Production and Quality Evaluation of Soymilk Beverage Fortified with Watermelon Juice

The physicochemical, phytochemical and sensory properties of soymilk fortified with watermelon juice were evaluated to determine the optimal blend ratio for beverage development. Soymilk-watermelon juice beverages were formulated at ratios of 100:0 (control), 90:10, 80:20, 70:30, 60:40 and 50:50, and analyzed for physical properties, proximate composition, mineral and phytochemical contents, sensory acceptability as well as storage studies. The physical properties revealed that the pH of the samples was near neutral for day 1, with a range of 6.53 – 6.03 for samples A – F, and decreased during the 7 days of storage. Viscosity values ranged from 3.3 – 2.07 cP while TSS values ranged from 11.7 – 9.9 0Brix for samples A – F. The proximate composition showed a range of values for moisture (80.4 – 87.0 %), crude protein (2.45 – 1.18 %), lipid (3.04 – 1.88 %), ash (0.333 – 0.240 %), fibre (0.95 – 0.753 %) and carbohydrates (12.83 – 8.95 %) for samples A –F respectively. The values for zinc (0.3 – 2.2 mg/100mL), iron (0.417 – 0.449 mg/100mL), magnesium (19.0 – 26.2 mg/100mL) and potassium (122 – 199 mg/100mL) all increased with increasing watermelon juice addition while calcium content (23.4 – 19.2 mg/100mL) decreased. The values for phytochemicals showed a range of 0.203 – 0.7 mg/100mL for beta-carotene, 1.62 – 4.43 mg/100mL for total flavonoids and 32 – 62.7 mgGAE/100mL for total phenolic compound (samples A – F). The sensory scores showed that Sample F (50:50 soymilk-watermelon juice) was the most preferred sample and is therefore recommended for adoption by food processors. The study demonstrated that fortification of soymilk with watermelon juice improved the nutritional quality, phytochemical content and consumer acceptance.