Mixed starter cultures made of Saccharomyces cerevisiae EC1118 and Schizosaccharomyces japonicus ... more Mixed starter cultures made of Saccharomyces cerevisiae EC1118 and Schizosaccharomyces japonicus #13 were inoculated in commercial grape must, and the impact of different inoculum ratios (1:1; 1:100; 1:10,000) on growth and fermentation kinetics and on the analytical profiles of the experimental wines was here evaluated. Results obtained showed that S. japonicus #13 affects S. cerevisiae growth and fermentative capability only for S. cerevisiae/S. japonicus inoculum ratio 1:10,000. The analytical profiles of the wines produced by mixed starter cultures indicated that this non-Saccharomyces yeast modulates the concentration of malic and acetic acids and of some of the most important volatile compounds, such as β-phenyl ethanol, in an inoculum-ratio-dependent fashion. Moreover, all experimental wines obtained with S. japonicus #13 in mixed cultures reached concentrations of total polysaccharides significantly higher than those obtained with pure cultures of S. cerevisiae EC1118, and total polysaccharides increased with the increase of S. japonicus #13 cell concentration. Based on these results, S. japonicus #13 might be profitably inoculated in combination with S. cerevisiae EC1118 to enhance wine complexity and aroma and to improve wine stability by increasing the final concentration of polysaccharides.
Over the last few years the use of multi-starter inocula has become an attractive biotechnologica... more Over the last few years the use of multi-starter inocula has become an attractive biotechnological practice in the search for wine with high flavour complexity or distinctive characters. This has been possible through exploiting the particular oenological features of some non-Saccharomyces yeast strains, and the effects that derive from their specific interactions with Saccharomyces. In the present study, we evaluated the selected strain Zygotorulaspora florentina (formerly Zygosaccharomyces florentinus) in mixed culture fermentations with Saccharomyces cerevisiae, from the laboratory scale to the winery scale. The scale-up fermentation and substrate composition (i.e., white or red musts) influenced the analytical composition of the mixed fermentation. At the laboratory scale, mixed fermentation with Z. florentina exhibited an enhancement of polysaccharides and 2-phenylethanol content and a reduction of volatile acidity. At the winery scale, different fermentation characteristics of Z. florentina were observed. Using Sangiovese red grape juice, sequential fermentation trials showed a significantly higher concentration of glycerol and esters while the sensorial analysis of the resulting wines showed higher floral notes and lower perception of astringency. To our knowledge, this is the first time that this yeasts association has been evaluated at the winery scale indicating the potential use of this mixed culture in red grape varieties.
Three enological yeast strains, belonging to the speciesDebaryomyces hansenii, Debaryomyces polym... more Three enological yeast strains, belonging to the speciesDebaryomyces hansenii, Debaryomyces polymorphus, andSaccharomyces cerevisiae, characterized by an exocellular β-glucosidase activity, were examined for their ability to hydrolize a glycosidic extract from grape juice. The enzymatic preparations (culture supernant fluid) of the different yeasts released different amounts of terpenols such as linalol, α-terpineol, geraniol, nerol, citronellol and benzyl and 2-phenylethyl alcohol. The extent of release of the flavour compounds was related to yeast species. When an enzymatic preparation (concentrate culture supernatant) ofDebaryomyces hansenii was incubated with a wine containing glycosidic precursors, significant production of monoterpenols and benzyl and 2-phenylethyl alcohol was observed.
ABSTRACT Spontaneous grape must fermentations are consistently characterized by a sequential colo... more ABSTRACT Spontaneous grape must fermentations are consistently characterized by a sequential colonization of the substrate according to which apiculate yeasts ( Hanseniaspora/Kloeckera ), that predominate at the beginning of the process, are quickly replaced by Saccharomyces yeasts. In addition, other yeasts such as those belonging to the genera Candida, Torulaspora, Kluyveromyces, Zygosaccharomyces and Metschnikowia , may be present during must fermentation (Fleet, 2003). These “wild” yeasts have been considered for a long time responsible for wine defects. Thus, to inhibit their development and ensure the production of wines with repeatable characteristics, grape must is commonly treated with SO2 and inoculated with selected cultures of Saccharomyces cerevisiae . However, quantitative studies on the composition of the microflora of fermenting musts indicate that wild non- Saccharomyces yeasts may persist during inoculated fermentations (Mora et al. , 1990) and produce high amounts of different metabolites and enzymes able to carry out the transformation of the aroma precursors present in grapes (Fernandez et al. , 2000). Thus, non- Saccharomyces yeasts may influence the perceivable characteristics of the final product (Romano et al. , 2003). In this context, the possibility “to mimic” natural fermentations, maintaining the control of the fermentative process, represents an interesting approach to the improvement of the final quality of wine. In this study 105 isolates of non- Saccharomyces yeasts, belonging to different genera, naturally involved in spontaneous fermentations and coming from grape-musts of different origins, were identified and evaluated for their principal oenological characters. Fifteen strains showing interesting oenological characteristic are currently evaluated in fermentation processes carried out by mixed culture with S. cerevisiae .
With the aim of exploring the possibility to improve wine quality through the utilization of wine... more With the aim of exploring the possibility to improve wine quality through the utilization of wine-related yeasts generally considered as spoilage, mixed cultures of Saccharomyces cerevisiae with Hanseniaspora osmophila, Pichia fermentans, Saccharomycodes ludwigii and Zygosaccharomyces bailii were inoculated in grape juice. All the fermentations got to completion and most of the compounds normally produced at high concentrations by pure cultures of non-Saccharomyces yeasts, and considered detrimental for wine quality, did not reach the threshold taste level in mixed fermentations with S. cerevisiae. Interestingly, the association of S. cerevisiae with P. fermentans, S. ludwigii and Z. bailii produced significant increases in the production of polysaccharides as compared to pure cultures of S. cerevisiae. Since polysaccharides improve wine taste and body, and exert positive effects on aroma persistence and protein and tartrate stability, a possible use for these yeasts can be envisaged in mixed starter cultures with S. cerevisiae for the enhancement of the final quality of wine.
Mixed fermentations using controlled inoculation of Saccharomyces cerevisiae starter cultures and... more Mixed fermentations using controlled inoculation of Saccharomyces cerevisiae starter cultures and non-Saccharomyces yeasts represent a feasible way towards improving the complexity and enhancing the particular and specific characteristics of wines. The profusion of selected starter cultures has allowed the more widespread use of inoculated fermentations, with consequent improvements to the control of the fermentation process, and the use of new biotechnological processes in winemaking. Over the last few years, as a consequence of the re-evaluation of the role of non-Saccharomyces yeasts in winemaking, there have been several studies that have evaluated the use of controlled mixed fermentations using Saccharomyces and different non-Saccharomyces yeast species from the wine environment. The combined use of different species often results in unpredictable compounds and/or different levels of fermentation products being produced, which can affect both the chemical and the aromatic composition of wines. Moreover, possible synergistic interactions between different yeasts might provide a tool for the implementation of new fermentation technologies. Thus, knowledge of the Saccharomyces and non-Saccharomyces wine yeast interactions during wine fermentation needs to be improved. To reach this goal, further investigations into the genetic and physiological background of such non-Saccharomyces wine yeasts are needed, so as to apply '-omics' approaches to mixed culture fermentations.
A total of 78 strains of non-Saccharomyces yeasts were isolated: 30 strains of Kloeckera apiculat... more A total of 78 strains of non-Saccharomyces yeasts were isolated: 30 strains of Kloeckera apiculata, 20 of Candida stellata, 8 of Candida valida and 20 of Zygosaccharomyces fermentati. The diversity of yeast species and strains was monitored by determining the formation of secondary products of fermentation, such as acetaldehyde, ethyl acetate and higher alcohols. Within each species, the strains were distinguishable in phenotypes through the production of different amounts of by-products. In particular, a great variability was found in C. stellata, where six different phenotypes were identified by means of the production of acetaldehyde, ethyl acetate, isobutanol and isoamyl alcohol. At different stages of the spontaneous fermentation different phenotypes of the non-Saccharomyces yeasts were represented, characterized by consistent differences in some by-products involved in the wine bouquet, such as acetaldehyde.
ABSTRACT Spontaneous grape must fermentations are consistently characterized by a sequential colo... more ABSTRACT Spontaneous grape must fermentations are consistently characterized by a sequential colonization of the substrate according to which apiculate yeasts ( Hanseniaspora/Kloeckera ), that predominate at the beginning of the process, are quickly replaced by Saccharomyces yeasts. In addition, other yeasts such as those belonging to the genera Candida, Torulaspora, Kluyveromyces, Zygosaccharomyces and Metschnikowia , may be present during must fermentation (Fleet, 2003). These “wild” yeasts have been considered for a long time responsible for wine defects. Thus, to inhibit their development and ensure the production of wines with repeatable characteristics, grape must is commonly treated with SO2 and inoculated with selected cultures of Saccharomyces cerevisiae . However, quantitative studies on the composition of the microflora of fermenting musts indicate that wild non- Saccharomyces yeasts may persist during inoculated fermentations (Mora et al. , 1990) and produce high amounts of different metabolites and enzymes able to carry out the transformation of the aroma precursors present in grapes (Fernandez et al. , 2000). Thus, non- Saccharomyces yeasts may influence the perceivable characteristics of the final product (Romano et al. , 2003). In this context, the possibility “to mimic” natural fermentations, maintaining the control of the fermentative process, represents an interesting approach to the improvement of the final quality of wine. In this study 105 isolates of non- Saccharomyces yeasts, belonging to different genera, naturally involved in spontaneous fermentations and coming from grape-musts of different origins, were identified and evaluated for their principal oenological characters. Fifteen strains showing interesting oenological characteristic are currently evaluated in fermentation processes carried out by mixed culture with S. cerevisiae .
World Journal of Microbiology and Biotechnology, 1996
Five, highly flocculeng strains of Saccharomyces cerevisiae, isolated from wine, were immobilized... more Five, highly flocculeng strains of Saccharomyces cerevisiae, isolated from wine, were immobilized in calcium alginate beads to optimize primary must fermentation. Three cell-recycle batch fermentations (CRBF) of grape musts were performed with the biocatalyst and the results compared with those obtained with free cells. During the CRBF process, the entrapped strains showed some variability in the formation of secondary products of fermentation, particularly acetic acid and acetaldehyde. Recycling beads of immobilized flocculent cells is a good approach in the development and application of the CRBF system in the wine industry.
ABSTRACT High performance thin layer chromatography with automated multiple development was used ... more ABSTRACT High performance thin layer chromatography with automated multiple development was used to determine 2,3-butanediol levels in wine produced by high and low acetoin-forming strains of Saccharomyces cerevisiae. An inverse correlation between acetoin and 2,3-butanediol content was found suggesting a leaky mutation in acetoin reductase of the low 2,3-butanediol producing strains.
The use of non-Saccharomyces yeasts that are generally considered as spoilage yeasts, in associat... more The use of non-Saccharomyces yeasts that are generally considered as spoilage yeasts, in association with Saccharomyces cerevisiae for grape must fermentation was here evaluated. Analysis of the main oenological characteristics of pure cultures of 55 yeasts belonging to the genera Hanseniaspora, Pichia, Saccharomycodes and Zygosaccharomyces revealed wide biodiversity within each genus. Moreover, many of these non-Saccharomyces strains had interesting oenological properties in terms of fermentation purity, and ethanol and secondary metabolite production. The use of four non-Saccharomyces yeasts (one per genus) in mixed cultures with a commercial S. cerevisiae strain at different S. cerevisiae/non-Saccharomyces inoculum ratios was investigated. This revealed that most of the compounds normally produced at high concentrations by pure cultures of non-Saccharomyces, and which are considered detrimental to wine quality, do not reach threshold taste levels in these mixed fermentations. On the other hand, the analytical profiles of the wines produced by these mixed cultures indicated that depending on the yeast species and the S. cerevisiae/non-Saccharomyces inoculum ratio, these non-Saccharomyces yeasts can be used to increase production of polysaccharides and to modulate the final concentrations of acetic acid and volatile compounds, such as ethyl acetate, phenyl-ethyl acetate, 2-phenyl ethanol, and 2-methyl 1-butanol. j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / i j fo o d m i c r o Please cite this article as: Domizio, P., et al., Outlining a future for non-Saccharomyces yeasts: Selection of putative spoilage wine strains to be used in association with Saccharomyces cerevisiae for grape.
The aim of this study was to determine the impact of Vinsanto mother sediment both on the growth ... more The aim of this study was to determine the impact of Vinsanto mother sediment both on the growth and biodiversity of the yeast microflora and on the production of ethanol under natural and inoculated fermentation of Vinsanto wines. To achieve this ten fermentation trials were carried out in 50-L barrels, five without added mother sediment and five with. Moreover, eight of the ten barrels were inoculated with four Saccharomyces cerevisiae wine strains, while the remaining two barrels were not inoculated and were used as controls to study the behaviour of the natural yeast microflora in the absence and presence of mother sediment. The counts of viable yeasts at three different sampling times indicated that the mother sediment had a positive influence on yeast growth and persistence during fermentation. Molecular characterization of the Saccharomyces type colonies isolated after three months of fermentation showed that the addition of mother sediment had no effects on the dominance of the wine starters. In contrast, the mother sediment had a positive influence on the biodiversity of the spontaneous S. cerevisiae yeasts. Moreover, possibly due to its content of fatty acids and sterols and other nutrients, the addition of mother sediment also showed a positive effect on the fermentative activities of wine yeasts as measured by their ethanol production.
Evolution of the microbial composition during the production of Vinsanto wine was investigated un... more Evolution of the microbial composition during the production of Vinsanto wine was investigated under different fermentation conditions to determine their impact on the yeast population and the wine sensorial characteristics. Fermentations were carried out according to the traditional process in 50-l barrels. Different fermentation conditions were applied (yeast inoculum, "mother sediment" addition and temperature) to standardise the Vinsanto production process. Fermentations and products were monitored over the aging period by chemical, microbial and sensory evaluation. The low temperature at the beginning of the fermentations under traditional cellar conditions results in prolonged survival of the non-Saccharomyces yeast. In contrast, Saccharomyces yeast populations dominated throughout the fermentation when the temperature of the cellar was maintained at a constant 16-18°C. Results indicate that inoculation with a commercial yeast strain and fermentation temperature strongly influence the evolution of Vinsanto wine. The "mother sediment" seems to have no direct role as a microbiological starter in Vinsanto production but, despite this, it does have a strong influence on the sensory attributes of the Vinsanto wine. Our work highlights the importance of managing the fermenting microflora to improve the sensorial characteristics of Vinsanto wine.
Eight non-Saccharomyces wine strains, previously selected for their ability to modulate the final... more Eight non-Saccharomyces wine strains, previously selected for their ability to modulate the final concentrations of various volatile compounds and to persist with Saccharomyces cerevisiae in mixed inocula fermentations of grape juice, have been analyzed in the present work to test their ability to release mannoproteins. The eight strains were members of different genera originally isolated from grape: Hansensiaspora osmophila, Lachancea thermotolerans, Metschnikowia pulcherrima, Pichia fermentans, Saccharomycodes ludwigii, Starmerella bacillaris, Torulaspora delbrueckii and Zygosaccharomyces florentinus. A synthetic polysaccharide-free grape juice, was used to characterize the mannoproteins released during the alcoholic fermentation. Mannoproteins profiles were characterized by gel electrophoresis and carbohydrate composition was analyzed both by HPLC and by mass spectrometry. The eight non-Saccharomyces yeasts demonstrated a higher capacity to release polysaccharides compared to S. cerevisiae. The proteins released by the eight yeast strains showed a wide variety of protein sizes, ranging from 25 kDa to greater than 250 kDa. The mass spectrometric profile of the N-glycans ranged from 1600 to 4000 Da and was characteristic for each strain. Detailed investigation of the degree of polymerization of released N-glycans revealed variable composition from 8 to 15 units of monosaccharides. Food Microbiology 43 (2014) 5e15 P. Domizio et al. / Food Microbiology 43 (2014) 5e15
Non-Saccharomyces yeasts are metabolically active during spontaneous and inoculated must fermenta... more Non-Saccharomyces yeasts are metabolically active during spontaneous and inoculated must fermentations, and by producing a plethora of by-products, they can contribute to the definition of the wine aroma. Thus, use of Saccharomyces and non-Saccharomyces yeasts as mixed starter cultures for inoculation of wine fermentations is of increasing interest for quality enhancement and improved complexity of wines. We initially characterized 34 non-Saccharomyces yeasts of the genera Candida, Lachancea (Kluyveromyces), Metschnikowia and Torulaspora, and evaluated their enological potential. This confirmed that non-Saccharomyces yeasts from wine-related environments represent a rich sink of unexplored biodiversity for the winemaking industry. From these, we selected four non-Saccharomyces yeasts to combine with starter cultures of Saccharomyces cerevisiae in mixed fermentation trials. The kinetics of growth and fermentation, and the analytical profiles of the wines produced indicate that these non-Saccharomyces strains can be used with S. cerevisiae starter cultures to increase polysaccharide, glycerol and volatile compound production, to reduce volatile acidity, and to increase or reduce the total acidity of the final wines, depending on yeast species and inoculum ratio used. The overall effects of the non-Saccharomyces yeasts on fermentation and wine quality were strictly dependent on the Saccharomyces/non-Saccharomyces inoculum ratio that mimicked the differences of fermentation conditions (natural or simultaneous inoculated fermentation).
Mixed starter cultures made of Saccharomyces cerevisiae EC1118 and Schizosaccharomyces japonicus ... more Mixed starter cultures made of Saccharomyces cerevisiae EC1118 and Schizosaccharomyces japonicus #13 were inoculated in commercial grape must, and the impact of different inoculum ratios (1:1; 1:100; 1:10,000) on growth and fermentation kinetics and on the analytical profiles of the experimental wines was here evaluated. Results obtained showed that S. japonicus #13 affects S. cerevisiae growth and fermentative capability only for S. cerevisiae/S. japonicus inoculum ratio 1:10,000. The analytical profiles of the wines produced by mixed starter cultures indicated that this non-Saccharomyces yeast modulates the concentration of malic and acetic acids and of some of the most important volatile compounds, such as β-phenyl ethanol, in an inoculum-ratio-dependent fashion. Moreover, all experimental wines obtained with S. japonicus #13 in mixed cultures reached concentrations of total polysaccharides significantly higher than those obtained with pure cultures of S. cerevisiae EC1118, and total polysaccharides increased with the increase of S. japonicus #13 cell concentration. Based on these results, S. japonicus #13 might be profitably inoculated in combination with S. cerevisiae EC1118 to enhance wine complexity and aroma and to improve wine stability by increasing the final concentration of polysaccharides.
Over the last few years the use of multi-starter inocula has become an attractive biotechnologica... more Over the last few years the use of multi-starter inocula has become an attractive biotechnological practice in the search for wine with high flavour complexity or distinctive characters. This has been possible through exploiting the particular oenological features of some non-Saccharomyces yeast strains, and the effects that derive from their specific interactions with Saccharomyces. In the present study, we evaluated the selected strain Zygotorulaspora florentina (formerly Zygosaccharomyces florentinus) in mixed culture fermentations with Saccharomyces cerevisiae, from the laboratory scale to the winery scale. The scale-up fermentation and substrate composition (i.e., white or red musts) influenced the analytical composition of the mixed fermentation. At the laboratory scale, mixed fermentation with Z. florentina exhibited an enhancement of polysaccharides and 2-phenylethanol content and a reduction of volatile acidity. At the winery scale, different fermentation characteristics of Z. florentina were observed. Using Sangiovese red grape juice, sequential fermentation trials showed a significantly higher concentration of glycerol and esters while the sensorial analysis of the resulting wines showed higher floral notes and lower perception of astringency. To our knowledge, this is the first time that this yeasts association has been evaluated at the winery scale indicating the potential use of this mixed culture in red grape varieties.
Three enological yeast strains, belonging to the speciesDebaryomyces hansenii, Debaryomyces polym... more Three enological yeast strains, belonging to the speciesDebaryomyces hansenii, Debaryomyces polymorphus, andSaccharomyces cerevisiae, characterized by an exocellular β-glucosidase activity, were examined for their ability to hydrolize a glycosidic extract from grape juice. The enzymatic preparations (culture supernant fluid) of the different yeasts released different amounts of terpenols such as linalol, α-terpineol, geraniol, nerol, citronellol and benzyl and 2-phenylethyl alcohol. The extent of release of the flavour compounds was related to yeast species. When an enzymatic preparation (concentrate culture supernatant) ofDebaryomyces hansenii was incubated with a wine containing glycosidic precursors, significant production of monoterpenols and benzyl and 2-phenylethyl alcohol was observed.
ABSTRACT Spontaneous grape must fermentations are consistently characterized by a sequential colo... more ABSTRACT Spontaneous grape must fermentations are consistently characterized by a sequential colonization of the substrate according to which apiculate yeasts ( Hanseniaspora/Kloeckera ), that predominate at the beginning of the process, are quickly replaced by Saccharomyces yeasts. In addition, other yeasts such as those belonging to the genera Candida, Torulaspora, Kluyveromyces, Zygosaccharomyces and Metschnikowia , may be present during must fermentation (Fleet, 2003). These “wild” yeasts have been considered for a long time responsible for wine defects. Thus, to inhibit their development and ensure the production of wines with repeatable characteristics, grape must is commonly treated with SO2 and inoculated with selected cultures of Saccharomyces cerevisiae . However, quantitative studies on the composition of the microflora of fermenting musts indicate that wild non- Saccharomyces yeasts may persist during inoculated fermentations (Mora et al. , 1990) and produce high amounts of different metabolites and enzymes able to carry out the transformation of the aroma precursors present in grapes (Fernandez et al. , 2000). Thus, non- Saccharomyces yeasts may influence the perceivable characteristics of the final product (Romano et al. , 2003). In this context, the possibility “to mimic” natural fermentations, maintaining the control of the fermentative process, represents an interesting approach to the improvement of the final quality of wine. In this study 105 isolates of non- Saccharomyces yeasts, belonging to different genera, naturally involved in spontaneous fermentations and coming from grape-musts of different origins, were identified and evaluated for their principal oenological characters. Fifteen strains showing interesting oenological characteristic are currently evaluated in fermentation processes carried out by mixed culture with S. cerevisiae .
With the aim of exploring the possibility to improve wine quality through the utilization of wine... more With the aim of exploring the possibility to improve wine quality through the utilization of wine-related yeasts generally considered as spoilage, mixed cultures of Saccharomyces cerevisiae with Hanseniaspora osmophila, Pichia fermentans, Saccharomycodes ludwigii and Zygosaccharomyces bailii were inoculated in grape juice. All the fermentations got to completion and most of the compounds normally produced at high concentrations by pure cultures of non-Saccharomyces yeasts, and considered detrimental for wine quality, did not reach the threshold taste level in mixed fermentations with S. cerevisiae. Interestingly, the association of S. cerevisiae with P. fermentans, S. ludwigii and Z. bailii produced significant increases in the production of polysaccharides as compared to pure cultures of S. cerevisiae. Since polysaccharides improve wine taste and body, and exert positive effects on aroma persistence and protein and tartrate stability, a possible use for these yeasts can be envisaged in mixed starter cultures with S. cerevisiae for the enhancement of the final quality of wine.
Mixed fermentations using controlled inoculation of Saccharomyces cerevisiae starter cultures and... more Mixed fermentations using controlled inoculation of Saccharomyces cerevisiae starter cultures and non-Saccharomyces yeasts represent a feasible way towards improving the complexity and enhancing the particular and specific characteristics of wines. The profusion of selected starter cultures has allowed the more widespread use of inoculated fermentations, with consequent improvements to the control of the fermentation process, and the use of new biotechnological processes in winemaking. Over the last few years, as a consequence of the re-evaluation of the role of non-Saccharomyces yeasts in winemaking, there have been several studies that have evaluated the use of controlled mixed fermentations using Saccharomyces and different non-Saccharomyces yeast species from the wine environment. The combined use of different species often results in unpredictable compounds and/or different levels of fermentation products being produced, which can affect both the chemical and the aromatic composition of wines. Moreover, possible synergistic interactions between different yeasts might provide a tool for the implementation of new fermentation technologies. Thus, knowledge of the Saccharomyces and non-Saccharomyces wine yeast interactions during wine fermentation needs to be improved. To reach this goal, further investigations into the genetic and physiological background of such non-Saccharomyces wine yeasts are needed, so as to apply '-omics' approaches to mixed culture fermentations.
A total of 78 strains of non-Saccharomyces yeasts were isolated: 30 strains of Kloeckera apiculat... more A total of 78 strains of non-Saccharomyces yeasts were isolated: 30 strains of Kloeckera apiculata, 20 of Candida stellata, 8 of Candida valida and 20 of Zygosaccharomyces fermentati. The diversity of yeast species and strains was monitored by determining the formation of secondary products of fermentation, such as acetaldehyde, ethyl acetate and higher alcohols. Within each species, the strains were distinguishable in phenotypes through the production of different amounts of by-products. In particular, a great variability was found in C. stellata, where six different phenotypes were identified by means of the production of acetaldehyde, ethyl acetate, isobutanol and isoamyl alcohol. At different stages of the spontaneous fermentation different phenotypes of the non-Saccharomyces yeasts were represented, characterized by consistent differences in some by-products involved in the wine bouquet, such as acetaldehyde.
ABSTRACT Spontaneous grape must fermentations are consistently characterized by a sequential colo... more ABSTRACT Spontaneous grape must fermentations are consistently characterized by a sequential colonization of the substrate according to which apiculate yeasts ( Hanseniaspora/Kloeckera ), that predominate at the beginning of the process, are quickly replaced by Saccharomyces yeasts. In addition, other yeasts such as those belonging to the genera Candida, Torulaspora, Kluyveromyces, Zygosaccharomyces and Metschnikowia , may be present during must fermentation (Fleet, 2003). These “wild” yeasts have been considered for a long time responsible for wine defects. Thus, to inhibit their development and ensure the production of wines with repeatable characteristics, grape must is commonly treated with SO2 and inoculated with selected cultures of Saccharomyces cerevisiae . However, quantitative studies on the composition of the microflora of fermenting musts indicate that wild non- Saccharomyces yeasts may persist during inoculated fermentations (Mora et al. , 1990) and produce high amounts of different metabolites and enzymes able to carry out the transformation of the aroma precursors present in grapes (Fernandez et al. , 2000). Thus, non- Saccharomyces yeasts may influence the perceivable characteristics of the final product (Romano et al. , 2003). In this context, the possibility “to mimic” natural fermentations, maintaining the control of the fermentative process, represents an interesting approach to the improvement of the final quality of wine. In this study 105 isolates of non- Saccharomyces yeasts, belonging to different genera, naturally involved in spontaneous fermentations and coming from grape-musts of different origins, were identified and evaluated for their principal oenological characters. Fifteen strains showing interesting oenological characteristic are currently evaluated in fermentation processes carried out by mixed culture with S. cerevisiae .
World Journal of Microbiology and Biotechnology, 1996
Five, highly flocculeng strains of Saccharomyces cerevisiae, isolated from wine, were immobilized... more Five, highly flocculeng strains of Saccharomyces cerevisiae, isolated from wine, were immobilized in calcium alginate beads to optimize primary must fermentation. Three cell-recycle batch fermentations (CRBF) of grape musts were performed with the biocatalyst and the results compared with those obtained with free cells. During the CRBF process, the entrapped strains showed some variability in the formation of secondary products of fermentation, particularly acetic acid and acetaldehyde. Recycling beads of immobilized flocculent cells is a good approach in the development and application of the CRBF system in the wine industry.
ABSTRACT High performance thin layer chromatography with automated multiple development was used ... more ABSTRACT High performance thin layer chromatography with automated multiple development was used to determine 2,3-butanediol levels in wine produced by high and low acetoin-forming strains of Saccharomyces cerevisiae. An inverse correlation between acetoin and 2,3-butanediol content was found suggesting a leaky mutation in acetoin reductase of the low 2,3-butanediol producing strains.
The use of non-Saccharomyces yeasts that are generally considered as spoilage yeasts, in associat... more The use of non-Saccharomyces yeasts that are generally considered as spoilage yeasts, in association with Saccharomyces cerevisiae for grape must fermentation was here evaluated. Analysis of the main oenological characteristics of pure cultures of 55 yeasts belonging to the genera Hanseniaspora, Pichia, Saccharomycodes and Zygosaccharomyces revealed wide biodiversity within each genus. Moreover, many of these non-Saccharomyces strains had interesting oenological properties in terms of fermentation purity, and ethanol and secondary metabolite production. The use of four non-Saccharomyces yeasts (one per genus) in mixed cultures with a commercial S. cerevisiae strain at different S. cerevisiae/non-Saccharomyces inoculum ratios was investigated. This revealed that most of the compounds normally produced at high concentrations by pure cultures of non-Saccharomyces, and which are considered detrimental to wine quality, do not reach threshold taste levels in these mixed fermentations. On the other hand, the analytical profiles of the wines produced by these mixed cultures indicated that depending on the yeast species and the S. cerevisiae/non-Saccharomyces inoculum ratio, these non-Saccharomyces yeasts can be used to increase production of polysaccharides and to modulate the final concentrations of acetic acid and volatile compounds, such as ethyl acetate, phenyl-ethyl acetate, 2-phenyl ethanol, and 2-methyl 1-butanol. j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / i j fo o d m i c r o Please cite this article as: Domizio, P., et al., Outlining a future for non-Saccharomyces yeasts: Selection of putative spoilage wine strains to be used in association with Saccharomyces cerevisiae for grape.
The aim of this study was to determine the impact of Vinsanto mother sediment both on the growth ... more The aim of this study was to determine the impact of Vinsanto mother sediment both on the growth and biodiversity of the yeast microflora and on the production of ethanol under natural and inoculated fermentation of Vinsanto wines. To achieve this ten fermentation trials were carried out in 50-L barrels, five without added mother sediment and five with. Moreover, eight of the ten barrels were inoculated with four Saccharomyces cerevisiae wine strains, while the remaining two barrels were not inoculated and were used as controls to study the behaviour of the natural yeast microflora in the absence and presence of mother sediment. The counts of viable yeasts at three different sampling times indicated that the mother sediment had a positive influence on yeast growth and persistence during fermentation. Molecular characterization of the Saccharomyces type colonies isolated after three months of fermentation showed that the addition of mother sediment had no effects on the dominance of the wine starters. In contrast, the mother sediment had a positive influence on the biodiversity of the spontaneous S. cerevisiae yeasts. Moreover, possibly due to its content of fatty acids and sterols and other nutrients, the addition of mother sediment also showed a positive effect on the fermentative activities of wine yeasts as measured by their ethanol production.
Evolution of the microbial composition during the production of Vinsanto wine was investigated un... more Evolution of the microbial composition during the production of Vinsanto wine was investigated under different fermentation conditions to determine their impact on the yeast population and the wine sensorial characteristics. Fermentations were carried out according to the traditional process in 50-l barrels. Different fermentation conditions were applied (yeast inoculum, "mother sediment" addition and temperature) to standardise the Vinsanto production process. Fermentations and products were monitored over the aging period by chemical, microbial and sensory evaluation. The low temperature at the beginning of the fermentations under traditional cellar conditions results in prolonged survival of the non-Saccharomyces yeast. In contrast, Saccharomyces yeast populations dominated throughout the fermentation when the temperature of the cellar was maintained at a constant 16-18°C. Results indicate that inoculation with a commercial yeast strain and fermentation temperature strongly influence the evolution of Vinsanto wine. The "mother sediment" seems to have no direct role as a microbiological starter in Vinsanto production but, despite this, it does have a strong influence on the sensory attributes of the Vinsanto wine. Our work highlights the importance of managing the fermenting microflora to improve the sensorial characteristics of Vinsanto wine.
Eight non-Saccharomyces wine strains, previously selected for their ability to modulate the final... more Eight non-Saccharomyces wine strains, previously selected for their ability to modulate the final concentrations of various volatile compounds and to persist with Saccharomyces cerevisiae in mixed inocula fermentations of grape juice, have been analyzed in the present work to test their ability to release mannoproteins. The eight strains were members of different genera originally isolated from grape: Hansensiaspora osmophila, Lachancea thermotolerans, Metschnikowia pulcherrima, Pichia fermentans, Saccharomycodes ludwigii, Starmerella bacillaris, Torulaspora delbrueckii and Zygosaccharomyces florentinus. A synthetic polysaccharide-free grape juice, was used to characterize the mannoproteins released during the alcoholic fermentation. Mannoproteins profiles were characterized by gel electrophoresis and carbohydrate composition was analyzed both by HPLC and by mass spectrometry. The eight non-Saccharomyces yeasts demonstrated a higher capacity to release polysaccharides compared to S. cerevisiae. The proteins released by the eight yeast strains showed a wide variety of protein sizes, ranging from 25 kDa to greater than 250 kDa. The mass spectrometric profile of the N-glycans ranged from 1600 to 4000 Da and was characteristic for each strain. Detailed investigation of the degree of polymerization of released N-glycans revealed variable composition from 8 to 15 units of monosaccharides. Food Microbiology 43 (2014) 5e15 P. Domizio et al. / Food Microbiology 43 (2014) 5e15
Non-Saccharomyces yeasts are metabolically active during spontaneous and inoculated must fermenta... more Non-Saccharomyces yeasts are metabolically active during spontaneous and inoculated must fermentations, and by producing a plethora of by-products, they can contribute to the definition of the wine aroma. Thus, use of Saccharomyces and non-Saccharomyces yeasts as mixed starter cultures for inoculation of wine fermentations is of increasing interest for quality enhancement and improved complexity of wines. We initially characterized 34 non-Saccharomyces yeasts of the genera Candida, Lachancea (Kluyveromyces), Metschnikowia and Torulaspora, and evaluated their enological potential. This confirmed that non-Saccharomyces yeasts from wine-related environments represent a rich sink of unexplored biodiversity for the winemaking industry. From these, we selected four non-Saccharomyces yeasts to combine with starter cultures of Saccharomyces cerevisiae in mixed fermentation trials. The kinetics of growth and fermentation, and the analytical profiles of the wines produced indicate that these non-Saccharomyces strains can be used with S. cerevisiae starter cultures to increase polysaccharide, glycerol and volatile compound production, to reduce volatile acidity, and to increase or reduce the total acidity of the final wines, depending on yeast species and inoculum ratio used. The overall effects of the non-Saccharomyces yeasts on fermentation and wine quality were strictly dependent on the Saccharomyces/non-Saccharomyces inoculum ratio that mimicked the differences of fermentation conditions (natural or simultaneous inoculated fermentation).
Uploads
Papers by Paola Domizio