Asian Journal of Food Research and Nutrition

Aims: This study was carried out to investigate the influence of incorporating local rice (Oryza sativa L.) flour and water yam (Dioscorea alata) flour on wheat (Triticum aestivum) flour at different concentrations on the proximate composition, mineral, and water soluble vitamin contents of instant noodles samples.

Study design Mixture D-Optimal Design for three variables was used to get ten different combinations. The statistical software package was used get the design with 10 as the total number (N) of experiments. The minimum and maximum values for component proportions for the flour blends are given as: 20<=X₁<=100, 0<=X₂<=50, 0<=X₃<=30. Where X₁ = content of hard wheat flour (%), X₂ = content of rice flour (%), and X₃ = water yam flour.

Place and Duration of Study: The study took place at the Department of Food Technology, Abia State Polytechnic, Aba between January 2021 and December 2023.

Methodology: local rice (Oryza sativa L.) and water yam (Dioscorea alata) were processed into flours and used to substitute wheat (Triticum aestivum) flour as composite flours at different proportions of 100:0:0 (Wheat); 75:25:0 (Wheat: Rice); 75:0:25 (Wheat: Water yam);  proportions of 100:0:0 (Wheat); 75:25:25 (Wheat: Rice: Water yam); 75:25 (Wheat: Rice); 50:50 (Wheat: Rice); 50:25:25 (Wheat: Rice: Water yam); The formulated blends were used to produce 50:0:50 (Wheat: Water yam); 83.33: 8.33: 8.33 (Wheat: Rice: Water yam); 58.33: 33.33: 8.33 (Wheat: Rice: Water yam); 58.33: 8.33: 33.33 (Wheat: Rice: Water yam); 66.67: 16.67: 16.67 (Wheat: Rice: Water yam). The formulated blends were used to produce instant noodles. The proximate, mineral, and water soluble vitamin analysis were carried out on the noodle samples.

Results: The moisture contents of the instant noodle samples ranged from 11.29 to 12.49 % but their moisture contents were not significantly different (P>.05). However, varying the component proportions of the flours significantly (P<.05) affected the protein contents (3.07 to 7.42 %), the fat contents (18.24 to 21.50 %), the ash contents (1.37 to 6.15 %), the fibre contents (0.25 to 0.46 %), and the carbohydrate contents which ranged from 58.12 to 63.11 %. Inclusion of the water yam component of the blended flour sample caused decrease in the protein content in the instant noodles. Significant differences (P<.05) were observed the Phosphorus contents (4.3 to 77.00 mg/100g), Calcium contents (1.5 to 6.1 mg/100g), and Magnesium contents (0.70 to 4.20 mg/100g). However, Iron content (3.95 to 4.26 mg/ 100g) was not significantly (P>.05) different. The values of the water soluble vitamins ranged from 0.170 to 0.175 mg/100g in Vitamin B₁, 0.015 to 0.022 mg/100g in Vitamin B₂, 0.78 to 0.82 mg/100g in Vitamin B₃, and 15.50 to 16.50 mg/100g in Vitamin C. However, only vitamin B₂ varied significantly (P<.05).

Conclusion: Inclusion of local rice and water yam flours in the production of instant Noodles made significant changes in the proximate, mineral and water soluble vitamins contents. However, instant noodles should be fortified with protein, vitamins and minerals, or eaten together with other foods rich in protein, fibre, vitamins, and mineral to enhance their nutritional and health benefits.