Submitted to: Cereal Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/13/2003
Publication Date: 1/13/2004
Citation: Klamczynski, A., Knuckles, B.E., Glenn, G.M. 2004. Puffing and jet-cooking affect solubility and molecular characteristics of barley a-glucans. Journal of Food Processing and Preservation. 28(6):433-441. Interpretive Summary: Consumption of food products containing dietary fiber such as Beta-glucan may lower blood cholesterol and provide other beneficial health effects. During thermal processing the molecular structure of Beta-glucan molecules may be altered and affect their physiological impact. This study showed that thermal processing decreased the molecular weight of Beta-glucans by 50-75% and increased the solubility of barley Beta-glucan by 35 to 60%. This information is valuable to food processors and may lead to the development of foods with increased nutritional value.
Technical Abstract: Foods containing barley or oats are often marketed as healthy because of the dietary fiber, (1-3) (1-4)-Beta-D-glucan. Processing conditions can affect the molecular structure of these dietary fibers, which in turn, affect quality and properties of the products. In this study, the effect of puffing and jet-cooking conditions on changes in the solubility and molecular weight (MW) of barley ß-glucans was investigated. Commercial barley flour was extruded and chopped into particles similar in size and shape to rice. The particles were puffed at 230C, 250C and 270C for 6, 8 and 10 sec in a commercial rice cake machine. Solubility and molecular weight were determined using water extracts (25C or 65C). The amount of Beta-glucan extracted in water at 25C increased from 41.1% in cakes puffed at 230C/ 6 sec to 69.7% in cakes puffed at 270oC/10 sec. The amount of Beta-glucan extracted in water at 65C increased from 63.6% in samples puffed at 230C/6 sec to 99.1% in samples puffed at 270C/10 sec. Molecular weight (MW) of Beta-glucans in unpuffed barley particles (8.20 x 10E5 mol) was reduced in cakes puffed at 230oC/6 sec (5.14 x 10E5 g/mol) and 270C/10 sec (2.84 x 105 g/mol). In jet-cooked flour, the MW of Beta-glucans ranged from 3.02 to 3.33 x 10E5 while solubility ranged from 50.1% to 92.8%.