Antimicrobial activityof different concentrations (50, 100, 200, 300 and 500 ml/l) of essential oil extracts of three type of onions
(green, yellow and red) and garlic against two bacteria, Staphylococcus aureus, Salmomella Enteritidis, and three fungi, Aspergillus
niger, Penicillium cyclopium and Fusarium oxysporum, was investigated. The essential oil (EO) extracts of these Allium plants (garlic
and onions) exhibited marked antibacterial activity, with garlic showing the highest inhibition and green onion the lowest.
Comparatively, 50 and 100 ml/l concentrations of onions extracts were less inhibitory than 200, 300 and 500 ml/l concentrations.
However, with garlic extract, high inhibitoryactivity was observed for all tested concentrations. S. aureus showed less sensitivity
towards EO extracts inhibition, however S. Enteritidis was stronglyinhibited byred onion and garlic extracts. The fungus
F. oxysporum showed the lowest sensitivitytowards EO extracts, whereas A. niger and P. cyclopium were significantlyinhibited
particularlyat low concentrations.
1. Introduction
Onion and garlic maybe among the first cultivated
crops in the world due to their long storage time and
portability. They could be dried and preserved for
several months. At the present time, the Allium family
has over 500 members, each differing in appearance,
color and taste, but close in biochemical, phytochemical
and neutraceutical content. Alliums were revered to
possess antibacterial and antifungal activities, and
contain the powerful sulfur and other numerous
phenolic compounds which arouse great interest (Rivlin,
2001; Griffiths, Trueman, Crowther, Thomas, & Smith,
2002). Onions and garlic are composed mainlyof water
(85–90 g/100 g and 60–70 g/100 g fresh weight, respectively)
and the most significant components, medicinally,
are the organosulfur-containing compounds.
However, garlic contains nearlythree times as much
sulfur-containing compounds as onions (11–35 mg/100 g
fresh weight) (Lawson, 1996). The mature, intact
chemical methods. Among these numerous and abundant
naturallyoccurri ng compounds, essential oil
extracts have been considered as natural preservatives
or food additives, and can be used as additional
methods of controlling pathogens (Naidu, 2000). The
aim of this investigation was to studythe effect of
essential oils extracts of various onion types and garlic
on two major bacterial pathogens, and three fungal
species usuallycausing rotting of Allium crops during
their storage.
2. Materials and methods
2.1. Onions and garlic
Three type of onions (Allium cepa), green onion (var.
Blanc), yellow (var. Jaune d’Espagne) and red
(var. Rouge Amposta), and garlic (Allium sativum)
(var. Cristo), were selected for this investigation. Onions
and garlic were cultivated in Mascara region, and are
free of anypr e-harvest chemical treatment (organic
products). Onions and garlic samples freshlyha rvested
were sorted for uniformityan d absence of defects and
stored at 4_C prior analyses.