Optimization of Ultrasonic Assisted Extraction of Bioactive Compounds from Almond Hull

Abstract

Ultrasonic assisted extraction (UAE) of total phenolic content (TPC) from almond hull was optimized by response surface methodology (RSM). TPC and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity were used as response variables. Almond hull extract was chemically characterized by Fourier transform infrared spectrometer (FTIR) and gas chromatography mass spectrometer (GCMS). The extraction conditions were optimized by using independent extraction parameters; sample to solvent ratio (1:20-1:40 w/v), solvent concentrations (20-80%, v/v) and time (10-30 min), whereas, TPC and DPPH were used as response variables. At optimized extraction conditions (40 ml/g, 22.5 min and 80% of ethanol), the experimental values for TPC and DPPH inhibition were 110.17 ± 3.44 mg of GAE/g of extract and 87.45 ± 1.28%, respectively. For DPPH inhibition assay, IC50 value of almond hull extract was 51.64 μg/ml which was lower than the ascorbic acid (180 μg/ml). Almond hull extract showed antimicrobial effect against Escherichia coli, Staphylococcus aureus and Salmonella typhimurium. β-sitosterol (44 %), was identified as major phytoconstituent in almond hull extract. Due to antioxidant and antimicrobial potential, almond hull extract can be utilized as a functional food ingredient, and natural preservative.