“Solid state fermentation of sweet sorghum by Saccharomyces cerevisiae to bioethanol production” Karamousantas, D., Th. Varzakas (Technological Educational Institution of Kalamata – Hellas), D. Arapoglou, C. Israilides (Institute of Technology of Agricultural Products – Hellas)

BioFuel - Bioethanol Ethanol is attractive out of the many alternative energy sources because it can be widely used as an all around motor fuel.

Why Bioethanol? Politico-economic impact. Surplus value of raw material Increase of places of work and rural income Holding of rural population B. Environmental impact Renewable raw material (Biomass) Decrease of environmental pollution Reducing energy dependence

National target for Greece according the new E.U. Directive Share of energy from renewable sources in final consumption of energy (2005) Share Renewables in the final energy demand by 2020 6,9% 18%

Sweet Sorghum Sugar content 9.6 -20.3 per cent of raw whole stalks High content of soluble sugar and cellulose

S. cerevisiae Juice extraction Acidic Hydrolysis Whole stalks Sweet Sorghum Stalks Ethanol Production

Varieties Moisture % Extracted Juice (% v/w) Total Sugar of Juice % Moisture, extracted juice as per cent of whole fresh material and total sugar of juice, of 8 tested sweet sorghum varieties. Varieties Moisture % Extracted Juice (% v/w) Total Sugar of Juice % (g/v) No 1 86.32 45.85 11.35 No 2 69.20 46.60 12.54 No 3 88.08 55.33 12.96 No 4 69.90 52.63 14.70 No 5 74.26 55.36 8.89 No 6 69.95 47.15 13.56 No 7 70.66 42.64 8.93 H133 63.76 38.72 16.39

% of max theoretical yield Fermentation parameters of sweet sorghum juice with S. Cerevisiae var. Bayanus for ethanol production. Varieties Total Sugar Initial gL-1 Total Sugar Final Total Sugar Consumption (TSC) Ethanol ProducedgL-1 Ethanol Yield g EtOH / g TSC % of max theoretical yield No 1 18.923 1.084 17.839 5.295 0.297 59.36 No 2 20.893 1.690 19.203 8.143 0.424 84.81 No 3 21.596 1.707 19.889 7.288 0.366 73.29 No 4 24.500 1.601 22.899 8.739 0.382 76.33 No 5 14.821 0.850 13.971 5.627 0.403 80.55 No 6 22.604 2.246 20.358 7.180 0.353 70.54 No 7 14.881 1.276 13.605 4.611 0.339 67.79 H133 27.316 2.642 24.674 9.566 0.388 77.54

% of max theoretical yield Fermentation parameters of sweet sorghum stalk with S. Cerevisiae var. Bayanus for ethanol production. Varieties Total Sugar Entered gL-1 Total Sugar Final Total Sugar Consumption (TSC) gL-1 Ethanol gL-1 Ethanol Yield g EtOH / g TSC % of max theoretical yield No 1 28.267 1.388 26.879 8.925 0.332 66.41 No 2 30.973 1.850 29.124 12.215 0.419 83.88 No 3 24.236 1.476 22.760 10.632 0.467 93.43 No 4 30.932 1.701 29.230 13.109 0.448 89.69 No 5 26.432 1.928 24.504 9.405 0.384 76.76 No 6 30.273 2.051 28.222 10.770 0.382 76.32 No 7 29.894 1.364 28.530 8.565 0.300 60.04 H133 33.647 2.513 31.134 14.349 0.461 92.18

CONCLUSIONS The fermentation of extracted juice and hydrolyzed stalk from eight sweet sorghum varieties by Saccharomyces cerevisae var. bayanus for ethanol production was studied. There was great variation in ethanol production among different varieties. Ethanol production was in high levels in most of varieties. Whole stalks produced more ethanol than juice.