Physicochemical, Nutritional, Microbiological, and Sensory Evaluation of Composite Noodles from Orange-Fleshed Sweet Potato, Wheat Flour, and Egg Protein

In many rural communities across Rwanda and similar regions, a persistent health challenge looms over children: a diet that provides enough energy to keep them moving but lacks the essential vitamins and proteins needed for them to grow strong and stay healthy. This condition, often called malnutrition, is frequently driven by a reliance on staple foods like cassava or maize, which are filling but nutrient-poor. A common solution in modern diets is the consumption of noodles, a convenient and affordable food made primarily from refined wheat flour. While easy to prepare and widely accepted, these noodles are essentially a source of carbohydrates with very little of the micronutrients children desperately need, particularly vitamin A and high-quality protein. Without these nutrients, children face higher risks of vision loss, weakened immune systems, and stunted development. Scientists have long sought ways to fortify these everyday foods, turning them into vehicles for better health without sacrificing the convenience that makes them popular in the first place.

To address this gap, researchers in Rwanda set out to create a new kind of noodle by blending three specific ingredients: standard wheat flour, flour made from orange-fleshed sweet potatoes, and egg protein. The orange-fleshed sweet potato is a crop already grown in the region, known for its bright color which signals a high content of beta-carotene, the substance the body converts into vitamin A. Eggs were chosen as the protein source because they are a complete protein, containing all the essential building blocks the human body requires. The team aimed to mix these ingredients in varying amounts to see if they could boost the nutritional value of the noodles while keeping them safe to eat and pleasant to consume. They tested four different versions: one made entirely of wheat flour as a baseline, and three others where they replaced portions of the wheat with sweet potato flour while keeping the egg content steady.

The results showed that adding the sweet potato and egg dramatically changed the nutritional makeup of the noodles. As the amount of sweet potato flour increased, the levels of beta-carotene rose significantly, jumping from less than one microgram per gram in the plain wheat noodles to over eight micrograms per gram in the version with the most sweet potato. The protein content also climbed steadily, rising from about thirteen percent in the control sample to nearly nineteen percent in the highest substitution mix. Along with these improvements, the noodles gained more fiber, ash (which indicates mineral content), and fat, while the carbohydrate content decreased slightly. This shift meant the new noodles were denser in the very nutrients that were missing from the traditional diet. The researchers found that the process of drying the sweet potato slices at a moderate temperature was effective at preserving these vital nutrients, ensuring that the final product delivered a meaningful dose of vitamin A.

Beyond nutrition, the team examined how these new noodles behaved when cooked and stored. They discovered that as more sweet potato was added, the noodles absorbed more water and took a little longer to cook, requiring about two extra minutes for the version with the highest sweet potato content compared to the plain wheat noodles. The noodles also became slightly softer and lost a bit more of their solid material into the cooking water, a change that is common when gluten, the protein that gives wheat its elasticity, is diluted. Despite these physical changes, the noodles remained structurally sound. When tested for safety, the noodles were free of harmful bacteria, yeast, and mold immediately after production. Over four days of storage at room temperature, the microbial counts rose slightly but stayed within safe limits set by regional standards, except for the version with the most sweet potato, which approached the upper boundary of safety on the fourth day. This suggests that while the new noodles are safe, they might need slightly more careful storage or faster consumption if the sweet potato content is very high.

The final piece of the puzzle was how people actually felt about eating these noodles. A group of fifty mothers, who are the primary decision-makers for their children's meals, tasted the cooked noodles and rated them on a scale of how much they liked them. Every single version received a score above four out of five, meaning all were considered "liked" by the panel. The plain wheat noodles were the most preferred, scoring highest in color, taste, and texture. However, the version with a small amount of sweet potato flour, combined with the egg protein, scored almost as well as the plain noodles. As the amount of sweet potato increased further, the scores for color and texture dropped slightly, as the noodles became more orange and softer, but they remained acceptable. The researchers concluded that the blend containing eighty percent wheat flour, ten percent sweet potato flour, and ten percent egg protein offered the best balance. This specific mix provided a significant nutritional boost without changing the eating experience enough to turn people away.

This study demonstrates that it is possible to transform a common, nutrient-poor staple into a health-promoting food using ingredients that are already available locally. By carefully balancing the substitution of wheat with orange-fleshed sweet potato and egg, the researchers created a noodle that is richer in vitamin A and protein, safe to store for a few days, and acceptable to the families who need it most. The findings suggest that a modest adjustment to the recipe can deliver a powerful health benefit without compromising the familiar qualities that make noodles a practical choice for busy households. While further work is needed to test how these noodles hold up over longer periods and how they affect children's health in real-world feeding trials, the current results provide a clear, evidence-based path forward for improving nutrition in rural communities through simple, locally producible food.