Biomedical Engineering Reference
In-Depth Information
derivatives include both Gram-positive and Gram-negative bacteria such as
S. aureus, L. monocytogenes, B. cereus, E. coli, Shigella dysenteria
e, and
Salmonella
Typhimurium (Gyawali and Ibrahim
2014
). Chitosan has attracted
great attention for development of biodegradable edible coatings, singly or dosed
with other antimicrobial substances (Maher et al.
2013
).
2.3
Antimicrobials Derived from Plants
Herbs and spices have been recognized to possess a broad spectrum of active con-
stituents that exhibit antibacterial, antifungal, antiparasitic, and/or antiviral activi-
ties. Essential oils have been used for centuries as part of natural traditional
medicine. They are aromatic oily liquids obtained from plant material (fl owers,
buds, seeds, leaves, twigs, bark, herbs, wood, fruits and roots). The major groups of
principal components that make essential oils effective antimicrobials include sapo-
nins, fl avonoids, carvacrol, thymol, citral, eugenol, linalool, terpenes, and their pre-
cursors (Burt
2004
). The antimicrobial activity of alliums is mainly attributed to
various kinds of alk(en)yl alka/ene thiosulfi nates (thiosulfi nates; and their transfor-
mation products (Kyung
2012
). Allium-derived antimicrobial compounds inhibit
microorganisms by reacting with the sulfhydryl (SH) groups of cellular proteins. In
olive oil, distinctive antimicrobial compounds including oleuropein, oleuropein
aglycon, elenoic acid and oleocanthal (in addition to hydroxytyrosol and tyrosol)
have been described (Cicerale et al.
2012
). The antibacterial activities of essential
oils and other plant extracts has attracted great attention for application of the crude
extracts or their bioactive components in food biopreservation (Burt
2004
; Holley
and Patel
2005
; Richard and Patel
2005
; Tajkarimi et al.
2010
). In the concentration
range of 0.05-0.1 %, essential oils have demonstrated activity against pathogens, such
as
S.
Typhimurium,
E. coli
O157:H7,
L. monocytogenes
,
B. cereus
and
S. aureus
, in
food systems. However, activity against various microorganisms on food products
might be higher than the concentration applied for fl avoring purposes. As a result,
this might cause food tainting and/or adverse sensorial effects to food products
(Bagamboula et al.
2004
). It has been suggested that the adverse sensorial effects of
essential oils agents to food products can be overcome by masking the odor with
other approved aroma compounds (Gutiérrez et al.
2009
). Antimicrobial agents
derived from essential oils are interesting candidates for development of activated
fi lms or packagings.
Plants also produce a variety of antimicrobial peptides, many of which can be
grouped in different classes: thionins, defensins, lipid transfer proteins, cyclotides
and snakins (Padovan et al.
2010
). Some of them could possibly be exploited for
food biopreservation. Interestingly, plants can be a good source of antifungal pro-
teins and peptides, including chitinases, glucanases, thaumatin-like proteins, thion-
ins, and cyclophilin-like proteins (Ng
2004
).
