Bread-making properties of sweet potato flour

摘要

The National Aeronautics and Space Administration (NASA) Advanced Life Support (ALS) system has selected the sweet potato as a candidate crop to be grown on long-term space missions. There is limited research regarding the production of sweet potato bread. The objectives of this research were to: i) determine the chemical properties (moisture, loaf volume, and texture) of bread supplemented with different levels of sweetpotato flour (SPF); and ii) evaluate the structural properties of bread supplemented with different levels of SPF using Scanning Electron Microscopy (SEM) and Differential Scanning Calorimetry (DSC). Bread formulations were supplemented with different levels of SPF, namely: 50% SPF to 50% whole- wheat flour (WWF); 55% SPF to 45% WWF; 60% SPF to 40% WWF; and 65% SPF to 35% WWF. The maximum % strain required to cut the breads into two pieces was used to indicate texture (firmness). A Jeol jsm-5800 SEM and DSC 2010 were used to determine the morphological structure and enthalpies of the breads, respectively. The moisture contents of sweet potato bread ranged from 36.8±0.7% to 40.4±0.7%. Of the sweet potato breads, the 50%/50% had the highest loaf volume and were not significantly different (P<0.05) from each other. Loaf volumes were 6.2cm, 5.4cm, 5.3cm and 5cm, for the 50%/50%, 55%/45%, 60%/40%, and 65%/35% breads, respectively. All the sweet potato breads were less firm than the control. The SEM showed that the 50%/50% bread had the most gelatinization of starch granules when compared to the others. The sweet potato breads had high enthalpies, possibly because of the presence of larger granules in the sweet potato starch. The sweet potato breads had similar chemical and structural properties.