Isolation, Modification, and Characterization of Starches From Hawthorn Yam ( Dioscorea rotundata ) Grown in Colombia: Functional Properties and Morphological Analysis

ABSTRACT The study of yam starches can open a range of possibilities to meet the technological needs of the food industry. However, due to the wide diversity of varieties within the Dioscorea family, it is necessary to identify the specific characteristics and functionalities that starches derived from this plant can offer. The aim of this study was to evaluate the functional, morphological, and thermal properties of native and modified yam starches esterified with 2‐octenylsuccinic anhydride (OSA) and enzymatically modified with amyloglucosidase (AMG). Methodologically, the functional properties of the starches were determined, including the water absorption index (WAI), water solubility index (WSI), swelling power (SWP), water absorption capacity (WAC), oil absorption capacity (OAC), water retention capacity (WRC) and cold‐water solubility (CWS). Additionally, the amylose content, pasting curves, morphological characteristics, x‐ray diffraction pattern and glass transition temperature (T g ) of starches from hawthorn yam cultivated in Colombia were estimated. The study revealed that native starches had higher values of WAI (1.74 g gel/g starch), amylose content (26.47) and SWP (2.72 g water/g starch), while AMG starches had higher values of WAC (118.24%) and OAC (60.22%). Similarly, OSA starches had a higher value of WRC (116.50%). No statistically significant differences in WSI and CWS were found between the starches (p < 0.05). The pasting properties of all starches decreased in an acidic medium. The x‐ray diffraction patterns of all three starch samples corresponded to a C‐type crystalline structure. AMG modification led to lower T g (52.00°C) compared to OSA (57.78°C) and native starch (60.63°C) treatments, respectively. It is concluded that AMG modification enhances the absorption faculties of both water and oil and reduces viscosity when heated. This may be favorable for the processing of farinaceous or ice cream products. Similarly, the exocorrosion phenomena observed in OSA tend to make yam starches more susceptible to acid hydrolysis, which opens potentials for obtaining the dextrins with film‐forming properties.