|BURTON, CHARLOTTE - Retired ARS Employee|
|Evans, Christopher - Chris|
Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/13/2020
Publication Date: 3/16/2020
Citation: Hu, G., Ellberg, S., Evans, C.P., Satterfield, K.L., Bockelman, H.E. 2020. Application of an orcinol-ferric chloride colorimetric assay in barley and wheat accessions for water-extractable and total arabinoxylan. Cereal Chemistry. 93. https://doi.org/10.1016/j.jcs.2020.102962.
Interpretive Summary: Arabinoxylan is a natural fiber in plant cell walls. Some of the arabinoxylan can be extracted with water and is therefore called ‘water extractable arabinoxylan’ (WEAX). WEAX is an important barley and wheat ingredient that affects characteristics such as baking and malting quality. WEAX also has a prebiotic health-benefit component. Therefore, it is necessary to develop a convenient and reliable method to measure WEAX and to investigate the variation in WEAX among wheat and barley germplasm lines. We modified the wheat grain WEAX measurement protocol for use in barley. A total of 205 barley and 282 wheat germplasm lines were evaluated for WEAX. The results of our study can be used to improve WEAX content in barley through further plant breeding and genetics work.
Technical Abstract: Arabinoxylan is an important hemicellulose potentially affecting wheat baking qualities, barley malt quality, and may impart prebiotic benefits. Water-extractable (WEAX) and total arabinoxylan (TOAX) were characterized in 204 wheat and barley accessions, respectively, using an orcinol-ferric chloride assay. WEAX measurement accuracy was optimum when glucose concentration was greater than 12-13 times pentose concentration. The modified method removed enough excess glucose spectral absorbance to make the corrected and uncorrected lines different, but still significantly correlated (p = 0.009, R = 0.94). Mean WEAX (expressed as percentage WEAX of TOAX) for the wheat accessions was 15.90%, ranging from 8.82% to 24.87%, and for barley accessions WEAX the mean was 7.10%, and ranged from 2.98% to 13.86%. Conclusions are 1) the assay is useful for a breeding program because of its semi-high throughput design for the simultaneous analysis of 16 (WEAX) to 40 (TOAX) barley lines or 24 (WEAX) to 40 (TOAX) wheat lines, 2) the trichromatic measurement reduces the impact of glucose, and 3) the broad range of WEAX measured showed that barley and wheat accessions vary in their extractable and unextractable components.