Our study showed that sorghum and millet followed a similar pattern of changes when they were malted under similar conditions. When the malt from these cereals was mashed, both cereal types produced wide spectra of substrates (sugars and amino acids) that are required for yeast fermentation when malted at either lower or higher temperatures. At the germination temperatures of 20, 25, and 30 °C used in malting both cereal types, production of reducing sugars and that of free amino nitrogen (FAN) were similar. This is an important quality attribute for both cereals because it implies that variation in temperature during the malting of sorghum and millet, especially when malting temperature is difficult to control, and also reflecting temperature variations, experienced in different countries, will not have an adverse effect on the production and release of amino acids and sugars required by yeast during fermentation. Such consistency in the availability of yeast food (substrates) for metabolism during fermentation when sorghum and millet are malted at various temperatures is likely to reduce processing issues when their malts are used for brewing. Although sorghum has gained wide application in the brewing industry, and has been used extensively in brewing gluten-free beer on industrial scale, this is not the case with millet. The work described here provides novel information regarding the potential of millet for brewing. When both cereals were malted, the results obtained for millet in this study followed patterns similar to those of sorghum. This suggests that millet, in terms of sugars and amino acids, can play a role similar to that of sorghum in the brewing industry. This further suggests that millet, like sorghum, would be a good raw material for brewing gluten-free beer. Inclusion of millet as a brewing raw material will increase the availability of suitable materials (raw material sustainability) for use in the production of gluten-free beer, beverages, and other products. The availability of wider range of raw materials will not only help to reduce costs of beer production, but by extension, the benefit of reduced cost of production can be gained by consumers of gluten-free beer as the product would be cheaper and more widely available.

This study compared the use of three sensory and analytical techniques: Quantitative Descriptive Analysis (QDA), Napping, and Gas Chromatography-Mass Spectrometry (GC-MS) for the assessment of flavour in nine unmatured whisky spirits produced using different yeasts. Hierarchical Multiple Factor Analysis (HMFA) showed a similar pattern of sample discrimination (RV scores: 0.895–0.927) across the techniques: spirits were mostly separated by their Alcohol by Volume (ABV). Low ABV spirits tended to have heavier flavour characteristics (feinty, cereal, sour, oily, sulphury) than high ABV spirits, which were lighter in character (fruity, sweet, floral, solventy, soapy). QDA differentiated best between low ABV spirits and GC-MS between high ABV spirits, with Napping having the lowest resolution. QDA was time-consuming but provided quantitative flavour profiles of each spirit that could be readily compared. Napping, although quicker, gave an overview of the flavour differences of the spirits, while GC-MS provided semi-quantitative ratios of 96 flavour compounds for differentiating between spirits. Ester, arenes and certain alcohols were found in higher concentrations in high ABV spirits and other alcohols and aldehydes in low ABV spirits. The most comprehensive insights on spirit flavour differences produced by different yeast strains are obtained through the application of a combination of approaches.

This study examined the performance of rice and buckwheat when malted under various temperature conditions and for different lengths of time. The mashed malts produced from both rice and buckwheat contained a wide spectra of sugars and amino acids that are required for yeast fermentation, regardless of malting temperature. At the germination temperatures of 20, 25, and 30 °C used, production of reducing sugars and free amino nitrogen (FAN) followed similar patterns. This implies that temperature variations, experienced in different countries, will not have an adverse effect on the production and release of amino acids and sugars, required by yeast during fermentation, from these grains. Such consistency in the availability of yeast substrates is likely to reduce differences in processing when these malts are used for brewing. This study revealed that, while rice malt consistently produced more maltose than glucose, buckwheat malt gave several times more glucose than maltose, across all germination temperatures. Buckwheat malt also produced more soluble and free amino nitrogen than rice malt. Unlike sorghum, which has gained wide application in the brewing industry for the production of gluten-free beer, the use of rice and buckwheat is minimal. This study provides novel information regarding the potential of rice and buckwheat for brewing. Both followed similar patterns to sorghum, suggesting that they could play a similar role to sorghum in the brewing industry. Inclusion of rice and buckwheat as brewing raw materials will increase the availability of suitable materials for use in the production of gluten-free beer, potentially making it more sustainable, cheaper, and more widely available.

In Scotch malt whisky production, the use of copper for the construction of the pot stills for distillation is regarded as having an important effect on whisky aroma. During distillation in copper pot stills, the copper acts to reduce sulphury aromas in the resultant spirit by reducing the levels of sulphur compounds such as dimethyl trisulphide (DMTS). This work has shown that the copper is more effective in this role in some parts of the pot stills than others. This information can be used to help distillers maintain or, indeed, to alter new make spirit aroma. It was also noted that in addition to DMTS, other, as yet unidentified, compounds make a significant contribution to sulphury aromas, so future research efforts should focus on identifying such compounds.

Nondestructive phenolic compounds measurement and origin discrimination of peated barley malt using near-infrared hyperspectral imagery and machine learning. IEEE transactions on instrumentation and measurement [online], Early Access.

Peat is burned during malt kilning to provide flavor compounds in Scotch malt whisky. The aim of this work was to establish whether peats from different locations in Scotland are chemically distinct and could impart different flavors. Peat samples from four locations (Islay, Orkney, St. Fergus, and Tomintoul) were analyzed using Curie point pyrolysis in combination with gas chromatography-mass spectrometry (Py-GC-MS). Peat pyrolysates from Islay and St. Fergus were rich in lignin derivatives, while those from Orkney and Tomintoul had higher levels of carbohydrate derivatives. Also, Islay and Orkney peat pyrolysates were rich in nitrogen-containing compounds and aromatic hydrocarbons, respectively. The depth of peat extraction was found to have an additional effect on peat composition as the levels of carbohydrate derivatives reduced with increasing depth. Where peat is used in whisky production, the observed differences in peat composition could potentially impact flavor, an important consideration if the peat used for malt production is changed by either choice or necessity.

It is not known if peats derived from different areas of Scotland have distinctive chemical constituents that could impact on malt whisky in discernible organoleptic ways. Fourier transforminfrared (FT-IR) spectroscopy was used as a high throughput screening method to investigate discrimination of a large number of peat samples from six different geographical origins around Scotland. The data were analysed statistically (using principal component-discriminant function analysis) and the results showed a difference between peat samples from different geographical origins. Therefore, we have shown that FT-IR spectroscopy provides a quick and simple method for differentiating peat types.

Electrocoagulation, an electrochemical technique used to remove heavy metals from wastewaters, was explored in relation to its potential to remove copper from distillery waste streams. An initial laboratory-scale study demonstrated that copper in spent lees could be reduced by up to 95% using electrocoagulation. Copper could not be removed from caustic washwater, as passivation of the electrodes meant that no floc was formed. However, the washwaters could be treated if mixed with spent lees, with an 80% reduction in copper being obtained. The electrocoagulation system was scaled up and its performance evaluated in a trial at a large Scotch malt whisky distillery. Copper reductions of 88% were achieved at low power consumption (34 W h/m 3 ), while at 112 W h/m 3 residual copper levels were reduced by 96%. This trial was carried out at a flow rate of 1000 L/h, demonstrating that the technology could readily handle the volumes and flow rates required in practice. Both the capital and running costs of an electrocoagulation system are low, while the technique presents other advantages over the existing copper removal technologies currently in use in the distilled spirits sector.