Stability, across environments, of grain and alcohol yield, in soft wheat varieties grown for grain distilling or bioethanol production.

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.

Effect of environment and variety on the relationships of wheat grain physical and chemical characteristics with ethanol yield.

BACKGROUND: Following the Renewable Transport Fuel Obligation (RTFO), there is an increasing demand for wheat grain for liquid biofuel in the UK. In order to enhance productivity of the bioethanol industry, good quality wheat must be used. RESULTS: A total of 84 grain samples comprising 14 varieties collected from 11 sites in two harvest years were analysed for a range of grain quality parameters and ethanol yield (EY). The grain quality parameters studied were starch and protein concentration, specific weight, grain density, packing efficiency, thousand-grain weight (TGW), grain length, width, length/width ratio and hardness index. Regression analysis was used to establish the relationships between grain quality parameters and EY. Apart from grain length and density, all grain parameters had significant relationships with EY. In the order of importance, protein concentration, TGW, packing efficiency and specific weight showed good relationships with EY. All other parameters, including starch concentration, showed a poor correlation with EY. EY and the relationship with the grain parameters were affected more by environment than by variety. Some sites gave consistently higher EY than others. When site and variety were considered with TGW and protein, a good prediction of EY could be made (variance accounted for = 87%). CONCLUSION: Combining TGW and protein concentration could be a better indicator of EY than the current practice of specific weight and protein.

Relationships between disease control, green leaf duration, grain quality and the production of alcohol from winter wheat.

BACKGROUND: Since demand for distilling wheat is expected to increase rapidly as a result of the development of the bioethanol industry, efficient production will become of increasing importance. Achieving this will require an understanding of the agronomic factors that influence both grain yield and alcohol yield. Therefore five field experiments using the winter distilling wheat variety Glasgow were conducted over three seasons (2006-2007, 2007-2008 and 2008-2009) to study the relationships between foliar disease and alcohol yield. RESULTS: There was a significant relationship between alcohol yield and the severity of the disease septoria leaf blotch (Septoria tritici), which was present in the experiments from natural infection. Retention of green flag leaf area as affected by disease control following fungicide application was also shown to be important for achieving high alcohol yields. Measurements of grain quality showed that high thousand-grain weight and low grain protein concentration were significantly related to increased alcohol yield. CONCLUSION: The experiments showed the importance of disease management to protect alcohol yields in the distilling wheat crop. Fungicides that provide greater disease control and improved green leaf retention are likely to be beneficial to alcohol yield.

Proteomic analysis of a distilling strain of Saccharomyces cerevisiae during industrial grain fermentation.

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.