Mead production

Despite the excellent properties of honey, mead production faces several problems, namely, delays and pouts fermentations, lack of product uniformity, and production of yeast off-flavors. Many factors might be related with these problems, such as honey variety, temperature, medium composition (vitamin and nitrogen content), fermentative yeast, and pH. Due to all these factors, mead production has decreased over the years. To overcome this situation, more research is needed to optimize the production of this beverage. 

This chapter presents a comprehensive review of previous research on mead production. It will focus on honey characterization and mead production. The first section covers honey composition and the way this affects honey properties, as well as important parameters that are indicators of honey quality. The second section discusses mead production, including fermentative microorganisms, fermentation conditions, and required postfermentation adjustments and maturation conditions. The final section focuses on the problems that must be surpassed and what the future holds for mead production. 

Mead is a traditional alcoholic beverage obtained by fermenting mead wort that contains 8-18% (v/v) ethanol. Its production has been known since ancient times. However, mead fermentation and maturation requires an extended period, often lasting several months to years. Mead still remains a relatively empirical and manual exercise, requiring large capacity vessels and the investment of considerable capital in terms of the raw material. In addition, the fermentation rate depends on several factors, such as honey variety, yeast strain, yeast nutrition, and pH. Due to the lack of scientific investigation, mead production has suffered in comparison with other alcoholic beverages and so more research is needed to optimize the production process. 

The present study presents a comprehensive review of the scientific and technical research on the mead production. It is divided in two sections ... 

II. Mead production—under this heading are discussed fermentative microorganisms, fermentation conditions, postfermentation adjustments, and maturation conditions. 

In conclusion, problems that must be surmounted relative to the future of mead production are discussed. 

Seven S. cerevisiae strains were characterized relative to their resistance to sulfur dioxide (since it is a desirable feature in the fermentative yeast strains), ethanol (where tolerance is an indispensable property due to the high concentrations reached by the end of fermentation (Carrasco et al., 2001)), and osmotic stress (due to the high osmotic potential of mead at the commencement of fermentation). Pereira (2008) and Pereira et al. (2009) verified that significant differences did not exist between the strains. S. cerevisiae strains isolated from honey were similar to commercial and reference strains—all appearing to be suitable for mead production. 

Due to the high sugar contents involved in the mead production, fermentation tends to be slow and requires a yeast strain as well as pH, temperature, and growth conditions that are optimal. 

Some studies on continuous mead production have been performed, involving S. cerevisiae immobilized in calcium alginate gels (Qureshi and Tamhane, 1985) or calcium pectate (Navratil et ah, 2001). In the first situation, alcohol production was stable within a pH range of 2.5-6.0, with an optimum at pH 5.5, and a temperature range of 18-30 °C, with a sharp increase at 35 °C (Qureshi and Tamhane, 1985). Mead production proceeded continuously for more than 3 months and experienced less... 

Aging is important in mead production, particularly in relation to the development of aroma compounds, particularly ethyl acetate. Aging usually lasts between 1 and 10 years. Nevertheless, caution is required as ethyl acetate is sometimes considered an off-flavor, with a solvent-like odor (Mendes-Ferreira et al., 2010). Roldan et al. (2011) has observed that ethyl acetate content is related to the acetic acid content—meads with higher volatile acidity had higher ethyl acetate values. 

However, for mead production to become profitable, it is necessary to decrease production time. A major concern in mead fermentation is the notoriously long period required to reach completion. Although fermentation rate depends on the honey variety and its characteristics, through proper selection of yeast strain and fermentation conditions, such as, mixing during fermentation, yeast nutrition, and pH s control, it may be possible to dramatically increase fermentation rate. 

In relation to yeast strain selection, few studies have been conducted on this subject. It will be necessary to find/isolate yeast strains more resistant to, and with better fermentation performance under the harsh conditions of mead production, such as high osmotic values and low nitrogen content. Breeding may be an option. 

Mendes-Ferreira, A., Cosme, F., Barbosa, C., Falco, V., Ines, A., and Mendes-Faia, A. (2010). Optimization of honey-must preparation ad alcoholic fermentation by Saccharomyces cerevisiae for mead production. Int. J. Food Microbiol. 144,193-198. 

Navratil, M., Sturdik, E., and Gemeiner, P. (2001). Batch and continuous mead production with pectate immobilised, ethanol-tolerant yeast. Biotechnol. Lett. 23, 977-982. 

Pereira, A. P., Dias, T., Andrade, J., Ramalhosa, E., and Estevinho, L. M. (2009). Mead production Selection and characterization assays of Saccharomyces cerevisiae strains. Food Chem. Toxicol. 47, 2057-2063. 

Qureshi, N. and Tamhane, D. V. (1986). Mead production by continuous series reactors using immobilized yeast cells. Appl. Microbiol. Biotechnol. 23, 438—439. 

---