Science Direct


Essential oils from Citrus

Essential oils derived from the citrus industry have been screened for their antimicrobial properties against diverse foodborne pathogens such as Escherichia coli O157:H7, Salmonella Typhimurium, Staphylococcus aureus, Listeria monocytogenes, Campylobacter sp., and others. Several have shown to possess antimicrobial activity. 19,20 The major component of citrus oils is limonene (ranging from 32% to 98% depending on the citrus type), with sweet orange containing 69–98% and lemon containing 45–76%.10 The chemical, physical, and biological properties of limonene have an important impact on the biological properties of the major components of essential oil.18

Limonene has shown to be effective against S. aureus, L. monocytogenes, Salmonella enterica, and Saccharomyces bayanus, as well as other microorganisms.7 It was found to be effective against strains of E. coli,10Klebsiella pneumoniae,21 Mycoplasma pneumoniae,7 and Staphylococcus epidermidis.21 This component can exert potent, broad-spectrum antimicrobial activity.7 However, limonene is also susceptible to oxidative degradation, which causes a reduction of activity.7Linalool exhibits antimicrobial properties against Shigella sonnei, Salmonella flexneri,10 Staphylococcus epidermidis,21Arcobacter butzleri,22 Campylobacter jejuni, E. coli O157, and L. monocytogenes.23Citrulline exerts potent, broad-spectrum antimicrobial activity.7 α-Terpineol has an important effect on E. coli, SalmonellaTyphimurium, L. monocytogenes, and S. aureus.24 Citral was reported with power against A. butzleri,22 C. jejuni, E. coli, Salmonella Typhimurium, L. monocytogenes, and S. aureus.23 Another important terpene that can be used in antimicrobial therapy is (4R)-(+)-carvone (monoterpene), which was effective against L. monocytogenes and showed activity against Enterococcus faecium and E. coli.13

In addition to the use of citrus essential oil components against pathogenic microorganisms, complete essential oils have been tested. Pathan et al.25indicated that Citrus aurantifolia showed high activity against K. pneumoniae and S. aureus. Mandarin essential oil has been reported to have antimicrobial effects against E. coli, K. pneumoniae, and Salmonella enterica.26 Lemon oil was reported to have properties against Lactobacillus plantarum and L. monocytogenes, which showed inhibition percentages around 99.9%26,27 and against Candida albicans, Bacillus subtilis, E. coli, K. pneumoniae, and Salmonella enterica.26,28,29 In addition, some studies demonstrated inhibition and reduction of the numbers of foodborne pathogens such as Salmonella spp., E. coli O157:H7, and L. monocytogenes by citrus essential oils.26 It has been observed that the activity of the essential oil used also depends on its concentration. Recently, it has been found that in lemon peel, the maximum concentration of volatile compounds occurs when the fruit is at the intermediate maturation stage.18

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