Kinetic modeling of brewery's spent grain autohydrolysis.

摘要

Isothermal autohydrolysis of brewers' spent grain, a by-product of brewing, was used for hemicellulose solubilization and production of xylooligosaccharides, non-digestible oligosaccharides that act as prebiotic substrates for bifidobacteria and have wide applications in functional foods. The concn. of residual hemicelluloses (made up of xylan and arabinan) and formation of reaction products were monitored with time in experiments carried out at temp. in the range 150-190degC using liquid-to-solid ratios of 8 and 10 g/g. To model the experimental findings on brewers' spent grain autohydrolysis, several kinetic models based on sequential pseudo-homogeneous 1st-order reactions were tested. Xylan and arabinan were assumed to yield oligosaccharides, monosaccharides (xylose or arabinose), furfural and other decomposition products in consecutive reaction steps. It is suggested that the models proposed provide a satisfactory interpretation of the hydrolytic conversion of xylan and arabinan. An additional model merging the 2 proposed models for xylan and arabinan degradation assuming that furfural was formed from both pentoses was developed and the results obtained are discussed. The dependence of the calculated kinetic coeff. on temp. was established using Arrhenius-type equations.