJ could be used as an alternative in order to carry out a more efficient and sustainable agriculture., Spanish MCIN/AEI/10.13039/ 501100011033 and “ERDF, A way of making Europe” through the projects NanoVIT (RTI-2018-095794- B-C21 and RTI-2018-095794-A-C22) and NanoSmart (RYC-2016-21042)., Junta de Andalucia for her postdoctoral contract within PAIDI 2020 program (DOC_01383)

Recently, the use of alternative vessels to oak barrels during winemaking has become increasingly popular, but little is known about their impact on the chemical composition of the resulting wines. To address this issue, a Sauvignon Blanc wine was elaborated from the same grape juice by using cylindrical stainless-steel tanks, oval-shaped concrete vessels, oval-shaped polyethylene vessels, and clay jars in triplicate. Each vessel was used for alcoholic fermentation and the aging of wines over its own lees. Wines elaborated in concrete vessels showed the highest pH and the lowest titratable acidity, most likely related to the observed release of inorganic compounds from the concrete walls. Little effect of the vessels was seen on the wine color and phenolic composition. Wines elaborated in clay jars showed the highest turbidity and the highest content of soluble polysaccharides, while those made using cylindrical stainless-steel tanks showed the highest content of volatile compounds. Despite the observed differences, all of the vessels tested seem suitable for white wine production since every wine showed chemical features that corresponded with the quality standards of Sauvignon Blanc wines. España Universidad de Sevilla, VI Plan Propio de Investigación y Transferencia (Contract number USE-18644-Z)

The production of white wines with the presence of grape skins is a historical technique used in different regions with winemaking tradition. However, the current trend is to maintain the presence of grape skins during white wine making only during the pre-fermentation phase in order to enrich and give greater complexity to the sensory profile of the wines. Given these precedents, this study is the first to consider the effect of the presence of different grape skins doses throughout the alcoholic fermentation process. To this end, the effect of 5 different doses of grape skins (20, 40, 60, 80 and 100%) has been studied with respect to a control (0%) during alcoholic fermentation, the physicochemical composition of the final wines and a preliminary sensory analysis. The presence of grape skins has led to an increase in viable biomass and speed of fermentation with respect to the control. However, no differences have been observed in terms of the consumption of nitrogenous sources by yeasts. The wines produced have not shown great differences in their physicochemical composition, except for the volatile acidity. In addition, the preliminary sensory analysis showed differences between the different grape skins doses studied, where the wine produced with 20% grape skins has been the best evaluated by the tasting panel. In this sense, the production of wines with a 20% grape skins presence during the entire alcoholic fermentation is presented as a viable technique that would allow the diversification of the production of white wines and meet the trends and expectations of current wine consumers.

This study deals with the effects of the use of a mixture of medium-chain fatty acids (MCFA) at the end of the alcohol fermentation process on the content of carbonyl compounds in wine. During the experiment, the effects of the addition of MCFA at doses of 10 and 20 mg/L were compared to the termination of alcohol fermentation using cross-flow filtration and chilling treatments. Individual carbonyl compounds were determined by HPLC analysis. The experiment showed that the addition of MCFA caused a reduction of the acetaldehyde content compared to the chilling process, and a reduction of the diacetyl content compared to cross-flow filtration. Throughout the experiment, a lower level of total carbonyl compounds was observed after the addition of MCFA. info:eu-repo/semantics/openAccess

An electrochemical portable device based on linear sweep voltammetry was evaluated for studying the redox behavior of polyphenolic compounds in industrial scale winemaking to infer the effects of selected early processing steps on the vinification trials of Pinot gris, Chardonnay, Vermentino and Sangiovese grapes. For each sample, the redox behavior showed a distinctive voltammetric signal pattern related to the processing step during winemaking, therefore being useful as a potential fingerprint for wine identification and to provide insights about the phenolic content. For instance, there was a high correlation (R2 = 0.72) between the total phenolic compounds (PhenOx) and the easily oxidizable compounds (EasyOx), the latter representing approx. 30% on average of the total phenolics. Furthermore, the maceration of red grapes was concluded after 29 days based on information driven by the phenolics pattern. As expected, during alcoholic fermentation, white wines showed a lower content of phenolic compounds than those found in red wines, with an average ratio PhenOx/EasyOx of about 4.7, 5.0 and 3.6 for Chardonnay, Pinot gris and Vermentino, respectively. The portable tool with miniaturized disposable electrodes showed interesting analytical features that can be exploited for on-site and real-time quality control for monitoring change in phenolic composition during wine processing and storage, and for tailoring winemaking practices to enhance the color stability of products.

The alcohol content in wine has increased due to external factors in recent decades. In recent reports, some non-Saccharomyces yeast species have been confirmed to reduce ethanol during the alcoholic fermentation process. Thus, an efficient screening of non-Saccharomyces yeasts with low ethanol yield is required due to the broad diversity of these yeasts. In this study, we proposed a rapid method for selecting strains with a low ethanol yield from forty-five non-Saccharomyces yeasts belonging to eighteen species. Single fermentations were carried out for this rapid selection. Then, sequential fermentations in synthetic and natural must were conducted with the selected strains to confirm their capacity to reduce ethanol compared with that of Saccharomyces cerevisiae. The results showed that ten non-Saccharomyces strains were able to reduce the ethanol content, namely, Hanseniaspora uvarum (2), Issatchenkia terricola (1), Metschnikowia pulcherrima (2), Lachancea thermotolerans (1), Saccharomycodes ludwigii (1), Torulaspora delbrueckii (2), and Zygosaccharomyces bailii (1). Compared with S. cerevisiae, the ethanol reduction of the selected strains ranged from 0.29 to 1.39% (v/v). Sequential inoculations of M. pulcherrima (Mp51 and Mp FA) and S. cerevisiae reduced the highest concentration of ethanol by 1.17 to 1.39% (v/v) in synthetic or natural must. Second, sequential fermentations with Z. bailii (Zb43) and T. delbrueckii (Td Pt) performed in natural must yielded ethanol reductions of 1.02 and 0.84% (v/v), respectively.

In agriculture, the wine sector is one of the industries most affected by the sustainability issue. It is responsible for about 0.3% of annual global greenhouse gas emissions from anthropogenic activities. Sustainability in vitiviniculture was firstly linked to vineyard management, where the use of fertilizers, pesticides and heavy metals is a major concern. More recently, the contribution of winemaking, from grape harvest to bottling, has also been considered. Several cellar processes could be improved for reducing the environmental impact of the whole chain, including microbe-driven transformations. This paper reviews the potential of microorganisms and interactions thereof as a natural, environmentally friendly tool to improve the sustainability aspects of winemaking, all along the production chain. The main phases identified as potentially interesting for exploiting microbial activities to lower inputs are: (i) pre-fermentative stages, (ii) alcoholic fermentation, (iii) stage between alcoholic and malolactic fermentation, (iv) malolactic fermentation, (v) stabilization and spoilage risk management, and (vi) by-products and wastewater treatment. The presence of proper yeast or bacterial strains, the management and timing of inoculation of starter cultures, and some appropriate technological modifications that favor selected microbial activities can lead to several positive effects, including (among other) energy savings, reduction of chemical additives such as sulfites, and reuse of certain residues.

There is a lack of knowledge about the use of different wood species on ros&eacute, wine production. Thus, this work focused on the impact of the addition of wood chips from oak and cherry trees during the alcoholic fermentation and maturation process on ros&eacute, wine characteristics. Therefore, phenolic composition and sensory characteristics were monitored during the ros&eacute, wines&rsquo, production. The use of wood chips during alcoholic fermentation induced a significant increase of phenolic content in ros&eacute, musts. During ros&eacute, wine maturation, the wood chip contact induced significantly higher values of colored anthocyanins, color intensity, and polymeric pigments, and significantly lower values of color hue in the corresponding ros&eacute, wines. In terms of sensory profile, a tendency for lower scores of &ldquo, overall appreciation&rdquo, were attributed to control ros&eacute, wine, while significantly higher scores for &ldquo, color intensity&rdquo, descriptor were attributed to all ros&eacute, wines matured in contact with wood chips. For the majority of phenolic parameters and individual phenolic compounds quantified, a clear and specific influence of the use of oak and cherry wood chips was not detected, except for (+)-catechin, where the ros&eacute, wines produced in contact with cherry chips showed the highest values. This study provides relevant information for winemakers about the impact of the use of wood chips on ros&eacute, wine quality.

This study investigates the effects of simultaneous inoculation of a selected Saccharomyces cerevisiae yeast strain with two different commercial strains of wine bacteria Oenococcus oeni at the beginning of the alcoholic fermentation on the kinetics of malolactic fermentation (MLF), wine chemical composition, and organoleptic characteristics in comparison with spontaneous MLF in Tempranillo grape must from Castilla-La Mancha (Spain). Evolution of MLF was assessed by the periodic analysis of L-malic acid through the enzymatic method, and most common physiochemical parameters and sensory traits were evaluated using a standardized sensory analysis. The samples were analyzed by GC/MS in SCAN mode using a Trace GC gas chromatograph and a DSQII quadrupole mass analyzer. Co-inoculation reduced the overall fermentation time by up to 2 weeks leading to a lower increase in volatile acidity. The fermentation-derived wine volatiles profile was distinct between the co-inoculated wines and spontaneous MLF and was influenced by the selected wine bacteria used in co-inoculation. Co-inoculation allows MLF to develop under reductive conditions and results in wines with very few lactic and buttery flavors, which is related to the impact of specific compounds like 2,3-butanedione. This compound has been also confirmed as being dependent on the wine bacteria used.

Review Spirits are alcoholic beverages commonly consumed in European countries. Their raw materials are diverse and include fruits, cereals, honey, sugar cane, or grape pomace. The main aim of this work is to present and discuss the source, quality control, and legal limits of methanol in spirits produced using fruit and honey spirits. The impact of the raw material, alcoholic fermentation, and the distillation process and aging process on the characteristics and quality of the final distilled beverage are discussed. In addition, a critical view of the legal aspects related to the volatile composition of these distillates, the origin and presence of methanol, and the techniques used for quantification are also described. The methanol levels found in the di erent types of spirits are those expected based on the specific raw materials of each and, almost in all studies, respect the legal limits info:eu-repo/semantics/publishedVersion

Non-Saccharomyces yeasts have long been considered spoilage microorganisms. Currently, oenological interest in those species is increasing, mostly due to their positive contribution to wine quality. In this work, the fermentative capacity and nitrogen consumption of several non-Saccharomyces wine yeast (Torulaspora delbrueckii, Lachancea thermotolerans, Starmerella bacillaris, Hanseniaspora uvarum, and Metschnikowia pulcherrima) were analyzed. For this purpose, synthetic must with three different nitrogen compositions was used: a mixture of amino acids and ammonium, only organic or inorganic nitrogen. The fermentation kinetics, nitrogen consumption, and yeast growth were measured over time. Our results showed that the good fermentative strains, T. delbrueckii and L. thermotolerans, had high similarities with Saccharomyces cerevisiae in terms of growth, fermentation profile, and nitrogen assimilation preferences, although L. thermotolerans presented an impaired behavior when only amino acids or ammonia were used, being strain-specific. M. pulcherrima was the non-Saccharomyces strain least affected by the nitrogen composition of the medium. The other two poor fermentative strains, H. uvarum and S. bacillaris, behaved similarly regarding amino acid uptake, which occurred earlier than that of the good fermentative species in the absence of ammonia. The results obtained in single non-Saccharomyces fermentations highlighted the importance of controlling nitrogen requirements of the wine yeasts, mainly in sequential fermentations, in order to manage a proper nitrogen supplementation, when needed.

Wine lees are defined as the sediment formed at the bottom of the tank or barrel after wine alcoholic fermentation. They have a heterogeneous composition and currently constitute 6% of the byproducts generated by each ton of wine grapes. However, it is the most under-researched of all the byproducts of the winemaking process. Therefore, with the aim of highlighting this byproduct, a physicochemical and nutritional characterization of winemaking lees from three different wine making processes (white, rosé, and red winemaking) was carried out. In addition, the technological properties of these winemaking lees were also analyzed. The lees analyzed in this research demonstrated an interesting nutritional and heterogeneous composition. Moreover, wine lees showed high values of emulsifying capacity. Thus, winemaking lees could be considered, in a preliminary way, as a new ingredient to be included in new food formulations.

Yeasts are able to act as biosorbents, as their cell wall includes several components capable of binding organic xenobiotic compounds that can potentially be removed during various fermentation processes. In the present investigation, two novel Saccharomyces cerevisiae strains (LMBF‐Y 16 and LMBF‐Y‐18), previously isolated from grapes, were studied regarding their physiological behavior (dry cell weight—DCW production, substrate uptake, and ethanol and glycerol biosynthesis) during fermentations of grape must, in some cases enriched with commercial glucose and fructose (initial total sugar concentration approximately 150 and 250 g/L, respectively). Myclobutanil (a chiral triazole fungicide broadly used as a protective agent of vine) was also added to the culture media at various concentrations in order to assess the ability of the yeasts to simultaneously perform alcoholic fermentations and detoxify the medium (i.e., to remove the fungicide). In the first set of experiments and for both tested strains, trials were carried out in either 250 mL or 2.0 L agitated shake flasks in either synthetic glucose-based experiments or grape musts. Since the results obtained in the trials where the cultures were placed in 2.0 L flasks with grape musts as substrates were superior in terms of both DCW and ethanol production, these experimental conditions were selected for the subsequent studies. Both strains showed high fermentative efficiency, producing high amounts of DCW (9.5–10.5 g/L) in parallel with high ethanol production, which in some cases achieved values very close to the maximum theoretical ethanol production yield (≈0.49 g of ethanol per g of sugar). When using grape must with initial total sugars at approximately 250 g/L (very high gravity fermentation media, close to winemaking conditions), significantly high ethanol quantities (i.e., ranging between 105 and 123 g/L) were produced. Myclobutanil addition slightly negatively affected sugar conversion into ethanol, however, in all cases, ethanol production was very satisfactory. A non-negligible myclobutanil removal during fermentation, which ranged between 5%–27%, as a result of the adsorptive or degradative capacity of the yeast was also reported. The presence of myclobutanil had no effect on DCW production and resulted in no significant differences in the biosynthesis of glycerol. Therefore, these newly isolated yeast strains could be excellent candidates for simultaneous high ethanol production and parallel pesticide removal in a general biorefinery concept demonstrating many environmental benefits.

The objective of this study was to obtain two types of fuels, i.e., bioethanol and biogas, in a sequential combination of biochemical processes from lignocellulosic biomass (corn straw). Waste from the agricultural sector containing lignocellulose structures was used to obtain bioethanol, while the post-fermentation (cellulose stillage) residue obtained from ethanol fermentation was a raw material for the production of high-power biogas in the methane fermentation process. The studies on obtaining ethanol from lignocellulosic substrate were based on the simultaneous saccharification and fermentation (SSF) method, which is a simultaneous hydrolysis of enzymatic cellulose and fermentation of the obtained sugars. Saccharomyces cerevisiae (D-2) in the form of yeast cream was used for bioethanol production. The yeast strain D-2 originated from the collection of the Institute of Agricultural and Food Biotechnology. Volatile compounds identified in the distillates were measured using gas chromatography with flame ionization detector (GC-FID). CH4 and CO2 contained in the biogas were analyzed using a gas chromatograph in isothermal conditions, equipped with thermal conductivity detector (katharometer) with incandescent fiber. Our results show that simultaneous saccharification and fermentation enables production of bioethanol from agricultural residues with management of cellulose stillage in the methane fermentation process.

Anhydrous ethanol is a promising alternative to gasoline in fuel engines. However, since ethanol forms an azeotrope with water, high-energy-consumption separation techniques such as azeotropic distillation, extractive distillation, and molecular sieves are needed to produce anhydrous ethanol. This work discusses the potential development of an integrated process for bioethanol production using ionic liquids and Ceratonia siliqua as a carbohydrate source for further fermentation of the aqueous extracts. A four-stage counter-current system was designed to improve the sugar extraction yield to values close to 99%. The alcoholic fermentation of the extracts showed ethanol concentrations of 95 g/L using the microorganism Saccharomyces cerevisae. The production of anhydrous ethanol through extractive distillation with ethylene glycol was simulated using CHEMCAD software, with an energy consumption of 13.23 MJ/Kg of anhydrous ethanol. Finally, several ionic liquids were analyzed and are proposed as potential solvents for the recovery of bioethanol for the design of an integrated extraction-fermentation-separation process, according to their ability to extract ethanol from aqueous solutions and their biocompatibility with the microorganism used in this study. This research was funded by the Fundación Séneca, grant number 20957/PI/18 and The Ministry of Economy and Competitiveness (MINECO) grant number RTI2018-099011-B-I00.

Mead is a traditional beverage that results from the alcoholic fermentation of diluted honey performed by yeasts. Although the process of mead production has been optimized in recent years, studies focused on its sensory properties are still scarce. Therefore, the aim of this work was to analyse the sensory ttributes of mead produced with free or immobilized cells of the Saccharomyces cerevisiae strains QA23 and ICV D47, and to establish potential correlations with its olatile composition. In the volatile composition of mead, the effect of yeast condition was more important than the strain. In respect to sensory analysis, the most pleasant aroma descriptors were correlated with mead obtained with free yeast cells, independently of the strain. Both sensory analysis and volatile composition indicates that the most pleasant mead was produced by free yeast cells. Although this study has provided a significant contribution, further research on the sensory quality of mead is still needed., Portuguese Foundation for Science and Technology (FCT) through a PhD grant (SFRH/BD/45820/2008). This research was partially supported through the PTDC project (PTDC/AGR-ALI/68284/2006) awarded by the FCT. This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by European Regional Development Fund under the scope of Norte2020 – Programa Operacional Regional do Norte, info:eu-repo/semantics/publishedVersion

The study and use of non-Saccharomyces yeasts to wine improvement and diversification has gained considerable relevance in recent years. The present work reports a pilot-scale winery assay of mixed fermentation with a commercial strain of Metschnikowia pulcherrima, tested in five white and nine red grape varieties. Two modalities were assayed, one with the addition of M. pulcherrima at time zero and addition of Saccharomyces cerevisiae after 24 h, and a control using only S. cerevisiae at time zero. Fermentation was monitored by daily measurement of density and temperature. Wine physicochemical analysis was performed after winemaking and repeated after four years of aging. Variance and multivariate analysis were used to examine these data. Triangle and ranking tests were performed on the wines obtained, using an experienced sensory panel. Alcoholic fermentation proceeded smoothly until there was complete consumption of the sugars. M. pulcherrima in mixed fermentation, although mainly recommended for white wine, was also tested for red wines. These wines generally presented higher glycerol, reducing sugars and total dry matter, and lower alcohol content, in line with the current market trend. Significant sensory differences among modalities were only obtained for three varieties. Results emphasized that grape variety is a relevant factor in studies with non-Saccharomyces yeasts.