Proximate composition and functional properties of sandbox seeds as influenced by processing methods

Abstract

Sandbox (Hura crepitans) seeds were processed as untreated (raw) sandbox flour (USF), cooked fermented flour (CFS), and soaked fermented flour (SFS). The three samples were defatted (with acetone) to obtain defatted untreated sandbox (DUS) flour, defatted cooked fermented (DCF) sandbox flour, and defatted soaked fermented (DSF) sandbox flour. The DSF was used to prepare sandbox protein concentration (SPC) and sandbox protein isolates (SPI). The physicochemical (pH and bulk density), functional properties (water absorption capacity, WAC), oil absorption capacity (OAC), least gelation concentration (LGFC), and in-vitro protein digestibility (IVPD) of defatted untreated and soaked fermented flours and protein concentrate and isolate were determined using standard procedures. The results showed that the moisture content varied between 5.13 – 8.23% and that processing treatments, such as fermentation and defatting significantly (at p ⩽ 0.05) increased protein, ash and carbohydrate contents of sandbox seed flour. Sandbox protein isolates exhibited highest protein content (87.49%), but the lowest crude fibre (0.02%), fat (1.31%) and ash (0.47%) contents. All the samples except SPC were acidic in aqueous solution and the bulk density values ranged between 0.45 g/mL – 0.67 g/mL. Defatted untreated sandbox (DUS) seed flour and sandbox protein isolate (SPI) had the lowest (1.06 mL/g) and highest (3.38 mL/g) significantly different (p ⩽ 0.05) WAC values, respectively, while DUS and SPI had the lowest (1.18 mL/g) and highest (2.30 ml/g) OAC, respectively. The foaming capacities for DUS, DSF, SPC and SPI were 42.00, 36.84, 20.00 and 12.00%, respectively, while emulsifying activity index ranged between 12.38 – 21.85m²g^-1. All processing treatments were found to increase the in-vitro protein digestibility with values between 50.90 and 87.21%.

Keywords: Sandbox seeds, Processing techniques, Nutrient composition, Functional properties