Location: Cereal Crops ResearchTitle: Extraction of beta-glucan from oats for soluble dietary fiber quality analysis Author
Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/16/2012
Publication Date: 9/1/2012
Citation: Doehlert, D.C., Simsek, S., Mcmullen, M.S. 2012. Extraction of beta-glucan from oats for soluble dietary fiber quality analysis. Cereal Chemistry. 89:230-236. Interpretive Summary: Oats contain a soluble fiber called ß-glucan that can reduce cholesterol levels in humans when oats are included in the diet. The solubility of the fiber is thought to be important to the health benefits of this fiber, yet very little systematic work has been done to determine factors that affect the solubility of ß-glucan. In this study, we have tested a wide range of physical conditions to determine the most effective means to determine ß-glucan solubility. We have found that many factors can affect the extraction of ß-glucan, but given enough time, a maximum amount of ß-glucan can be recovered under many different conditions. However, some ß-glucan usually remains not extractable. We have found that the growth environment of the oats appeared to have a strong effect on the potential extractability of ß-glucan in oat flour. The physical basis for this observed variability is not yet known.
Technical Abstract: BACKGROUND: We have tested extraction protocols for soluble ß-glucan in order to optimize conditions for production of ß-glucan solutions for quality evaluation. We applied varied extraction time, temperature, pH, flour/water ratio, number of re-extractions, hydrothermal treatments and tested genotypic and environmental variation. RESULTS: Many approaches provided good ß-glucan extraction. A serial extraction with 2 g of flour in 50 mL water with 5 mM NaN3 stirred at 40º C for 18 hr, centrifuged, and then repeated was best for most purposes. Many variations from this protocol are equally efficient. ß-Glucan yields from a single sample could vary from 300 to 530 g kg-1 oat flour and also contained abundant protein and carbohydrates including arabinose, xylose, mannose and galactose. Samples from replicated plots indicated no oat genotype effect on the extractability of ß-glucan, but an environmental effect was significant, where the extractable/total ß-glucan ratio varied from 0.63 to 1.0 among six growth environments. CONCLUSIONS: Extraction time, temperature, frequency, solvent concentration, flour source and hydrothermal treatments all affected ß-glucan solubility; many variations in conditions could provide excellent extraction. Growth environment of the grain appeared to have the most profound effect on extractability of ß-glucan.