Quality of High-Fiber Pasta Supplemented with Watermelon Rind Powder with Different Particle Sizes

Research background. Watermelon rind, a by-product of watermelon juice processing, contains high amounts of dietary fiber and phenolics with antioxidant capacity. The use of agro-industrial by-products would improve the economic benefits as well as reduce the environmental emissions. The goal of this research was to examine the impacts of particle size of watermelon rind powder on the quality of high-fiber pasta. Experiment approach. Three samples of watermelon rind powder passed through three sieves with aperture sizes of 400, 210, and 149 μm were determined for their nutritional, physical and physicochemical quality. Wheat durum semolina and watermelon rind powder (90:10 by mass) were then mixed and used to make pasta. Nutritional, textural, and cooking quality, sensory acceptability, in vitro glycemic index, and antioxidant bioaccessibility of high-fiber pasta added with watermelon rind powder with different particle size means were evaluated and compared. Results and conclusions. When the sieve aperture size was reduced from 400 to 149 µm, the soluble dietary fiber and total phenolic contents of watermelon rind powder were enhanced by 35 and 15%, respectively while its insoluble dietary fiber content was decreased by 21%. Decrease in sieve aperture size from 410 to 149 µm for watermelon rind powder reduced phenolic bioaccessibility of the fortified pasta from 63 to 57% but enhanced its predicted glycemic index from 50 to 69; such decrease also lowered the pasta hardness by 13% but improved its elongation rate and tensile strength by 13 and 40%, respectively. The finer the watermelon rind powder particles, the longer the optimal cooking time, the greater the water absorption index, and the less the cooking loss of the supplemented pasta. Consumers did not notice any significant difference in the overall acceptability among all pasta samples. Novelty and scientific contribution. Particle size of watermelon rind powder had great impacts on nutritional, textural and cooking quality of the fortified pasta. Particularly, the predicted glycemic index and antioxidant bioaccessibility of high-fiber pasta were significantly affected by the particle size of dietary fiber material used in the recipe.