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 μm with over 80% of the granules in the size range of 5.50-9.49 μm. 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 °C, and the peak gelatinization temperatures and endothermic enthalpies were 74.5-78.8 °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 Pa s 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.