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Manuel Ramirez - One of the best experts on this subject based on the ideXlab platform.
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genome organization of a new double stranded rna la helper virus from wine Torulaspora delbrueckii killer yeast as compared with its saccharomyces counterparts
Frontiers in Microbiology, 2020Co-Authors: Manuel Ramirez, Rocio Velazquez, Matilde Maqueda, Alberto MartinezAbstract:Wine killer yeasts such as killer strains of Torulaspora delbrueckii and Saccharomyces cerevisiae contain helper large-size (4.6 kb) dsRNA viruses (V-LA) required for the stable maintenance and replication of killer medium-size dsRNA viruses (V-M) which bear the genes that encode for the killer toxin. The genome of the new V-LA dsRNA from the T. delbrueckii Kbarr1 killer yeast (TdV-LAbarr1) was characterized by high-throughput sequencing (HTS). The canonical genome of TdV-LAbarr1 shares a high sequence identity and similar genome organization with its Saccharomyces counterparts. It contains all the known conserved motifs predicted to be necessary for virus translation, packaging, and replication. Similarly, the Gag-Pol amino-acid sequence of this virus contains all the features required for cap-snatching and RNA polymerase activity, as well as the expected regional variables previously found in other LA viruses. Sequence comparison showed that two main clusters (99.2-100% and 96.3-98.8% identity) include most LA viruses from Saccharomyces, with TdV-LAbarr1 being the most distant from all these viruses (61.5 62.5% identity). Viral co-evolution and cross transmission between different yeast species are discussed based on this sequence comparison. Additional 5΄ and 3΄ sequences were found in the TdV-LAbarr1 genome as well as in some newly sequenced V-LA genomes from S. cerevisiae. A stretch involving the 5΄ extra sequence of TdV-LAbarr1 is identical to a homologous stretch close to the 5΄ end of the canonical sequence of the same virus (self-identity). Our modelling suggests that these stretches can form single-strand stem loops, whose unpaired nucleotides could anneal to create an intramolecular kissing complex. Similar stem loops are also found in the 3΄ extra sequence of the same virus as well as in the extra sequences of some LA viruses from S. cerevisiae. A possible origin of these extra sequences as well as their function in obviating ssRNA degradation and allowing RNA transcription and replication are discussed.
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genetic improvement of Torulaspora delbrueckii for wine fermentation eliminating recessive growth retarding alleles and obtaining new mutants resistant to so2 ethanol and high co2 pressure
Microorganisms, 2020Co-Authors: Rocio Velazquez, Alberto Martinez, Emiliano Zamora, Maria L Alvarez, Luis M Hernandez, Joaquin Bautistagallego, Manuel RamirezAbstract:The use of Torulaspora delbrueckii has been repeatedly proposed to improve a wine’s organoleptic quality. This yeast has lower efficiency in completing wine fermentation than Saccharomyces cerevisiae since it has less fermentation capability and greater sensitivity to SO2, ethanol, and CO2 pressure. Therefore, the completion of fermentation is not guaranteed when must or wine is single-inoculated with T. delbrueckii. To solve this problem, new strains of T. delbrueckii with enhanced resistance to winemaking conditions were obtained. A genetic study of four wine T. delbrueckii strains was carried out. Spore clones free of possible recessive growth-retarding alleles were obtained from these yeasts. These spore clones were used to successively isolate mutants resistant to SO2, then those resistant to ethanol, and finally those resistant to high CO2 pressure. Most of these mutants showed better capability for base wine fermentation than the parental strain, and some of them approached the fermentation capability of S. cerevisiae. The genetic stability of the new mutants was good enough to be used in industrial-level production in commercial wineries. Moreover, their ability to ferment sparkling wine could be further improved by the continuous addition of oxygen in the culture adaptation stage prior to base wine inoculation.
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using Torulaspora delbrueckii killer yeasts in the elaboration of base wine and traditional sparkling wine
International Journal of Food Microbiology, 2019Co-Authors: Rocio Velazquez, Emiliano Zamora, Maria L Alvarez, Manuel RamirezAbstract:Abstract For still wines, killer strains of Torulaspora delbrueckii can be used instead of non-killer strains to improve this species' domination during must fermentation, with an ensured, reliable impact on the final wine quality. The present work analysed the usefulness of these killer yeasts for sparkling-wine making. After the first fermentation, the foaming capacity of T. delbrueckii base wines was very low compared to Saccharomyces cerevisiae base wines. Significant positive correlations of foaming parameters were found with the amounts of C4–C16 ethyl esters and proteins, and negative with some anti-foaming alcohols produced by each yeast species. There were, however, no evident positive effects of polysaccharides on those parameters. The organoleptic quality of the T. delbrueckii base wines was judged inappropriate for sparkling-wine making, so that the following second-fermentation experiments only used a single assemblage of S. cerevisiae base-wines. While second fermentation was completed with inoculation of S. cerevisiae (both alone and mixed with T. delbrueckii) to yield dry sparkling wines with high CO2 pressure, single inoculation with T. delbrueckii did not complete this fermentation, leaving sweet wines with poor CO2 pressure. Yeast death due to CO2 pressure was much greater in T. delbrueckii than in S. cerevisiae, making any killer effect of S. cerevisiae over T. delbrueckii irrelevant because no autolysed cells were found during the first days of mixed-inoculated second fermentation. Nonetheless, the organoleptic quality of the mixed-inoculated sparkling wines was better than that of wines single-inoculated with S. cerevisiae, and showed no deterioration in foam quality. This seemed mainly to be because T. delbrueckii increased the amounts of ethyl propanoate and some acids (e.g., isobutyric and butanoic), alcohols (e.g., 3‑ethoxy‑1‑propanol), and phenols (e.g., 4‑vinylguaiacol). For these sparkling wines, no significant correlations between foaming parameters and aroma compounds were found, probably because the differences in foaming parameter values among these wines were fairly small. This is unlike the case for the base wines for which there were large differences in these parameters, which facilitated the analysis of the influence of aroma compounds on base-wine foamability.
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The Yeast Torulaspora delbrueckii: an interesting but difficult-to-use tool for winemaking
Fermentation, 2018Co-Authors: Manuel Ramirez, Rocio VelazquezAbstract:Torulaspora delbrueckii is probably the non-Saccharomyces yeast that is currently most used for winemaking. Multiple advantages have been claimed for it relative to conventional S. cerevisiae strains. However, many of these claimed advantages are based on results in different research studies that are contradictory or non-reproducible. The easiest way to explain these discrepancies is to attribute them to the possible differences in the behaviour of the different strains of this yeast that have been used in different investigations. There is much less knowledge of the physiology, genetics, and biotechnological properties of this yeast than of the conventional yeast S. cerevisiae. Therefore, it is possible that the different results that have been found in the literature are due to the variable or unpredictable behaviour of T. delbrueckii, which may depend on the environmental conditions during wine fermentation. The present review focusses on the analysis of this variable behaviour of T. delbrueckii in the elaboration of different wine types, with special emphasis on the latest proposals for industrial uses of this yeast.
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influence of the dominance of must fermentation by Torulaspora delbrueckii on the malolactic fermentation and organoleptic quality of red table wine
International Journal of Food Microbiology, 2016Co-Authors: Manuel Ramirez, Rocio Velazquez, Matilde Maqueda, Emiliano Zamora, Antonio Lopezpineiro, Luis M HernandezAbstract:Torulaspora delbrueckii can improve wine aroma complexity, but its impact on wine quality is still far from being satisfactory at the winery level, mainly because it is easily replaced by S. cerevisiae yeasts during must fermentation. New T. delbrueckii killer strains were selected to overcome this problem. These strains killed S. cerevisiae yeasts and dominated fermentation better than T. delbrueckii non-killer strains when they were single-inoculated into crushed red grape must. All the T. delbrueckii wines, but none of the S. cerevisiae wines, underwent malolactic fermentation. Putative lactic acid bacteria were always found in the T. delbrueckii wines, but none or very few in the S. cerevisiae wines. Malic acid degradation was the greatest in the wines inoculated with the killer strains, and these strains reached the greatest dominance ratios and had the slowest fermentation kinetics. The T. delbrueckii wines had dried-fruit/pastry aromas, but low intensities of fresh-fruit aromas. The aroma differences between the T. delbrueckii and the S. cerevisiae wines can be explained by the differences that were found in the amounts of some fruity aroma compounds such as isoamyl acetate, ethyl hexanoate, ethyl octanoate, and some lactones. This T. delbrueckii effect significantly raised the organoleptic quality scores of full-bodied Cabernet-Sauvignon red wines inoculated with the killer strains. In particular, these wines were judged as having excellent aroma complexity, mouth-feel, and sweetness.
Thierry Doco - One of the best experts on this subject based on the ideXlab platform.
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polysaccharides and oligosaccharides produced on malvar wines elaborated with Torulaspora delbrueckii cli 918 and saccharomyces cerevisiae cli 889 native yeasts from d o vinos de madrid
Journal of Agricultural and Food Chemistry, 2017Co-Authors: Margarita Garcia, Pascale Williams, Julia Crespo, Teresa Arroyo, Rafael Apolinarvaliente, Braulio Estevezarzoso, Thierry DocoAbstract:Polysaccharides and oligosaccharides released into Malvar white wines elaborated through pure, mixed, and sequential cultures with Torulaspora delbrueckii CLI 918 and Saccharomyces cerevisiae CLI 889 native yeasts from D.O. “Vinos de Madrid” were studied. Both fractions from different white wines were separated by high-resolution size-exclusion chromatography. Glycosyl composition and wine polysaccharide linkages were determined by GC–EI-MS chromatography. Molar-mass distributions were determined by SEC–MALLS, and intrinsic viscosity was determined by differential viscometer. Yeast species and type of inoculation have a significant impact on wine carbohydrate composition and structure. Mannose residues from mannoproteins were significantly predominant in those cultures where T. delbrueckii was present in the fermentation process in comparison with when pure cultures of S. cerevisiae were present in the fermenation process. Galactose residues from polysaccharides rich in arabinose and galactose presented g...
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Polysaccharides and oligosaccharides produced on Malvar Wines elaborated with Torulaspora delbrueckii CLI 918 and Saccharomyces cerevisiae CLI 889 native yeasts from D.O. “Vinos de Madrid”
Journal of Agricultural and Food Chemistry, 2017Co-Authors: Margarita Garcia, Pascale Williams, Teresa Arroyo, Rafael Apolinar Valiente, Braulio Esteve-zarzoso, Julia Crespo Garcia, Thierry DocoAbstract:Polysaccharides and oligosaccharides released into Malvar white wines elaborated through pure, mixed and sequential cultures with Torulaspora delbrueckii CLI 918 and Saccharomyces cerevisiae CLI 889 native yeasts from D.O. “Vinos de Madrid” were studied. Both fractions from different white wines were separated by high-resolution size-exclusion chromatography. Glycosyl composition and linkages of wine polysaccharides were determined by GC-EI-MS chromatography. Molar-mass distributions were determined by SEC-MALLS and intrinsic viscosity by differential viscometer. Yeast species and type of inoculation have a significant impact on wine carbohydrate composition and structure. Mannose residues from mannoproteins were significantly predominant in those cultures where T. delbrueckii was present in the fermentation process in comparison with pure culture of S. cerevisiae, whereas galactose residues from Polysaccharides Rich in Arabinose and Galactose presented higher values in pure culture of S. cerevisiae, indicating that S. cerevisiae released less mannoproteins than T. delbrueckii. Moreover, we reported structural differences between mannoproteins released by T. delbrueckii CLI 918 and those released by S. cerevisiae CLI 889. These findings help to provide important information about the polysaccharides and oligosaccharides released from cell wall of Malvar grapes and the carbohydrates released from each yeast species.
Rocio Velazquez - One of the best experts on this subject based on the ideXlab platform.
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genome organization of a new double stranded rna la helper virus from wine Torulaspora delbrueckii killer yeast as compared with its saccharomyces counterparts
Frontiers in Microbiology, 2020Co-Authors: Manuel Ramirez, Rocio Velazquez, Matilde Maqueda, Alberto MartinezAbstract:Wine killer yeasts such as killer strains of Torulaspora delbrueckii and Saccharomyces cerevisiae contain helper large-size (4.6 kb) dsRNA viruses (V-LA) required for the stable maintenance and replication of killer medium-size dsRNA viruses (V-M) which bear the genes that encode for the killer toxin. The genome of the new V-LA dsRNA from the T. delbrueckii Kbarr1 killer yeast (TdV-LAbarr1) was characterized by high-throughput sequencing (HTS). The canonical genome of TdV-LAbarr1 shares a high sequence identity and similar genome organization with its Saccharomyces counterparts. It contains all the known conserved motifs predicted to be necessary for virus translation, packaging, and replication. Similarly, the Gag-Pol amino-acid sequence of this virus contains all the features required for cap-snatching and RNA polymerase activity, as well as the expected regional variables previously found in other LA viruses. Sequence comparison showed that two main clusters (99.2-100% and 96.3-98.8% identity) include most LA viruses from Saccharomyces, with TdV-LAbarr1 being the most distant from all these viruses (61.5 62.5% identity). Viral co-evolution and cross transmission between different yeast species are discussed based on this sequence comparison. Additional 5΄ and 3΄ sequences were found in the TdV-LAbarr1 genome as well as in some newly sequenced V-LA genomes from S. cerevisiae. A stretch involving the 5΄ extra sequence of TdV-LAbarr1 is identical to a homologous stretch close to the 5΄ end of the canonical sequence of the same virus (self-identity). Our modelling suggests that these stretches can form single-strand stem loops, whose unpaired nucleotides could anneal to create an intramolecular kissing complex. Similar stem loops are also found in the 3΄ extra sequence of the same virus as well as in the extra sequences of some LA viruses from S. cerevisiae. A possible origin of these extra sequences as well as their function in obviating ssRNA degradation and allowing RNA transcription and replication are discussed.
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genetic improvement of Torulaspora delbrueckii for wine fermentation eliminating recessive growth retarding alleles and obtaining new mutants resistant to so2 ethanol and high co2 pressure
Microorganisms, 2020Co-Authors: Rocio Velazquez, Alberto Martinez, Emiliano Zamora, Maria L Alvarez, Luis M Hernandez, Joaquin Bautistagallego, Manuel RamirezAbstract:The use of Torulaspora delbrueckii has been repeatedly proposed to improve a wine’s organoleptic quality. This yeast has lower efficiency in completing wine fermentation than Saccharomyces cerevisiae since it has less fermentation capability and greater sensitivity to SO2, ethanol, and CO2 pressure. Therefore, the completion of fermentation is not guaranteed when must or wine is single-inoculated with T. delbrueckii. To solve this problem, new strains of T. delbrueckii with enhanced resistance to winemaking conditions were obtained. A genetic study of four wine T. delbrueckii strains was carried out. Spore clones free of possible recessive growth-retarding alleles were obtained from these yeasts. These spore clones were used to successively isolate mutants resistant to SO2, then those resistant to ethanol, and finally those resistant to high CO2 pressure. Most of these mutants showed better capability for base wine fermentation than the parental strain, and some of them approached the fermentation capability of S. cerevisiae. The genetic stability of the new mutants was good enough to be used in industrial-level production in commercial wineries. Moreover, their ability to ferment sparkling wine could be further improved by the continuous addition of oxygen in the culture adaptation stage prior to base wine inoculation.
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using Torulaspora delbrueckii killer yeasts in the elaboration of base wine and traditional sparkling wine
International Journal of Food Microbiology, 2019Co-Authors: Rocio Velazquez, Emiliano Zamora, Maria L Alvarez, Manuel RamirezAbstract:Abstract For still wines, killer strains of Torulaspora delbrueckii can be used instead of non-killer strains to improve this species' domination during must fermentation, with an ensured, reliable impact on the final wine quality. The present work analysed the usefulness of these killer yeasts for sparkling-wine making. After the first fermentation, the foaming capacity of T. delbrueckii base wines was very low compared to Saccharomyces cerevisiae base wines. Significant positive correlations of foaming parameters were found with the amounts of C4–C16 ethyl esters and proteins, and negative with some anti-foaming alcohols produced by each yeast species. There were, however, no evident positive effects of polysaccharides on those parameters. The organoleptic quality of the T. delbrueckii base wines was judged inappropriate for sparkling-wine making, so that the following second-fermentation experiments only used a single assemblage of S. cerevisiae base-wines. While second fermentation was completed with inoculation of S. cerevisiae (both alone and mixed with T. delbrueckii) to yield dry sparkling wines with high CO2 pressure, single inoculation with T. delbrueckii did not complete this fermentation, leaving sweet wines with poor CO2 pressure. Yeast death due to CO2 pressure was much greater in T. delbrueckii than in S. cerevisiae, making any killer effect of S. cerevisiae over T. delbrueckii irrelevant because no autolysed cells were found during the first days of mixed-inoculated second fermentation. Nonetheless, the organoleptic quality of the mixed-inoculated sparkling wines was better than that of wines single-inoculated with S. cerevisiae, and showed no deterioration in foam quality. This seemed mainly to be because T. delbrueckii increased the amounts of ethyl propanoate and some acids (e.g., isobutyric and butanoic), alcohols (e.g., 3‑ethoxy‑1‑propanol), and phenols (e.g., 4‑vinylguaiacol). For these sparkling wines, no significant correlations between foaming parameters and aroma compounds were found, probably because the differences in foaming parameter values among these wines were fairly small. This is unlike the case for the base wines for which there were large differences in these parameters, which facilitated the analysis of the influence of aroma compounds on base-wine foamability.
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The Yeast Torulaspora delbrueckii: an interesting but difficult-to-use tool for winemaking
Fermentation, 2018Co-Authors: Manuel Ramirez, Rocio VelazquezAbstract:Torulaspora delbrueckii is probably the non-Saccharomyces yeast that is currently most used for winemaking. Multiple advantages have been claimed for it relative to conventional S. cerevisiae strains. However, many of these claimed advantages are based on results in different research studies that are contradictory or non-reproducible. The easiest way to explain these discrepancies is to attribute them to the possible differences in the behaviour of the different strains of this yeast that have been used in different investigations. There is much less knowledge of the physiology, genetics, and biotechnological properties of this yeast than of the conventional yeast S. cerevisiae. Therefore, it is possible that the different results that have been found in the literature are due to the variable or unpredictable behaviour of T. delbrueckii, which may depend on the environmental conditions during wine fermentation. The present review focusses on the analysis of this variable behaviour of T. delbrueckii in the elaboration of different wine types, with special emphasis on the latest proposals for industrial uses of this yeast.
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influence of the dominance of must fermentation by Torulaspora delbrueckii on the malolactic fermentation and organoleptic quality of red table wine
International Journal of Food Microbiology, 2016Co-Authors: Manuel Ramirez, Rocio Velazquez, Matilde Maqueda, Emiliano Zamora, Antonio Lopezpineiro, Luis M HernandezAbstract:Torulaspora delbrueckii can improve wine aroma complexity, but its impact on wine quality is still far from being satisfactory at the winery level, mainly because it is easily replaced by S. cerevisiae yeasts during must fermentation. New T. delbrueckii killer strains were selected to overcome this problem. These strains killed S. cerevisiae yeasts and dominated fermentation better than T. delbrueckii non-killer strains when they were single-inoculated into crushed red grape must. All the T. delbrueckii wines, but none of the S. cerevisiae wines, underwent malolactic fermentation. Putative lactic acid bacteria were always found in the T. delbrueckii wines, but none or very few in the S. cerevisiae wines. Malic acid degradation was the greatest in the wines inoculated with the killer strains, and these strains reached the greatest dominance ratios and had the slowest fermentation kinetics. The T. delbrueckii wines had dried-fruit/pastry aromas, but low intensities of fresh-fruit aromas. The aroma differences between the T. delbrueckii and the S. cerevisiae wines can be explained by the differences that were found in the amounts of some fruity aroma compounds such as isoamyl acetate, ethyl hexanoate, ethyl octanoate, and some lactones. This T. delbrueckii effect significantly raised the organoleptic quality scores of full-bodied Cabernet-Sauvignon red wines inoculated with the killer strains. In particular, these wines were judged as having excellent aroma complexity, mouth-feel, and sweetness.
Margarita Garcia - One of the best experts on this subject based on the ideXlab platform.
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polysaccharides and oligosaccharides produced on malvar wines elaborated with Torulaspora delbrueckii cli 918 and saccharomyces cerevisiae cli 889 native yeasts from d o vinos de madrid
Journal of Agricultural and Food Chemistry, 2017Co-Authors: Margarita Garcia, Pascale Williams, Julia Crespo, Teresa Arroyo, Rafael Apolinarvaliente, Braulio Estevezarzoso, Thierry DocoAbstract:Polysaccharides and oligosaccharides released into Malvar white wines elaborated through pure, mixed, and sequential cultures with Torulaspora delbrueckii CLI 918 and Saccharomyces cerevisiae CLI 889 native yeasts from D.O. “Vinos de Madrid” were studied. Both fractions from different white wines were separated by high-resolution size-exclusion chromatography. Glycosyl composition and wine polysaccharide linkages were determined by GC–EI-MS chromatography. Molar-mass distributions were determined by SEC–MALLS, and intrinsic viscosity was determined by differential viscometer. Yeast species and type of inoculation have a significant impact on wine carbohydrate composition and structure. Mannose residues from mannoproteins were significantly predominant in those cultures where T. delbrueckii was present in the fermentation process in comparison with when pure cultures of S. cerevisiae were present in the fermenation process. Galactose residues from polysaccharides rich in arabinose and galactose presented g...
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Polysaccharides and oligosaccharides produced on Malvar Wines elaborated with Torulaspora delbrueckii CLI 918 and Saccharomyces cerevisiae CLI 889 native yeasts from D.O. “Vinos de Madrid”
Journal of Agricultural and Food Chemistry, 2017Co-Authors: Margarita Garcia, Pascale Williams, Teresa Arroyo, Rafael Apolinar Valiente, Braulio Esteve-zarzoso, Julia Crespo Garcia, Thierry DocoAbstract:Polysaccharides and oligosaccharides released into Malvar white wines elaborated through pure, mixed and sequential cultures with Torulaspora delbrueckii CLI 918 and Saccharomyces cerevisiae CLI 889 native yeasts from D.O. “Vinos de Madrid” were studied. Both fractions from different white wines were separated by high-resolution size-exclusion chromatography. Glycosyl composition and linkages of wine polysaccharides were determined by GC-EI-MS chromatography. Molar-mass distributions were determined by SEC-MALLS and intrinsic viscosity by differential viscometer. Yeast species and type of inoculation have a significant impact on wine carbohydrate composition and structure. Mannose residues from mannoproteins were significantly predominant in those cultures where T. delbrueckii was present in the fermentation process in comparison with pure culture of S. cerevisiae, whereas galactose residues from Polysaccharides Rich in Arabinose and Galactose presented higher values in pure culture of S. cerevisiae, indicating that S. cerevisiae released less mannoproteins than T. delbrueckii. Moreover, we reported structural differences between mannoproteins released by T. delbrueckii CLI 918 and those released by S. cerevisiae CLI 889. These findings help to provide important information about the polysaccharides and oligosaccharides released from cell wall of Malvar grapes and the carbohydrates released from each yeast species.
Shaoquan Liu - One of the best experts on this subject based on the ideXlab platform.
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The potential of spent coffee grounds hydrolysates fermented with Torulaspora delbrueckii and Pichia kluyveri for developing an alcoholic beverage: The yeasts growth and chemical compounds modulation by yeast extracts
'Elsevier BV', 2021Co-Authors: Yunjiao Liu, Shaoquan LiuAbstract:This study evaluated the effects of yeast extracts (YE) addition (0 % and 0.25 %, w/v) on the no-volatile and volatile compounds of spent coffee grounds (SCG) hydrolysates fermented with single-cultures of two non-Saccharomyces wine yeasts, Torulaspora delbrueckii and Pichia kluyveri. The added YE improved the growth of both T. delbrueckii and P. kluyveri, especially P. kluyveri, resulting in higher ethanol production (1.98 % vs 1.47 %, v/v) by the latter yeast. In addition, the added YE did not impact on most of the alkaloids production regardless of yeast type, while significantly decreasing the contents of chlorogenic, and caffeic acids in SCG hydrolysates fermented with P. kluyveri. Furthermore, more odor-active compounds such as acetate esters and 2-phenylethyl alcohol were produced when YE was added, and P. kluyveri generated significantly higher amounts of esters compared to that of T. delbrueckii. Moreover, YE addition showed a more noticeable effect on the fermentation performance of P. kluyveri relative to that of T. delbrueckii. These findings indicated the potential of SCG hydrolysates fermented with evaluated non-Saccharomyces yeasts and may expand the applications on utilizing SCG to develop new value-added alcoholic products
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understanding the interaction of isoleucine paired with other amino acids in soy whey alcohol fermentation using Torulaspora delbrueckii
International Journal of Food Microbiology, 2020Co-Authors: Jianyong Chua, Si Jia Tan, Shaoquan LiuAbstract:Abstract Soy (tofu) whey is a liquid by-product generated from tofu (soybean curd) production and it is often discarded off as a waste liquid by the tofu manufacturers. Previous studies have demonstrated that soy whey can be biotransformed into a soy alcoholic beverage by using Saccharomyces and non-Saccharomyces yeasts even though soy whey is low in yeast assimilable nitrogen (YAN) content. In this study, the initial YAN of the soy whey was estimated to be 46.6 mg N/L and Torulaspora delbrueckii Biodiva was used to ferment soy whey supplemented with either isoleucine only or isoleucine paired with valine, leucine or phenylalanine (each amino acid supplemented at a dosage of 30 mg N/L). Amino acid supplementation was found to enhance sugar utilization by the yeast, which led to higher ethanol production (7.49% v/v in control versus 8.35–8.80% v/v in supplemented samples). Samples supplemented with isoleucine only experienced slower sugar utilization during the fermentation as compared to the paired amino acid samples, but the yeast was still able to utilize the sugar to low levels at the end of the fermentation. The presence of leucine supplementation counteracted the “inhibition” induced by the presence of isoleucine at the first day of the fermentation. Amino acid supplementation slowed down glutamic acid utilization and resulted in higher levels of residual glutamic acid and alanine. Amino acid supplementation increased the corresponding fusel alcohol production and the presence of other amino acids reduced the active amyl alcohol production. Therefore, interactions between amino acids can impact the metabolism of the yeast as well as the flavor modulation during soy whey fermentation.
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effects of pectinase treatment on the physicochemical and oenological properties of red dragon fruit wine fermented with Torulaspora delbrueckii
Lwt - Food Science and Technology, 2020Co-Authors: Xiaohui Jiang, Shaoquan LiuAbstract:Abstract Red dragon fruit is a popular tropical fruit that has been highly prized for its health benefits partially attributed to the high antioxidant content. Nevertheless, besides being consumed fresh, further processing into juice or other products is scarce due to its high pectin content that presents a challenge in industrial processing. In this study, we evaluated the effects of pectinase pre-treatment on red dragon fruit wine fermented with Torulaspora delbrueckii. Pectinase enzyme (Pectinex® Ultra SP-L, added at 0.1% v/v) was applied after pasteurization of juice followed by fermentation with T. delbrueckii at 20 °C for 14 days. Pectinase pre-treatment did not affect the yeast growth, nor the production of ethanol (8% v/v) and glycerol (6 g/L), but significantly increased juice/wine yield by 16% v/v. In addition, pectinase treated samples after fermentation remained significantly higher levels of residual nitrogen containing compounds, indicating unfavorable fermentation conditions and impaired metabolism of the yeast. Moreover, fermented pectinase treated samples possessed the aroma compound profiles with enriched esters and terpenes but decreased higher alcohols. Furthermore, pectinase treatment increased the total phenolic content, but decreased betacyanins content and color intensity compared to control sample. The findings would have practical significance for diversifying products from red dragon fruit.
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effect of single amino acid addition on growth kinetics and flavor modulation by Torulaspora delbrueckii in soy tofu whey alcoholic beverage fermentation
Food Research International, 2020Co-Authors: Jianyong Chua, Shaoquan LiuAbstract:Abstract Soy (tofu) whey is a by-product commonly disposed of by tofu manufacturers around the world. Due to its nutritious nature, direct disposal of soy whey into the sewage can result in a detrimental impact on the environment in the long-run. In this study, soy whey supplemented with four individual amino acids (valine, leucine, isoleucine and phenylalanine) equivalent to 120 mg N/L was fermented with a yeast Torulaspora delbrueckii Biodiva. The supplementation of an individual amino acid resulted in faster sugar utilization and lower levels of residual sugar than the unsupplemented whey but did not result in a significantly higher amount of ethanol (7–8% v/v) at the end of fermentation. Isoleucine supplementation resulted in a slightly slower initial yeast growth rate when compared to the control while the other three amino acids had identical yeast growth kinetics to the control. Isoleucine supplementation also resulted in slower sugar utilization during the first four days. Therefore, isoleucine is least preferred by the yeast. The supplementation of amino acids resulted in greater formation of higher alcohols and their corresponding alcohol-derived esters. Overall, the supplementation of a single amino acid enhanced sugar utilization and impacted flavor compounds of the resultant soy whey alcoholic beverage.
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effects of different yeasts on physicochemical and oenological properties of red dragon fruit wine fermented with saccharomyces cerevisiae Torulaspora delbrueckii and lachancea thermotolerans
Microorganisms, 2020Co-Authors: Xiaohui Jiang, Shaoquan LiuAbstract:A new type of fruit wine made from red dragon fruit juice was produced through alcoholic fermentation (AF) with different yeasts: Saccharomyces cerevisiae EC-1118, Torulaspora delbrueckii Biodiva and Lachancea thermotolerans Concerto. Complete AF with similar fermentation rates in terms of sugar utilisation and ethanol production (8–9%, v/v) was achieved by three yeast strains. T. delbrueckii produced a significantly lower amount of glycerol and acetic acid, while L. thermotolerans produced more lactic and succinic acids. In addition, the two non-Saccharomyces strains were more efficient in proline utilisation. For volatile compounds, S. cerevisiae produced the highest amounts of esters, while T. delbrueckii produced more higher alcohols, isoamyl acetate and terpenes. On the other hand, AF caused significant degradation of betacyanin pigments and total phenolic compounds. Nevertheless, better retention of antioxidant activity and colour stability was found in L. thermotolerans and T. delbrueckii fermented wines than that of S. cerevisiae. This study suggested that it is feasible to use pure non-Saccharomyces yeast to produce red dragon fruit wine for commercialization.