Optimization of pectin extraction from lemon peels using hydrochloric acid and response surface methodology
Belkis Akachat, Louiza Himed, Salah Merniz, Maria D’Elia, Saoud Zomorroda, Ramoul Ali, Luca Rastrelli, Malika Barkat
Abstract
The increasing industrial demand for pectin has put significant pressure on existing sources, prompting the search for sustainable alternatives. This study aimed to optimize the extraction of pectin from lemon peel, a potential underutilized source, using acid hydrolysis. Pectin was extracted from lemon peel powder with three acids, hydrochloric acid (HCl), nitric acid, and citric acid, under controlled conditions (temperature 80°C, pH 1.6, extraction time 80 minutes). The optimal extraction conditions were determined through experimental design, focusing on HCl as the acid and varying three key parameters: temperature (70-120°C), pH (1.25-3), and extraction time (70-120 minutes). Response surface methodology (RSM) was applied for statistical optimization. The yield ranged from 1.7% to 35% across 20 trials, with optimal conditions identified as temperature 70°C, pH 1.25, and extraction time 70 minutes, resulting in a 43% yield. The extracted pectin’s quality was characterized by a water content of 8.77±0.69%, an equivalent weight of 664.70±1.72 g/mol, methoxyl content of 8.07±0.22%, and a degree of esterification (DE) of 80.33±1.52%. Fourier Transform Infrared (FTIR) spectroscopy confirmed the pectin’s microstructural characteristics, consistent with reported values in the literature, indicating its suitability for food and pharmaceutical applications.