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Advisor(s)
Abstract(s)
Mead is a traditional drink, containing 8-18% (v/v) of ethanol, which results from the
alcoholic fermentation of diluted honey performed by yeasts. It has been reported that
mead fermentation is a time-consuming process, often taking several months to complete,
depending on the type of honey, yeast strain and honey-must’s composition. An important
objective of mead makers is to reduce the fermentation time without decreasing the quality
of the end product. It has been shown that significant time can be saved in the fermentation
process by increasing the pitching rate, i.e., the amount of suspended yeast cells added to a
batch fermenter. Therefore, the aim of this study was to determine the adequate inoculum size
of two commercial winemaking strains of Saccharomyces cerevisiae (Lalvin QA23 and Lalvin ICV
D47) for the optimisation of mead fermentation. Honey must was prepared according to the
recipe developed by our team, supplemented with potassium tartrate, pH adjusted to 3.7 with
malic acid and the nitrogen concentration adjusted to 267 mg/L with diammonium phosphate.
The appropriate amounts of inoculum were pitched into the honey-must to obtain five different
pitching rates. Several parameters were determined during the fermentation to evaluate the
effect of the inoculum size on yeast growth, fermentation profile and mead composition. Minor
differences between the two strains in respect to growth kinetics were detected. As expected
the increasing of the inoculum size resulted in significant increases in cell biomass and CFUs’
numbers but also decreased the yeast net growth. The time required to reach the same stage
of fermentation ranged from 24 to 96 hours depending on the inoculum size. In accordance to
the results obtained the strain ICV D47 appears to be more suitable for the production of high
quality meads, although the strain QA23 provided better fermentation profile. However, sugars
were not fully consumed and about 25 mg/L of assimilable nitrogen remained at the end of all
fermentations. This is the first study of the effect of inoculum size on the optimisation of mead
fermentation, however further research is needed to improve its quality.
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Citation
Pereira, Ana Paula; Ferreira, Alexandra Mendes; Estevinho, Leticia M.; Faia, Arlete Mendes (2012). Effects of high cell density fermentations on the optimisation of mead fermentation. In II International Symposium on Bee Products. Annual Meeting of IHC: book of abstracts. Bragança. ISBN 987-972-745-140-1
Publisher
Instituto Politécnico de Bragança