Ultrasound-Assisted Extraction of Chlorophyll from Pea Pod Waste: Optimization, Kinetics, and Stability Study

Presently, natural pigments from plant sources are in limelight. This study is focused to provide a feasible technology route for effective utilization of garden pea waste as a source of natural green pigment (chlorophyll). The extraction parameters were optimized with a three-variable, three-level RSM Box–Behnken design (BBD) experiment. The BBD analysis predicted 92.85% ethanol, 27.7 min sonication time, and 46.05 h soaking time as optimum parameters for enhancing the pigment yield by 37.4%. Validation at optimal conditions gave a recovery of pigment close to that of predicted (TCC 0.642 mg/g) confirming the suitability of the model. Spectral analysis of data obtained through Fourier transformation infrared (FTIR) spectroscopy confirmed the presence of functional groups characteristic of chlorophyll in the extract. Furthermore, the extracted pigment was found stable up to 60 °C and pH range of 4.0–9.0. Degradation kinetics of extracted chlorophyll revealed lower activation energy at around 40 °C in both photo ( E a 8.31 kJ/mol) and thermostability ( E a 11.11 kJ/mol) studies indicating sensitivity of pigment to light followed by temperature. This study is the first report where pea pod waste was effectively exploited to produce valuable green pigment for its application in food and non-food industries.