Optimization of microwave‐assisted extraction of soluble dietary fiber from potato pulp and its properties

In this study, the microwave‐assisted sodium hexametaphosphate (SHMP) method was applied for soluble dietary fiber (SDF) extraction from potato pulp; the extraction conditions were optimized by response surface methodology (RSM). The water holding capacity (WHC), swelling capacity (SC), oil binding capacity (OBC), adsorption capacity for cholesterol (ACC), and DPPH and ABTS free radical scavenging capacities of potato pulp SDF were then evaluated. The optimal extraction conditions were 1.0% SHMP, liquid to solid (L:S) ratio; 40:1, and microwave time; 1.26 min. The WHC and SC were 2.66 g/g and 4.47 ml/g, respectively. Adsorption capacities for unsaturated fatty acid (UFA) and saturated fatty acid (SFA) were 1.405 and 1.302 g/g, respectively. At pH 2 and 7, the ACC was 1.87 and 1.33 mg/g, respectively. The free radical scavenging assays show that potato pulp SDF has moderate antioxidative activity. This study serves as a reference for the full processing of potatoes and the comprehensive utilization of potato pulp. PRACTICAL APPLICATIONS: Potato pulp is often thrown away in starch manufacture, which not only causes waste of resources but also environmental pollution. Extracting functional components such as SDF is one direction for the comprehensive utilization of potato pulp. Compared to traditional methods, microwave‐assisted technology is more efficient and environment‐friendly. In this study, the optimal microwave‐assisted extraction conditions were obtained by single‐factor experiments and RSM, which provides a reference for the application of microwave‐assisted technology in the potato‐processing industry. Moreover, compared with other sources of SDF, the property assays reveal that SDF from potato pulp has good SC, as well as moderate WHC, OBC, and antioxidative activity, which suggest that it has potential for applications in the functional food industry.