Nutrient Composition, Functional Properties and Glycaemic Effect of Nigerian Rice-Based Flour Improved With Cucumber Flour and Garden Egg Flour

ABSTRACT
This study aimed to ascertain the nutrient composition, functional properties and glycaemic effect of Nigerian rice-based flour improved with cucumber flour and garden egg flour. The study adopted an experimental design. The cucumber (Cucumis sativus) and garden egg (Solanum aethiopicum) samples were washed with brine solution, sliced, dehydrated, milled into flour while the rice sample was washed with brine solution, oven dried and milled into flour. The individual samples were analysed in the lab for their available carbohydrates content and result from this analysis was used for the formulation of the composite flour which was used for further analysis. The composite flour samples were analysed in the laboratory using standard methods for their nutrient composition (proximate, vitamins and minerals composition) and functional properties. The composite flour samples were coded as RCG1, RCG2, and RCG3 and sensory evaluation was carried out using 30 trained panellists. A glycaemic study was carried out using 10 normoglycaemic subjects. Data obtained from this study were analyzed using Statistical Product and Service Solution (SPSS) version 23.0 and presented as means standard deviations. One-way Analysis of variance (ANOVA) was used to compare means while Turkey HSD-test was used to separate means at 5% probability level (p < 0.05). Cucumber flour had the lowest available carbohydrates content (13.07%), followed by garden eggs (18.19%), then rice flour (73.74%) and glucose powder had the highest (89.62%).. The proximate composition for sample RCG1 (40g rice flour, 10g garden egg flour) contained 6.50% moisture, 4.50% ash, 10.07% protein, 0.98% fat, 5.90% crude fibre and 72.06% carbohydrate. Sample RCG2 (40 g rice flour, 10g cucumber flour) contained 6.50% moisture, 6.50% ash, 11.06% protein, 0.98% fat, 5.70% crude fibre and 69.27% carbohydrates and sample RCG3 (40g rice flour, 5g garden egg flour, 5g cucumber flour) contained 9.00% moisture, 3.00% ash, 11.38% protein, 1.98% fat, 8.95% crude fibre and 65.70% carbohydrates. Vitamin B1 contents of the samples ranged from 0.28mg in sample RCG1 to 0.04 mg in sample RCG3, Vitamin B2 values were from 0.05-0.12 mg, Vitamin B3 content was from 0.20 in sample RCG1 to 0.27 mg in RCG 3, Vitamin D values also ranged from 221.18 IU to 364.28 IU, and vitamin E values were from 0.38mg to 1.18 mg. The average scores for taste range from (3.77%) in RCG2 to (4.43%) in RCG1, RCG1 has the highest taste perception. The colour perception ranges from (5.27%) in RCG2 to (5.77%) in RCG1. The score of flavour was lowest in RCG2 (4.37%), followed by RCG3 (4.80%) and highest in RCG1 (5.00%). In texture attribute, the lowest was in RCG3 (5.37%), followed by RCG1 (5.43) and RCG2 had the highest (5.77%). The general acceptability ranged from (3.67%) in RCG3 to (4.40) in RCG1 of the samples. Results from the glycaemic study indicates that the reference food maintained the highest value (124.00 mg/dl), while RCG3 (107.60 mg/dl) and RCG2 (105.30 mg/dl) displayed higher glycaemic responses than RCG1 (103.70 mg/dl). These results suggest that RCG1 had the slowest and most stable glucose release over time. This study revealed that the incorporation of cucumber flour and garden egg flour into rice flour yielded stiff dough rich in protein, carbohydrates, calcium, iron and vitamin D. It is recommended that rice flour be improved with garden egg and cucumber flour to develop nutritionally enhanced and low-glycaemic food products that support dietary fibre intake, glycaemic control, and functional food innovation.