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VIRUSES
The effect of chitosan on the
infectivity of murine norovirus, feline caliciovirus,
and MS2 bacteriofage.
Su X., Zivanovic S., D'Souza DH.
(2009) J Food Protection. In press.
BACTERIA
Molecular weight of chitosan
influences antimicrobial activity in oil-in-water
emulsions.
Zivanovic S., Basurto C.C., Chi
S., Davidson P.M., Weiss J. 2004. J. Food
Protection. 67:952-959.
The
objective of this study was to evaluate the
antimicrobial efficiency of chitosans in oil-in-water
emulsions. Model emulsions were prepared with 20% corn
oil, 1.5% Tween 20, 1.5% Trypticase soy broth, 0.58%
acetic acid, and chitosan polysaccharide or chitosan
oligosaccharide in concentrations of 0, 0.1, 0.2, 0.5,
and 0.7%. A control containing HCl was included to
determine the role of acetic acid in the overall
antibacterial activity. The pH of samples and controls
was adjusted to 4.5. Emulsions were inoculated with
Listeria monocytogenes (strains Scott A and 310) or
Salmonella Typhimurium DT104 (strains 2486 and
2576) at a level of 107 CFU/ml. Inoculated
emulsions were incubated at 10 and 25°C for 4 days and
analyzed for bacterial count every 24 h. Both tested
Salmonella strains were more susceptible to acetic
acid than Listeria. However, L. monocytogenes
was more affected by chitosan than either Salmonella
strain. During the storage at 25°C, initial inoculum in
the emulsions with 0.58% acetic acid and 0.1% chitosan
polysaccharide was reduced to below the detection limits
after 24, 48, 72, or 96 h for L. monocytogenes
310, Salmonella Typhimurium DT104 2576,
Salmonella Typhimurium DT104 2486, or L.
monocytogenes Scott A, respectively. Chitosan
oligosaccharide was less effective against all tested
bacteria and showed a concentration-dependent effect.
The antimicrobial efficacy of chitosan was reduced at
10°C, and reduction of microbial loads was delayed for
approximately 24 h compared with 25°C. Results suggest
that addition of 0.1% chitosan polysaccharide would be
sufficient to ensure the microbial safety of
oil-in-water emulsions regardless of storage temperature
Physical, mechanical and
antimicrobial properties of chitosan/PEO blend
films.
Zivanovic S., Li J., Davidson
P.M., Kit K. 2007. Biomacromolecules 8(5):1505-1510.
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Films formed by blending of two polymers usually have modified
physical and mechanical properties compared to films made of the
individual components. Our preliminary studies indicated that
incorporation of chitosan in polyethylene oxide (PEO) films may
provide additional functionality to the PEO films and may
decrease their tendency to spherulitic crystallization. The
objective of this study was to determine the correlation between
chitosan/PEO weight ratio and the physical, mechanical, and
antibacterial properties of corresponding films. Films with
chitosan/PEO weight ratios from 100/0 to 50/50 in 10% increments
were characterized by measuring thickness, puncture strength
(PS), tensile strength (TS), elongation at break (%E),
water vapor permeability (WVP), and water solubility (WS).
Additionally, the films were examined by polarized microscopy,
wide-angle X-ray diffraction (WAXD), and Fourier transform
infrared (FTIR) spectroscopy, and their antibacterial properties
were tested against Escherichia coli. The chitosan
fraction contributes to antimicrobial effect of the films,
decreases tendency to spherulitic crystallization of PEO, and
enhances puncture and tensile strength of the films, while
addition of the PEO results in thinner films with lower water
vapor permeability. Films with 90/10 blend ratio of chitosan/PEO
showed the most satisfactory PS, TS, %E, and
antibacterial properties of all tested ratios
Application of chitosan films enriched with oregano essential
oil on Bologna – active compounds and sensory attributes
Chi S., Zivanovic S., Penfield
M. 2006. Food Sci. Technol. Intern. 12(2):111-117.
Chitosan
films prepared with oregano essential oil were applied on
bologna slices. Release of the essential oil compounds during
film preparation and application on the meat product and
consumer acceptability of bologna enriched with oregano
essential oil were tested. Oregano essential oil compounds were
quantified by gas chromatography mass spectroscopy (GCMS) after
extraction from the film-forming solution, films before and
after application on bologna and from bologna slices before and
after application of the films. The results indicated that the
concentration of components of the essential oil sharply
decreased during film preparation, e.g. from 757.7 ppm carvacrol
in film-forming solution to 2.1 ppm in dried films. No carvacrol
was detected in the films after application on bologna for 5
days at 4 degrees C, mainly due to its diffusion into bologna.
It seemed that the moisture and high lipid content of bologna
helped the diffusion of the oregano essential oil from the
chitosan film matrix into the product. Sensory evaluation
suggested that addition of 45 ppm or less of oregano oil to
bologna would be acceptable to consumers. Results support the
potential use of chitosan-oregano essential oil films as an
antimicrobial packaging material for processed meat.
Antimicrobial activity of essential oils incorporated in chitosan films
Zivanovic S., Chi S., Draughon F.A. 2005.. J. Food Sci. 70:M45-M51.
http://www3.interscience.wiley.com/cgi-bin/fulltext/118645675/PDFSTART
Antimicrobial and physicochemical properties of chitosan films and
chitosan films enriched with essential oils (EO) were determined in
vitro and on processed meat. Antimicrobial effects of pure EO of anise,
basil, coriander, and oregano, and of chitosan-essential oil films
against Listeria monocytogenes and Escheri-chia coli
O157:H7 were determined by an agar diffusion test. The antibacterial
effects of the EO were similar when applied alone or incorporated in the
films. The intensity of antimicrobial efficacy was in the following
order: oregano > > coriander > basil > anise. The chitosan films and
chitosan-oregano EO films were applied on inoculated bologna samples and
stored 5 d at 10 °C. Pure chitosan films reduced L. monocytogenes
by 2 logs, whereas the films with 1% and 2% oregano EO decreased the
numbers of L. monocytogenes by 3.6 to 4 logs and E. coli
by 3 logs. Pure chitosan films were 89 μm thick, whereas addition of 1%
and 2% oregano EO increased thickness to 220 and 318 μm, respectively.
During application on bologna discs, the films absorbed moisture,
resulting in the final thickness of 143, 242, and 333 μm, respectively.
Addition of oregano essential oil into the chitosan films decreased
water vapor permeability, puncture and tensile strength, but increased
elasticity of the films. The films have the potential to be used as
active biodegradable films with strong antimicrobial effects.
Inactivation of Escherichia coli K-12 in apple juice using
combination of high pressure homogenization and chitosan.
Kumar S.,
Thippareddi H., Subbiah J., Zivanovic S., Davidson P.M., Harte F. 2009. J. Food
Sci. 74(1):M8-M14.
http://www3.interscience.wiley.com/cgi-bin/fulltext/121495050/PDFSTART
Apple juice and apple cider were inoculated with Escherichia coli
K-12 and processed using a high-pressure homogenizer to study bacterial
inactivation. Seven levels of pressure ranging from 50 to 350 MPa were
used in the high-pressure homogenizer. Two types of chitosan (regular
and water soluble) with 2 levels of concentration 0.01% and 0.1% were
investigated for synergistic effect with high-pressure homogenization
for the bacterial inactivation. E. coli K-12 inactivation was
evaluated as a function of homogenizing pressure at different
concentration of 2 types of chitosan in apple juice and cider.
High-pressure homogenization (HPH) induced significant inactivation in
the range of 100 to 200 MPa, while thermal inactivation was the primary
factor for the bacterial inactivation above 250 MPa. Significant (P
< 0.05) 2-way interactions involving pressure and type of substrate or
pressure and chitosan concentration were observed during the study. The
homogenization pressure and the incremental quantity of chitosan (both
types) acted synergistically with the pressure to give higher
inactivation. Significantly (P < 0.05) higher inactivation was
observed in apple juice than apple cider at same homogenizing pressure.
No effect of type of chitosan was observed on the bacterial
inactivation.
Performance improvement of chitosan films by blending with poly (vinyl
pyrrolidone).
Li J,
Zivanovic S, Davidson PM, Kit K. 2008. Institute of Food Technologists
Annual Meeting; June 28-July 1, 2008; New Orleans, LA.
Antimicrobial activity of hydrophobically modified chitosan.
Wu T,
Zivanovic S, Davidson PM, 2008. Institute of Food Technologists Annual
Meeting; June 28-July 1, 2008; New Orleans, LA.
Antimicrobial properties of chitosan films enriched with essential oils.
Chi S.,
Zivanovic S., Weiss J., Draughon F.A. 2003. Institute of Food
Technologists Annual Meeting; June 12-16, 2003; Chicago, IL. Abstract
29F-15. p 78.
Molecular weight and concentration influences antimicrobial activity of
chitosan in oil-in-water emulsions.
Basurto
C., Zivanovic S., Davidson P.M., Chi S., Weiss J. 2003. Institute of
Food Technologists Annual Meeting; June 12-16, 2003; Chicago, IL.
Abstract 29G-12. p 83.
YEASTS and MOLDS
Physicochemical properties and bioactivity of fungal chitin and chitosan.
Wu T.,
Zivanovic S., Draughon F.A., Conway W.S., Sams C.E. 2005. J. Agri. Food
Chem. 53(10):3888-3894.
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Chitinous material was extracted from mycelia of Aspergillus niger
and Mucor rouxii grown in yeast peptone dextrose broth for 15 and
21 days, respectively. The extracted material was characterized
for purity, degree of acetylation, and crystallinity and tested for
antibacterial and eliciting properties. The maximum glucosamine level
determined in the mycelium of A. niger was 11.10% dw and in the
mycelium of M. rouxii was 20.13% dw. On the basis of the stepwise
extraction of freeze-dried mycelia, it appeared that M. rouxii
mycelia contained both chitin and chitosan, whereas A. niger
contained only chitin. The yields of crude chitin from A.
niger and M. rouxii were 24.01 and 13.25%,
respectively, and the yield of chitosan from M. rouxii was
12.49%. Significant amounts (7.42−39.81%) of glucan were associated with
chitinous compounds from both species and could not be eliminated by the
extraction method used. The degrees of acetylation were determined to be
76.53 and 50.07% for chitin from A. niger and M.
rouxii, respectively, and 19.5% for M. rouxii chitosan. The
crystallinity of fungal chitin and chitosan was estimated to be less
intense than in corresponding materials from shrimp shells. The
extracted chitin and chitosan in a concentration of 0.1% reduced
Salmonella Typhimurium DT104 2576 counts by 0.5−1.5 logs during a 4
day incubation in tryptic soy broth at 25 °C. Furthermore, all tested
chitinous materials from fungal sources significantly reduced lesions
caused by Botrytis cinerea and Penicillium expansum in
harvested apples.
Flocculation of yeast cells as affected by natural biopolymer chitosan.
Michael
L.M., Golden D., Zivanovic S. 2005. Institute of Food Technologists
Annual Meeting; July 16-20, 2005; New Orleans, LA. Abstract 89D-22.
Effects of chitosan and water-soluble chitosan coatings on quality of
small fruits.
Noh J.,
Mount J., Zivanovic S., Sams C.E. 2005. Institute of Food Technologists
Annual Meeting; July 16-20, 2005; New Orleans, LA. Abstract 36E-88.
Fungal chitin extracts are as effective in reducing decay caused by
Botrytis cinerea, Penicillium expansum and Penicillium
solitum as commercial seashell chitin extracts.
Sams C.,
Zivanovic S., Charron C., Wu T., Blodgett A., Conway C. 2004 Annual
Meeting of the American Phytopathological Society, July 31 - August 4,
2004. Anaheim, CA. Abstract 59B.
Extension of fresh produce shelf-life with novel chitosan coatings.
Sams T.,
Zivanovic S., Draughon F.A., Mount J.R., Sams C.E. 2004. Institute of
Food Technologists Annual Meeting; July 12-16, 2004; Las Vegas, NE.
Abstract 49F-19.
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