Optimization and kinetic studies of d-galacturonic acid extraction from basil seed using different extraction techniques

Abstract

This study presents d-galacturonic acid extraction from basil seeds using stirred reactor extraction, conventional soxhlet extraction, and ultrasonic extraction techniques. Different process parameters such as type of solvent, pH (2–9.5), solid-to-solvent ratio (0.5:100–2:100), time(10–70 min), temperature (40–90 °C), and agitation speed (100-700RPM) were optimized. The yield of D-gala using ultrasound-assisted extraction (104.25 mg/g of basil seeds) was higher as compared to the stirred reactor (92.64 mg/g of basil seeds) and soxhlet extraction (52.2 mg/g of basil seeds). Moreover, the time required for extraction using ultrasound was significantly less (15 min) as compared to the stirred reactor (60 min) and soxhlet extraction (280 min). The process effectiveness in terms of yield of D-gala per unit energy dissipated in ultrasound-assisted extraction (12.46 mg/g of basil seed kJ) was around 13 times greater than stirred reactor (0.975 mg/g of basil seed kJ) and about 63 times greater than soxhlet extraction (0.201 mg/g of basil seed kJ). As a result, ultrasonic extraction is regarded as the best alternative approach to the stirred reactor and soxhlet extraction for getting a higher d-galacturonic acid yield from basil seeds. An empirical kinetic model of second order rate equation and a mathematical model using a nonlinear regression technique was investigated for the process, which shows numerical correlation and significance factor between the yield and all other parameters. The detailed characterization of the extracted components has been carried out using Fourier transform infrared spectroscopy (FTIR), Nuclear magnetic resonance (NMR), and Liquid chromatography and mass spectroscopy (LCMS).