Fruit wine produced from cagaita (Eugenia dysenterica DC) by both free and immobilised yeast cell fermentation

The aims of this work were to elaborate a fruit wine from cagaita (Eugenia dysenterica DC) pulp and to compare the fermentations conducted with free and with Ca-alginate immobilised cells. Two strains of Saccharomyces cerevisiae (UFLA CA11 and CAT-1) were tested and four fermentation batches were performed, in triplicate, at 22 °C for 336 h: UFLA CA11 in free and immobilised cells and CAT-1in free and immobilised cells. Fermentation time and ethanol production were influenced by the yeast strain and by the cell status, with immobilised cells of UFLA CA11 and CAT-1 fermenting faster (4 days and 8 days, respectively) than UFLA CA11 and CAT-1 free cells (10 days and 12 days, respectively). Ethanol content (g/L) was slightly higher when the fermentation was conducted with free cells (94.63 and 94.94 for UFLA CA11 and CAT-1, respectively) than with immobilised cells (86.82 and 87.21 for UFLA CA11 and CAT-1, respectively). The beverage from CAT-1 free cells showed the highest concentration of higher alcohols (82,086.12 ??/L), whereas the lowest concentration (37,812.17 ??/L) was found in the beverage from immobilised UFLA CA11. The ethyl ester concentration ranged from 1511.42 ??/L (CAT-1 free cells) to 2836.34 ??/L (UFLA CA11 free cells). According to the sensory evaluation, the fruit wine acceptability was greater than 70% for colour, flavour and taste for all cagaita beverages.     

Acetic acid removal by Saccharomyces cerevisiae during fermentation in oenological conditions. Metabolic consequences

The commercial Saccharomyces cerevisiae strains used in champagne winemaking were tested for their ability to metabolise acetic acid during alcoholic fermentation. Fermentation tests were performed in conditions close to oenological ones using a Chardonnay grape juice supplemented with acetic acid. The amount of acetic acid metabolised by wine yeast increased with increasing initial acetic acid concentration and this elimination occurred during the second part of the exponential growth phase. When the initial acetic acid concentration exceeds 1 g/l, and whatever the yeast strain used, the concentration of acetic acid in the resulting wine cannot be reduced to an acceptable level according to the current legislation. Acetic acid removal modified yeast metabolism, since more acetaldehyde, less glycerol and less succinic acid were produced. Considering the reduction of the NADPH/NADP⁺ ratio following acetic acid consumption, we propose, as a new hypothesis, that acetic acid could modify yeast metabolism by reducing the activity of the NADP⁺ dependent aldehyde dehydrogenase Ald6p.     

Evaluation of different Saccharomyces cerevisiae strains on the profile of volatile compounds and polyphenols in cherry wines

Tart cherries of ‘Early Richmond’, widely grown in Shandong (China), were fermented with six different Saccharomyces cerevisiae strains (BM4×4, RA17, RC212, D254, D21 and GRE) to elucidate their influence on the production of volatiles and polyphenols. Acetic acid and 3-methylbutanol were found in the highest concentrations among all identified volatiles with all six yeast strains, followed by 2-methylpropanol and ethyl lactate. RA17 and GRE cherry wines were characterised by a higher amount of esters and acids. D254 wine contained a higher concentration of alcohols. With respect to polyphenols, five phenolic acids and four anthocyanins were identified among all tested samples, with chlorogenic and neochlorogenic acids, cyanidin 3-glucosylrutinoside and cyanidin 3-rutinoside being the major compounds. When using principal component analysis to classify the cherry wines according to the volatiles and polyphenols, they were divided into three groups: (1) RA17 and GRE, (2) RC212 and D254 and (3) BM4×4 and D21.     

Removing gluconic acid by using different treatments with a Schizosaccharomyces pombe mutant: Effect on fermentation byproducts

Three different treatments involving inoculation with Schizosaccharomyces pombe YGS-5 and Saccharomyces cerevisiae G1 strains were tested with a view to reducing the amount of gluconic acid in synthetic medium. The treatments involved (a) simultaneous inoculation with S. cerevisiae and S. pombe (SpSc); (b) depletion of gluconic acid with S. pombe and subsequent inoculation with S. cerevisiae following removal of S. pombe from the medium (Sp − Sp + Sc); and (c) as (b) but without removing S. pombe from the medium (Sp + Sc). The results thus obtained were compared with those for a control treatment involving fermentation with S. cerevisiae alone (Sc). The amounts of volatile compounds quantified in the fermented media were similar with the treatments where gluconic acid was previously depleted (viz.Sp − Sp + Sc and Sp + Sc). Amino acids were used in large amounts by S. pombe during removal of gluconic acid; this affected subsequent fermentation by S. cerevisiae and the formation of byproducts. Based on the gluconic acid uptake, fermentation kinetics, volatile composition and absence of off-flavours in the fermented media, both treatments (Sp − Sp + Sc and Sp + Sc) can be effectively used in winemaking processes to remove gluconic acid from must prior to fermentation.     

Effect of dilution rate and nutrients addition on the fermentative capability and synthesis of aromatic compounds of two indigenous strains of Saccharomyces cerevisiae in continuous cultures fed with Agave tequilana juice

Knowledge of physiological behavior of indigenous tequila yeast used in fermentation process is still limited. Yeasts have significant impact on the productivity fermentation process as well as the sensorial characteristics of the alcoholic beverage. For these reasons a better knowledge of the physiological and metabolic features of these yeasts is required. The effects of dilution rate, nitrogen and phosphorus source addition and micro-aeration on growth, fermentation and synthesis of volatile compounds of two native Saccharomyces cerevisiae strains, cultured in continuous fed with Agave tequilana juice were studied. For S1 and S2 strains, maximal concentrations of biomass, ethanol, consumed sugars, alcohols and esters were obtained at 0.04 h⁻¹. Those concentrations quickly decreased as D increased. For S. cerevisiae S1 cultures (at D = 0.08 h⁻¹) supplemented with ammonium phosphate (AP) from 1 to 4 g/L, concentrations of residual sugars decreased from 29.42 to 17.60 g/L and ethanol increased from 29.63 to 40.08 g/L, respectively. The S1 culture supplemented with AP was then micro-aerated from 0 to 0.02 vvm, improving all the kinetics parameters: biomass, ethanol and glycerol concentrations increased from 5.66, 40.08 and 3.11 g/L to 8.04, 45.91 and 4.88 g/L; residual sugars decreased from 17.67 g/L to 4.48 g/L; and rates of productions of biomass and ethanol, and consumption of sugars increased from 0.45, 3.21 and 7.33 g/L·h to 0.64, 3.67 and 8.38 g/L·h, respectively. Concentrations of volatile compounds were also influenced by the micro-aeration rate. Ester and alcohol concentrations were higher, in none aerated and in aerated cultures respectively.     

Aromatic series in sherry wines with gluconic acid subjected to different biological aging conditions by Saccharomyces cerevisiae var. capensis

Wines from healthy grapes supplemented with gluconic acid were subjected to biological aging under two experimental conditions. The first one was carried out under flor yeast velum as in the traditional biological aging and the second one under submerged cultures. The highest gluconic acid consumption was observed in aged wines in submerged cultures. Nine aromatic series were obtained by grouping the 48 volatile compounds quantified in wines. The aroma profile based on the aromatic series allows comparison of the changes due to the gluconic acid consumption and the changes due to the different aging conditions assayed. Only the herbaceous and fatty series showed diminished values of consequence of gluconic acid consumption. The fatty, herbaceous and roasty series show highest values, whereas the fruity, floral, solvent and medicinal series reached lower values in the submerged cultures assay. The application of the assay conditions to winemaking can reduce the gluconic acid concentration in wines obtained from rotten grapes.     

A novel alcoholic beverage developed from shiitake stipe extract and cane sugar with various Saccharomyces strains

The stipe of shiitake, a disposable byproduct in mushroom industry, was applied as a nitrogen source in alcoholic fermentation. Four yeast strains were screened by evaluating their fermentative efficiency and ethanol tolerance. The results showed that shiitake stipe extract could enable yeast cell proliferation and be sequent to good performance of sugar utilization and ethanol production, depended on strains. The ethanol production (mL/100 mL) of 13.7 ± 0.8, 14.1 ± 0.9, 11.9 ± 0.1 and 10.9 ± 0.3 was obtained from strains 20262, 22236, 21686 and 21992, respectively, at the end of fermentation. Ethanol tolerance of strain in term of glucose utilization rate was more consistent with the extent of ethanol production during fermentation than that of survival rate. Therefore, the evaluation of glucose utilization rate in external ethanol condition might help establish a simple and quick method to screen the strains capable of high ethanol production. The shiitake stipe alcoholic beverage would also provide comparable consumer acceptances with a commercial Taiwanese white wine.     

Changes in the Lipid Composition of Saccharomyces cerevisiae Race Capensis (G-1) During Alcoholic Fermentation and Flor Film Formation

The cellular lipid composition of one flor-forming strain of Saccharomyces cerevisiae during fermentation and the subsequent period of film formation with different oxygen levels was studied. Irrespective of fermentation conditions, only those yeasts which came into contact with oxygen after fermentation formed a flor film. After the fermentation, these yeasts entered an adaptation phase in which the percentage of oleic acid increased considerably at the expense of other long-chain fatty acids. Their phospholipid contents remained high, as well as the unsaturation index of their fatty acids and the ergosterol/phospholipids ratio was maintained below 1. These changes allowed an increased viability of yeasts in the wine of up to 80% and the acquisition of sufficient hydrophobicity and floatability to reach the surface and form flor film.     

Antithrombotic activity of fractions and components obtained from raspberry leaves (Rubus chingii)

The 70% ethanol fraction from an aqueous extract of raspberry leaves was shown to be the most antithrombotic fraction in in vitro and in vivo tests. The total flavonoids and phenolics in this fraction were 0.286 g/g and 0.518 g/g by colorimetry. Six compounds, including salicylic acid, kaempferol, quercetin, tiliroside, quercetin 3-O-β-d-glucopyranoside and kaempferol 3-O-β-d-glucopyranoside, were isolated from the active fraction. Among them, kaempferol, quercetin and tiliroside obviously delayed plasma recalcification time (PRT) in blood.     

Solid-state fermentation of red raspberry (Rubus ideaus L.) and arbutus berry (Arbutus unedo, L.) and characterization of their distillates

The aim of the present study was to obtain two distilled alcoholic beverages from red raspberry and arbutus berry by solid-state fermentation and subsequent distillation of the fermented fruits. The mean concentrations of ethanol and volatile substances in the distillates from red raspberry (41.3 and 200.1 g/hL aa) and arbutus berry (44.3 and 267.1 g/hL aa) were higher than the corresponding minimum limits (38.5 and 200 g/hL aa) fixed by the European Council (Regulation 110/2008) for fruit distillates. In addition, the mean concentrations of methanol in the two alcoholic beverages (113.9 g/hL aa in case of red raspberry, and 320.5 g/hL aa in case of arbutus berry) were much lower than the maximum levels of acceptability that the aforementioned regulation fixed for red raspberry (1200 g/hL aa) and arbutus berry (1000 g/hL aa) distillates. These results showed that both fruits can be used as fermentation substrates for producing two alcoholic beverages with high quality, which are safe for the consumers without any repercussion to their health from methanol concentrations.     

Effect of grape indigenous Saccharomyces cerevisiae strains on Montepulciano d'Abruzzo red wine quality

The growth of selected, indigenous Saccharomyces cerevisiae added as starters (SRS1, MS72 and RT73) was monitored during Montepulciano d'Abruzzo wine production. In all the fermentations the addition of the starter, caused a decrease of the non-Saccharomyces yeasts. When strains MS72 and RT73 were used as starters they were detected in the first phases of fermentations, while strain SRS1 competed successfully with native yeasts during all the process. Wines obtained by fermentation with the indigenous starters showed some different characteristics, according to the chemical and sensory analyses. This study highlighted that among selected starters with high fermentative capacity, some are able to dominate better than other natural wine yeast biota, whereas some strains can interact and survive besides native yeast populations during the fermentation. As a consequence, the dominance character can have a positive or negative effect on wine quality and has to be considered in the frame of yeast selection in order to improve or characterize traditional wines. Winemakers could choose among different degrees of yeast dominance to modulate the interaction among starter and native wine yeast population.     

Proteolytic activity of Saccharomyces cerevisiae strains associated with Italian dry-fermented sausages in a model system

Strains of Saccharomyces cerevisiae isolated from Italian salami were screened for proteolytic activity in a model system containing sarcoplasmic (SMS) or myofibrillar (MMS) proteins, at 20 °C for 14 days, to evaluate the possible influence on the proteolysis of fermented sausages.SDS-PAGE revealed that 14 of the most osmotolerant strains were responsible for the extensive hydrolysis of the main myofibrillar proteins, while only one strain was able to hydrolyze sarcoplasmic proteins. Free amino acids (FAA) accumulated during proteolysis were strain-dependent with different patterns from sarcoplasmic or myofibrillar protein fraction. In general, proteolysis lead Cys, Glu, Lys and Val as the most abundant FAA in the inoculated MMS samples. Volatile compound analysis, determined by SPME-GC-MS, evidenced 3-methyl butanol in MMS, and 2-methyl propanol and 3-methyl-1-butanol in SMS as major compounds. Our findings highlight that S. cerevisiae could influence the composition in amino acids and volatile compounds in fermented sausages, with a strain-dependent activity.     

Co-inoculation of different Saccharomyces cerevisiae strains and influence on volatile composition of wines

Wine is the result of the performance of different yeast strains throughout the fermentation in both spontaneous and inoculated processes. 22 Saccharomyces cerevisiae strains were characterized by microsatellite fingerprinting, selecting 6 of them to formulate S. cerevisiae mixed cultures. The aim of this study was to ascertain a potential benefit to use mixed cultures to improve wine quality. For this purpose yeasts behavior was studied during co-inoculated fermentations. Aromatic composition of the wines obtained was analyzed, and despite the fact that only one strain dominated at the end of the process, co-cultures released different concentrations of major volatile compounds than single strains, especially higher alcohols and acetaldehydes. Nevertheless, no significant differences were found in the type and quantity of the amino acids assimilated. This study demonstrates that the final wine composition may be modulated and enhanced by using suitable combinations of yeast strains.     

Multifactorial analysis of acetaldehyde kinetics during alcoholic fermentation by Saccharomyces cerevisiae

Acetaldehyde is the terminal electron acceptor in the alcoholic fermentation by Saccharomyces cerevisiae. Quantitatively the most important carbonyl by-product, it has relevance for ethanol production yields as well as product stabilization and toxicology. The aim of this study was to investigate the effect of various enological parameters on acetaldehyde kinetics during alcoholic fermentations. Two commercial yeast strains were tested in two grape musts and the pH, temperature, SO₂ and nutrient addition were varied. All incubations had uniform kinetics where acetaldehyde reached an initial peak value followed by partial reutilization. Peak acetaldehyde concentrations and residual concentrations after 15 days of fermentations ranged from 62 to 119 mg l^− 1 and 22 to 49 mg l^− 1, respectively. A positive linear relationship was found between peak and final acetaldehyde levels in Gewürztraminer, but not Sauvignon Blanc fermentations, where sluggish fermentations were observed. Several factors had a significant effect on peak and/or final acetaldehyde levels. SO₂ addition, grape cultivar and fermentation nutrition were important regulators of peak acetaldehyde production, while final acetaldehyde concentrations were correlated with SO₂ addition, grape cultivar and temperature. The results allowed to estimate the acetaldehyde increase caused by SO₂ addition to 366 ??g of acetaldehyde per mg of SO₂ added to the must. The course of the final fermentation phase was shown to determine acetaldehyde residues. Comparison of acetaldehyde and hexose kinetics revealed a possible relationship between the time of occurrence of peak acetaldehyde concentrations and the divergence of glucose and fructose degradation rates.     

Analysis of volatile composition of siriguela (Spondias purpurea L.) by solid phase microextraction (SPME)

In order to investigate the volatile composition of the siriguela fruit (Spondias purpurea L.), the pulp of the fresh fruit was submitted to solid phase microextracton (SPME) using different fibers, divinylbenzene-carboxen-polydimethylsiloxane (DVB/CAR/PDMS), carbowax-divinylbenzene (CW/DVB), carboxen-polydimethylsiloxane (CAR/PDMS) and polydimethylsiloxane (PDMS) fibers. DVB/CAR/PDMS showed to be the more efficient qualitative and semi-quantitatively fiber in trapping these compounds. It was made possible to identify ketones, alcohols, aldehydes, esters and terpenic hydrocarbons in the headspace. The major compounds identified were hexanal, trans-2-hexenal, 3-hexen-1-ol, 2-hexen-1-ol, ethyl acetate and hexyl acetate. To have a clear picture of the retention indices of these compounds a new protocol, in which the standard hydrocarbon mixture is submitted to SPME, was developed and successfully used.     

Oleic acid and ergosterol supplementation mitigates oxidative stress in wine strains of Saccharomyces cerevisiae

During fermentation of high-sugar-containing medium lacking lipid nutrients, wine yeasts undergo oxidative stress and oxidative damage to cell membranes and proteins. Considering that cell membranes are important stress sensors, and that under hypoxic conditions wine yeasts modulate cell membranes composition by incorporating lipids available in the growth medium, in the present work, the effects of lipid nutrition on wine yeast oxidative stress response were evaluated on two strains of Saccharomyces cerevisiae. Biomarkers of oxidative stress, oxidative damage and antioxidant response were evaluated together with viability and acetic acid production during fermentation of a synthetic must lacking lipid nutrients as compared to added oleic acid and ergosterol. The results show that the availability of lipid nutrients causes a significant reduction in the intracellular content of reactive oxygen species and in the oxidative damage to membranes and proteins, as indicated by flow cytometry of cells stained with dihydroethidum (DHE) and propidium iodide (PI) and by Western blot of protein carbonyls. Accordingly, lipid nutrients feeding results in the increase in cell viability and superoxide activity, and the reduction in trehalose accumulation, proteinase A activity and production of acetic acid. In summary, these results are compatible with the hypothesis that the supplementation of lipid nutrients mitigates oxidative stress and oxidative damage in wine strains of S. cerevisiae during growth under unfavourable conditions.     

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.