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Active packaging film of chitosan and Santalum album essential oil: Characterization and application as butter sachet to retard lipid oxidation

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Chitosan with sandalwood (Santalum album) essential oil (SEO) using malic acid as solvent were evaluated as an active packaging film. It was applied as sachet to butter packaging. The effects of SEO concentration (0.5 %, 1 % and 2 % v/v) on chitosan film properties were studied by measuring the equilibrium moisture content, solubility, water vapor permeability (WVP), mechanical, optical, heat sealability, antioxidant properties, surface morphology and thermostability. SEO showed a significant effect on the film properties except for the puncture properties and the equilibrium moisture values. SEO promoted a significant decrease in tensile strength from 5.78 to 2.99 MPa, Young’s Modulus (YM) from 35.74 to 6.81 MPa, WVP from 6.70·10⁻¹¹ to 3.34·10⁻¹¹ g/m·s·Pa, and sealability from 195.20 to 107.94 N/m. The antioxidant properties of the films were improved with the presence of SEO. The addition of SEO significantly improved the UV-barrier of the films. The color and transparency of the samples showed significant variations by the addition of SEO. The active packaging film was evaluated as butter sachet. After 3 months of butter storage, a significant decrease of the thiobarbituric acid reactive substances was observed, showing a 36 % decrease in the lipid oxidation compared to unpackaged samples. The films are completely water-soluble and can be easily removed from foodstuffs after use without generating solid wastes.
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Food Packaging and Shelf Life 34 (2022) 100938
Available online 5 September 2022
2214-2894/© 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Active packaging lm of chitosan and Santalum album essential oil:
Characterization and application as butter sachet to retard lipid oxidation
María Fl´
orez , Patricia Caz´
on , Manuel V´
azquez
*
Department of Analytical Chemistry, Faculty of Veterinary, University of Santiago de Compostela, 27002 Lugo, Spain
ARTICLE INFO
Keywords:
Film
Sandalwood essential oil
Chitosan
Antioxidant activity
UV-barrier properties, sachets
ABSTRACT
Chitosan with sandalwood (Santalum album) essential oil (SEO) using malic acid as solvent were evaluated as an
active packaging lm. It was applied as sachet to butter packaging. The effects of SEO concentration (0.5 %, 1 %
and 2 % v/v) on chitosan lm properties were studied by measuring the equilibrium moisture content, solubility,
water vapor permeability (WVP), mechanical, optical, heat sealability, antioxidant properties, surface
morphology and thermostability. SEO showed a signicant effect on the lm properties except for the puncture
properties and the equilibrium moisture values. SEO promoted a signicant decrease in tensile strength from
5.78 to 2.99 MPa, Youngs Modulus (YM) from 35.74 to 6.81 MPa, WVP from 6.7010
11
to 3.3410
11
g/msPa,
and sealability from 195.20 to 107.94 N/m. The antioxidant properties of the lms were improved with the
presence of SEO. The addition of SEO signicantly improved the UV-barrier of the lms. The color and trans-
parency of the samples showed signicant variations by the addition of SEO. The active packaging lm was
evaluated as butter sachet. After 3 months of butter storage, a signicant decrease of the thiobarbituric acid
reactive substances was observed, showing a 36 % decrease in the lipid oxidation compared to unpackaged
samples. The lms are completely water-soluble and can be easily removed from foodstuffs after use without
generating solid wastes.
1. Introduction
Food packaging design is one of the most important phases in the
food chain. A perfect food packaging material should protect food
quality over time, being transportable, convenient to use, economical,
and renewable or biodegradable (Priyadarshi & Rhim, 2020). Moreover,
if the packaging has a positive effect on the food, as in the case of active
packaging, its use becomes even more interesting. Active lms are lms
deliberately enriched with active components. These components
release or absorb chemicals in order to prolong the shelf life of the food
while maintaining its sensory and quality characteristics (Yildirim et al.,
2018). Natural and renewable materials are gaining interest due to the
major environmental problems generated by the uncontrolled use of
petroleum derivatives, but also because the consumer has undergone a
trend towards eco-friendly habits.
A wide variety of polysaccharides are being studied for development
as lms intended for food use, such as cellulose (Sirvi¨
o et al., 2014),
starch (Abreu et al., 2015), alginate (Parreidt et al., 2018) and chitosan
(Priyadarshi et al., 2018). Chitosan is the second most abundant
polysaccharide in the world. The exoskeleton of crustaceans is the main
source to obtain chitin and then chitosan by deacetylation. Chitosan and
its derivatives can inhibit the growth of a wide range of molds, yeasts
and bacteria. Chitosan properties like solubility, lm forming ability,
viscosity, chelating ability, antimicrobial properties, among others,
make it an interesting material to apply in multiple areas, including food
packaging (Priyadarshi & Rhim, 2020). Chitosan is soluble in dilute
organic acid which facilitates its application as a lm or coating. The
properties of the chitosan matrix are highly dependent on the type of
solvent used (Rhim et al., 1998). The correct selection of the acid used as
solvent will allow to adapt the properties of the matrix to its purpose. For
example, the use of malic acid results in water-soluble lms that can be
easily removed from foodstuff (Caz´
on et al., 2021). Water soluble lms
can be applied in foods with high fat content and low moisture content,
such as butter, margarine, lard, and oil.
On the other hand, several natural substances, as essential oils are
often added to chitosan lms to enhance their active properties.
Essential oils are aromatic oily liquids obtained from various parts of
plants, such as owers, seeds, roots, wood, herbs, leaves or shoots (Burt,
* Corresponding author.
E-mail address: manuel.vazquez@usc.es (M. V´
azquez).
Contents lists available at ScienceDirect
Food Packaging and Shelf Life
journal homepage: www.elsevier.com/locate/fpsl
https://doi.org/10.1016/j.fpsl.2022.100938
Received 18 May 2022; Received in revised form 4 August 2022; Accepted 22 August 2022
Food Packaging and Shelf Life 34 (2022) 100938
2
2004). Sandal is a type of wood from trees of the genus Santalum. San-
dalwood essential oil (SEO) is clear to yellowish in hue and thick. Its
main use is in the perfume industry, due to its aroma and xative
properties. However, it is also used in the food industry as a avor
ingredient. This essential oil is made up of two main components known
as sesquiterpene alcohols: cis-
α
-santalol (760 %) and cis-β-santalol
(733 %). These alcohols are responsible of the characteristic odor of
sandalwood. Nevertheless, there are minor constituents that should be
taken into account, such as sesquiterpene hydrocarbons (6 %), esters
(24 %), phenols, lactones, terpenes, volatile compounds and fragrant
substances (Burdock & Carabin, 2008; Subasinghe et al., 2013).
SEO has been approved as generally recognized as safe (GRAS) for
use in food as a avoring component by the Flavor and Extract Manu-
facturers Association (No. 3005). It also has been approved by the FDA
as a natural avoring substance that can be used in combination with
other avors. Council of Europe added sandalwood to the list of sub-
stances, spices, and seasonings (Burdock & Carabin, 2008).
The chitosan lms enriched with essential oils have been tested in
multiple foodstuffs. However, no studies have been carried out on water-
soluble chitosan-based active lms for extending the shelf-life of foods.
The main advantage of these lms is that they are easily disposable
without environmental impact, but their soluble nature limits their ap-
plications in foods with high moisture content. Nevertheless, they can be
an useful tool for preserving foods with high lipid content. This type of
food tends to suffer easily from lipid oxidation, which causes off-avors
and degradation of colors and nutrients (Vieira et al., 2017).
To our knowledge, SEO-chitosan lms have not been studied.
Considering the potential application of SEO in food packaging and the
suitability of chitosan as a matrix to carry active agents, the objectives of
this study were to develop and characterize the physic-chemical prop-
erties of a novel SEO-chitosan lm. The effect of SEO at different ratio on
the mechanical, water vapor permeability (WVP), optical, equilibrium
moisture content (%W), solubility, sealability (S), and antioxidant
properties of chitosan lms were evaluated. The surface morphology,
compatibility, and thermostability of the lm were also evaluated using
scanning electron microscope (SEM), Fourier transform infrared spec-
troscopy (FT-IR) and simultaneous thermal analysis (TGA/DSC).
Considering the water-soluble nature of chitosan lm from malic acid
solutions (Caz´
on et al., 2021), its antioxidant and lipid oxidation
retarding capacity has been evaluated in high-fat foods, by selecting
butter as a model food. Its application in butter has been tested by
analysing the antioxidant and optical properties of the lms as well as
the thiobarbituric acid reactive substances (TBARS) of the butter sam-
ples after 90 days of storage.
2. Experimental
2.1. Materials
Chitosan (M
w
100000300000 and CAS number 9012764) was
purchased from Acros organics (Geel, Belgium) and DL-malic acid extra
pure (CAS number 6915157) was provided by Scharlau Microbiology
(Barcelona, Spain). Soy lecithin supplied by Ynsadiet (Madrid, Spain)
and pure sandalwood essential oil supplied by Pranarˆ
om (Ghislenghien,
Belgium) were used to prepare the chitosan lm-forming solution. The
food packaging properties of the developed lms were tested on butter
purchased from Mantequería Arias (Madrid, Spain).
2.2. Preparation of lms
Chitosan lms were made by dissolving 1 % (w/w) chitosan in an
aqueous solution of 2 % (w/v) malic acid (Table 1). The acid concen-
tration was adjusted until the chitosan was completely dissolved,
yielding a clear solution. The stock solution was kept stirred overnight at
room temperature. As a natural emulsier, soy lecithin (0.1 % w/v) was
added to the solution. Chitosan-soy lecithin solution was homogenized
at 15,000 rpm for 5 min (Ultra Turrax®, IKA, Staufen, Germany). The
foam formed in the mixture was removed with the aid of an ultrasonic
bath for 15 min. Subsequently, the SEO was added until a nal con-
centration ranged 02% (v/v), and homogenized at 15,000 rpm for 5
min following by a degassed step in an ultrasonic bath for 15 min.
From the resulting lm-forming solution, 40 ml were poured in a
Petri dishes of 210 mm diameter and dried for 48 h at room temperature.
The lms were cut to a specic size and stored for 5 days at determined
conditions depending on the test. The thickness (mm) was measured at
ve random locations using a Thickness Meter ET115S (Etari GmbH,
Stuttgart, Germany).
2.3. Scanning electron microscope (SEM)
SEM pictures were used to examine and characterize the morphology
of SEO-chitosan lms made with malic acid as solvent. High-vacuum
microscope (JEOL JSM-6360LV, Jeol Ltd, Tokyo, Japan) was used to
photograph dried and gold-coated samples at an accelerating voltage of
20 kV. Using conductive double-sided carbon tape, samples were
adhered to slides.
2.4. Fourier transform infrared spectroscopy (FT-IR)
FT-IR ABB Bomen 102 (ABB Ltd, Zurich Switzerland) tted with a
Universal Attenuated Total Reectance (UATR) accessory (SPECAC
Golden Gate) with diamond crystal was used to examine the presence of
certain chemical groups and crosslinking in the lms. The selected
samples were conditioned for 48 h at 65 ±2 % relative humidity and 21
±1 ºC. FTIR spectra in the range (4004000) cm
1
were recorded at a
spectral resolution of 4 cm
1
.
2.5. Water solubility, equilibrium moisture and water vapor permeability
Water solubility of the samples was measured using the gravimetric
method of immersion in a known volume of distilled water, as described
elsewhere (Caz´
on et al., 2019). The equilibrium moisture content (%W)
was estimated using the gravimetric method by comparing the weights
of conditioned samples at 33 % relative humidity (% RH) and dried
samples (Caz´
on et al., 2019). Water vapor permeability (WVP) was
measured following the ASTM Standard Test Method E96 (https://www.
astm.org/Standards/E96.htm). The WVP of the samples was determined
at 30 ºC and considering 50 % RH, as an intermediate value between the
two levels which dene the RH gradient utilized in the WVP determi-
nation. The test was run at least 4 h, enough time to reach a dynamic
equilibrium in the vapor ux. Each test was carried out by triplicate.
2.6. Mechanical properties analysis
Tensile and puncture tests were performed on the lms with a tex-
turometer (TA-XT plus, Stable Micro System, UK) and the accessories
recommended for each test. Tensile strength (TS, MPa), percentage of
elongation at break (%E, %) and Youngs Modulus (YM, MPa) were
measured by the tensile test. The test was performed using the ASTM
standard method D-882 (https://www.astm.org/d088218.html), with
the initial grips spacing set to 40 mm and the load rate at 1 mm/s. The
Table 1
Films composition of lecithin and sandalwood essential oil (SEO). Samples
contains also chitosan 1 % (w/w) and malic acid 2 % (w/v).
Film samples Lecithin SEO
% (w/v) % (v/v)
SEO-chitosan_0 0 0
SEO-chitosan_0.5 0.1 0.5
SEO-chitosan_1 0.1 1.0
SEO-chitosan_2 0.1 2.0
M. Fl´
orez et al.
Food Packaging and Shelf Life 34 (2022) 100938
3
samples were cut to 15 ×100 mm and conditioned for 5 days at room
temperature and 57 % RH before being clamped between the grips of the
texturometer. Seven replicates were tested for each batch (Caz´
on et al.,
2018).
In the puncture test, a lm holder (Reference HDP/FSR, Stable Micro
System, UK) was used with the texturometer to hold the lm sample.
Sample squares for each batch were cut to 30 ×30 mm and conditioned
at 57 % RH for at least 5 days before analysis. A cylindrical probe (d =3
mm) with a speed of 1 mm/s was used and the force was recorded until
rupture. The burst strength (BS) and distance to burst (DB) were
computed using the force (g) against strain (mm) curves.
2.7. Seal strength property
Film samples were cut into 15 ×100 mm. Two lm were placed
together and an area of 10 ×10 mm at the edge of the lms was heat-
sealed using a vacuum heat-sealer (Model PH7 Food Machinery,
Madrid, Spain) and a sealing time of 2.5 s. Seal strength of the heat-
sealed lms was determined according to the ASTM standard method
F88/F88M-21 (https://www.astm.org/f0088_f0088m-21.html) using a
texturometer (TA-XT plus, Stable Micro System, UK). Each tail of the
sealed lm was clamped to the opposing grips and the seal remains
unsupported while the test is being conducted (technique A: unsup-
ported) (Fig. 1). The distance between the grips was set to 50 mm. A 5 kg
load cell and a test speed of 30 mm/min were used. The seal strength (N/
m) was given as the highest force required to cause seal failure. Seal
strength was calculated by the following Eq. 1 (Prateepchanachai et al.,
2019):
Seal strength (N/m) =peak force/film width (1)
2.8. Antioxidant properties of lms
Two procedures were used to determine the antioxidant capacity of
the pure SEO and the SEO-chitosan lms: 1,1-diphenyl-2-picrylhydrazyl
radicals (DPPH
) and the 2,2-azino-bis (3-ethylbenzothiazoline-6-
sulfonic acid) (ABTS
•+
) free radical scavenging assay. The aliquots were
obtained by the methanolic extracts of the lms, using 1 g of sample in
24 ml of methanol and left overnight in darkness.
UV-Vis spectrophotometer V-670 (Jasco Inc, Japan) at 515 nm was
used to examine the radical scavenging on DPPH
, and at 734 nm to
analyze the ABTS
•+
radical cation scavenging activity following the
method described elsewhere (Antoniewska et al., 2018; Rutkowska
et al., 2020). The results were expressed as % DPPH
and % ABTS
•+
scavenging activity.
2.9. Optical and thermal (TGA/DSC) properties of lms
Spectrophotometer V-670 (Jasco Inc, Japan) was used to measure
the UV-Vis spectra of the lm samples in the UV-Vis light ranges
(190800 nm) and optical properties of the samples were determined as
described elsewhere (Caz´
on et al., 2019).
TGA/DSC (Mettler Toledo, Switzerland) thermogravimetry and dif-
ferential scanning calorimetry equipment were used to analyze the
thermal stability properties of the lms. The samples were placed in
hermetic aluminum pans, and the test was carried out at a heating rate of
10 ºC/min from 50 to 400 ºC, in a nitrogen atmosphere (50 ml/min).
2.10. Storage stability of butter packed in SEO-chitosan sachets
Rectangular samples of butter (6 g) were packed in chitosan sachets
with different SEO concentration (02 %). Unpackaged butter samples
were considered as control sample. The samples were stored at 5 C for 3
months. The storage time was selected based on previous studies which
indicate that there are signicant changes in the quality of butter after 3
months in the refrigerator (Krause et al., 2008; Okturk et al., 2001).
The DPPH
and ABTS
•+
parameters were analysed in unpacked and
packed butter samples after 3 months of storage. The procedure fol-
lowed was as aforementioned and the analysis was by triplicated.
The TBARS values in the butter samples were determined using a
spectrophotometric method (Zeb & Ullah, 2016). Butter samples (1 g)
was mixed with 5 ml of acetic acid glacial. Then, the solution was added
to 0.5
μ
L butylhydroxytoluene (BHT). Extraction was performed with
funnel and lter paper. Aliquot of 1 ml of extract was mixed with 1 ml of
thiobarbituric acid solution. The mixture was incubated at 95 ºC for 1 h,
then the absorbance was measured at 532 nm. The results were
expressed as mg malondialdehyde (MDA)/kg butter.
Samples of packaged butter with the lms were analyzed for color
(L*, a*, and b* values) after 3 months of refrigerated storage at 5ºC using
a colorimeter ColorStriker (Mathai, Hannover, Germany). Two measures
were carried out for control, each treatment and replicate.
2.11. Statistical analysis
The results obtained were statistically analyzed employing Microsoft
Excel® software by one-way analysis of variance (ANOVA). The Tukey
Post Hoc test was used to analyze differences between pairs of values
based on condence intervals. The least signicance difference was
p<0.05.
3. Results and discussion
The formulations of the experiments are shown in Table 1. The lm-
forming solution was prepared at room temperature, which resulted in a
low-energy procedure. For complete dissolution of chitosan, a malic acid
concentration of 2 % was required. During the incorporation of soy
lecithin and SEO, some foam was formed under stirring. An ultrasonic
bath was applied to remove the foam, resulting in a bubble-free solution
with a milky appearance. The lms were peeled off the Petri dishes.
They were easy to handle. It was detected a certain adhesion charac-
teristic that could be of interest for their application as food packaging.
Fig. 1. SEO-chitosan lm running sealability test. SEO is sandalwood essen-
tial oil.
M. Fl´
orez et al.
Food Packaging and Shelf Life 34 (2022) 100938
4
3.1. Scanning electron microscopy (SEM)
The SEM images of the bottom, top and cross section are shown in
Fig. 2. Pure chitosan lms showed a smooth and at surface. Never-
theless, a discernible change in the chitosan lm microstructure was
detected when the concentration of SEO in the lms increased. The
bottom SEM images, which correspond to the side in direct contact with
the Petri dish, suggested that the addition of soy lecithin allowed a ho-
mogeneous distribution of the oil in the lms. No irregularities or breaks
were detected on the lms that could indicate that the ultrasonic bath
was effective to remove any bubbles (Caz´
on et al., 2021).
However, the top SEM images indicated that when SEO was incor-
porated into the chitosan lm, the uniformity of the lms morphology
was compromised. The top surface suggested that there were certain
areas of heterogeneity. This is attributed to oil droplets trapped in the
polysaccharide network. When the SEO concentration reached 2 %, the
formation of larger oil droplets was observed, this could be due to a
higher frequency of collisions between oil droplets, resulting in a
probable coalescence (Peng & Li, 2014). These oil droplets were not
exactly spherical, as is usual in other emulsions such as oil/water. This
could be related to the traction forces generated by the chitosan network
when the solvent evaporates (Hafsa et al., 2016).
On the other hand, the cross-section images conrm the presence of
an oil phase in the lm, which also causes the lm to cut less cleanly
compared to pure chitosan lm. This was also noticeable when handling
the lms, an increase in adhesiveness could be observed as the oil
concentration increased. Similar behavior has been described for chi-
tosan lms with Citrus limonia essential oil (Gonçalves De Oliveira Filho
Fig. 2. Scanning electron microscopy images of the top, bottom and cross section of the SEO-chitosan lms using malic acid as solvent. SEO is sandalwood
essential oil.
M. Fl´
orez et al.
Food Packaging and Shelf Life 34 (2022) 100938
5
et al., 2020) or Eucalyptus globulus essential oil (Hafsa et al., 2016).
3.2. Fourier transform infrared spectroscopy (FT-IR)
Fig. 3a shown the FT-IR spectra in the range between 4000 and
800 cm
1
of SEO-chitosan lms. This analysis was done with the aim of
identifying possible molecular interactions between the functional
groups of chitosan, malic acid, soy lecithin and SEO in the lm structure.
The FT-IR spectra of pure chitosan samples showed all the characteristic
bands. The stretching vibrations of -OH and -NH are represented by the
absorption bands at 35003400 cm
1
. The stretching vibrations of the
C-H bond in the -CH
2
group give the absorption peaks at 2928 cm
1
(Kalaycıo˘
glu et al., 2017). Whereas the amide-I vibrations of stretching
C
O are represented by the absorption at 1700 cm
1
, the amide-II vi-
brations of stretching NH
2
are represented by the absorption at
1554 cm
1
(Priyadarshi et al., 2018). The vibrations of the C-C y C-O
stretches and the bending of C-H bonds in polysaccharide structure can
explain the spectrum absorption between 1200 and 800 cm
1
(Liu et al.,
Fig. 3. a) FT-IR spectra of SEO-chitosan lms using malic acid as solvent, b) UVVIS spectra prole of SEO-chitosan lms using malic acid as solvent. SEO is
sandalwood essential oil.
Table 2
Physical and mechanical properties of chitosan lms. Film composition is described in Table 1.
Film samples %W WVP TS %E
% g/msPa MPa %
SEO-chitosan_0 0.78 ±0.13 6.7010
11
±7.0910
12 a
5.78 ±2.62
a
27.68 ±2.91
a
SEO-chitosan_0.5 0.60 ±0.06 4.5210
11
±5.2210
12 b
11.40 ±2.70
b
48.86 ±6.38
b
SEO-chitosan _1 0.68 ±0.11 4.2610
11
±1.5610
12 bc
2.20 ±0.43
c
74.01 ±10.9
c
SEO-chitosan _2 0.78 ±0.20 3.3410
11
±8.2810
12c
2.99 ±0.43
c
94.53 ±9.98
d
Film samples YM BS DB Sealability (S)
MPa g mm N/m
SEO-chitosan_0 35.74 ±12.07
a
3209.49 ±1222.02 7.18 ±0.78 195.20 ±33.74
a
SEO-chitosan_0.5 68.43 ±12.89
b
3147.06 ±404.13 6.34 ±0.67 80.88 ±6.49
bc
SEO-chitosan_1 7.84 ±0.74
c
2680.35 ±543.72 6.36 ±0.89 79.09 ±1.72
b
SEO-chitosan_2 6.81 ±0.80
c
2874.04 ±380.04 6.19 ±0.34 107.94 ±8.45
c
SEO sandalwood essential oil; %W - equilibrium moisture content; WVP - water vapor permeability; TS - tensile strength; %E - percentage of elongation to break; YM -
Youngs modulus; BS - burst strength (puncture properties); DB - distance to burst (puncture properties);
Values are expressed as mean ±standard deviation. Different letters in the same column indicate signicant differences (p ˂ 0.05).
M. Fl´
orez et al.
Food Packaging and Shelf Life 34 (2022) 100938
6
2013). An important change was found with a new peak at 1745 cm
1
,
indicating that with increasing SEO concentration there was an increase
in the interaction between CH and the essential oil. The C
O stretching
vibrations in the ester structures contained in fatty acids were respon-
sible for this band, which is the distinctive band of oils (Priyadarshi
et al., 2018). As a result of the probable interactions between chitosan,
oil and soy lecithin, the intensity of the amide-II peak of chitosan in the
blend lm was reduced.
It can be determined that the addition of SEO to the chitosan lms
exerts modications on the spectra of the chitosan lms. All these
changes could be related to a possible intermolecular interaction and
molecular compatibility between the functional groups of the essential
oil and the hydroxyl and amino groups of the chitosan matrix. Similar
results were observed when various types of fats (Akyuz et al., 2018),
citronella and cedarwood essential oil (Shen & Kamdem, 2015) or
turmeric extract (Kalaycıo˘
glu et al., 2017) were added to chitosan lms.
3.3. Evaluation of the water solubility, equilibrium moisture content and
water vapor permeability (WVP)
To determine the water solubility of the lms, the soluble matter of
the samples was analysed. After a few seconds of immersion in distilled
water, the lms lost the whole structure and is completely water soluble.
This is because malic acid is not a volatile solvent, therefore it remained
in the matrix and improved lm solubility. In addition, it was observed
that the presence of SEO in the matrix did not decrease the solubility of
the lms. This is an interesting because the lm can be easily removed
from foodstuffs avoiding solid wastes.
The equilibrium moisture content (%W) of SEO-chitosan lms
ranged between 0.60 % and 0.78 % as shown in Table 2. The addition of
SEO to the chitosan lms showed no signicant differences (p>0.05) in
equilibrium moisture content.
The WVP values calculated for chitosan lms were ranged between
3.3410
11
6.7010
11
g/msPa, as shown Table 2. The addition of
SEO showed a signicant difference on WVP values (p<0.05) as
compared with pure chitosan lms. The presence of hydrophobic
compounds of the essential oil promoted the decrease of WVP, reaching
a reduction of almost 50 % at a 2% SEO concentration. The presence of
the oil droplets observed in the SEM images (Fig. 2) created a tortuous
path that made it difcult for the water molecules to permeate through
the matrix. Moreover, the increased number of hydrogen bonds between
the functional groups of the chitosan and the SEO may decrease the
availability of hydrophilic groups to interact with water molecules,
resulting in a more water-resistant layer (Shen & Kamdem, 2015).
The observed effect of SEO addition on chitosan lms in the present
study is in agreement with the results obtained by Shen and Kamdem
(2015), who found that adding 10 % (w/w) citronella and cedarwood
essential oil into chitosan lms resulted in a considerable reduction in
the WVP of the samples. In a similar way, Yuan et al. (2016) observed a
signicant decrease in the WVP of chitosan lms with cinnamon
essential oil.
It should be noted that certain factors such as chitosan properties,
lm composition, WVP method and measurement conditions or lm
thickness, are important for the subsequent WVP results (Rhim et al.,
1998).
3.4. Evaluation of the mechanical properties
Table 2 shows the results of mechanical properties obtained from the
tensile and puncture tests. The tensile test for SEO-chitosan lms showed
values in the range 2.2011.40 MPa for TS, 27.6894.53% for E% and
6.8168.43 MPa for YM. The addition of SEO to chitosan lm had a
signicant effect (p<0.05) on the three tensile properties analysed.
The values of TS and YM decreased while the %E values increased by
the addition of SEO, indicating a decrease in the resistance to break and
an increase in the deformation capacity by the addition of SEO. The
changes in the mechanical behavior could be explained by the structural
arrangement of the lipid phase in the chitosan matrix, as shown the SEM
images (Fig. 2). The structural arrangements resulted in a discontinuous
and open matrix with unequal physical interactions (Fl´
orez et al., 2022).
Besides, the incorporation of essential oil into chitosan lms could
disrupt polymer-polymer interactions, leading to weaker essential
oil-polymer interactions, resulting in a plasticizing effect of the essential
oil (Hosseini et al., 2015). The new interactions gave a less stiff structure
due to the reduction of the cohesion of the polymer network forces,
decreasing the TS and YM values and increasing the %E. Same trend in
the mechanical properties was observed when Origanum vulgare (Hos-
seini et al., 2015) or Melaleuca alternifolia (Caz´
on et al., 2021) essential
oil were added to chitosan lms.
The puncture test results revealed a statistically non-signicant ef-
fect of SEO concentration on BS and DB values, despite a slightly
decrease of the values was observed (Table 2). The samplesdeformation
and how the polymer chains must arrange under deformation forces in
several directions differ from the restructuring and deformation produce
Table 3
Antioxidant properties of the developed chitosan-based lms and SEO. Film
composition is described in Table 1.
Samples DPPH
(%)
ABTS
•+
(%)
SEO 78.23 ±4.87 15.65 ±0.86
SEO-chitosan_0.5 7.34 ±1.64
a
2.54 ±0.27
a
SEO-chitosan_1 12.74 ±3.38
a
8.75 ±0.10
b
SEO-chitosan_2 23.69 ±6.03
b
19.22 ±0.57
c
SEO - sandalwood essential oil
Values are expressed as mean ±standard deviation.
Different letters in the same column indicate signicant differences (p ˂ 0.05).
Table 4
Optical properties and color parameters of the lms. Film composition is described in Table 1.
Film samples UV-C UV-B UV-A Transparency Opacity
%T %T %T
SEO-chitosan_0 6.01 ±0.78 16.53 ±1.28 35.88 ±1.84 34.90 3.87
SEO-chitosan_0.5 1.59 ±0.01 6.54 ±0.04 19.73 ±0.08 37.40 8.38
SEO-chitosan_1 0.33 ±0.00 2.45 ±0.01 7.87 ±0.03 32.22 19.39
SEO-chitosan_2 0.16 ±0.18 1.14 ±0.95 3.50 ±2.09 18.01 22.13
Samples L* a* b*
SEO-chitosan_0 84.73 ±3.81
a
-0.48 ±0.27
a
6.18 ±0.45
a
SEO-chitosan_0.5 66.62 ±8.17
b
1.67 ±1.01
b
15.1 ±4.45
b
SEO-chitosan_1 59.87 ±11.14
a
1.21 ±0.31
b
8.40 ±1.27
a
SEO-chitosan_2 33.88 ±6.52
a
1.62 ±0.71
b
8.15 ±1.50
a
SEO - sandalwood essential oil; UV-C (200280 nm); UV-B (280315 nm); UV-A (315400 nm); %T - percentage of transmittance; L* , lightness: black =0 and white
=100; a* , green =-a* and red = +a* ); b* , blue =-b* and yellow= +b* .
Values are expressed as mean ±standard deviation.
Different letters in the same column indicate signicant differences (p ˂ 0.05).
M. Fl´
orez et al.
Food Packaging and Shelf Life 34 (2022) 100938
7
by a single horizontal force. Hence, under tensile or puncture defor-
mation forces, the same matrix can exhibit different resistance and
deformation behavior (Caz´
on et al., 2021).
In the manufacture of lms, heat sealability of the material and its
durability is important. In addition, if these lms are intended for food
use, they should be strong enough to keep the product sealed and not
release their contents during storage and handling. The SEO-chitosan
samples showed a sealability values ranged from 79.09 to 195.20 N/m
(Table 2). The addition of SEO to the chitosan lms had a signicant
effect (p<0.05) on the sealability of the lms, resulting in a decrease in
sealability values as the SEO concentration increased. It was noted that
the lm without SEO showed the highest values of sealability
(195.20 N/m). This could be explained by the different active compo-
nents of sandalwood essential oil, which could exert a modication on
the network of the lm. Results are in the range obtained for lms of
chicken protein/sh skin gelatin mixtures containing gallic acid or
tannic acid where values of 64.83113.5 N/m in the sealability of the
lms were observed (Nilsuwan et al., 2021).
3.5. Evaluation of antioxidant properties
Antioxidant activity of pure SEO and SEO-chitosan lms was eval-
uated by two methods: ABTS
•+
and DPPH
(Table 3). Pure sandalwood
results showed values of 78.23 % for DPPH
and 15.65 % for ABTS
•+
verifying the antioxidant capacity of the essential oil and its suitability
for application in food lms. The results obtained from the lm extracts
showed values from 7.34 % to 23.69 % DPPH
and the scavenging
ABTS
•+
activity ranged from 2.54 to 19.22 %. Both scavenging activities
increased signicantly (p<0.05) with increasing oil concentration.
After the addition of SEO (from 0.5 % to 2 %), the antioxidant capacity
of the lms increased signicantly. Sandalwood essential oil contains a
great variety of sesquiterpenoid alcohols called santalols (Demole et al.,
1976).
α
-santalol is the main bioactive principle of the oil, therefore
most of the antioxidant activities are attributed to it (Misra & Dey,
2013). This behavior can be attributed to the presence of these active
components from the essential oil, which can exert their antioxidant
activity by several possible mechanisms: free-radical scavenging activ-
ity, hydrogen donors, transition-metal-chelating activity, and/or
singlet-oxygen-quenching capacity (Liyana-Pathirana & Shahidi, 2006).
3.6. Evaluation of the optical properties
The UV-barrier properties of the SEO-chitosan lms were determined
from the transmittance values in the UV region. The color and opacity of
the lms were determined from the transmittance values in the visible
region.
Table 4 shows the average percentage of transmittance (%T) of the
examined SEO-chitosan lms in the UV-C (200280 nm), UV-B
(280315 nm) and UV-A (315400 nm) regions. Fig. 3b shows the UV
prole spectra of the lms. SEO-chitosan lms showed %T values ranged
6.010.16 %, 16.531.14 % and 35.883.50 % in the UV-C, UV-B and
UV-A regions, respectively. The results concluded that the addition of
SEO to the chitosan lms exerted a signicant decrease in the trans-
mittance values and thus improving the UV blocking capacity of the
lms.
The best results were obtained on lms with 2% SEO, where the
transmittance percentage was below 5 % in the 200400 nm wavelength
region, which reafrmed the good UV-barrier properties of the lm.
These results showed that chitosan lms containing SEO may retard UV-
induced lipid oxidation.
Other important factors when assessing optical properties are
transparency and opacity, as these have a direct impact on the visual
appearance of the product to be coated. Table 4 shows the values of
transparency ranged 18.0137.40, while opacity values ranged
22.133.87. As can be seen, the addition of SEO promoted the decrease
in the transparency values and an increase in the opacity of the lms. A
decrease in light transmission with the addition of SEO, with a conse-
quent increase in opacity and a decrease in transparency, was also
previously observed by the addition of essential oils in edible lms
(Tongnuanchan et al., 2012).
Table 4 shows the CIE coordinates of the SEO-chitosan lms. Light-
ness (L*) varied from 33.88 to 84.73. The addition of SEO had a sig-
nicant effect (p<0.05) compared to pure chitosan lms. Increasing
SEO concentration, a signicant decrease in L* values was shown,
indicating a tendency of the lm to darken (Zhang et al., 2018).
Fig. 4. Thermogravimetry and differential scanning calorimetry of SEO-
chitosan lms using malic acid as solvent. SEO is sandalwood essential oil.
M. Fl´
orez et al.
Food Packaging and Shelf Life 34 (2022) 100938
8
However, the b* and a* values increased signicantly from 6.18 to 15.1
and from 0.481.67 when the oil was at a concentration of 0.5%. The
increase in a* and b* values explains that the samples have a tendency
towards redness and yellowness compared to the pure chitosan lm. The
same trend in the results was observed when Melaleuca alternifolia
essential oil was added to chitosan lms (Caz´
on et al., 2021).
3.7. Evaluation of the thermal properties (TGA/DSC)
The SEO-chitosan lms were evaluated by TGA/DSC for study the
effects of sandalwood essential oil on the thermal physical property.
Fig. 4 shows the thermograms of chitosan lms, pure or enriched with
SEO up to 2 % (v/v).
Thermogravimetric curves indicated similar thermal behaviors with
three steps. There are slight differences related to the composition of the
samples. The weight loss between 50 and 150 ºC is due to the loss of
water linked to the internal structure of the lm (Chu et al., 2019). In
comparison, weight loss was slower in pure chitosan lms in agreement
with the data obtained for %W. It must be taken into account that some
of the water present in the lm may evaporate before the TGA/DSC
analysis is carried out and the temperature of 50 ºC is reached (Caz´
on
et al., 2021). The second weight loss step is due to thermal degradation
of the chitosan (Chen et al., 2008; Lewandowska, 2009). Finally, in the
third step there is a weight loss probably due to the degradation of
by-product generated by chitosan during the thermal degradation
process.
Endothermic peaks were found between 140 and 240 ºC. These peaks
correspond to chemisorbed water via hydrogen bonds, and the degra-
dation of the chitosan amino group and the malic acid (Bonilla et al.,
2014). At 225 ºC, the total weight losses of the samples increased with
the SEO concentration, being 38.01 %, 33.68 %, 35 % and 40 %. Ac-
cording to that, the lms incorporated with SEO up to 1.5 % showed a
decreased weight loss compared to the control lm, indicating greater
thermal stability. However, when the SEO addition is up to 2 % there
was a slight decrease in this property. This could be explained due to the
presence of high concentrations of SEO in the lms leads to an increase
in the discontinuity of the lm matrix. This generated a decrease in the
compatibility of the multiphase system, which causes the lms to lose
more weight and therefore have lower heat resistance (Noshirvani et al.,
2017). Similar results were obtained by Xu et al. (2019) when cinnamon
and clove essential oil were added to gum arabic-chitosan lms.
The results obtained suggest that the interactions produced in the
matrix between chitosan and SEO (from 0.5 % to 1 %) increases the
thermal stability of the lms by reducing their weight. On the other
hand, these lms were stable until they reached 120ºC. This is an
interesting nding, because it means that as the developed SEO-chitosan
lms could have applicability in pasteurization treatments.
3.8. Storage stability of butter packed in SEO-chitosan sachets
The antioxidant properties of the chitosan lms as sachets for butter
were tested after 3 months at 5 ºC refrigerated storage. Fig. 5 shows the
butter samples sealed in SEO-chitosan lms at day 90 of storage at 5 ºC.
Table 5 shows DPPH
and ABTS
•+
values in the lms used for packaging
butter after 90 days. Results revealed a signicant increase (p<0.05) of
the DPPH
values from 10.70 % to 23.14 % for chitosan lms with 1 %
and 2 % SEO, respectively. ABTS
•+
values ranged from 6.68 % to 19.34
% with a signicant increase by the addition of any concentration of SEO
compared with the chitosan lms without SEO. DPPH
and ABTS
•+
re-
sults suggested that the active lms successfully kept the antioxidant
properties after 3 months of storage.
The TBARS value was used to indicate that the second stage of lipid
auto-oxidation is occurring. This assay detects malonaldehyde (MDA),
an unfolded product of endoperoxides resulting from the oxidation of
Fig. 5. Butter samples sealed in SEO-chitosan lms stored at 4ºC for 90 days. SEO is sandalwood essential oil.
Table 5
Antioxidant and optical properties of chitosan lms applied on butter after 3
months of storage. TBARS of butter after 3 months of storage. Film composition
is described in Table 1.
Samples DPPH
ABTS
•+
TBARS
(%) (%) mg MDA / kg
butter
Butter w/o lm 616.90 ±9.58
a
Butter with SEO-chitosan_0 10.70
±2.46
a
6.68 ±0.31
a
417.91 ±4.43
b
Butter with SEO-chitosan
_0.5
6.68 ±1.65
a
11.42
±0.72
b
414.66 ±5.60
b
Butter with SEO-chitosan
_1
12.11
±3.40
a
11.87
±0.38
b
410.77 ±8.27
b
Butter with SEO-chitosan
_2
23.14
±6.07
b
19.34
±0.12
c
393.25 ±6.22
c
Samples L* a* b*
Butter w/o lm 83.74 ±0.29 -1.03
±0.07
bc
36.26 ±0.64
Butter with SEO-chitosan_0 80.28 ±2.22 1.54 ±1.01
a
38.81 ±4.73
Butter with SEO-chitosan
_0.5
81.83 ±0.99 1.09
±0.55
ac
37.14 ±2.71
Butter with SEO-chitosan
_1
78.17 ±2.19 1.96 ±0.72
a
45.17 ±2.24
Butter with SEO-chitosan
_2
78.47 ±1.51 1.13 ±0.39
a
44.01 ±1.49
SEO - sandalwood essential oil; TBARS Thiobarbituric reactive substances
Values are expressed as mean ±standard deviation (SD).
Different letters in the same column indicate signicant differences (p ˂ 0.05).
Values of L* and b* showed no signicant differences.
M. Fl´
orez et al.
Food Packaging and Shelf Life 34 (2022) 100938
9
unsaturated fatty acids (Han Lyn et al., 2021). Table 5 shows TBARS
values of the unpackaged (control) and packaged butter after 3 months
of refrigerated storage. The TBARS values for control sample was
616.90 mg MDA/kg butter and for packaged butter ranged from 417.91
to 393.25 mg MDA/kg butter. TBARS values showed a signicant effect
of packaged samples (p<0.05) compared to the control. After 3 months
of butter storage, a 36 % decrease in the lipid oxidation was observed
due to the SEO-chitosan lms. This behavior can be explained by the
radical scavenging properties of the lms, as supported by the results of
the antioxidant assays (Han Lyn et al., 2021). On the other hand, butter
samples packaged with SEO-chitosan lms decreased lipid oxidation
compared to butter packed with control lms without oil. Therefore, the
presence of sandalwood essential oil further decreases the oxidation of
the butter. Same trend was observed in chitosan/graphene oxide bio-
composite lms that stored palm-oil based margarine (Han Lyn et al.,
2021).
3.9. Optical properties of butter wrapping lms
Table 5 shows the CIE coordinates of the unwrapped and wrapped
butter samples with SEO-chitosan lms. In this case, the lightness (L*)
varied from 80.28 to 78.47 and the b* values were from 38.81 to 44.01.
For both values, no signicant difference was observed (p>0.05).
However, the a* (redness parameter) values varied from 38.81 to 44.01,
producing a signicant effect (p<0.05) compared to butter without
lm. Results suggested that the brightness of the lms and the yellowish
of the samples were not affected by the presence of the lm that wraps
around the butter, only the redness color of the lms was slightly
modied. Hence, the lms had sufcient transparency to maintain the
visual appearance of the butter and the consumer could observe it
without signicant alterations.
4. Conclusions
The incorporation of SEO into chitosan matrix was successfully
performed to obtain antioxidant lms. The lms are completely water-
soluble and can be easily removed from foodstuffs after use without
generate solid wastes. The lms can be heat sealed and used as sachets.
This makes them a good option for use in the food packaging industry
partially replacing plastic containers. Regarding the optical properties,
the color and transparency of the lms applied on butter allowed to see
the real color of the butter. The concentration of essential oil present in
the lm did not inuence the visual appearance of the wrapped product
under study. Considering the TBARS results, it can be stated that the
application of SEO on chitosan lms successfully delayed butter
oxidation.
CRediT authorship contribution statement
Maria Fl´
orez: Writing- Original draft preparation. Patricia Caz´
on:
Conceptualization, Supervision, Writing- Reviewing and Editing. Man-
uel V´
azquez: Methodology, Writing- Reviewing and Editing, Project
administration.
Declaration of Competing Interest
The authors declare that they have no known competing nancial
interests or personal relationships that could have appeared to inuence
the work reported in this paper.
Acknowledgments
The authors appreciate the funding support of Xunta de Galicia,
within the postdoctoral fellowship granted to Patricia Caz´
on Díaz (No.
ED481B-2021040). The use of RIAIDT-USC analytical facilities is
acknowledged.
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M. Fl´
orez et al.
... W/O emulsion products always have a major issue called lipid oxidation [89]. Lipid oxidation further causes flavor problems, unsuitable colors, and nutrient degradation in the W/O emulsion products [89,76]. Lipid oxidation becomes fast when fatty acids, especially unsaturated fatty acids react with oxygen gas encouraging the formation of toxic compounds, which contribute to rancidity, off-flavors, and color issues in butter and margarine products quality [89]. ...
... The authors concluded that the integration of bilayer film in the packaging of margarine significantly contributed to inhibiting lipid oxidation and preventing other forms of chemical contamination within the product. Another study conducted by Florez et al. [76] focused on designing active packaging film materials using chitosan and santalum album essential oil (SEO) to inhibit the lipid oxidation of butter. The production of chitosan films was explored using different concentrations of SEO at concentrations of 0.5, 1, and 2%. ...
... The production of chitosan films was explored using different concentrations of SEO at concentrations of 0.5, 1, and 2%. The authors [76] examined various characteristics of films, which included moisture content, mechanical properties, antioxidants, thermostability, solubility, and water vapor permeability (WVP). Except for puncture and equilibrium moisture content, the chitosan-SEO film showed a significant effect due to SEO. ...
... Other plant extracts and EOs, or their active constituents, have been successfully tested as food antioxidants in oils and fats, including sandalwood (Santalum album) essential oil (Flórez et al., 2022), macroalgae extracts (Agregán et al., 2017), lycopene (Siwach et al., 2016), α-tocopherol (Bodoira et al., 2017), ascorbyl palmitate (Bodoira et al., 2017), gallic acid, rutin, and β-carotene (Şahin et al., 2020) ( Fig. 11.8). There is also an increasing tendency toward the use of agri-food waste and industrial by-products for the extraction of antioxidant compounds. ...
... However, the authors did not assess the sensory aspects of the migration of the active compounds through the PLA films toward the food products. Another example is the study performed by Flórez et al. (2022), where they evaluated the effect of sandalwood (S. album) essential oil on butter oxidation. In this case, the natural antioxidant was applied to chitosan films and successfully decreased lipid oxidation. ...
Chapter
Oils and fats are a valuable part of our daily diet and the major constituent of edible lipids. The most important issue to address regarding their shelf-life is lipid oxidation, which occurs when free radicals react with lipids, usually with the double bonds present in the chain. Lipid oxidation produces different volatile compounds that have a negative impact in the sensory attributes of oils and fats, resulting in rancidity. To inhibit or reduce lipid oxidation synthetic antioxidants have been used, such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and tert-butylhydroquinone (TBHQ). These are very cost-effective but are being rejected by consumers due to their toxicity. As a replacement, natural antioxidants are gaining attraction amongst food scientists and have become a viable option in the food industry. Among these, different alternatives have been evaluated, such as plants, herbs and spice extracts and essential oils, and their main constituents, including rosemary and green tea extracts, lycopene, and α-tocopherol. Recent studies have also been focusing on the extraction of natural antioxidants from agri-food wastes and industrial by-products. This chapter will focus on natural preservatives for oils and fats, namely, natural antioxidants to avoid lipid oxidation during processing and storage, and extend their shelf-life, the different application methods that have been studied, the effect on the quality of the product, and future trends.
... The results concluded that adding AP and SAP to TPS/PBAT blend films significantly reduced the film's UV light transmittance values, enhancing their ability to block UV light. The best results were obtained by all samples, with the transmission percentage falling below 5% in the 200-400 nm wavelength range [46]. Nonetheless, the TPS/PBAT film's light transmission increased with the addition of AP 1%. ...
... AP gave a higher free volume by its ascorbic acid linkages between TPS and PBAT, leading to increased light transmission. Generally, TPS granules produce a window that lets UV light through, but PBAT functions as a semi-transparent barrier, absorbing part of the UV radiation and giving the area a white tint [7,14,34,46]. ...
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The development of biodegradable active packaging is a relevant topic demanding the development of film properties, biodegradability, and the potential to preserve food quality. This study aimed to develop thermoplastic starch (TPS) blended with polybutylene adipate-co-terephthalate (PBAT) films via blown-film extrusion containing ascorbyl palmitate (AP) and sodium ascorbyl phosphate (SAP) as antioxidants. The morphology, mechanism, and barrier and antioxidant properties of the films were analyzed to determine the presence of AP, SAP, and their interaction effect on the film properties. SEM showed that increasing AP and SAP content increased fibrous-like morphology, improving the TPS dispersion. AP slightly decreased mechanical properties, while SAP increased the tensile properties and seal strength of the films. All of the YM values were increased by adding AP and SAP content. The addition of AP and SAP content enhanced the interaction with TPS/PBAT networks due to increasing C-O stretching of ester bonds, compatibility, and hydrophobicity of the polymer. Both water vapor and the oxygen barrier were insignificantly affected by AP and SAP up to 1%, while the permeabilities greatly increased at higher AP and SAP contents due to non-homogeneous and void spaces between the film matrix. TPS/PBAT containing AP and SAP (≥0.5%) effectively enhanced antioxidant capacity in 95% ethanol as a food simulant and reduced the UV light transmission of the films. Finding, the interaction between AP, SAP, and TPS/PBAT matrices effectively changed the microstructures and properties as functionalized antioxidant biodegradable packaging.
... Saricaoglu and Turhan (2020) also reported a similar phenomenon when clove essential oil was added to a polymer film. A new peak was found at 1743 cm − 1 in the CN-REO films, indicating increased interactions between the essential oil and the film matrix with increasing REO concentration (Flórez, Cazón, & Vázquez, 2022). The C--O tensile vibration in the ester structure of fatty acids was the cause of this band, which was the unique band of oil (Flórez, Cazón, & Vázquez, 2022). ...
... A new peak was found at 1743 cm − 1 in the CN-REO films, indicating increased interactions between the essential oil and the film matrix with increasing REO concentration (Flórez, Cazón, & Vázquez, 2022). The C--O tensile vibration in the ester structure of fatty acids was the cause of this band, which was the unique band of oil (Flórez, Cazón, & Vázquez, 2022). In addition, due to the interaction between the essential oil and the film matrix, the peak strength at 1216 and 1743 cm − 1 attributed to the amide-III and amide I bands for the CS-based blend film increased (Pan, et al., 2023). ...
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Active films were developed based on chitosan, esterified chitin nanofibers and rose essential oil (REO). The joint effects of chitin nanofibers and REO on structure and physicochemical properties of chitosan film were investigated. Scanning electron microscopy and Fourier transform infrared spectroscopy showed that the chitin nanofibers and REO had significant effects on the morphology and chemical structure of chitosan composite films. The negatively charged esterified chitin nanofibers formed a compact network structure through inter-molecular hydrogen bonding and electrostatic interactions with the positively charged chitosan matrix. Chitin nanofibers and REO synergistically enhanced the water resistance, mechanical properties and UV resistance of chitosan-based films, but the addition of REO increased the oxygen permeability. Furthermore, the addition of REO enhanced the inhibition of ABTS and DPPH free radicals and microorganisms by chitosan-based film. Therefore, chitosan/chitin nanofiber-based active films containing REO as food packaging materials can potentially provide protection to extend food shelf life.
Chapter
Edible food packaging has emerged as an innovative solution to address the environmental issues of plastic pollution and excessive packaging. Traditional petroleum-based plastics, commonly used for food packaging due to their availability, strength, and cost-effectiveness, contribute significantly to landfill waste, water pollution, and health problems. In contrast, edible packaging made from natural polymers like proteins and polysaccharides offers a sustainable alternative. However, these materials often have weaker mechanical properties, durability, and barrier characteristics than plastics. This chapter reviews the development of edible packaging, such as films, coatings, and fibers, emphasizing their environmental benefits and recent advancements in the field. Despite their potential, edible packaging faces challenges in protecting food products effectively due to their inferior gas barrier and water resistance properties. To overcome these limitations, innovative methods, such as advanced emulsion technology under controlled conditions (pH, temperature, and ionic strength), are being researched to enhance the barrier properties, texture, antimicrobial effects, and rheological behavior of lipid-based films. This chapter highlights the importance of addressing these challenges to create effective, sustainable edible packaging solutions that offer both environmental benefits and improved functionality.
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The massive and uncontrolled use of food packaging derived from petroleum-based plastics has created a serious environmental problem. Hence, the food packaging industry needs to develop packaging from biodegradable polymers. Among the many raw materials studied in the literature, chitosan is one of the most abundant polysaccharides in the nature. Chitosan attracted attention due to its non-toxicity, antimicrobial, and antifungal properties. Because of this, chitosan is considered a perfect material for the development of films for food use. In this review, recent studies on active and/or intelligent chitosan-based films has been evaluated. Active packaging maintains or improves the condition of packaged food or extends its shelf-life meanwhile intelligent packaging monitors the condition of packaged food or the environment surrounding the food. The effect of the addition of active compounds on the mechanical, barrier and functional properties of chitosan-based films has been assessed. The antimicrobial and antioxidant activity, as well as the potential application of these active and intelligent composite films has also been revised. Literature shows that the presence of phenolic compounds improves both mechanical and barrier properties of chitosan films. The antimicrobial and antioxidant capacity of the films improved significantly by the addition of essential oils, phenolic compounds, and other fruit extracts. Intelligent pH-indicator chitosan-based films have been extensively studied. Further research on chitosan and its combinations with other materials is needed to study which type of foodstuffs could be in contact with chitosan packaging.
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Chitosan - tea tree essential oil (TTEO) films were obtained as a new biodegradable material. Malic acid or lactic acid solvents were evaluated to obtain easy-removing films. The microstructure by SEM and FT-IR, the thermal properties by TGA/DSC, the mechanical properties, the water vapor permeability, the antioxidant (DPPH• and ABTS•+) activity and the optical properties of the formulated films were evaluated. A complete dissolution of the film in water was obtained. The elongation to break was higher in the films with malic acid (145.88–317.33%), comparing with those with lactic acid (25.54–44.08%). Chitosan film obtained in malic acid with TTEO showed the highest antioxidant activity. The colour and transparency of the samples did not suffer significant variations by TTEO addition. Films showed good UV-barrier properties, with a slightly improvement by TTEO addition. The films obtained showed a great potential for food packaging applications.
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The study aimed at assessing effects of black chokeberry polyphenol extract (ChPE) added (0.025–0.075%) to xylitol-containing muffins to reduce lipid oxidation, especially in preventing degradation of hydroperoxides throughout the storage period. Among polyphenolic compounds (3092 mg/100 g in total) in ChPE, polymeric procyanidins were the most abundant (1564 mg/100 g). ChPE addition resulted in a significantly increased capacity of scavenging free radicals and markedly inhibited hydroperoxides decomposition, as reflected by low anisidine values (AnV: 3.25–7.52) throughout the storage. On the other hand, sucrose-containing muffins had increased amounts of primary lipid oxidation products and differed significantly from other samples in conjugated diene hydroperoxides (CD values), which was in accordance with the decrease of C18:2 9c12c in those muffins after storage. In addition, sucrose-containing muffins were found to be those with the highest level of contamination with toxic carbonyl lipid oxidation products. Throughout the storage, no yeast or moulds contamination were found in higher enriched muffins. The incorporation of polyphenols to xylitol-containing muffins resulted in preventing decomposition of polyunsaturated fatty acids (PUFAs), and in reducing the content of some toxic aldehydes. ChPE could be regarded as a possible solution to xylitol-containing muffins to extend their shelf life. The results support the use of xylitol in muffin manufacture as being favourable in terms of suitability for diabetics.
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This study investigated the application of active packaging from chitosan (CS) incorporated with graphene oxide (GO) to maintain the quality and extend the storage life of palm-oil based margarine. Composite films containing various concentrations of CS (1.5 and 2.0%w/v) and GO (0, 0.5, 1.0, and 2.0%w/w CS) were produced using the solution casting method and were characterized regarding their mechanical, barrier, and antioxidant properties. For both concentrations of CS, the composite films with 2.0% GO exhibited significantly (p<0.05) lower water vapor permeability and oxygen permeability by ∼43 and ∼55%, respectively. The transmittance of UV light was virtually undetectable in CSGO composites. In addition, the radical scavenging activity increased (p<0.05) with the increasing GO concentration, as demonstrated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The changes in the peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) of the margarine samples were monitored for 30 d at 4 ºC. The margarine sample that was wrapped with the CS1.5 GO2.0 film sample showed lower (p<0.05) PV and TBARS values in comparison to the samples wrapped with CS1.5 and low-density polyethylene (LDPE) films. In conclusion, the CSGO composite film in this study shows great potential as an antioxidant food packaging material.
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The present study describes the preparation and characterization of composite films from bacterial cellulose produced by Komagataeibacter xylinus combined with poly(vinyl alcohol) and chitosan. The unique bacterial cellulose structure provides an expanded surface area with high porosity, easing the combination with other soluble polymers by dipping. This blending method effectively reinforces the bacterial cellulose structure. Toughness, puncture strength, water solubility, and swelling degree were measured to assess the effect of poly(vinyl alcohol) and chitosan on the analyzed properties. The morphology and optical and thermal properties were evaluated by scanning electron microscopy, UV-vis spectral analysis, thermogravimetry, and differential scanning calorimetry, respectively. Results showed that the films have good UV-barrier properties and high thermal stability. Toughness values ranged from 0.26 to 7.18 MJ/m3, burst strength ranged from 58.88 to 3234.62 g, and distance to burst ranged from 0.39 to 3.24 mm. Poly(vinyl alcohol) affected the water solubility and increased the swelling degree.
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Chitosan-gum arabic-based polyelectrolyte complexed films with cinnamon essential oil (CEO) and clove essential oil (CLO) were developed. The effect of EO concentrations, types and their combinations on the physical, thermal and antimicrobial properties of films were investigated. The results showed that the incorporation of EOs decreased the ζ-potential and viscosity, but increased the particle size of film-forming dispersions. Films incorporated with CEO and combined EOs exhibited better water barrier properties compared to those with CLO and single EO. Films containing CEO showed lower EO loss and higher thermal stability compared to those containing CLO, and the reason was attributed to the stronger interactions between chitosan, gum arabic and CEO. The combination of EOs resulted in higher retention and delayed release rate in food stimulant, resulting in stronger antimicrobial activities. The performance of films with the CEO and the combined EOs brought new formulation ideas in antimicrobial films.
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Effects of partial replacement (17–50%) of wheat flour (WF) with buckwheat flakes/amaranth flour blend (B-A) on quality attributes of muffins during storage, with special attention on their antioxidative, nutritional and sensory properties, were studied. Increasing the B-A content in muffins resulted in progressing antioxidative activity, e.g. 1,1-diphenyl-2-picrylhydrazyl scavenging by 26–51%, as well as in increased mono- and polyunsaturated fatty acid (FA) contents; e.g., linolenic acid content was 0.34 g/100 g FA in control (C-muffins), and 0.53 g/100 g FA in the muffins with the highest WF substitution. Moreover, fibre content in that latter case was 2.5-fold higher than in C-muffins. The content of secondary lipid oxidation products did not exceed the upper safety limits in muffins with higher WF substitution of by B-A. Intensities of cereal, nut aroma and taste increased with increasing B-A content, but that of buttery aroma decreased. Intensities of off-aroma and of bitter taste were low in fresh muffins but increased with storage due to increased secondary lipid oxidation products. Higher WF replacement by B-A (33 or 50%) in muffins improved their nutritional and antioxidative properties, effectively inhibiting hydroperoxide decomposition, thus preventing generation of toxic secondary lipid oxidation products.