Heat-induced gelation of whole egusi (Colocynthis citrullus L.) seeds

Despite the use of whole egusi (Colocynthis citrullus L.) seeds as a food ingredient for generations, there is no report on its gelling ability. This study evaluates the potentials of egusi seeds as a structure enhancer in food systems. Gelation and thermal characteristics of egusi seeds were examined by dynamic rheological testing and differential scanning calorimetry. Rheological data of gels, prepared at varied protein concentrations (3%, 6%, 10% and 20%, w/v) in 0.15 M NaCl, indicated that 6% (w/v) egusi protein was sufficiently high to produce properly-crosslinked networks (G′=8724 Pa). Gels prepared at 10% (w/v) protein in 0.15 M NaCl, (G′=22,530 Pa) were superior to gels treated with 0.5 M NaCl (G′=8385 Pa). Structural stability of egusi meal increased as salt level increased. Elastic gels developed above the denaturation temperature (Td=93.7 °C) in the heating phase and continued during cooling, indicating that egusi seeds can be used as a gelling food ingredient.