Structure and properties of Treculia africana, (Decne) seed starch

Starch isolated from seed flours of four Treculia africana (African breadfruit) trees ranged from 36.0 to 41.7% (w/w, flour). Digital microscopy and image particle size analysis showed smooth, small to medium elliptical granules of sizes 3.56-13.60 mu m with over 80% of the granules in the size range of 5.50-9.49 mu m. T. africana starch displayed an A-type X-ray diffraction pattern with crystallinities in the range of 40.21-43.14%. The apparent amylose content ranged from 21.2 to 23.1% while the absolute amylose content was 13.7-21.7%. The gelatinization characteristics, swelling power and amylose leaching, paste clarity, freeze thaw stability and rheological properties were studied. The gelatinization onset temperatures ranged from 71.5 to 75.1 degrees C, and the peak gelatinization temperatures and endothermic enthalpies were 74.5-78.8 degrees C and 12.22-13.99 J/g, respectively. Rheological examination of 5% starch paste over the range of shear rate 0.1-1000/s gave shear viscosities of 3.357-8.285 Pas and rate indices of 0.44-0.53 and the mechanical spectra indicated that the gels were formed with G' > G '' over the frequency range studied. T. africana starch exhibited low level of syneresis after six freeze thaw cycles (32-38%); however, it would require modification to enhance its application in processed foods. (C) 2010 Elsevier Ltd. All rights reserved.