The brewing and distilling industries are of enormous economic importance to the UK. They have a major impact on farming because they use almost 2M tonnes of UK-grown barley (about one third of the crop, occupying one third of a million hectares of land) every year, they provide employment for tens of thousands of people, and their products are enjoyed not only in the UK but in many countries around the world. There is strong pressure on the industry to increase the efficiency with which barley grain is converted into beer and whisky. This is in part to maintain profitability, but also to reduce the production of waste and the amount of energy used in the conversion process.
The basic conversion process occurs in four main stages. First, during malting, the barley grains are soaked in water then allowed to start to germinate. Inside the germinating grain, enzymes are produced that can convert the starch stored in the grain to sugars. Second, during kilning, the grain is heated to dry it out so that germination stops. Third, the grain is milled then mixed with hot water. During this mashing process, the enzymes convert the starch to sugars. Finally, the sugar-containing liquid is drained off and yeast is added. The yeast converts the sugars to alcohol.
One of the major losses during the conversion of grain to beer and whisky occurs during malting. As soon as the enzymes are produced, they start to convert starch to sugars inside the seed, and the sugars fuel the growth of rootlets. Thus some of the starch store is lost before the mashing stage, reducing the potential yield of alcohol and resulting in the production of unwanted rootlets. This loss is between 5% and 10% of the starch. In the context of a market value of £20bn for the brewing industry alone, even a small reduction in the extent of starch loss during malting would have huge economic benefits.
Because of the economic importance of this malting loss, several different methods to prevent rootlet growth have been tested. However these have not been applied commercially, because of cost, toxicity, or adverse effects on the quality of the malt.
We (Alison Smith, JIC) have discovered that both rootlet growth and starch loss in germinating barley seeds can be reduced or prevented by the application of tiny amounts of natural plant products, called iminosugars. These products have the potential to reduce malting losses without undesirable side effects. Understanding how they work inside the seed will also provide new information that will help in developing better varieties of barley for brewing and distilling. In this project we tested many different natural products in a “micromalting” system that mimics real malting, to identify which ones were suitable for commercial trials. We used biochemical and molecular methods to discover precisely how these products prevent the growth of rootlets, and the loss of starch. This information helped us to identify genes in barley that are important in determining the malting quality of the grain.
At JHI, to translate the research and meet the needs of the brewing and distilling industries, we conducted an extensive series of field trials of barley cultivars, micromalted the harvested grain and subjected the malts to various analyses (see figure) that allowed us to identify how well each cultivar responded to a standard malting regime. We then submitted this data to a type of genetic analysis called genome wide association mapping (GWAS) to see if the location of genes that were important in malting from this approach converged upon the same genomic locations that contained the targets of the malt inhibitors discovered in the other components of the project.
For further information on this project please contact Robbie Waugh (email@example.com) from the James Hutton Institute.