Lotus root soluble dietary fiber (SDF) has numerous health-promoting benefits, and high hydrostatic pressure (HHP) combined with enzymatic hydrolysis can enhance SDF extract efficacy and functional properties. This study investigated the SDF concentration in lotus root pulp utilizing α-amylase and protease simultaneously under varying high pressures. Subsequently, the concentration of SDF was maximized using response surface experimental design based on HHP conditions, resulting in a 2.25-fold increase of content comparing with the untreated sample. Furthermore, the hypoglycemic effect of lotus root SDF on diabetic mice (DM) under optimal extraction conditions was systematically evaluated. The results showed that 800 mg/kg/day of SDF reduced fasting blood glucose by 21.03%, improved insulin sensitivity, and reduced hepatic glycogen and muscle glycogen accumulation. In addition, SDF could regulate lipid metabolism and improve dyslipidemia, as well as enhance the antioxidant capacity by lowering malondialdehyde content and elevating glutathione peroxidase and superoxide dismutase activities. In conclusion, HHP-combined enzymatic treatment can substantially increase the SDF content in lotus root pulp, and the SDF derived from this method can successfully ameliorate symptoms in DM. These findings present a safe and convenient method for obtaining lotus pulp/juice abundant in SDF as food composition and demonstrate its potential beneficial effects on glycemic regulation. PRACTICAL APPLICATIONS: The HHP-assisted enzymatic hydrolysis technique developed in this study can shorten processing time and reduce insoluble residues during lotus root processing. It may also be extended to the processing of similar vegetables. The SDF obtained by this technique could be further used to develop functional foods with hypoglycemic and antioxidant activities.
Feng et al. (Wed,) studied this question.