Kinetic modeling of valuable phenolic compounds extraction from strawberry and apple agro‐industrial by‐products

Abstract

Extracting valuable compounds from waste plant tissues is a challenging process. To better understand this process, kinetic modeling was used to study the extraction of phenolic compounds from the waste tissues of industrial strawberry (RF) and apple (GS) processing using green solvents. The experimental design variables included type of solvent (W: water, EtOH: ethanol 80%), solid–liquid ratio (1:20, 1:30, 1:40), and temperature (20, 70°C). The model of Peleg (MI) and an empirical model (MII) were applied to determine the kinetic constants for total phenolic compounds (TPC) and antioxidant capacity (AC). The phenolic compound profile was determined at each experimental assay. The extraction variables affected (p < 0.001) TPC and AC of RF and GS extracts. Using EtOH increased TPC extraction yields from both tissues (up to 62% for RF). The highest AC was determined in EtOH extracts at 20°C (119 and 25 μmol TE/g for RF and GS, respectively). Temperature, extraction ratio, and solvent type significantly affected the kinetic constants of both models. The study identified nine phenolic compounds from both waste tissues, with Agrimoniin being the main compound in RF (0.49 g/kg) and quercetin pentoxide being the main compound in GS (0.23 g/kg). There was no significant increase in TPC and AC of the extracts after 90 min at 20°C and 60 min at 70°C. The kinetic modeling of phenolic compound extraction from strawberry and apple agro-industrial by-products using green solvents enabled the determination of the best extraction conditions, promoting the use of these waste tissues by obtaining bioactive compounds with antioxidant potential.