Nutrient Composition and Sensory Properties of Cake Fortified with Watermelon (Citrullus lanatus) Rind Flour

Abstract

The study determined the nutrient composition and sensory properties of cakes fortified
with watermelon (Citrullus lanatus) rind flour. A quasi-experimental research design
guided by four specific objectives was adopted. Cake samples were produced using
wheat flour and watermelon rind flour blends formulated as K0 (100:0), K1 (80:20), K2
(70:30), and K3 (60:40). Sensory evaluation of the product was conducted first using a
nine-point hedonic scale with 30 panelists to determine the most acceptable blend for
subsequent nutritional evaluation. The most acceptable composite flour blend was
analysed alongside the control sample for the nutrient content, including proximate,
vitamin (provitamin A, B6, and C), and mineral (iron, zinc, and calcium) contents using
standard methods. Data were analysed using mean, standard deviation, and
paired-samples t-test in IBM SPSS version 23.0 at a significance level of p < 0.05. Results
showed that for the proximate analysis, protein content increased from 4.925% in the
control sample (K0; cake made with 100% wheat flour) to 5.280% in the fortified sample
(K2; sample with 70:30), while the moisture content decreased from 21.580% in K0 to
19.425% in K2. Similarly, ash content increased markedly from 0.090% in K0 to 1.855% in
K2, whereas crude fat content decreased from 12.635% in the control to 1.390% in the
fortified sample. Although carbohydrate content remained relatively unchanged,
increasing slightly from 59.320% in K0 to 59.475% in K2, crude fibre content increased
appreciably from 1.395% in the control sample to 2.585% in the fortified sample. The
mineral analysis showed that K0 had higher levels of zinc (0.144±0.000), calcium
(175.000±3.932), and iron (5.859±1.081) than K2 (zinc [0.325±0.050], calcium
[152.780±3.932], and iron [5.349±0.360]). The vitamin results also showed that provitamin
A (1.115±0.021), vitamin B6 (0.450±0.070), and vitamin C (0.800±0.141) were higher in the
fortified sample. This study concludes that fortifying cake products with watermelon rind
flour enhances their proximate composition, vitamins, and mineral content and,
therefore, recommends its use in pastry production, particularly cakes, to improve their
nutritional quality.