Pasta making from wheat semolina and watermelon rind: Effects of ratios of watermelon rind flour on the product quality

Abstract

Watermelon juice production generates watermelon rind. This by-product contained high levels of dietary fiber and phenolic compounds with antioxidant activity. In the present study, watermelon rind was dried, pulverized and screen through a 40-mesh sieve to yield watermelon rind flour which was subsequently supplemented to wheat semolina at 0% (control sample), 5%, 10%, 15%, 20%, and 25% of the blend weight for pasta making. The quality of the obtained pasta samples was then evaluated and compared. When the ratio of watermelon rind flour was varied from 0 to 25%, the content of total dietary fiber and phenolics of the product increased by 3,3 and 8,5 times, respectively, while its 2,2-diphenyl-1-picrylhydrazyl scavenging capacity and ferric reducing antioxidant power were improved by 7,5 and 3,1 times, respectively. At the 25% supplementation level, the adhesiveness of pasta was enhanced by 56% while its cooking loss was increased by 87%. The elongation rate and tensile strength of pasta added with 25% watermelon rind flour were 59 and 27% lower, respectively, than those of the control pasta. In addition, the water absorption index and swelling index of high fiber pasta were gradually decreased as the watermelon rind ratio in the product recipe was augmented. The increased ratio of watermelon rind flour in the pasta formulation slightly enhanced the darkness (reduced L* value) and yellowness intensity (increased b* value) of the product while the change in redness intensity (a* value) was very little. Supplementation of watermelon rind flour to pasta making also reduced the overall sensory score of the product. Nevertheless, the pasta samples with 10-20% watermelon rind flour were considered as high fiber product and their overall sensory scores were acceptable. Watermelon rind flour was a fiber and antioxidant material for improvement in nutritional quality of pasta.