Bioalcohol production from regional wastes

OROFINO, A.B.; SEOANE, I.T.; WAGNER, G.; SANZ SMACHETTI, M.E.; DURRUTY, I.

Buenos Aires

Congreso; WCCE11 - 11th world congress of chemical engineering; 2023

Asociación Argentina de Ingenieros Químicos

The production of bioethanol is gaining importance due to the reduction of this non-renewable resource. In addition to fuel, ethanol is a solvent, sanitizer and is used to obtain organic chemical products and derivatives. The present work proposes bioalcohol obtention from food industry residues, by-products of local production processes, of the region's potato [1, 2] and beer industry. It is proposed to hydrolyze starch-rich wastes from the potato industry, using enzymes present in the exhausted beer bagasse, and carry out the further fermentation with commercial yeasts. In a parametric study: (a) Several initial concentration of commercial potato starch were tested and the selected starch concentration was 50 gr / 50 gr of dry base malt. (b) Different enzyme sources were tested: bagasse obtained from a commercial brewery demonstrated to be able to hydrolyze commercial potato starch although bagasse obtained from base malt after lab maceration process (ph 5,2-5,4; 90 min @ 65 °C) showed better yield and allowed a better reproducibility. Control tests were performed using commercial enzymatic extract. (c) Different storage times were tested for both bagasses. For lab-made bagasse the yields were similar for fresh bagasse and up to 72 hs storage @5 °C. In the case of the commercial bagasse, its performance decreased significantly in 48 hs (storage @ 5 °C). In all the hydrolysis assays 3:1 water to dry malt ratio were used. The obtained hydrolyzate was separated from the solids, and sterilized. The fermentation stage was carried out by adding 0.1% w/v yeast, under mesophilic conditions (19 °C) at free pH, and without stirring until complete conversion (constant density). Four different yeasts were tested: Fermentis T-58 Safbrew, Alcotec 48 Pure Turbo Superjäst, Lalvin 71B wine yeast, and a brewery reused yeast cream. The percentage of alcohol obtained was monitored by densimetry and was calculated by mass balances. The bioalcohol production for all the tested yeasts fall in the interval 6.51 % ± 0.27 % alcohol. The control tests were conducted over glucose solutions of the same brix % than the hydrolysis product. In conclusion the present work shows the potential of obtaining bioalcohol by enzymatic hydrolysis of potato starch in presence of exhausted beer bagasse and further fermentation.