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A single Saccharomyces cerevisiae wine yeast strain produces a range of aroma and flavour metabolites (e.g. volatile thiols), as well as unfavourable metabolites (e.g. volatile acidity [VA]), during the alcoholic fermentation of white wine, especially Sauvignon blanc. The former contribute to the organoleptic quality of the final wine. Previous research showed that yeast-derived enzymes (proteins) are involved in the release of wine quality-enhancing or quality-reducing metabolites during fermentation. Small-scale winemaking trials were initiated to evaluate the protein expression and metabolite release of S. cerevisiae hybrid yeasts producing tropical fruit aroma. Commercial 'thiol-releasing' wine yeasts (TRWY) were included in winemaking trials as references. Improved hybrids were identified that showed enhanced thiolreleasing abilities, specifically 3-mercaptohexanol (3MH), and lower VA formation during the production of Sauvignon blanc wines compared to some commercial TRWY references. It is noteworthy that the hybrid NH 56 produced wines with the second highest 3MH levels after hybrid NH 84, and with the lowest acetic acid of all strains included in this study. This yeast was also the only strain to have downregulated proteins linked to amino acid biosynthesis, the pentose phosphate pathway, glycolysis, and fructose and galactose metabolism during the lag phase. Furthermore, differences in protein expression were reflected in the variation in metabolite release by different strains, thereby confirming that enzymes (proteins) are the final effectors of metabolite release.A single Saccharomyces cerevisiae wine yeast strain produces a range of aroma and flavour metabolites (e.g. volatile thiols), as well as unfavourable metabolites (e.g. volatile acidity [VA]), during the alcoholic fermentation of white wine, especially Sauvignon blanc. The former contribute to the organoleptic quality of the final wine. Previous research showed that yeast-derived enzymes (proteins) are involved in the release of wine quality-enhancing or quality-reducing metabolites during fermentation. Small-scale winemaking trials were initiated to evaluate the protein expression and metabolite release of S. cerevisiae hybrid yeasts producing tropical fruit aroma. Commercial 'thiol-releasing' wine yeasts (TRWY) were included in winemaking trials as references. Improved hybrids were identified that showed enhanced thiolreleasing abilities, specifically 3-mercaptohexanol (3MH), and lower VA formation during the production of Sauvignon blanc wines compared to some commercial TRWY references. It is noteworthy that the hybrid NH 56 produced wines with the second highest 3MH levels after hybrid NH 84, and with the lowest acetic acid of all strains included in this study. This yeast was also the only strain to have downregulated proteins linked to amino acid biosynthesis, the pentose phosphate pathway, glycolysis, and fructose and galactose metabolism during the lag phase. Furthermore, differences in protein expression were reflected in the variation in metabolite release by different strains, thereby confirming that enzymes (proteins) are the final effectors of metabolite release. [ABSTRACT FROM AUTHOR]

A study was taken to evaluate growth performance, carcass characteristics, and blood metabolite concentrations when ensiled corncobs were included in indigenous and commercial pig diets. Fifty Large White x Landrace (LWxLR) crossbred pigs and 30 South African Windsnyer-type indigenous pigs (SAWIP) were evaluated. They were fed a control (CON), a low inclusion of ensiled corncob (LMC), and a high inclusion of ensiled corncob (HMC) diet in a completely randomized block design. The LWxLR crosses had greater (P < 0.05) final weight, ADFI, DMI, ADG, and G:F ratios than the SAWIP at both the grower and finisher stages. The SAWIP consumed more feed per metabolic BW (BW0.75) than LWxLR crosses at the grower stage while LWxLR crosses consumed more than SAWIP at the finisher stage (P < 0.05). The finishers' G:F ratio was greater (P < 0.05) in the CON than in the HMC diet. The LWxLR growers and finishers had greater (P < 0.05) warm carcass weight (WCW), cold carcass weight (CCW), carcass length, drip loss, pH at 24 h, eye muscle area, and lean percent than those of SAWIP growers and finishers. The LWxLR finishers on the CON diet had greater (P < 0.05) WCW and CCW than those on the HMC and LMC diets. There were diet x breed interactions for dorsal fat thickness at first rib (DFT1), dorsal fat thickness at last lumbar vertebra (DFT3), backfat thickness (BFT), and hindquarter weight proportion (HQWP) in the growers. The LWxLR growers and finishers had greater values (P < 0.05) of hindquarter length, hindquarter circumference, HQWP, and shoulder weight proportion than the SAWIP growers and finishers, respectively. The SAWIP growers and finishers had greater values (P < 0.05) of DFT1, dorsal fat thickness at last rib, DFT3, and BFT than the LWxLR growers and finishers, respectively. There were breed x diet interactions (P < 0.05) for alanine aminotransferase and amylase (AMYL). The LWxLR crosses had greater (P < 0.05) values of creatinine, phosphorus, alkaline phosphatase, cholesterol, and AMYL than the SAWIP. The breed of pig influenced most of the growth performance and carcass parameters more than the diet did. There was no clear link between the blood metabolite levels and the diets. Since the inclusion of ensiled corncobs in diets did not affect negatively the selected important commercial pork cuts in South Africa, this could imply that they have a greater role as a pig feed resource. [ABSTRACT FROM AUTHOR]

Although Saccharomyces cerevisiae is the yeast species predominantly used for alcoholic fermentation, non-Saccharomyces yeast species are also important because they produce secondary metabolites that can contribute to the final flavour and taste of wines. In this study, 37 strains representing seven non- Saccharomyces species were characterised and evaluated for potential use in wine production, as well as for their effects on malolactic fermentation (MLF). Contour-clamped homogeneous electric field (CHEF) gel electrophoresis and matrix-assisted laser desorption ionisation using a time-of-flight mass spectrometer (MALDI-TOF MS) were used to verify species identity and to determine intra-species variation. Extracellular enzyme production, malic acid degradation and the fermentation kinetics of the yeasts were also investigated. CHEF karyotyping and MALDI-TOF MS were useful for identifying and typing Hanseniaspora uvarum, Lachancea thermotolerans, Candida zemplinina (synonym: Starmerella bacillaris) and Torulaspora delbrueckii strains. Only H. uvarum and Metschnikowia pulcherrima strains were found to have β-glucosidase activity. M. pulcherrima strains also had protease activity. Most of the strains showed limited malic acid degradation, and only Schizosaccharomyces pombe and the C. zemplinina strains showed mentionable degradation. In synthetic wine fermentations, C. stellata, C. zemplinina, H. uvarum, M. pulcherrima and Sc. pombe strains were shown to be slow to medium fermenters, whereas L. thermotolerans and T. delbrueckii strains were found to be medium to strong fermenters. The effect of the yeasts on MLF varied, but inhibition was strain dependent. [ABSTRACT FROM AUTHOR]

A study was taken to evaluate growth performance, carcass characteristics, and blood metabolite concentrations when ensiled corncobs were included in indigenous and commercial pig diets. Fifty Large White× Landrace (LW×LR) crossbred pigs and 30 South African Windsnyer-type indigenous pigs (SAWIP) were evaluated. They were fed a control (CON), a low inclusion of ensiled corncob (LMC), and a high inclusion of ensiled corncob (HMC) diet in a completely randomized block design. The LW×LR crosses had greater (P<0.05) final weight, ADFI, DMI, ADG, and G:F ratios than the SAWIP at both the grower and finisher stages. The SAWIP consumed more feed per metabolic BW (BW0.75) than LW×LR crosses at the grower stage while LW×LR crosses consumed more than SAWIP at the finisher stage (P<0.05). The finishers' G:F ratio was greater (P<0.05) in the CON than in the HMC diet. The LW×LR growers and finishers had greater (P<0.05) warm carcass weight (WCW), cold carcass weight (CCW), carcass length, drip loss, pH at 24 h, eye muscle area, and lean percent than those of SAWIP growers and finishers. The LW×LR finishers on the CON diet had greater (P<0.05) WCW and CCW than those on the HMC and LMC diets. There were diet×breed interactions for dorsal fat thickness at first rib (DFT1), dorsal fat thickness at last lumbar vertebra (DFT3), backfat thickness (BFT), and hindquarter weight proportion (HQWP) in the growers. The LW×LR growers and finishers had greater values (P<0.05) of hindquarter length, hindquarter circumference, HQWP, and shoulder weight proportion than the SAWIP growers and finishers, respectively. The SAWIP growers and finishers had greater values (P<0.05) of DFT1, dorsal fat thickness at last rib, DFT3, and BFT than the LW×LR growers and finishers, respectively. There were breed×diet interactions (P<0.05) for alanine aminotransferase and amylase (AMYL). The LW×LR crosses had greater (P< 0.05) values of creatinine, phosphorus, alkaline phosphatase, cholesterol, and AMYL than the SAWIP. The breed of pig influenced most of the growth performance and carcass parameters more than the diet did. There was no clear link between the blood metabolite levels and the diets. Since the inclusion of ensiled corncobs in diets did not affect negatively the selected important commercial pork cuts in South Africa, this could imply that they have a greater role as a pig feed resource.