Influence of particle size distribution on nutritional composition, microstructural and antioxidant properties of orange and purple‐fleshed sweet potato flour

Abstract

Influence of particle size distribution on nutritional composition, microstructural, physicochemical, and antioxidant properties of orange and purple-fleshed sweet potato flour (SPF) with particle sizes 75–355 µm were investigated. As particle size decreased, protein content, water absorption capacity, and water solubility index of both SPF decreased, whereas starch, reducing sugar, and crude fat increased. Total polyphenol contents (TPC) in purple-fleshed SPF (8.25–9.27 mg GAE/g DW) were higher than orange ones (0.22–0.28 mg GAE/g DW), whereas vitamin C contents in orange-fleshed SPF (23.59–29.26 mg/100 g DW) were higher than purple ones (4.24–4.89 mg/100 g DW). Antioxidant capacities of both SPF were gradually increased with decrease of particle size due to the contribution of higher TPC and vitamin C contents. All SPF fractions exhibited irregular-shaped surface. SPF with particle size 75 µm might be used to produce novel food products with desired nutrients and functional properties. Novelty Impact Statement Both orange and purple-fleshed SPF with different particle sizes possessed significant difference in nutritional composition and antioxidant properties. TPC contents in purple-fleshed SPF were higher than orange ones, whereas vitamin C contents in orange-fleshed SPF were higher than purple ones. SPF with particle size 75 µm with higher polyphenols and vitamin C contents and stronger antioxidant activities might be used to produce novel food products.