Evaluation of the alkaline treatment on extraction of acetate, phenolic compounds and furans in brewer’s spent grain

In the present work, brewer’s spent grain (BSG) was submitted to alkaline treatment aiming to evaluate the solubilization profile of acetate, phenolic compounds and furans at temperature of 60 °C in different NaOH concentrations (from 0.25 to 2% w/v). The results showed that the solubilizing capacity of acetate, phenolic compounds and furans increased with increasing concentration of NaOH until 40 min, and the maximum concentration observed was 0.86 g/L, 13.0 g/L and 0.58 g/L from 1%, 2% NaOH and 2%, respectively. The treated BSG solids were then submitted to dilute acid hydrolysis (1.2% w/v H₂SO₄, 10% w/v consistency, 121°C for 27 minutes) to investigate the effects of alkaline treatment on hemicellulose hydrolyzate composition. For all evaluated conditions, the alkali treatment of BSG reduced the acetic acid concentration in hemicellulosic hydrolyzate, in which the lowest concentration (0.026 g/L) was obtained from BSG treated with 2% NaOH for 20 minutes. Regarding to xylose concentration, the lower content of this pentose (8.3 g/L) was obtained from BSG treated with 0.25% NaOH for 2 minutes and the highest (22.0 g/L) with 0.5 % NaOH for 60 minutes. Based on these results, it was concluded that all evaluated conditions of alkaline treatment of BSG promoted partial solubilization of acetyl groups, and hence reduced the concentration of acetic acid in hydrolyzate. Considering that acetic acid is one of the main inhibitors of microbial metabolism, this strategy might be helpful to improve the fermentability of BSG hemicellulose hydrolyzate.

 

Supported by FAPESP, CNPq and CAPES (BRAZIL)