Chemical and biological characterization of essential oils extracted from citrus fruits peels

Abstract

In Morocco, citrus fruits processing produces large quantities of waste and by-products, which represent 50% to 60% of the fresh mass of fruit. In eastern Morocco, generally citrus processing by-products ends up being thrown in the public landfill. These by-products are rich in bioactive compounds such as antioxidants and essential oils. The objective of this study is the chemical and biological characterization of essential oils extracted from citrus peels of four species, including Lemon (Citrus limon), Bitter orange (Citrus aurantium), Berkane clementine (Citrus Clementina) and Navel, a species of orange (Citrus sinensis). The efficiency of two extraction techniques used, hydro-distillation (Traditional method) and microwave assisted extraction (Eco-friendly green method), is highlighted by comparing yields of essential oils (EOs). Thus microwave assisted extraction green method has shown the highest yields ranging from 10,47% (Clementine) to 11,5% (Navel). While by hydrodistillation, the yield of (OE) did not exceed (5,95%). Besides, chemical composition and antioxidant activity of EOs of the four citrus were studied. Thus, the CPG-MS analyzes identified some twenty minor compounds and the D-limonene as the major constituent with contents generally greater than 55% and which reached almost (97,12%). In the case of EO of Lemon (Citrus lemon), the antioxidant activity was determined by the DPPH free-radical scavenging ability, the highest antioxidant activity (44,45%) is registered in the Navel’s EO, and the lowest was observed in the Bigarade’s EO (10,66%). In addition, antimicrobial activity was tested, EOs of lemon have shown the strongest antifungal power with values of 35 mm of antagonistic effect, but no antibacterial activity was detected for the four types of Eos. These EOs would be of interest in both agriculture and the food industry by acting as bio-fungicide but also as additives for compounds of medical and cosmetic interest.