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Scotch whisky fermentations typically employ high-gravity fermentation practices to maximize product formation and to minimize both energy and water inputs. This approach increases ethanol concentrations at the end of fermentation, creating stressful conditions for the yeast. In this work we examined the relative tolerance of four Saccharomyces cerevisiae distilling yeast strains, supplied in dried, creamed, cake or slurry format, to ethanol under CO2-induced anaerobic conditions. The cells were assessed for their capacity to recover and grow on inhibition spot plates and to maintain cell viability in ethanol-dosed suspensions. Variations in ethanol tolerance were observed between strains and between the same strain supplied in different formats. The creamed yeast format typically exhibited a higher tolerance to ethanol. One possible explanation for this observation is that cells surviving the dehydration and rehydration process might incur sub-lethal genome damage. Thus the genetic integrity of the most ethanol-tolerant strain was assessed as a function of supply format (two dried and one creamed). The mitochondrial DNA was examined using mitochondrial restriction fragment length polymorphism and the chromosomal DNA using pulsed field gel electrophoresis and polymerase chain reaction with both ITS and delta-specific primers. In one dried yeast sample, genetic integrity was compromised, highlighting the requirement for yeast intake quality assurance programmes. Copyright © 2012 The Institute of Brewing & Distilling [ABSTRACT FROM AUTHOR]

The malting performance of two different batches of Oxbridge barley was studied. The study showed that a single 24 h continuous laboratory steep was suitable for steeping the two batches of Oxbridge to provide good quality malt. Although each batch represented the same variety, and was of similar malting quality, they behaved differently in terms of friability scores, filtration rate and predicted spirit yield (PSY) by day 4 of the germination period. Worts prepared from the two malts gave different patterns of filtration rates, showing that each batch of Oxbridge modified at a different rate and in a different way, although they achieved similar final PSY results at the end of the malting period. The two batches of Oxbridge both malted rapidly, but behaved differently in terms of modification pattern, as revealed by the Rapid Visco-Analysis peak viscosities, as well visual germination results. The results of this study confirmed that, given the same malting conditions, batch 1 germinated more rapidly than batch 2, and supports the view that Oxbridge shows some inconsistency as a malting barley variety. The study further showed that the PSY result per se is not necessarily a good indicator of optimum modification of finished malted barley. This study showed that, while a particular barley variety, such as Oxbridge, may be associated with certain qualities and can produce good quality malt when a short steeping cycle is used, other factors are likely to cause batch-to-batch variations from the same barley variety. While the short steeping cycle was very successful in producing high-quality laboratory malt from Oxbridge, and results in a significant reduction of the quantity of water required for steeping, reduces malting time and also saves costs, there is evidence that there may be some additional variability associated with Oxbridge malting barley. Copyright © 2012 The Institute of Brewing & Distilling [ABSTRACT FROM AUTHOR]

The fermentation performance of industrial yeast strains is influenced, among other things, by their genetic composition and the nature of the fermentable sugar, availability of nitrogen, and temperature. Therefore, to manipulate the fermentation process, it is important to understand, at a molecular level, the changes occurring in the yeast cell throughout industrial fermentation processes. With this aim in mind, using two-dimensional gel electrophoresis and matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF MS), we have examined the proteome of distillers yeast in an industrial context. Using yeast sampled from a local grain whisky distillery, we have prepared a detailed reference map of the proteome of distillers yeast and have examined in some detail the alterations in protein levels that occur throughout fermentation. In particular, as fermentation progresses, there is a significant increase in the levels of a variety of proteins involved in protecting against stress and nitrogen limitation. These results therefore give an insight into the stresses that yeast are exposed to in industrial fermentations and reveal some of the proteins and enzymes that are either necessary or important for efficient fermentation. [ABSTRACT FROM AUTHOR]

The key to optimizing alcohol production from cereals is a full understanding of the physiology and processing characteristics of different cereals. This study examined the maximum alcohol yields that can be obtained from wheat and maize using different processing technologies. Lower processing temperatures (85°C) resulted in high alcohol yields from wheat (a temperate crop), whereas higher processing temperatures (142°C) gave maximum alcohol yields from maize (a tropical crop). Similar trends were also observed when the spent grains from these cereals were processed using commercial enzymes. Mill settings were additional factors in influencing alcohol production. Wheat has the potential to produce higher alcohol yields when compared with maize, when residual biomass (i.e. spent grains) saccharification using selected commercial enzymes is taken into account. While this approach is not applicable for the Scotch whisky industry owing to strict legislation forbidding the use of exogenous enzymes, this is pertinent for bioethanol production to increase the alcohol yield obtained from both starch and lignocellulosic components of whole cereal grains. Wheat and maize processing temperatures and the use of processing aids are of potential economic benefit to bioethanol producers and to beverage alcohol producers seeking to understand the factors influencing the processing properties of different cereals. Copyright © 2015 The Institute of Brewing & Distilling [ABSTRACT FROM AUTHOR]

BACKGROUND Soft-milling wheat has potential use for both grain whisky distilling and bioethanol production. Varietal comparisons over wide-ranging environments would permit assessment of both grain and alcohol yield potential and also permit the stability across environments, for these parameters, to be compared. RESULTS For 12 varieties, analysis of variance showed highly significant effects of variety, site, season and fertiliser application on grain and alcohol yield. There were also significant interactions between these factors and, consequently, varieties varied in stability across environments as well as in mean values for the parameters assessed. Alcohol production per hectare was affected more strongly by variation in grain yield than alcohol yield, but increasing grain protein content reduced alcohol yield and, therefore, utility for grain distilling. CONCLUSION To maximise energy production, the best varieties for bioethanol would combine high and stable grain yield with slower reduction of alcohol yield as grain protein increases. For grain distilling, where the energy balance is less important, high alcohol yield will remain the key factor. Data derived using near infrared spectroscopy can be valuable in assessing stability of quality traits across environments. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Abstract: The effects of nitrogen (N) fertiliser on grain size and shape, starch and protein concentration, vitreosity, storage protein composition, and alcohol yield of two winter wheat varieties contrasting in endosperm texture were studied in a field trial in Herefordshire, UK in 2004. Averaged across varieties, the alcohol yield was 439L/tonne for grain with a protein concentration of 11.5g/100g. The soft endosperm wheat variety Riband produced on average 7.7L more alcohol per tonne of grain at a given protein concentration than the hard endosperm variety, Option. At the same time, N fertiliser was shown to have significant effects on alcohol production through its major influence on grain protein concentration. Averaged over both varieties, there was a reduction in alcohol yield of 5.7L for each 10kg increase in protein content per tonne of grain. The starch concentration of Riband was 2.9g/100g higher than Option at a given grain protein concentration, supporting its higher observed alcohol yields. A low conversion of starch to alcohol in this study (6.30L/10kg starch) compared to the theoretical value (6.61L/10kg starch) indicated that there is potential for improvement of this character. The traits relating to grain size and shape were principally influenced by genotype, and were not influenced by N fertiliser. Conversely, there were only minor genotypic effects on grain protein concentration and vitreosity. An important finding was that there were no interactions between variety and N treatment for any of the variables considered, indicating that the response of the two varieties to changes in applied N was the same, resulting in consistent differences in starch concentration and alcohol yield between genotypes at different levels of grain protein. An analysis of the composition of the wheat storage proteins by size-exclusion chromatography showed that the gliadins increased on average by 0.56g per g increase in total grain protein and were quantitatively the major protein fraction, suggesting that selection for low gliadin content may be a desirable means by which to reduce grain protein, and thereby increase alcohol yield in wheat. The relationship between alcohol yield per unit area and applied N rate was described by a quadratic function and the maximum alcohol yield per unit area was ca. 3630L/ha. Statistical analysis suggested that the economic optimum rate of N applied for grain yield was close to the optimum N rate for maximum alcohol productivity. [Copyright &y& Elsevier]