Optimization and characterization of pectin extraction from lemon peels using heating and ultrasound assisted...

Fruit waste valorization offers sustainable way to unlock the hidden treasure stored in fruit processing industry. The present approach focuses on the extraction of pectin under optimal parameters by heating and ultrasound assisted extraction to attain maximum pectin yield from the lemon peels collected through local fruit juice shop of Kishangarh market (Rajasthan). The optimization process followed heating and ultrasound assisted extraction through varying reaction time (90-120 min and 30-50 min respectively), temperature (70-90 °C and 35-45 °C respectively) and solid solvent ratio (1:20-1:40 g/ml); Box Behnken Design (BBD) model was used and showed the statistically significant results. The extracted pectin was further analysed for physiochemical properties, functional properties, antioxidant property and instrumental characterization such as Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electon Microscopy (SEM), X-ray Diffraction (XRD), Thermogravimetric analysis (TGA), Differential Scanning Colorimetry (DSC) and zeta potential. The pectin extraction with ultrasound assisted and heating assisted extraction showed the maximum yield of 31 % and 29.8 % respectively. The functional properties includes ash content, moisture content, water holding capacity, oil holding capacity, emulsifying capacity and emulsifying stability observed is 4.6 ± 0.3 %, 3.91 ± 0.24 %, 7.39 ± 0.17 g/g, 2.27 ± 0.06 g/g, 46.17 ± 1.41 % and 87.76 ± 1.70 % of heating assisted extraction whereas 3.5 ± 0.3 %, 6.57 ± 0.35 %, 8.5 ± 0.31 g/g, 2.56 ± 0.16 g/g, 51.64 ± 1.46 % and 90.23 ± 1.41 % of ultrasound assisted extracted pectin respectively. The antioxidant activity observed to be 87.19 ± 0.30 % and 85.16 ± 0.70 % of ultrasound and heating assisted extraction respectively. This study revealed that within less time and temperature; ultrasound assisted extraction provides better yield as compare to heating assisted extraction instead of it the study also focuses on the circular solvent strategy used during the process.