Antimicrobial Film: Encapsulation of Allyl-Isothiocyanate in β-Cyclodextrin
Dao Yang, Joongmin Shin, Khanah Mokwena
Manufacturing and Packaging Engineering Department, University of Wisconsin-Stout, Menomonie, WI 54751, Email: yangdao@my.uwstout.edu
Abundance
Abstract
Antimicrobial film, including allyl-isothiocyanate (AITC), was performed by
means of compression molding. In order to sustain the release of AITC, a
pungent antimicrobial agent, it was encapsulated into β-cyclodextrin (β-CD) prior
to compression with low density polyethylene (LPDE) resins. Several molar ratios
of AITC-β-CD complex were prepared at (0.5:1.0, 1.0:1.0, 2.0:1.0, 3.0:1.0, and
1.0:2.0) respectively, and more than 90% of AITC was included at the molar ratio
of (2.0:1.0). Various concentration levels of AITC-β-CD complex (0%, 1%, 2%, 4%,
6%, 8%, and 10%) were impregnated into LDPE resins. The release of AITC from
these films was determined in different conditions (relative humidity and
temperature). Results showed that the addition of the AITC-β-CD complex
significantly changed the film’s mechanical properties (tensile strength and
elongation), and optical property (light transmittance). However, the
complexation of AITC and β-CD provided constant releasing rate and maintained
consistent AITC concentration levels during the test period. AITC-β-CD
impregnated with LPDE may be useful as potential antimicrobial packaging films.
Introduction
•
•
•
1.1e+07
1e+07
•
•
AITC reagents
9000000
8000000
7000000
6000000
5000000
4000000
noises
e
3000000
2000000
1000000
0
4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 12.00 13.00 14.00 15.00 16.00
Time-->
5. Impregnation of AITC-β-CD in LDPE
4. Gas Chromatography (GC) analysis
6. Prepare films for analyzing processes
Elongation at break (in.)
0
1
7.6219a
7.6234a
13.2567a
2.5654b
2
7.5654a
2.0641b
4
6.6223b
1.4039c
6
6.5640b
1.1343d
8
6.4538c
0.6931e
10
5.2010d
0.3880f
7. GC analysis of released AITC in films
0% of AITC-β-CD
1% of AITC-β-CD
2% of AITC-β-CD
6% of AITC-β-CD
4% of AITC-β-CD
* Encapsulation efficiency of β-CD (%) = (Recovered AITC/Initially input AITC)(100)
Develop an effective antimicrobial packaging film that is composed of AITC
and β-CD compounds.
Evaluate the release of AITC from AITC-β-CD impregnated in LDPE film
Compare its mechanical properties (tensile strength and elongation) and
optical property (light transmittance) with control LDPE
Table 2. Release of AITC in compression films, as function of time
1%
2%
4%
6%
8%
10%
6.00
Methodology
8% of AITC-β-CD
Conclusion
AITC Reagents (µl/l)
4.00
• 2.0 molar ratio AITC-β-CD complex is the most effective and the AITC encapsulation
efficiency was up to 91.10%.
• AITC-β-CD complex in LDPE maintained a consistent release rate during the 1st week
of test period.
• The impregnation of AITC-β-CD complex into LDPE causes significant changes in
mechanical properties (Tensile strength and Elongation at break)
• Significant changes in distribution were noticed in films above 4% of the applied AITCβ-CD complex
• Immiscibility between films may be due to the hydrophilic and hydrophobic nature of
agents and plastics, respectively.
• Further studies, including barrier property changes on file and actual antimicrobial
effectiveness, will be conducted in the future.
3.00
2.00
1.00
Chemical Structure of β-CD
0.00
Sample preparation & analyzing methods:
0
2
4
6
Day
1. Define molar ratio (AITC:β-CD)
Table 3. Compressed films with concentration of (1%, 2%, 3%, 4%, 6%, 8% and 10%)
Source of Variation
3. SPME absorption of AITC reagents
10% of AITC-β-CD
* Actual size of image is 0.8in x 0.8in
5.00
Materials :
• Low Density Polyethylene (LDPE) from Industrial Arts Supply
• Allyl-isothiocyanate, ≥ 93%, FCC, Food Grade (SAFC)
• β-Cyclodextrin (Sigma-Aldrich)
2. Encapsulate AITC in β-CD
TS (Mpa)
Figure 1. Distribution of antimicrobial film using compression molding method
Antimicrobial packaging is an innovative concept that involves interactions
between the packaging materials, antimicrobial agent, and surrounding
environment to hinder spoilage and pathogenic microorganisms without
damaging the integrity of the packaged food.
AITC is a member of the Brassicaceae family and can be extracted from
common everyday food staples such as mustard, horseradish, and wasabi. If
9. Evaluate optical property
8. Evaluate mechanical properties
frequently consumed, studies have shown that AITC can provide essential
benefits against deoxyribonucleic acid (DNA) damage and cancer due to its
Results and Discussion
high biological activities. Furthermore, this component is also known for its
Table 1. Efficiency of encapsulated AITC-β-CD complex molar ratios
high antioxidative, superoxide scavenging potency, and antimutagenic activity.
Molar ratio of AITC/β-CD
Efficiency (%)*
However, AITC can easily become volatilized when exposed to any
0.5
63.84
nucleophilic agents or foods, thus shortening its effectiveness.
1.0
76.16
β-CD can be produced by means of extraction or obtained by degradation of
starch. It is often used as an application for a control or subsidizing agent due
2.0
91.10
to its excellent polar hydrophilic outer shell and relatively hydrophobic cavity.
3.0
92.59
Chemical Structure of AITC
% of AITC-β-CD Complex
* The letters in each column indicate significantly different means (p<0.05)
Objectives
•
Table 4. Mechanical properties as a function of AITC-β-CD complex contents in LDPE films
SS
df
% of AITC-β-CD complex
Days
Interaction
Within
182.721
12.235
4.063
65.703
5
2
10
144
Total
264.722
161
MS
F
36.5442 80.0938
6.1177 13.4081
0.4063 0.8904
0.4563
P-value
F crit
0.0000
0.0000
0.5438
2.2770
3.0589
1.8970
Acknowledgement
Author would like to thank Dr. Brent Ristow in the chemistry department at UW-Stout
for his assistance and facilities support (including GC-MS and Raman microscope).
Additional thanks to Prof. John Schultz in the plastic engineering department at UWStout for his assistance and facilities support (including compression molder).