Fermentable sugar production throug acid hydrolysis of Beta vulgaris L.

Abstract

With the purpose of increasing the amount of sugars that benefit the yield of ethanol in fermentation, it was performed hydrolysis of Beta vulgaris L. with H₂SO₄. The following parameters were used to evaluate the degree of hydrolysis of substrate: stirring, acid concentration, mass, and temperature. The mass was tested in the range of 5 to 40 g and stirring from 100 to 250 rpm. The temperature and reaction time were evaluated in the range of 30 to 90 ºC and 2 to 6 h, respectively. The tested particle size was 0.5 mm and a reaction volume of 50 mL was used for all cases. The rate of 150 rpm had a better effect over hydrolysis. By comparison of means it was determined that concentrations higher than 0.5 N of H₂SO₄ showed no significant effect (p<0.05) on the release of total sugars. The highest yield of hydrolysis was obtained with 10 g of substrate in the reaction medium. The temperature of 90 ºC provided the highest hydrolysis and at 50 ºC the amount of total sugars was 3 g/L lower than that generated with 90 ºC. The best pretreatment conditions were: 40 ºC, 150 rpm and 10 g of substrate. The increase in the reaction time indicates that hemicellulose degradation occurs inside the matrix of substrate and that amorphous regions are generated, promoting cellulose availability.