Characterisation of Jicama (Mexican Potato) (Pachyrhizus erosus L. Urban) Starch From Taproots Grown in USA and Mexico

摘要

Characteristics of starch extracted from roots of Jicama (Pachyrhizus erosus L. Urban) cultivated in Texas and two locations in Mexico were studied. Jicama starch granules were spherical or polygonal with diameters ranging from 1-15 jim. Jicama starchexhibited C_A-type X-ray diffraction pattern, an apparent amylose content of 28.1 % and absolute amylose content of 23.6%. Jicama amylopectin weight-average molar mass (M_w) was 3.9 x 10~8 g/mol and gyration radius (R_z) was 363 nm. Average amylopectinbranch chain-length was short (DP 22.7). Onset gelatinisation temperature was very low (52.0 deg C) and enthalpy change was 15.1 J/g. Thermal transition of amylose-lipid dissociation was not observed. Peak (282 RVU), final (221 RVU) and breakdown (137 RVU) viscosity of 8% Jicama starch paste were high relative to other starches and pasting temperature was 72.3 deg C. Starch characteristics were similar among all three growing locations except M_w, R_z and pasting properties. High paste viscosity and lowgelatinisation temperature could give Jicama starch advantages in some industrial applications.