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2012 AACC Annual Meeting

Podium Presentation

11-O

Composition and properties of pinto bean flour subjected to air classification and extrusion
C. SIMONS (1), C. Hall (1), M. Tulbek (2)
(1) North Dakota State University, Fargo, ND, U.S.A.; (2) Alliance Grain Traders, Regina, SK, Canada

Fractionation and extrusion can alter properties of bean flour. Pinto beans were milled and air classified in a commercial mill to obtain high starch flour (HSF), followed by extrusion of the HSF. Properties of HSF and its extrudate were compared to whole pinto flour (WPF). Expansion index and hardness of extrudates was 3.3 and 1949 g, respectively. Composition (d.b.) of WPF included 10% moisture, 4% ash, 1.64% extractable lipid (EL), 22% protein, 48.1% resistant starch (RS), 6.5% soluble starch (SS), and 46.4% total starch (TS). Significant differences in composition of HSF were observed in moisture (9.5%), ash (2.75%), EL (1.14%), protein (13.3%), RS (39.9%), SS (7.9%) and TS (56%). Extrudate composition was significantly different from WPF and HSF in moisture (7.4%), RS (0.0%), SS (55.7%) and EL (0.14%). Color of WPF, HSF and extrudates were significantly different. HSF was the lightest (l = 87.5) compared to WPF (l = 81.5) and extrudates (l = 77). Water solubility index of HSF was 14.1% compared to 24.7% in WPF and 32.7% in extrudates, and were significantly different. Water absorption index of HSF and extrudates was significantly lower than WPF by over 30%. Pasting and gelatinization evaluation by rapid visco analyser and differential scanning calorimetry did not produce peaks for extrudates but showed significant differences between WPF and HSF. Peak, breakdown, trough, setback and final viscosities of HSF were higher by over 34%, while pasting temperature and peak time were less by 1.9% and 23.5%, respectively. HSF had significantly lower onset (To), peak (Tp), and end temperature (Tc) while gelatinization enthalpy (ΔH) was not significantly different. Gelatinization and retrogradation temperature range (Tc – To) was 14.7°C (WPF) and 13.3°C (HSF), and were not significantly different. Differences in flours evaluated indicate potential for different food applications.

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