A simplified method for analyzing arabinoxylan in malting barley [Hordeum vulgare], and effects of arabinoxylan on malting quality
1999
Kodama, M. (Tochigi-ken. Agricultural Experiment Station, Utsunomiya (Japan)) | Ishikawa, N. | Ohtsuka, M. | Kashima, N.
There are reports that arabinoxylan in mailing barley increases wort viscosity and delays filtration, but there exists no single report which describes in detail the relationship between arabinoxylan content and other mailing qualities. Methods generally used for the analysis of arabinoxylan are liquid chromatography, gas chromatography and orcinol reaction method, but liquid chromatography and gas chromatography require a lot of time and labour. In this study, we intended to develop simplified method for quantification of arabinoxylan utilizing orcinol coloration, with a view to enabling simplified and multi-point analysis of arabinoxylan to be used for the selection. As a result, it was found that the best method for quantification of arabinoxylan is a method comprising the steps of extracting of arabinoxylan from 1g of barley flour for an hour with 30 mL of hot 5N hydrochloric acid at 95degrees C, putting 0.4 mL of extract in a test tube together with 1.4 mL of water, adding 5 mL of 0.1% ferric chloride/5N hydrochloric acid solution and 0.5 mL of 1% orcinol/100% ethanol solution for 30-minute reaction at 95 degrees C, and determining the quantity of arabinoxylan from the difference in absorbency between 660 nm and 590 nm by spectrophotometry. Analysis of typical types of mailing barley made by using this method indicated some differences in arabinoxylan contents among types (6.3%-7.4%). Moreover, as for the relationship between arabinoxylan content and mailing qualities, it became clear that the higher the arabinoxylan content the lower the malt extract content as a general trend
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