Understanding yeast stress under conditions associated with very high gravity fermentations

Very High Gravity (VHG) fermentations of 20-25P are increasingly employed within fermentation industries to maximise process efficiency. However, it is known that the use of concentrated substrates (worts) can create issues leading to prolonged or incomplete fermentations, poor conversion of sugar to ethanol and, within the beverage industry, inappropriate flavour development. The cause of such effects is strongly linked to yeast health, with the majority of current industrial strains showing poor tolerance to such conditions. This is especially problematic within the brewing and biofuel industries where yeast cultures are often re-used a number of times prior to discard.
While it is accepted that 'VHG stress' includes a range of environmental pressures, little is known regarding the precise character and intensity of these individual stress factors or their effects on individual cell components. For the first time we aim to investigate the impact of VHG stress factors on cell physiology, including analysis of functionality change, cellular damage and the overall cellular response to mitigate negative impacts. It is anticipated that this research will lead to process improvements which have the potential to impact on yeast handling on a global scale.