PROSES PRODUKSI ETANOL OLEH SACCHAROMYCES CERIVISIAE DENGAN OPERASI KONTINYU PADA KONDISI VAKUM

Abstract

Fermentation is one of method for ethanol production. The problem which occurring in fermentation process is ethanol inhibition. The influences of ethanol inhibition are destruction of membrane stucture of the yeast cell and protein denaturation. Those effects makes the growth of microbes inhibited and decrease its productivity. Inhibition problem can be solved by removal ethanol from fermentation system continously. One of the way is perfom the fermentation by vacuum condition. In vacuum condition, boiling point of etanol will decrease, therefore some ethanol as fermentation product will be vaporized The aims of this research are to study the effects of operation pressure to ethanol and yeast cell productivities. The substrat used in this research was molasses with 50; 75; 100; 125; 150 gram/l of sugar concentrations. The operation pressure used were 10 and 0,49 atm. The experiment was started with pretreatment of molasses, cultivation of saccaromyces cereviseae, and starter production. Fermentation was carried out in continuous operation with flow rate of substrat is 62.5 ml/h into 3 litres fermentor which contains of mixed substrat and starter (10% v/v). The highest productivity of ethanol was 0,767 gram/l/h obtained at 125 gram/l in substrat concentration with 0,098 atm in pressure. This research shows that the raising of sugar concentration will increase productivity of ethanol and biomass. In addition, vacuum condition gives some influnces for the ethanol productivity. In vacuum condition, productivity curve of ethanol was more stable and growth of yeast was better.