High-cell-density fermentation of Saccharomyces cerevisiae for the optimisation of mead production

Abstract

a b s t r a c tMead is a traditional drink that contains 8%e18% (v/v) of ethanol, resulting from the alcoholic fermentation of diluted honey by yeasts. Mead fermentation is a time-consuming process and the quality of the final product is highly variable. Therefore, the present investigation had two main objectives: first, to determine the adequate inoculum size of two commercial wine-making strains of Saccharomyces cerevisiae for the optimisation of mead fermentation; and second, to determine if an increase in yeast pitching rates in batch fermentations altered the resulting aroma profiles. Minor differences were detected in the growth kinetics between the two strains at the lowest pitching rate. With increasing pitching rates net growth of the strain ICV D47 progressively decreased, whereas for the QA23 the increasing inoculum size had no influence on its net growth. The time required to reach the same stage of fermentation ranged from 24 to 96 h depending on the inoculum size. The final aroma composition was dependent on the yeast strain and inoculum size. Fourteen of the twenty-seven volatile compounds quantified could contribute to mead aroma and flavour because their concentrations rose above their respective thresholds. The formation of these compounds was particularly pronounced at low pitching rates, except in mead fermented by strain ICV D47, at 10 6 CFUs/mL. The esters isoamyl acetate, ethyl octanoate and ethyl hexanoate were the major powerful odourants found in the meads. The results obtained in this study demonstrate that yeast strain and inoculum size can favourably impact mead's flavour and aroma profiles.

Influence of Saccharomyces cerevisiae strain on the profile of volatile organic compounds of blossom honey mead

“…Similarly like in Mendes-Ferreira et al (2010), Šmogrovičová et al (2012), and Pereira et al (2013), the predominant ester in our mead samples was ethyl acetate in concentrations 2.4-and 4.6-times above its threshold concentration. Ethyl octanoate has a very low threshold concentration (5 µg/l), therefore even at a low concentration it can influence the bouquet of beverages (Pereira et al 2013). A statistically significant difference was determined in the content of octanoic acid between meads fermented by strains MM-R2 (2.16 mg/l) and FM-R-Fix1 (0.51 mg/l).…”

“…However, in mead fermented by the yeast strain MM-R2 of s. cerevisiae var. bayanus only Honey must dilution 1 : 4; reducing sugars t 0 = 282.4 g/l; total acids t 0 = 0.92 g/l; extract t 0 = 296.3 g/l; proteins t 0 = 154.2 mg/l, pH t 0 = 5.69; the data are mean values of triplicate samples; P < 0.001; same characters in the same column (*) correspond to statistically not significant difference (P > 0.05) Šmogrovičová et al (2012), but lower than those of Pereira et al (2013). Although the concentration of 1-propranol in mead fermented by the strain MM-R2 was much higher (121.47 mg/l), it was still under its threshold concentration (830 mg/l).…”

Comparative Assessment of Ecosystem and Biodiversity Conservation Measures in Indian Smart Cities: A City Biodiversity Index Approach

“…Utilization of CBI can motivate and provide incentives for municipalities to start making inventories and monitoring their programs on biodiversity. As per Pereira et al 2013, in recent days, integrating remote sensing data and in situ observations to monitor several essential biodiversity variables such as habitat structure and phenology would be realistic and effective.…”

“…Motivating the city municipalities to conduct more biodiversity surveys would also help to mainstream biodiversity in the planning process, as well as to help raising awareness about biodiversity. For example, it is possible today to integrate remote sensing data and in situ observations to monitor several essential biodiversity variables such as habitat structure and phenology [64].…”

Evaluación del proceso fermentativo en la producción de hidromieles monoflorales colombianas

“…En el producto se reconocen aún propiedades vigorizantes debido al residual de azúcares no fermentados y a la fracción de etanol presente en el cuerpo de la bebida; la presencia de antioxidantes confiere a las hidromieles un valor especial que las posiciona en el mercado de productosconvalorañadido (Ramalhosa, Gomes, Pereira, Dias, & Estevinho, 2011). El proceso convencional mediante el cual transcurre la fermentación, tarda varios meses en completarse y es necesario el uso de levadura como cultivos iniciadores (Pereira et al, 2013;Pereira et al, 2009). La producción de hidromieles en la actualidad representa una posible alternativa económica a los productores apícolas que tengan la intención de obtener nuevos productos con valor añadido.…”