Cereal Chem. 71:451-458 | VIEW
Functional Properties of Oat Starches and Relationships Among Functional and Structural Characteristics.
L. Z. Wang and P. J. White. Copyright 1994 by the American Association of Cereal Chemists, Inc.
The pasting, gel strength, and thermal properties of oat (Avena sativa L.) starches, isolated from three types of groats containing a range of lipid contents (6.2, 8.0, and 11.2%), were investigated. The relationships between these functional properties and structural characteristics were determined. Two corn (Zea mays L.) starches also were evaluated for comparison. The oat starches tended to have a higher pasting temperature and a lower peak viscosity (89.5-93 C and 155-210 BU, respectively) than did corn starches (83.6-86.8 C and 270-310 BU, respectively) as measured by the Brabender Viscoamylograph. The firmness, as measured by the Voland-Stevens texture analyzer, was less for oat than it was for corn starch gels and was negatively correlated with starch-lipid content during all storage periods. The stickiness was greater for oat than it was for corn starch gels at 5 hr of storage; it was the same for both starches during remaining storage. The stickiness was positively correlated with the starch-lipid content during all storage periods. Differential scanning calorimetry revealed that the oat starches had a lower gelatinization temperature (To) and a lower enthalpy ([Delta]H) value for transition of the starch crystallites than did the corn starches. This suggests less order in the crystalline structure of the former starches. The oat starches also had a higher (Delta)H value for the transition of the amylose-lipid complex and a lower percentage of retrogradation (%r) than did the corn starches, maybe because of a greater starch-lipid content in the former starches. Furthermore, the To of oat starches was positively correlated with amylose (r = 0.97) and starch-lipid (r = 0.92) contents (P less than 0.01), whereas %r was negatively correlated with amylopectin content (r = -0.84, P less than 0.01).