Orange waste peel to high value soluble dietary fiber concentrate: comparison of conversion methods and their environmental impact

Soluble dietary fibers (SDF) have great importance in a healthy human diet. Fruits and vegetables have limited quantity of SDF; hence, external supplement of SDF is recommended. In this study, extrusion and ultrasonication methods are applied to convert insoluble dietary fiber (IDF) into SDF from total dietary fiber (TDF) rich orange peels waste. In extrusion, peels were processed at 105, 115, 125,135, and 145 degrees C barrel temperature, while in ultrasonication peels were processed at 300, 350, 400, 450, and 500-W power. Both methods are compared for their environmental impact using life cycle assessment (LCA) approach. In extrusion, SDF increased from 4.7 to 24.28% at 135 degrees C, while with ultrasonication, the increase was to 22.27% at 400 W. Global warming potential (GWP) of extrusion and ultrasonication are 1.5 and 3.97 kg CO2 equivalent, respectively. Both methods are compared based on various decision-making factors like technical, economic, and environmental. Furthermore, physicochemical properties and microstructural analysis like water-holding capacity (WHC), oil-holding capacity (OHC), water-swelling capacity (WSC), and scanning electron microscopy (SEM) were studied for both unprocessed and extracted dietary fiber. From the detailed comparison, it was found that extrusion is more suitable route compared to ultrasonication.

Automated summary

This study converts the insoluble dietary fiber in orange peel waste into soluble dietary fiber using extrusion and ultrasonication methods. The environmental impact of both methods is compared, and extrusion is found to be more suitable for the process.