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Influence of Jet Cooking and pH on Extraction and Molecular Weight of β-Glucan and Arabinoxylan from Barley (Hordeum vulgare Prowashonupana)

¹Food Science and Technology Department, University of Nebraska-Lincoln, 252 Food Industry Complex, Lincoln, NE 68583. ²Plant Polymer Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, U.S. Department of Agriculture, 1815 N. University St., Peoria, IL 61604. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. ³Functional Foods Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, USDA, Peoria, IL 61604. ⁴Corresponding author: Phone: 309-681-6363. Fax: 309-681-6685. E-mail: George.Inglett@ars.usda.gov

Food processing conditions may affect the extractability and molecular weight of β-glucans and arabinoxylans in cereal products. This can dramatically affect the functional and physiological properties of the final products. Therefore, the purpose of this research was to explore the effects of jet cooking on the content, extractability, and molecular weights of these polymers in barley flour from a high β-glucan, waxy barley genotype, Prowashonupana. Barley flours were jet cooked without pH adjustment or after adjusting to pH 7, 9, or 11. Jet cooking without pH adjustment increased the extractability of β-glucans from 15.4 to 38.0% when extracted with water at 30°C. As pH during jet cooking increased, the extractability further increased to 63.5% at pH 11. Arabinoxylan extractability was only substantially affected when the pH of jet cooking was alkaline (extractability increased from 11.4 to 48.5% when jet cooked at pH 11). Jet cooking without pH adjustment resulted in slight increases in peak molecular weights for both polymers (β-glucan increased from 420,000 to 443,000; arabinoxylan increased from 119,000 to 125,000); higher pH values during jet cooking resulted in minor decrease in molecular weights.