Use of corn cob through xylan extraction and its potential use as a substrate for the quantification of xylanase enzymatic activity

In Mexico, it is estimated that the amount of residues produced by the planting of the ten main crops is approximately 45 million tons of dry matter, of which just over 25 million tons are corn cob. The corn cob contains large amounts of hemicellulose, mainly composed of xylan, which can have various industrial uses. For this reason, in the present study, fresh and dry corn cob was used with two particle sizes: 0.105 mm and 0.42 mm, to carry out an exhaustive alkaline extraction of xylan and where eight fractions of hemicelluloses extracts were obtained. Each of the fractions were subjected to enzymatic hydrolysis for eight hours with a commercial xylanase (Livanol Devisco 1500) and as internal control, beechwood xylan (Sigma Aldrich, X4252) was used, of which only 6.9 ± 2.25 g/L were released. reducing sugars. It was found that the fractions from the steam treatment and the fraction from the alkaline extraction precipitated with alcohol, both for fresh corn cob, were released a quantity of reducing sugars very similar to commercial xylan with 7.10 ± 2.02 and 7.24 ± 0.37 g/L, respectively. Finally, it was possible to determine that although the 8 fractions obtained in the present study can be used as substrates to determine the xylanase enzymatic activity, the best was the fraction of the alkaline extraction since 0.236 ± 0.03 IU/mL were quantified, while for the commercial substrate (beechwood xylan) an activity of 0.287 ± 0.01 IU/mL was obtained.