Complementarity of the raw material composition of Very High Gravity (VHG) mashes as a method to improve efficiency of the alcoholic fermentation process

The aim of the research was to optimize the composition of the VHG (Very High Gravity) media by selecting the proportions of various plant materials, complementary in terms of the composition of substrates affecting the fermentation process and efficiency. The addition of 25, 33 and 50% of molasses in VHG mash resulted in higher ethanol concentration above 112 g L-1. The highest ethanol concentration of 129.96 +/- 0.58 g L-1 and high actual fermentation yield as compared to theoretical one of 90.47 +/- 0.40% was found for VHG mash made from all four plant materials used in the same proportions (25%). Raw spirit obtained by distillation of this medium was also characterized by the lowest content of acetaldehyde (332.8 8.3 mg L-1 EtOH) and esters (94.3 +/- 1.6 mg L-1 EtOH) in comparison with the spirit samples obtained from mash with a similar degree of attenuation. Addition of molasses to VHG mashes resulted also in lowering the concentration of higher alcohols in distillates to 3815 mg L-1 EtOH as compared to spirits obtained from substrates using starchy materials only. Use of only a complementary raw material composition ensuring that VHG mashes are rich in nutrients resulted in intensification of the alcoholic fermentation process.