Potential of purple sweet potato (Ipomoea batatas L.) peel powder to enhance textural, cooking, and sensory quality, glycemic index, and antioxidant bioaccessibility of fiber-enriched pasta

Abstract

Purple sweet potato peel (Ipomoea batatas L.), a by-product of processing, is a potential source of dietary fiber and bioactive compounds. This study aimed to utilize locally available sources of purple sweet potato peel powder (SPP) as a dietary fiber and an antioxidant source that was blended with durum wheat semolina (DWS) in pasta making. Compared to the control, pasta incorporating the highest SPP level of 40% SPP showed significant improvements in phytochemicals and fiber, with increases of 6.3, 4.6, and 31.1-fold in dietary fiber, phenolics, and flavonoids respectively. No anthocyanins were detected in the control samples, but inclusion of 40% SPP in the pasta formulation resulted in an anthocyanin content of 49 mg C3GE/100 g dw. The increased levels of SPP considerably decreased the optimal cooking time and swelling capacity of pasta but led to an increase in cooking loss. The textural attributes were increased in terms of firmness, hardness, gumminess, and chewiness, while demonstrating reduction in cohesiveness, tensile strength, and elongation rate. The pasta fortified with 10 to 30% SPP fell within the medium glycemic index (GI) category while the pasta supplemented with 40% SPP was classified as belonging to the low GI group. In contrast, the control exhibited a high GI of 71.1. The bioavailability of phenolic compounds, flavonoids, and anthocyanins increased by 2.1- to 3.3-fold as the SPP supplementation ratio was elevated from 10% to 40%. These enhanced bioactive compounds likely contributed to the increased release of antioxidant activities during digestion, with the pasta containing 40% SPP replacement demonstrating the highest proportion of antioxidant activity.