Kinetic modeling of ultrasonic-assisted extraction of punicalagin from pomegranate peel

Ultrasonic-assisted extraction of punicalagin from pomegranate peel was investigated. The influence of individual parameters, namely, solvent volume (20-60 mL), amplitude (30-70%), and duty cycle (60-100%) on punicalagin extraction was studied. The optimal condition of extraction was found to be: 40 mL solvent volume, 60% amplitude, and 90% duty cycle. Different kinetic models such as Peleg's model, first order kinetics, power law model, and mass transfer model were used to mathematically describe the extraction mechanism. Initial extraction rate, equilibrium punicalagin concentration, effective diffusivity, model constants, and diffusional exponent have been calculated using these models. The study revealed that first order kinetics (RAdj2=0.964) best fitted the experimental data. Fifteen other hydrolysable tannins were identified using liquid chromatography mass spectrometry in the polyphenolic extract obtained under optimized condition. Practical application There has been a paradigm change to functional food due to prevailing lifestyle diseases. Hence, the interest in the extraction of bioactive compounds from food processing by-products has increased as a result of various health benefits exhibited by these compounds. Punicalagin (C48H28O30) is an ellagitannin that is predominantly found in pomegranate peel. It is a great natural source of antioxidants, and therefore, it can find its application in products such as food additives, pharmaceuticals (as drugs and supplements), and cosmetics. The finding of this study emphasizes the kinetic investigation of the punicalagin extraction process to describe the mechanisms that drive them.