Ultrasonic assisted deep eutectic solvent-based green extraction of insoluble dietary fiber (IDF) from tomato pomace: A comparative study with conventional extraction methods

Dominance of green technologies over conventional extraction processes had led to emergence of deep eutectic solvents (DES). In this study, three different extraction methods of insoluble dietary fiber (IDF) from tomato pomace (TP) were evaluated, i.e., alkaline extraction method (IDF-A), enzymatic extraction method (IDF-E), and ultrasonic assisted deep eutectic solvent (IDF-D), and the grounded tomato pomace was used as a control group. Based on the extraction yield, IDF-D exhibited the highest yield of 67.12%. Fourier transform infrared spectroscopy (FTIR) and Field Emission-Scanning Electron Microscopy (FE-SEM) data indicated the critical differences in the structural profiles of extracted IDF’s. The highest crystallinity values of IDF-A and IDF-E at 2θ value of around 20–21° was demonstrated by X-ray diffractogram. Physiochemical, functional, and antioxidant properties were examined in relation to extraction treatment. As per the results, antioxidant values and glucose and cholesterol binding capacities exhibited the following trend: IDF-D > IDF-E > IDF-A. Frequency sweep and complex viscosity data indicated the dominance of IDF-E over other extraction methods. These results indicate the efficacy of the DES for the extraction of IDF and highlights its potential impact on the techno-functional properties of IDF.