Optimization of bioethanol production from soybean molasses using different strains of Saccharomyces cerevisiae / Optimizacija proizvodnje bioetanola na sojinoj melasi primenom razlicitih sojeva kvasca Saccharomyces cerevisiae

Bioethanol technology represents an important scientific research area because of the high market value and wide availability of its primary and by-products. Worldwide interest in utilizing bioethanol as a renewable and sustainable energy source has significantly increased in the last few years due to limited reserves of fossil fuels and concerns about climate change. Therefore, improvement of the bioethanol production process is a priority research field at the international scale, due to both economic and environmental reasons. The aim of this study was to optimize production of bioethanol from soybean molasses based media using response surface methodology. Three different strains of the yeast Saccharomices cerevisiae, commercially available in dried form, were used as production microorganisms, and the best results were obtained by using dried baker's yeast. The results of optimization of alcoholic fermentation using dried baker's yeast indicate that the highest value of the overall desirability function (0.945) is obtained when the initial sugar content is 18.10 % (w/v) at the fermentation time of 48.00 h. At these conditions the model predicts that bioethanol concentration is 8.40 % (v/v), yeast cell number 2.21*[10.sup.8] cells/mL and the residual sugar content is 0.35 % (w/v). Keywords: bioethanol; Saccharomyces cerevisiae; soybean molasses; response surface methodology; desirability function Tehnologija bioetanola predstavlja znacajnu naucnu oblast zbog visoke trzisne vrednosti i siroke dostupnosti njenih glavnih i sporednih proizvoda. Interesovanje koje u svetu vlada za bioetanolom kao obnovljivim i odrzivim izvorom energije znacajno je poraslo u poslednjih nekoliko godina sto je posledica ogranicenih rezervi fosilnih goriva i zabrinutosti zbog klimatskih promena. Stoga je poboljsanje postupka proizvodnje bioetanola prioritetna oblast istrazivanja na medunarodnom niovu, kako iz ekonomskih tako i iz ekoloskih razloga. Cilj ovih istrazivanja je bio optimizacija proizvodnje bioetanola na medijumu cija je osnova sojina melasa primenom postupka odzivne povrsine. Tri razlicita soja kvasca Saccharomices cerevisiae, komercijalno dostupna u suvoj formi, su koriscena kao proizvodni mikroorganizmi, a najbolji rezultati dobijeni su primenom suvog pekarskog kvasca. Rezultati optimizacije alkoholne fermentacije primenom suvog pekarskog kvaca ukazuju da se najveca vrednost ukupne zeljene funkcije (0,945) dobija kada je pocetni sadrzaj secera u medijumu 18,10% (