4.1 The procedure, in brief, consists of solubilization of biomass using cold caustic extraction, an enzymatic removal of starch and yeast glucan followed by precipitation of hemicellulosic material, and acid hydrolysis of the residual carbohydrate pellet before measurement of glucose and galactose derived from cellulose and hemicellulose.

4.2 The starch removal procedure is identical to that employed in the NREL assay2 which was itself adapted from the Megazyme-published starch analysis procedure: RTS-NaOH, 2019.5^,6

4.3 The cellulosic pellet hydrolysis and monosaccharide measurements are identical to those described in the NREL laboratory analytical procedure “Determination of Structural Carbohydrates and Lignin in Biomass,” NREL/TP-5100-42618 and “Determination of Cellulosic Glucan Content in Starch Containing Feedstocks,” NREL/TP-2800-76724.7

4.4 This test method references Practices E1757 and E3181.

4.5 This test method is intended for use in the measurement of the fermentable portion of cellulosic content in pre- and post-fermentation corn biomass specifically for the apportionment of a percentage of the total ethanol produced in a fermentation as cellulosic.

1.1 This procedure can be used to quantify the cellulose/hemicellulose-derived glucan and galactan (CHDGG) content in corn biomass samples that also contain varying levels of starch-derived and yeast-derived glucan. The method has been shown to provide accurate values for samples with cellulose content up to 40 % w/w.3

1.2 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.