Optimization of extrusion conditions increases soluble dietary fiber yield from pomegranate peels with improved physico-chemical and biological properties

Soluble dietary fiber (SDF) is thought to be highly beneficial portion of dietary fiberfor human health. In this research, the extrusion technique was successfully used to improve the SDF from waste pomegranate peels. An attempt was made to process the pomegranate peels in laboratory single-screw extruder for studying the effect of barrel temperatures (X₁: 120, 135, 150 °C) and feed moisture (X₂: 15, 20, 25%) on the yield of SDF and optimize the process parameters using response surface methodology (RSM). A significant improvement was seen in the amount of SDF after extrusion since the unextruded pomegranate peels contained 5.87% SDF, while a maximum of 13.86% SDF was obtained after extrusion. The ideal extrusion parameters were the barrel temperature of 120 °C and feed moisture of 15%. Furthermore, the influence of the extrusion technique upon the physicochemical as well as biological properties was studied; there was found significant growth in water-holding capacity, bulk density, as well as cation exchange capacity, whereas reduction was observed in oil holding capacity.