Formulation of a fiber-enriched instant soup mixed with pumpkin peel and evaluation of physicochemical, nutritional characteristics and storage stability

Abstract

Recently, there has been growing interest in utilizing fruit and vegetable by-products for food product development. This study investigates the potential of pumpkin peel (PP), a fiber-rich by product abundant in minerals, polyphenols and antioxidants, as a functional ingredient in the formulation of an instant soup mix. Five vegetable soup mix samples were formulated using potato flour as the base material, substituted with PP at five levels: 0%, 25%, 50%, 75%, and 100%. The best formula was selected based on sensory evaluation with 30 semi-trained panelists, and its physicochemical properties and storage stability were subsequently analyzed. The results revealed that 50% substitution of potato flour with PP was the most preferred sample in terms of taste and other sensory attributes, comparable to the control. Furthermore, the addition of PP significantly increased (p<0.05) the crude fiber (7.50%), total dietary fiber (9.9%) ash content (22.72%) phenolic content and antioxidant capacity, while reducing the carbohydrate content (51.30%) compared to a control. No significant differences (p>0.05) were observed in moisture content, pH, viscosity, or L* value between the control and PP-enriched samples. However, PP incorporation significantly decreased the a* value (from 2.29±0.13 to 1.58±0.09) and increased the b* value (from 21.47±0.89 to 23.37±0.27), indicating a shift towards a more yellowish color. Storage studies conducted over three months at 25 °C revealed reductions in moisture content, pH, viscosity and color parameters (L*, a*, b*) in the PP-added sample, while microbial counts remained within safe limits. In conclusion, pumpkin peel flour demonstrates potential as a functional ingredient in instant soup formulations by enhancing fiber content, nutritional quality, and storage stability. The valorization of such agro-industrial by-products supports sustainable food production and promotes environmental sustainability.