Determining levels of water-extractable and water-unextractable arabinoxylan in commercial Swedish wheat flours by a high-throughput method

A high-throughput method for quantification of water extractable arabinoxylan (WE-AX) and water unextractable arabinoxylan (WU-AX) was adapted for and evaluated on 197 commercial Swedish wheat flours, collected continuously during harvest years 2018 and 2019. In the method, starch was hydrolysed by alpha-amylase and WE-AX was precipitated with 80% ethanol. AX residues were quantified by gas chromatography after acid hydrolysis. The method had a good repeatability (2.1% RSDr for total AX). Spring wheat flour had a higher WE-AX content (0.68%) and lower WU-AX content (1.19%) than winter wheat flour (0.56% and 1.31%). The variation of total AX content was high for winter wheat flour (1.5-2.2%), with no correlation to ash or protein content. Total AX content differed significantly both between harvest years and locations, indicating an impact from environment on AX composition. Overall, the method enabled high-throughput analysis of wheat flour and can be further used to study how endogenous AX impacts baking quality.

Automated summary

A high-throughput method was developed to quantify water extractable arabinoxylan (WE-AX) and water unextractable arabinoxylan (WU-AX). The method showed good repeatability and was used to evaluate 197 commercial Swedish wheat flours. Results indicated higher WE-AX content in spring wheat flour compared to winter wheat flour, while winter wheat flour had higher WU-AX content. Total AX content varied significantly between harvest years and locations, suggesting an environmental impact on AX composition. This method enables high-throughput analysis of wheat flour and can be used to study the impact of endogenous AX on baking quality.