Changes of Peel Essential Oil Composition of Four Tunisian Citrus during Fruit Maturation

Abstract

The present work investigates the effect of ripening stage on the chemical composition of essential oil extracted from peel of four citrus: bitter orange (Citrus aurantium), lemon (Citrus limon), orange maltaise (Citrus sinensis), and mandarin (Citrus reticulate) and on their antibacterial activity. Essential oils yields varied during ripening from 0.46 to 2.70%, where mandarin was found to be the richest. Forty volatile compounds were identified. Limonene (67.90–90.95%) and 1,8-cineole (tr-14.72%) were the most represented compounds in bitter orange oil while limonene (37.63–69.71%), β-pinene (0.63–31.49%), γ-terpinene (0.04–9.96%), and p-cymene (0.23–9.84%) were the highest ones in lemon. In the case of mandarin, the predominant compounds were limonene (51.81–69.00%), 1,8-cineole (0.01–26.43%), and γ-terpinene (2.53–14.06%). However, results showed that orange peel oil was dominated mainly by limonene (81.52–86.43%) during ripening. The results showed that ripening stage influenced significantly the antibacterial activity of the oils against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. This knowledge could help establish the optimum harvest date ensuring the maximum essential oil, limonene, as well as antibacterial compounds yields of citrus.

Chemical Composition and Antimicrobial Activity of Leaf, Ripe and Unripe Peel of Bitter Orange (Citrus aurantium) Essential Oils

“…Comparison of limonene content of the peels essential oils (Table 1) indicates that the amount of limonene was increased during the fruit maturation, which is in agreement with the results of Bourgou et al (2012) in Tunisia. The variation in limonene content, from 59.88% to 91.76%, is possibly because of the decomposition of linalool and its acetate (13).…”

“…Several studies on the chemical composition of C. aurantium essential oils seem to be matched with our observation (16,17). GC-MS analysis of bitter orange leaf oil of north of Iran showed that linalool, linalyl acetate and alpha terpineol were the main components of the oil (16).…”

“…GC-MS analysis of bitter orange leaf oil of north of Iran showed that linalool, linalyl acetate and alpha terpineol were the main components of the oil (16). Hashemi et al (2014) reported that linalool and alpha tepineol as the major compositions of C. aurantium leaf essential oil grown in Khouzestan (17).…”

Biomethane production tests on ensiled orange peel waste

“…In particular, at the beginning of the process, low methane percentages have been registered (15-20%), especially for OPW ensiled for 7 days; subsequently, the percentage increases, reaching values of 60-70% in correspondence of the 20 th day of digestion. During the last days of the experiment, cumulated methane production grows slowly, due probably to the reduction of the available substrate [20][21]. Figure 5 shows the same results of Figure 4, underlining the differences among bottles of different groups, with sometimes pronounced differences even within the same group.…”

Optimization of Headspace Solid-Phase Microextraction Conditions for the Identification of Volatiles Compounds from the Whole Fruit of Lemon, Lime, Mandarin and Orange

“…The SPME extractions were carried out in three-phase Divinylbenzene/carboxen/polydimethylsiloxane DVB/CAR/PDMS fibre, 50/30 μm (Sigma-Aldrich Australia, catalog number 57347-U), which was designed for analytes with a broad range of polarities (suitable for C2-C20 range) [21] [22] (Sigma-Aldrich Australia, catalog number 57347-U), attached to a manual SPME holder (Supelco Inc.). The fibres were conditioned as recommended by the manufacturer and the supplier specifications before analyses.…”