Optimization of Enzyme-assisted Revalorization of Sweet Lime (Citrus limetta Risso) Peel into Phenolic Antioxidants

Muhammad Mushtaq, Bushra Sultana, Haq Nawaz Bhatti, Muhammad Asgher


Enzymatic treatment was used to induce liberation of antioxidant phenolics from under-utilized sweet lime peel (CLP). Small rotatable central composite design (SRCCD) was selected to optimize the conditions of enzymatic processing, i.e., enzyme concentration (2 to 5%), pH (5 to 8), temperature (30 to 75 °C), and incubation time (30 to 120 min). The morphological characterization of enzymatically hydrolyzed CLP was performed using field emission scanning electron microscopy (FESEM). Extracts obtained under suitable conditions were characterized for their phenolic profile by use of reverse-phase high-performance liquid chromatography coupled with a diode array detector (RP-HPLC-DAD) and evaluated for in vitro antioxidant activities. The observed results revealed that optimum enzymatic pre-treatment doubled the recovery of phenolic antioxidants with maximum Trolox equivalent antioxidant capacity (TEAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging potential (IC50). The observed results indicate that enzyme-assisted extraction might be a green choice to revalorize agro-processing residues.


Multi-response optimization; Citrus fruit; Antioxidant phenolics; TEAC; HPLC-DAD

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