Evelyn de Souza Oliveira

Use of selected indigenous Saccharomyces cerevisiae strains for the production of the traditional cachaça in Brazil

Aims:  To test indigenous Saccharomyces cerevisiae as starters to produce cachaça in large‐scale in a traditional distillery, establishing the period in which, each strain predominates in the vats, chemical composition and sensory attributes of the beverage, and to compare these data with vats prepared by spontaneous fermentation.

Selection, growth, and chemo-sensory evaluation of flocculent starter culture strains of Saccharomyces cerevisiae in the large-scale production of traditional Brazilian cachaça

The physiological and kinetic capabilities of 233 Saccharomyces cerevisiae isolates, originating from traditional Brazilian cachaça fermentation, were evaluated under laboratory conditions to select flocculent and non-H2S producing strains to be employed in beverage production. Three flocculent S. cerevisiae strains were selected, two non-H2S producing and one H2S producing, and their kinetic performances were analysed during two large-scale fermentation experiments in a traditional cachaça distillery. One non-flocculent H2S-producing S. cerevisiae strain was also used for comparison with the flocculent strains. The results of mitochondrial DNA restriction analysis showed that the three flocculent starter S. cerevisiae strains, as well as the non-flocculent strain, remained in the process during the whole fermentation period, with cells numbering around 10(7) cfu/ml. All selected strains produced ethanol yields that were typically higher in the distillery than in the laboratory conditions, except for strain UFMGA-1240. The greatest diversity of non-Saccharomyces yeasts was observed prior to day 21 of cachaça fermentation; Pichia membranifaciens and Hanseniaspora guilliermondii were the most frequently isolated species. These yeasts were present in lower densities throughout the whole process. The cachaça produced by the selected strains contained concentrations of chemical compounds in accordance with current Brazilian legislation, and all cachaças scored well in sensory effective tests. In addition to the advantage of being flocculent, the strain UFMGA-1031 is non-H2S producing and also produces cachaça with good sensory acceptance. Therefore, this flocculent and non-H2S producing S. cerevisiae strain is highly suitable as a starter for production of high quality traditional cachaça.

Identification of aroma-active volatiles in banana Terra spirit using multidimensional gas chromatography with simultaneous mass spectrometry and olfactometry detection☆

Fruit spirits have been produced and consumed throughout the world for centuries. However, the aroma composition of banana spirits is still poorly characterised. We have investigated the aroma-impact compounds of the banana Terra spirit for the first time, using multidimensional gas chromatography (MDGC and GC × GC) in a multi-hyphenated system - i.e., coupled to flame ionisation detection (FID), mass spectrometry (MS), and olfactometry (O). Solid-phase microextraction (SPME) was used to isolate the headspace aroma compounds of the banana spirit. The detection frequency (DF) technique was applied and aroma regions, detected in the first column separation at >60% Nasal Impact Frequency (NIF), were screened as target potent odour regions in the sample. Using a polar/non-polar phase column set, the potent odour regions were further subjected to MDGC separation with simultaneous O and MS detection for correlation of the aroma perception with MS data for individual resolved aroma-impact compounds. GC-O analysis enabled 18 aroma-impact regions to be located as providing volatiles of interest for further study; for example, those comprising perceptions of flower, whisky, green, amongst others. Compounds were tentatively identified through MS data matching and retention indices in both first and second dimensions. The principal volatile compounds identified in this work, which are responsible for the characteristic aroma of the banana spirit, are 3-methylbutan-1-ol, 3-methylbutan-1-ol acetate, 2-phenylethyl acetate and phenylethyl alcohol. This is the first such study to reveal the major aroma compounds that contribute to banana spirit aroma.

Addition of proteic nitrogen during alcoholic fermentation for the production of cachaça

Cachaca is the denomination of a typical and exclusive Brazilian spirit produced from the distillation of fermented sugarcane juice must. The objective of this study was to evaluate the effect of adding yeast extract to the sugarcane juice used for sugarcane liquor production, because for the artisanal process no studies are available on nitrogen addition nor beverage quality, involving nitrogen complementation. Results of previous studies in the laboratory scale showed that sugarcane juice complementation with proteic nitrogen can be a beneficial practice for yeast multiplication and cellular growth, and also for the improvement of fermentation yield and liquor productivity. In this pilot scale study, using recycled yeast, the addition of proteic nitrogen influenced positively the cell viability, confirmed the yeast recycling operation, and also reduced the fermentation time. The proteic nitrogen addition did not affect the sensory acceptance of the distillate, and did not change the contents of volatile compounds, indicating that assimilable forms of proteic nitrogen can be helpfull to improve the alcoholic fermentation for cachaca production.

Saccharomyces cerevisiae and non-Saccharomyces yeasts in grape varieties of the São Francisco Valley

The aims of this work was to characterise indigenous Saccharomyces cerevisiae strains in the naturally fermented juice of grape varieties Cabernet Sauvignon, Grenache, Tempranillo, Sauvignon Blanc and Verdejo used in the São Francisco River Valley, northeastern Brazil. In this study, 155 S. cerevisiae and 60 non-Saccharomyces yeasts were isolated and identified using physiological tests and sequencing of the D1/D2 domains of the large subunit of the rRNA gene. Among the non-Saccharomyces species, Rhodotorula mucilaginosa was the most common species, followed by Pichia kudriavzevii, Candida parapsilosis, Meyerozyma guilliermondii, Wickerhamomyces anomalus, Kloeckera apis, P. manshurica, C. orthopsilosis and C. zemplinina. The population counts of these yeasts ranged among 1.0 to 19 × 105 cfu/mL. A total of 155 isolates of S. cerevisiae were compared by mitochondrial DNA restriction analysis, and five molecular mitochondrial DNA restriction profiles were detected. Indigenous strains of S. cerevisiae isolated from grapes of the São Francisco Valley can be further tested as potential starters for wine production.

Increase in yeast biomass production in batch and semi-continuous aerated propagators in the production of sugarcane spirit

Tradicionalmente, a propagacao de leveduras e feita diretamente dentro das dornas de fermentacao nas fabricas de cachaca de alambique. Contudo, estas nao dispoem de quaisquer dispositivos que permitam otimizar a propagacao, na qual a eficiencia da aeracao e fator primordial para a predominância do metabolismo respiratorio, que permite maximizar a reproducao das celulas e minimizar a formacao de etanol. Neste trabalho, avaliou-se o crescimento de leveduras Saccharomyces cerevisiae em um equipamento dotado de sistema de aeracao pelo processo de batelada simples (descontinuo) e pelo processo semicontinuo, utilizando-se um meio complexo ou um meio agroindustrial. O uso do equipamento com aeracao permitiu maior conversao de substrato em celula e reduziu o nivel de etanol e acidez produzidos. A propagacao realizada pelo processo semicontinuo foi mais eficiente do que o de batelada simples. A utilizacao de um meio agroindustrial suplementado com uma fonte proteica, tal como geralmente e realizado na propagacao de leveduras para producao de cachaca de alambique, forneceu maiores aumentos de biomassa e melhores parâmetros de propagacao, quando comparado com um meio complexo. Estes resultados contribuirao para o desenvolvimento de um protocolo operacional de propagacao de fermento a ser utilizado para producao de cachaca de alambique.

Spencermartinsiella silvicola sp. nov., a yeast species isolated from rotting wood.

Three strains of a new xylanase-producing yeast species were isolated from rotting wood samples collected in the Atlantic Rain Forest of Brazil. The sequences of the internal transcribed spacer region and D1/D2 domains of the large subunit of the rRNA gene showed that this novel yeast species belongs to the genus Spencermartinsiella, and its closest relatives among recognized species are Spencermartinsiella europaea and Spencermartinsiella ligniputridi. A novel species, named Spencermartinsiella silvicola sp. nov., is proposed to accommodate these isolates. The type strain is UFMG-CM-Y274T ( = CBS 13490T). The MycoBank number is MB 813053. In addition, Candida cellulosicola is reassigned to the genus Spencermartinsiella as a new combination.

Assessment of volatile organic compounds from banana Terra subjected to different alcoholic fermentation processes

Banana characteristics could provide yeast growth and support the action of yeast to produce beverages. The effects of enzymatic treatment, centrifugation, commercial yeast and two selected strains of Saccharomyces cerevisiae were investigated using the fermented banana Terra. Volatile organic compounds (VOCs) were determined by solid phase microextraction using gas chromatography mass spectrometry. The results showed that the condition employing enzymatic treatment, centrifugation and wet commercial yeast provided maximum ethanol yield (86%) and effiency (98%). Twenty-two compounds of distinct chemical classes were analysed including alcohols, esters, acids and aldehydes. The concentrations of the VOCs differed depending on the fermentation condition and were more influenced by using different yeasts. The limits of detection and quantification ranged from 0.056 to 2.694 mg L–1 and 0.057 to 2.904 mg L–1 respectively. Among the most prevalent VOCs the higher alcohols ranged from 353 to 1017 mg per 100 mL of anhydrous alcohol. The fermented banana studied showed a composition similar to other fermented fruit pulps.

Selection of starter cultures for the production of sour cassava starch in a pilot-scale fermentation process

Sour cassava starch (Polvilho azedo) is obtained from a spontaneous fermentation conducted by microorganisms from raw materials and fermentation tanks. This product is traditionally used in the baking industry for the manufacture of biscuits and Brazilian cheese breads. However, the end of fermentation is evaluated empirically, and the process occurs without standardization, which results in products of inconsistent quality. Predominant microbiota from a cassava flour manufacturer was isolated in order to select starter cultures for the production of sour cassava starch in a pilot-scale fermentation process. Lactic acid bacteria and yeasts were isolated, enumerated and grouped by Restriction Fragment Length Polymorphism, and PCR fingerprinting, respectively. One isolate of each molecular profile was identified by sequencing of the rRNA gene. LAB were prevalent throughout the entire process. Lactobacillus brevis (21.5%), which produced the highest values of acidity, and Lactobacillus plantarum (13.9%) were among the most frequent species. Pichia scutulata (52.2%) was the prevalent yeast and showed amylolytic activity. The aforementioned species were tested as single and mixed starter cultures in a pilot-scale fermentation process for 28 days. L. plantarum exhibited better performance as a starter culture, which suggests its potential for the production of sour cassava starch.