Valorization of Citrus industry by-products through supercritical CO₂ extraction of natural compounds

This research study assessed the applicability of supercritical fluid extraction (SFE) to the valorization of lemon peels, a vegetable by-product derived from Citrus fruits, to assess the recovery of bioactive compounds. Different combinations of parameters were explored to find optimized extraction conditions, showing yield results ranging from 1.11% to 10.18%. The highest yield (10.18%) was achieved at a temperature of 50 °C, a pressure of 300 bar, and a CO₂ flow rate of 10 kg∙h^-1. Chemical characterization of the extracts was performed by gas chromatography mass spectrometry (GC-MS), revealing a complex profile rich in mono- and sesquiterpenes, discrete percentages of linalool, geraniol, and nerol, along with aldehydes and esters recognized for their role as plant metabolites. In vitro bioscreening, using human skin cell models, demonstrated the biocompatibility of the lemon peel extracts, suggesting they could potentially serve as an ingredient for personal care formulations. These findings support the idea that the optimized SFE process is effective for the recovery of high-value bioactive compounds from lemon peels, representing a sustainable strategy for valorizing agricultural by-products in line with green chemistry principles.