The Use of Candida pulcherrima in Combination with Saccharomyces cerevisiae for the Production of Chenin blanc Wine

Wine fermentations are conducted by naturally occurring or selected industrial wine yeast strains of Saccharomyces cerevisiae. However, non-Saccharomyces yeasts also occur naturally in fermenting grape musts, especially in the initial stages of the fermentation. It has been speculated that these yeasts can contribute to the overall characteristics of the wine. Generally, it is accepted that Kloeckera apiculata is the predominant non-Saccharomyces yeast species in grape must. However, it was shown previously that Candida pulcherrima was the predominant non-Saccharomyces yeast species in a grape must after sedimentation and prior to inoculation with commercial wine yeast. Subsequently, this yeast was investigated in laboratory and small-scale wine fermentations of Chenin blanc wine. As it could not ferment grape juice to dryness on its own, it was used in combination with a S. cerevisiae wine yeast strain. The effect of SO2, di-ammonium phosphate (DAP), pH and temperature on the growth of C. pulcherrima was also investigated. In combined fermentations, no change in overall fermentation rate or standard wine chemical analyses could be observed in comparison to a control S. cerevisiae fermentation.However, wine production in three consecutive years showed that the wine produced by the combined fermentation was of higher quality than that produced by the S. cerevisiae only

The Role and Use of Non-Saccharomyces Yeasts in Wine Production

The contribution by the numerous grape-must-associated non-Saccharomyces yeasts to wine fermentation has beendebated extensively. These yeasts, naturally present in all wine fermentations, are metabolically active and theirmetabolites can impact on wine quality. Although often seen as a source of microbial spoilage, there is substantialcontrary evidence pointing to a positive contribution by these yeasts. The role of non-Saccharomyces yeasts in winefermentation is therefore receiving increasing attention by wine microbiologists in Old and New World wineproducing countries. Species that have been investigated for wine production thus far include those from theCandida, Kloeckera, Hanseniaspora, Zygosaccharomyces, Schizosaccharomyces, Torulaspora, Brettanomyces,Saccharomycodes, Pichia and Williopsis genera. In this review the use and role of non-Saccharomyces yeast in wineproduction is presented and research trends are discussed

The Effect of Non-Saccharomyces Yeasts on Fermentation and Wine Quality

Research has shown that non-Saccharomyces yeast strains can be detected throughout wine fermentation.  Non-Saccharomyces yeasts can therefore influence the course of fermentation and also the character of the resultant wine. Previously it was shown that four non-Saccharomyces species, i.e. Kloeckera apiculata, Candida stellata, Candida pulcherrima and Candida colliculosa, predominated in grape must at the start of fermentation. In this study these four yeasts were used singularly and in combination with an industrial wine yeast (Saccharomyces cerevisiae strain VIN 13) to ferment must on a laboratory scale. The resultant wine was analysed for ethanol, volatile acidity, total S02 and glycerol. Results show that, in comparison with the industrial wine yeast, the non-Saccharomyces yeast strains could not ferment all the sugar. Furthermore, while the individualnon-Saccharomyces-fermented wines had different chemical analyses, the wines fermented by the combinations were similar to the wine produced by the industrial yeast only. In subsequent, small-scale winemaking trials some of the wines produced by combined fermentations were judged to be of better quality than those produced by the S. cerevisiae only. However, this quality increase could not be linked to increased ester levels

The Occurrence of Non-Saccharomyces cerevisiae Yeast Species Over Three Vintages in Four Vineyards and Grape Musts From Four Production Regions of the Western Cape, South Africa

The role of non-Saccharomyces yeasts in wine production has been extensively debated and there is growing evidence that non-Saccharomyces yeasts play an important role in wine quality. It has been suggested that metabolites formed by some non-Saccharomyces species may contribute to wine quality. Recently a comprehensive, longterm research programme was launched by role players in the South African wine industry, whose aims include the isolation, characterisation and preservation of the natural yeast biodiversity of the Western Cape. As part of the programme, this paper investigates the presence of non-Saccharomyces yeast species over three vintages in four vineyards and musts in four distinct areas of the Western Cape. Samples were taken and the non-Saccharomyces yeast isolates were characterised by biochemical profiling and pulse field gel electrophoresis. In total 720 yeasts representing 24 species were isolated. Predominant species found in the must samples, i.e. Candida stellata, Kloeckera apiculata, Candida pulcherrima and Candida colliculosa, should have the most impact on subsequent fermentation

Characterisation of Thiol-releasing and Lower Volatile Acidityforming Intra-genus Hybrid Yeast Strains for Sauvignon blanc Wine

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 contributes 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 reducing metabolites during fermentation. Small-scale winemaking trials were initiated to evaluate protein expression and metabolite release of tropical fruit aroma wine producing S. cerevisiae hybrid yeasts. Commercial ‘thiol-releasing’ wine yeasts (TRWY) were included in winemaking trials as references. Improved hybrids were identified which showed enhanced thiol-releasing, 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 lowest acetic acid of all strains included in this study. This yeast was also the only strain to have down-regulated proteins linked to amino acid biosynthesis, pentose phosphate pathway, glycolysis and fructose and galactose metabolism during the lag phase. Furthermore, differences in protein expression were reflected in the variation of metabolite release by different strains, thereby confirming that enzymes (proteins) are the final effectors for metabolite release. 

Screening Non-Saccharomyces Yeasts as Low Ethanol Producing Starter Cultures

Non-Saccharomyces yeasts are known for their low fermentation rate in comparison to Saccharomyces cerevisiae.  In this study, non-Saccharomyces yeasts were inoculated into Chenin blanc grape must and fermented under aerobic and anaerobic conditions.  Saccharomycodes ludwigii displayed a strain-dependent fermentation rate, which yielded between 5.2% and 9.9% ethanol concentration under both conditions, albeit with residual sugar.  Aerobic conditions favoured the production of reduced ethanol which was between 5.8% and 9.7% for non-Saccharomyces yeasts in comparison to S. cerevisiae (10%).  This trend was observed for Wickerhamomyces anomalus, Stamerella bacillaris (Candida zemplinina), Metshnikowia pulcherrima, Cyberlindnera saturnus, Wickerhamomyces subpelliculosus and Cyberlindnera jadinii.  The laboratory-scale wines prepared with the aforementioned yeasts yielded ripe fruit and floral aroma attributes while other non-Saccharomyces yeasts resulted in wines with spicy, acidic and solvent aroma notes

Effect of Torulaspora delbrueckii Yeast Treatment on Flavanols and Phenolic Acids of Chenin blanc Wines

The non-Saccharomyces yeast Torulaspora delbrueckii contributes positively to the sensory properties of wines by affecting aroma and flavour due to changes in alcohols, esters, fatty acids and lactone levels.  One of the less-studied aspects of T. delbrueckii is its effect on phenolic compounds relating to sensory attributes. An HPLC-DAD technique was used for the quantification of phenolic compounds in Chenin blanc wines made with S. cerevisiae and two T. delbrueckii yeasts over three vintages. Chemical andsensory data were subjected to ANOVA and PCA. VIN13, M2/1 and VIN13+M2/1 had a positive effect on the phenolic compound concentrations of Chenin blanc wines. Mouthfeel was highest in VIN13+654 wines and astringency highest in VIN13 wines. An association was evident between flavanols, astringency and mouthfeel for the VIN13, M2/1 and VIN13+M2/1 wines. Chenin blanc wines made with M2/1 and VIN13+M2/1 may result in increased phenolic compound concentrations and astringency, whereas 654 and VIN13+654 may result in wines with increased mouthfeel properties

Torulaspora delbrueckii Yeast Strains for Small-scale Chenin blanc and Pinotage Vinifications

Nine Torulaspora delbrueckii yeast strains, a commercial T. delbrueckii strain and a commercial Saccharomyces cerevisiae yeast strain were used in the production of small‑scale Chenin blanc and Pinotage vinifications. The fermentations were carried out at 15°C and 24°C respectively. Four T. delbrueckii yeasts were used as single inoculants, while the remainder were inoculated sequentially. The commercial S. cerevisiae yeast strains were added at zero, 24 and 48 hours after the T. delbrueckii strain. The wines were evaluated chemically and sensorially and the data was analysed statistically. The results for the white wine vinification trial showed that two T. delbrueckii treatments could produce novel wines, either on their own or as a component of co‑inoculated fermentations. These compared well with, and even exceeded, the quality of wine produced by the S. cerevisiae reference treatment regarding chemical composition and overall sensory quality. One T. delbrueckii strain showed its robustness by being re-isolated from the yeast lees at the end of fermentation. The red wine vinifications were less conclusive, and no distinctive T. delbrueckii “fingerprint” was observed in the chemical and sensory data, neither was a pattern observed regarding the different inoculation times

Characterisation of Saccharomyces cerevisiae hybrids selected for low volatile acidity formation and the production of aromatic Sauvignon blanc wine

Wine yeasts (Saccharomyces cerevisiae) vary in their ability to develop the full aroma potential of Sauvignon blanc wine due to an inability to release volatile thiols. Subsequently, the use of ‘thiolreleasing’ wine yeasts (TRWY) has increased in popularity. However, anecdotal evidence suggests that some commercially available TRWY intermittently exhibit undesirable characteristics for example, volatile acidity (VA) formation. Therefore, a trial was undertaken to select and evaluate S. cerevisiae hybrids for the production of Sauvignon blanc wine with enhanced fruity and tropical aromas, but low VA. Hybrids were characterised by clamped homogeneous electrical field (CHEF) DNA karyotyping and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) biotyping, and subsequently trialled against top commercial TRWY that is, Zymaflore VL3 and Zymaflore X5 (Laffort Oenologie), and Fermicru 4F9 (DSM Oenology) in laboratory-scale Sauvignon blanc vinifications during 2013. Most hybrids produced wines with VA levels significantly lower than those produced with Zymaflore VL3, Zymaflore X5 and Fermicru 4F9. Low VA forming hybrids also produced wines with tropical wine aroma notes. Wines produced by Fermicru 4F9 had the lowest acetic acid (the main volatile acid) of the commercial TRWY in this study. However, some hybrid yeasts produced wines with less acetic acid on average than wines produced by Fermicru 4F9. Overall, hybrids NH 6, NH 48, NH 56, NH 88 and NH 145 produced wines with enhanced tropical fruity aroma, but lower VA compared to wines produced by commercial TRWY.Keywords: Hybrid yeasts, CHEF, MALDI-TOF/TOF MS biotyping, Sauvignon blanc, tropical fruit aroma, volatile acidit

Effect of Torulaspora delbrueckii Yeast on the Anthocyanin and Flavanol Concentrations of Cabernet franc and Pinotage Wines

Pinotage and Cabernet franc grape must were inoculated with Saccharomyces cerevisiae and Torulasporadelbrueckii yeasts. Differences in colour were observed between Pinotage (S. cerevisiae) and Pinotage (T.delbrueckii) wines, whereas differences in berry and herbaceous character were observed between Cabernetfranc (S. cerevisiae) and Cabernet franc (T. delbrueckii) wines. Mouthfeel properties between treatmentsfor both wines were not significantly different. Overall quality was slightly higher in wines inoculatedwith T. delbrueckii compared to wines inoculated with S. cerevisiae. Anthocyanins and flavanols measuredin Pinotage wines made with T. delbrueckii were higher compared to Pinotage must inoculated with S.cerevisiae. Cabernet franc wines made with S. cerevisiae were higher in anthocyanin glycoside and flavanolconcentrations compared to Cabernet franc wines made with T. delbrueckii. Insignificant differencesin acetylated and coumarylated anthocyanins were evident between Cabernet franc (S. cerevisiae) andCabernet franc (T. delbrueckii) wines. Principal component analysis showed that epigallocatechin gallate,epicatechin gallate, procyanidin B2, peonidin 3-O-glucoside, delphinidin 3-(6-acetyl) glucoside, petunidin3-(6-acetyl) glucoside, malvidin 3-(6-acetyl) glucoside and malvidin 3-O-glucoside concentrationswere highest in Pinotage wines inoculated with T. delbrueckii. Cabernet franc wines inoculated with S.cerevisiae yeasts were highest in malvidin 3-(6-p-coumaroyl) glucoside, petunidin 3-(6-p-coumaroyl)glucoside, petunidin 3-O-glucoside, epicatechin gallate and epigallocatechin gallate concentrations. Totalanthocyanins were highest in Pinotage (S. cerevisiae) wines and Cabernet franc (T. delbrueckii) wines.Flavanols were highest in Pinotage (T. delbrueckii) and Cabernet franc (S. cerevisiae) wines. It is evidentfrom the results that yeast species has an impact on the flavonoid concentrations within a grape variety