| Title: | Aroma-active ester profile of ale beer produced under different fermentation and nutritional conditions |
| Author(s): | Hiralal L; Olaniran AO; Pillay B; |
| Address: | "Discipline of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal (Westville Campus), Private Bag X54001, Durban 4000, South Africa. Discipline of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal (Westville Campus), Private Bag X54001, Durban 4000, South Africa. Electronic address: olanirana@ukzn.ac.za" |
| DOI: | 10.1016/j.jbiosc.2013.06.002 |
| ISSN/ISBN: | 1347-4421 (Electronic) 1347-4421 (Linking) |
| Abstract: | "A broad range of aroma-active esters produced during fermentation are vital for the complex flavour of beer. This study assessed the influence of fermentation temperature, pH, and wort nutritional supplements on the production of yeast-derived ester compounds and the overall fermentation performance. The best fermentation performance was achieved when wort was supplemented with 0.75 g/l l-leucine resulting in highest reducing sugar and FAN (free amino nitrogen) utilization and ethanol production. At optimum fermentation pH of 5, 38.27% reducing sugars and 35.28% FAN was utilized resulting in 4.07% (v/v) ethanol. Wort supplemented with zinc sulphate (0.12 g/l) resulted in 5.01% ethanol (v/v) production and 54.32% reducing sugar utilization. Increase in fermentation temperature from 18 degrees C to room temperature (+/- 22.5 degrees C) resulted in 17.03% increased ethanol production and 14.42% and 62.82% increase in total acetate ester concentration and total ethyl ester concentration, respectively. Supplementation of worth with 0.12 g/l ZnSO4 resulted in 2.46-fold increase in both isoamyl acetate and ethyl decanoate concentration, while a 7.05-fold and 1.96-fold increase in the concentration of isoamyl acetate and ethyl decanoate, respectively was obtained upon 0.75 g/l l-leucine supplementation. Wort supplemented with l-leucine (0.75 g/l) yielded the highest beer foam head stability with a rating of 2.67, while highest yeast viability was achieved when wort was supplemented with 0.12 g/l zinc sulphate. Results from this study suggest that supplementing wort with essential nutrients required for yeast growth and optimizing the fermentation conditions could be an effective way of improving fermentation performance and controlling aroma-active esters in beer" |
| Keywords: | Beer/*analysis/microbiology Esters/analysis/*metabolism *Fermentation Flavoring Agents/*metabolism Hordeum/chemistry Leucine/chemistry *Odorants Saccharomyces cerevisiae/physiology Temperature Volatile Organic Compounds/*metabolism Zinc/chemistry Aroma-ac; |
| Notes: | "MedlineHiralal, Lettisha Olaniran, Ademola O Pillay, Balakrishna eng Research Support, Non-U.S. Gov't Japan 2013/07/13 J Biosci Bioeng. 2014 Jan; 117(1):57-64. doi: 10.1016/j.jbiosc.2013.06.002. Epub 2013 Jul 9" |
