Effects of sequentially inoculated Williopsis saturnus and Saccharomyces cerevisiae on volatile profiles of papaya wine

The effects of sequential inoculation of yeasts Williopsis saturnus var. mrakii NCYC2251 and Saccharomyces cerevisiae var. bayanus R2 on the volatile profiles of papaya wine were investigated at an inoculum ratio of 1000 (W. saturnus) to 1 (S. cerevisiae). Inoculation of S. cerevisiae after seven days' fermentation with W. saturnus produced papaya wine with more acetate esters and fruitiness than the control (simultaneous inoculation). However, inoculation of W. saturnus after two days' fermentation with S. cerevisiae resulted in most of the volatile composition being comparable to the control, except for the enhanced amount of ethyl esters. The first inoculated yeast dominated the fermentation. The study suggests that sequential inoculation of non-Saccharomyces and Saccharomyces yeasts at a certain inoculum ratio may be a valuable tool to manipulate yeast succession and to modulate the volatile profiles and organoleptic properties of papaya wine.     

Profile of volatile compounds during papaya juice fermentation by a mixed culture of Saccharomyces cerevisiae and Williopsis saturnus

This study investigated the formation and utilization of volatile compounds during papaya juice fermentation by a mixed culture of Saccharomyces cerevisiae and Williopsis saturnus. Time-course papaya juice fermentations were carried out using pure cultures of S. cerevisiae var. bayanus R2 and W. saturnus var. mrakii NCYC2251 and a mixed culture of the two yeasts at a ratio of 1:1000 (R2:NCYC2251). Changes in S. cerevisiae cell population, Brix, sugar consumption and pH were similar in the mixed culture and in the S. cerevisiae monoculture. There was an early growth arrest of W. saturnus in the mixed culture fermentation. A range of volatile compounds were produced during fermentation including fatty acids, alcohols, aldehydes and esters and some volatile compounds including those initially present in the juice were utilized. The mixed culture fermentation of S. cerevisiae and W. saturnus benefited from the presence of both yeasts, with more esters being produced than the S. cerevisiae monoculture and more alcohols being formed than the W. saturnus monoculture. The study suggests that papaya juice fermentation with a mixed culture of S. cerevisiae and W. saturnus may be able to result in the formation of more complex aroma compounds and higher ethanol level than those using single yeasts.     

Evolution of volatile compounds in papaya wine fermented with three Williopsis saturnus yeasts

The changes in volatile compounds during papaya juice fermentation with three Williopsis saturnus yeasts were investigated in this study. Time‐course papaya juice fermentations were carried out using three Williopsis saturnus yeasts: W. saturnus var. mrakii NCYC2251, W. saturnus var. saturnus NCYC22 and W. saturnus var. sargentensis NCYC2727. Changes in yeast cell population, Brix and pH were similar among the three yeasts, which preferentially utilised glucose over fructose while partially degrading l ‐malic acid. A range of volatile compounds were produced during fermentation including fatty acids, alcohols and esters with esters being the most abundant volatile compounds produced. Benzyl isothiocyanate, butyric acid, 2‐ethylhexanol, benzaldehyde and β‐damascenone present in the papaya juice were metabolised to trace levels during fermentation. There were significant variations among the three yeasts in their ability to produce and metabolise volatile compounds during fermentation. The study suggests that papaya juice fermentation with W. saturnus yeasts is able to result in the formation of a more complex aroma compounds.     

Growth and fermentation kinetics of a mixed culture of Saccharomyces cerevisiae var. bayanus and Williopsis saturnus var. saturnus at different ratios in longan juice (Dimocarpus longan Lour.)

Cofermentation of longan juice by mixed cultures of Saccharomyces cerevisiae var. bayanus EC‐1118 and Williopsis saturnus var. saturnus CBS254 at two inoculation ratios (EC‐1118:CBS254 = 1:100 and 1:1000 cfu mL^?1) was performed to ascertain their impact on longan wine aroma compound formation. The results showed improved aroma compound profiles in the longan wine fermented with mixed yeasts in comparison with the longan wines fermented with single yeasts in terms of increased production of acetate esters, fatty acid ethyl esters, alcohols and carboxylic acids. The impact of cofermentation on longan wine aroma formation was affected by the ratio of S. cerevisiae EC‐1118 to W. saturnus CBS254 with 1:100 cfu mL^?1 being more effective. This research suggests that the inoculation ratio of mixed yeasts may be used as an effective means of manipulating longan wine aroma.     

Effects of Pure and Mixed-Cultures of Saccharomyces cerevisiae and Williopsis saturnus on the Volatile Profiles of Grape Wine

Non-Saccharomyces yeasts are being recognised for their ability to produce wines with unique character. This study assessed the production of volatiles by co-inoculating Saccharomyces cerevisiae and Williopsis saturnus. Laboratory-scale fermentations were carried out using pure and mixed-cultures of S. cerevisiae and W. saturnus at a ratio of 1:1000. The mixed-culture fermentation was dominated by S. cerevisiae, while W. saturnus had an early growth arrest. Changes of oenological parameters and volatiles were similar in both the mixed- and the S. cerevisiae monocultures. A range of volatiles was formed with alcohols and esters constituting the majority of volatiles produced. Volatiles initially present in the grape juice, particularly (E)-2-hexen-1-ol, 1-hexanol, trans-2-hexenal and n-hexanal, were metabolized. Wines produced using mixed-cultures closely resembled those fermented by the S. cerevisiae monoculture but acquired minor flavor characteristics from the initial presence of W. saturnus. These findings suggest that the ratio of S. cerevisiae and W. saturnus is critical to the survival of the non-Saccharomyces yeast and the impact on the perceivable characteristics of the resultant quality and flavor of wines.     

Effects of mediums on fermentation behaviour and aroma composition in pure and mixed culture of Saccharomyces cerevisiae with Torulaspora delbrueckii

The nutrient status and composition in mediums have a significant effect on yeast metabolism and phenotypic characteristics in wine fermentation. In this study, the effects of three frequently used mediums, including synthetic grape juice (SGJ), grape juice without grape pericarp and seeds (GJ) and grape must with grape pericarp and seeds (GMPS), on yeast fermentation behaviour and aroma compounds produced by pure and mixed culture of Saccharomyces cerevisiae T73 with Torulaspora delbrueckii TD20 were investigated after alcoholic fermentation. The results showed that high fermentation activities and cell population were always found in GJ medium irrespective of inoculated approach. More esters and higher alcohols were produced in GMPS medium fermented by pure S. cerevisiae, while SGJ medium had increased levels of fatty acids. Consistent with previous literatures, the mixed fermentation of T. delbrueckii and S. cerevisiae produced more acetate esters and fatty acids than the pure culture of S. cerevisiae, while this enological trait was only found in SGJ and GJ, not in GMPS. Our results highlighted that more attention should be paid to the fermentation medium when evaluating the enological and aromatic properties of selected yeasts used in industrial winemaking. In this regard, the combined use of GJ and GMPS medium might be a suitable choice.     

Impact of two Williopsis yeast strains on the volatile composition of mango wine

The aim of the research was to study the volatile composition of mango wine fermented with two Williopsis yeast strains: Williopsis saturnus var. mrakii NCYC500 and W. staurnus var. suaveolens NCYC2586. Thirty terpenoids, twenty‐six esters, ten alcohols, nine acids, seven aldehydes and ketones, two ethers, two phenols and one sulphur compound were identified in the mango wine fermented with strain NCYC500, while twenty‐seven terpenoids, thirty esters, eleven alcohols, eight acids, eight aldehydes and ketones, three ethers, two phenols, one sulphur compound and one furan were detected in the mango wine fermented with the strain NCYC2586. The kinetic changes, final concentrations and odour activity values of major volatiles were compared between the two Williopsis yeast strains and also with other yeast reported in the literature. The results showed that Williopsis yeast strains NCYC500 and NCYC2586 were high producers of acetic acid and acetate esters, but low producers of medium‐ to long‐chain fatty acids and their corresponding ethyl esters. Unlike mango wine fermented with Saccharomyces cerevisiae, most terpenoids derived from mango juice were retained in the resultant mango wine fermented with the two Williopsis yeast strains, suggesting the mango wine could retain the aromatic hints of fresh mango.     

Effect of fusel oil addition on volatile compounds in papaya wine fermented with Williopsis saturnus var. mrakii NCYC 2251

The impact of fusel oil addition on volatile compounds formation in papaya wine fermented with yeast Williopsis saturnus var. mrakii NCYC2251 was studied with a view to enhancing papaya wine aroma production. Time-course papaya juice fermentations were carried out using W. saturnus var. mrakii NCYC2251 with fusel oil added (0, 0.1 and 0.5% v/v). Fermentation characteristics in terms of yeast growth, Brix and pH changes were similar for all fermentations except for those added with 0.5% (v/v) fusel oil. The addition of 0.5% (v/v) fusel oil inhibited yeast growth. A wide range of volatile compounds were produced during fermentation including acids, alcohols, esters and aldehydes with esters being the most abundant volatile compounds produced. The addition of 0.1% (v/v) fusel oil reduced the production of undesirable volatiles such as ethyl acetate and acetic acid, while increasing the desirable volatiles production such as ethanol and acetate esters. This study suggests that papaya juice fermentation with W. saturnus var mrakii NCYC 2251 together with a low concentration of added fusel oil can be another means of modulating papaya wine aroma compound formation.     

Contribution of wild yeasts to the formation of volatile compounds in inoculated wine fermentations

The aim of this work was to study the contribution of wild yeasts to the volatile composition of wine in inoculated fermentations. To do so, Parellada must, sterilized and inoculated with Saccharomyces cerevisiae strain Na33 (pure inoculated fermentation), inoculated Parellada must (mixed inoculated fermentation) and Parellada must that fermented with its wild yeasts (control fermentation) were used. From the results obtained in the pure inoculated fermentation it can be seen that S. cerevisiae produced appreciable quantities of isoamyl acetate, ethyl hexanoate, ethyl octanoate, and ethyl decanoate. However, the wild yeasts also contributed to the synthesis of esters since the total concentration of these substances was higher in the mixed inoculated fermentation than in the pure inoculated fermentation. 2-Phenylethyl acetate was only synthesized by wild yeasts when they did not compete with S. cerevisiae. The concentration of total alcohols was similar in the three samples; the important production of isobutanol and 2-phenylethanol in the control fermentation is noteworthy. As regards the acids, the greatest concentration corresponded to the mixed inoculated fermentation. The wild yeasts contributed to the synthesis of these compounds to a significant extent and S. cerevisiae synthesized appreciable amounts of short-chain fatty acids.     

Biotransformation of durian pulp by mono- and mixed-cultures of Saccharomyces cerevisiae and Williopsis saturnus

Durian is a seasonal tropical fruit widely grown and highly prized in Southeast Asia. This is a first study to assess the transformation of durian constituents during fermentation with mono- and mixed-cultures of Saccharomyces cerevisiae and Williopsis saturnus with a view to developing a novel alcoholic beverage. A diversity of volatiles was produced especially alcohols and esters, while those volatiles initially present in durian, particularly the character-impact sulphur-containing odorants, were transformed. Most of the sulphur-containing compounds decreased with fermentation. 3-(Ethylthio)-1-propanol was produced initially then remained relatively stable, whereas ethyl thioacetate was formed initially then decreased in all culture types. The kinetic changes and concentrations of volatile compounds were similar in both the mixed-culture and the S. cerevisiae monoculture, except for higher amounts of alcohols in the mixed-culture. The W. saturnus monoculture, on the other hand, was the main producer of acetate esters. Sensory evaluation revealed a strong sulphury note retained in all fermentations but less unfavourable metallic and yeasty notes in the mixed-culture. The study suggests that biotransformation by yeasts can be effective in modifying the constituents and modulating the organoleptic properties of durian.     

Influence of SO<Subscript>2</Subscript> on the evolution of volatile compounds through alcoholic fermentation of must stabilized by pulsed electric fields

The aim of this work was to study the influence of sulphur dioxide (SO₂) on the formation of volatile compounds by yeast through wine alcoholic fermentation. Thus Parellada must was microbiologically stabilized using a pulsed electric field (PEF) treatment and inoculated with Saccharomyces cerevisiae Na33 strain. Fermentation was carried out with or without SO₂ and the results showed that the evolution of the volatile compounds profile throughout the process was similar. The content of volatile acids in wine obtained by using sulphur dioxide was not significantly different from that fermented without adding the compound. However, the final content of total alcohols and esters was significantly different even thought the differences were small. Consequently, when grape must is treated by PEF the sulphur dioxide concentration usually used in winemaking could be reduced to safer levels or even eliminated without an important effect on the volatile compounds content of the final product. Therefore, the absence of sulphur dioxide should not have a negative impact on the sensory characteristics of wine.     

Antagonism between Saccharomyces cerevisiae and Williopsis mrakii and significance for mixed yeast alcoholic beverage fermentations

This research was carried out to investigate the antagonism between Saccharomyces cerevisiae and Williopsis saturnus var. mrakii. When glucose level was ≥12% (w/v) (potential ethanol ≥7.2% v/v), W. mrakii that was co‐inoculated with S. cerevisiae died early, while W. mrakii alone could not survive in broth with ≥8% (v/v) ethanol. Moreover, when glucose was ≥15% (w/v) (potential ethanol ≥9.0% v/v), higher inoculums of S. cerevisiae induced faster cell decline of W. mrakii; when glucose was ≤2% (w/v), there was no early cell decline of W. mrakii at any inoculum ratio, but there was inoculum ratio‐dependent growth retardation. These results indicate that ethanol was at least one of the factors causing early cell decline of W. mrakii in co‐culture with S. cerevisiae. Further, S. cerevisiae was inhibited when it was inoculated sequentially into a W. mrakii monoculture; the former yeast was also suppressed when it was inoculated into the supernatants of a W. mrakii monoculture. This suggests that S. cerevisiae was sensitive to the mycosin (killer toxin) produced by W. mrakii. These findings have implications for controlling mixed yeast alcoholic beverage fermentations.     

Effects of seven yeast strains on the volatile composition of Palomino wines

The must obtained from Palomino grapes was inoculated with seven different commercial yeast strains (three Saccharomyces cerevisiae cerevisiae– MO5, CEG and IOC BR 8000 and four Saccharomyces cerevisiae bayanus– ALB, KD, REIMS and IOC 2007) and fermented under identical conditions. Standard chemical analyses were done on the final industrial wines and the major volatile compounds extracted and analysed by gas chromatography coupled to mass spectrometry. No differences were found in gross chemical composition, but the wines had significantly different volatile characteristics and the results demonstrated that large sensory differences were generated by the different yeast strain that had been used in the vinification. The major constituents that contributed to the volatile composition in this wine were the higher alcohols, ethyl esters, acetates, fatty acids and volatile phenols. In terms of floral and fruity odours, the best results were obtained for the wines inoculated with IOC 2007, ALB and REIMS S. cer. bayanus strain.     

Yeast and bacterial modulation of wine aroma and flavour

Wine is a highly complex mixture of compounds which largely define its appearance, aroma, flavour and mouth‐feel properties. The compounds responsible for those attributes have been derived in turn from three major sources, viz. grapes, microbes and, when used, wood (most commonly, oak). The grape‐derived compounds provide varietal distinction in addition to giving wine its basic structure. Thus, the floral monoterpenes largely define Muscat‐related wines and the fruity volatile thiols define Sauvignon‐related wines; the grape acids and tannins, together with alcohol, contribute the palate and mouth‐feel properties. Yeast fermentation of sugars not only produces ethanol and carbon dioxide but a range of minor but sensorially important volatile metabolites which gives wine its vinous character. These volatile metabolites, which comprise esters, higher alcohols, carbonyls, volatile fatty acids and sulfur compounds, are derived from sugar and amino acid metabolism. The malolactic fermentation, when needed, not only provides deacidification, but can enhance the flavour profile. The aroma and flavour profile of wine is the result of an almost infinite number of variations in production, whether in the vineyard or the winery. In addition to the obvious, such as the grapes selected, the winemaker employs a variety of techniques and tools to produce wines with specific flavour profiles. One of these tools is the choice of microorganism to conduct fermentation. During alcoholic fermentation, the wine yeast Saccharomyces cerevisiae brings forth the major changes between grape must and wine: modifying aroma, flavour, mouth‐feel, colour and chemical complexity. The wine bacterium Oenococcus oeni adds its contribution to wines that undergo malolactic fermentation. Thus flavour‐active yeasts and bacterial strains can produce desirable sensory results by helping to extract compounds from the solids in grape must, by modifying grape‐derived molecules and by producing flavour‐active metabolites. This article reviews some of the most important flavour compounds found in wine, and their microbiological origin.     

Production of Dairy-Based,Natural Sulphur Flavor Concentrate by Yeast Fermentation

Production of sulphur flavor concentrate by yeast fermentation was investigated using dairy media (milk and cream) spiked with L-methionine. The yeasts studied included so-called dairy yeasts Candida kefyr, Kluyveromyces marxianus, Debaryomyces hansenii, Geotrichum candidum, and Yarrowia lipolytica as well as wine yeasts Saccharomyces cerevisiae and Saccharomyces bayanus. Methionol was produced as the predominant volatile sulphur flavor compound. Other volatile sulphur flavor compounds produced were dimethyl disulphide, S-methyl thioacetate, 3-methylthio-1-propanoic acid, methional, 3-methylthio-1-propene, and ethyl 3-methylthio-1-propanoate. In addition, numerous other volatile flavor compounds were produced, including ethanol, branched-chain alcohols, aromatic alcohol, ethyl esters, branched-chain esters, branched-chain fatty acids, and branched-chain aldehydes. The sensory attribute of a methionol sulphur flavor concentrate in cream is concentration-dependent, ranging from a savory-slight potato note to a strong potato-savory note to a cooked cheese-potato note.     

Production of Isoamyl Acetate from Sugar Beet Molasses by Williopsis saturnus var. saturnus

Three strains of Williopsis saturnus var. saturnus were employed for the production of natural isoamyl acetate (the character impact compound of banana flavour) using sugar beet molasses as the carbon source and batch cultivation at 25°C under anaerobic conditions. Of the three strains, strain HUT 7087 was the best producer of isoamyl acetate, producing 20.7 mg/L. Sugar beet molasses was deemed to be an acceptable carbon source for the production of this flavour compound.     

Influence of the fermentation yeast strain on the composition of wine spirits

Fifteen indigenous strains of Saccharomyces cerevisiae, differentiated by their genetic polymorphism, were compared in standard conditions for their respective ability to produce volatile compounds during the alcoholic fermentation of grape must. The results were processed using analysis of variance and of principal components. They exhibited significant differences between strains, in particular for the higher alcohols, fatty acid esters, acetates or acetaldehyde. On the basis of their analytical profile, five strains were selected and compared on the pilot scale. Overall, the pilot results confirmed laboratory findings. As the strain effect appears to be determinant on the aromatic composition of wine spirits, a programme of selection based on both intraspecific molecular characterisation and chromatographic analysis is carried out to obtain specific yeast strains for high-quality spirits.     

Influence of a Mixed Culture with Debaryomyces vanriji and Saccharomyces cerevisiae on the Volatiles of a Muscat Wine

ABSTRACT: :
A non- Saccharomyces yeast strain, Debaryomyces vanriji , isolated from grape berry flora was found to influence wine volatiles of the cv. Muscat of Frontignan when co-cultured with native or inoculated with a selected strain of Saccharomyces cerevisiae during fermentation. The concentrations of several volatiles were significantly different (p < 0.05) between the control and the 2 wines inoculated with D. vanriji. The latter were richer in fatty acids, esters, and terpenols. The increase in geraniol concentration in D. vanriji wines could be attributed to the hydrolysis of the corresponding glucosidic precursor by D. vanriji β-glucosidase. D. vanriji inoculated musts showed higher levels of β-glucosidase activity through fermentation compared to the control sample.     

Production of flavour-active methionol from methionine metabolism by yeasts in coconut cream

Yeasts Candida kefyr NCYC143, Candida utilis CUM, Kluyveromyces lactis KL71, Saccharomyces bayanus SB1, Saccharomyces cerevisiae EC1118, Saccharomyces chevalieri CCICC1028, Candida famata (previously Torulopsis candida) CCICC1041 and Williopsis saturnus var. saturnus CBS254 were screened for their ability to produce flavour-active methionol (3-methylthio-1-propanol) in coconut cream supplemented with l-methionine. The yeasts varied with their ability to produce methionol from methionine with Saccharomyces cerevisiae EC1118 producing the most, followed by Kluyveromyces lactis KL71. Little methionol was produced by the other yeasts. Methionol production by Kluyveromyces lactis KL71 was subjected to further studies under different conditions of initial pH (4.0-6.3), temperature (20-33 °C), l-methionine concentration (0.05-0.25%) and yeast extract concentration (0-0.50%); optimal conditions were established at pH 5.0, 33.0 °C, 0.15% l-methionine and 0.05% yeast extract. CharmAnalysis™ using SPME-GC-MS was conducted on the coconut cream ferment; methional (3-methylthio-1-propanal), methionol and 2-phenylethyl acetate were found to be the most potent aroma-active compounds. The product of coconut cream fermentation by Kluyveromyces lactis KL71 may be considered as a novel, plant-based, natural and complex flavoring bioingredient in food applications.     

Effect of autochthonous starter cultures on the volatile flavour compounds of Chinese traditional fermented fish (Suan yu)

Effect of autochthonous starter cultures on the volatile flavour compounds of Chinese traditional fermented fish was studied. Lactobacillus plantarum 120, Staphylococcus xylosus 135 and Saccharomyces cerevisiae 31, isolated from Suan yu, were selected as starter cultures. Volatiles were extracted by headspace solid‐phase microextraction (SPME) and analysed by gas chromatography–mass spectrometry technology (GC‐MS). Esters and alcohols were the main components of volatiles, accounting for over 50 percentage points in all samples. The highest content of esters (3034.54 μg kg^?1) was observed in S1 inoculated with L. plantarum 120, while the highest content of alcohols (2164.53 μg kg^?1) and ketones (379.98 μg kg^?1) was detected in S3 inoculated with S. cerevisiae 31. The content of acids and aldehydes was lower in inoculated samples. Principal component analysis revealed that the volatile composition was primarily influenced by the nature of the starter cultures. L. plantarum 120 and S. xylosus 135 could accelerate fermentation.