Physicochemical, mineral and sensory characteristics of instant citrullus lanatus mucosospermus (Egusi) soup

Abstract

Defatted egusi flour offers a food option high in protein and essential micronutrients. An instant processing method was adopted in a ready-to-eat instant soup using egusi grit, hydrocolloid, and defatted flour. A D-optimal quadratic mixture model was used to study the effect of the independent variables (grit, flour, and hydrocolloid) qualities. The quadratic model was adequate to navigate the design space for taste and appearance. The numerical optimization for appearance and taste of instant soup (IES) was used to obtain the optimal soup mix of 10 g of hydrocolloid, 57.2 of defatted flour and 17 g of grits. Sixteen trace and five major mineral elements were found in the egusi soup, with a high concentration of phosphorus (1220.4, 1326.2 and 1277.9 mg/100 g), potassium (1220.4, 1326.2 and 1277.9 mg/100 g), magnesium (822.2, 905.3 and 863.70 mg/100 g), calcium (172.3, 190.9 and 183.4 mg/100 g) and iron (53.7, 57.5 and 29.5 mg/100 g), and for instant egusi soups from boiled egusi grit (IESBG), instant egusi grit from spherified grit (IESSG) and instant egusi grit from extruded grit (IESEG), respectively. The amino acid profile of instant egusi soup offers all essential amino acids necessary to nourish the body. Phosphorus content was significantly (p ≤ 0.05) high across the three soups: 1742, 1836 and 1838 mg/100 g for IESBG, IESSG, and IESEG, respectively; IESSG and IESEG were significantly (p ≤ 0.05) higher in minerals when compared with IESBG. Instant egusi soup differed significantly (p ≤ 0.05) in lightness (L*), while the redness (a*) and yellowness (b*) did not vary significantly.