Journal of Environmental Engineering and Studies
Vol. 10, Issue 2 (May – August, 2025) pp: (48-58)
e-ISSN: 2582-3132
DOI: https://doi.org/10.46610/JoEES.2025.v010i02.005
Tenable Properties of Sodium Alginate-Gelatin
Biopolymer Membranes: Development and
Comprehensive Characterization
1
2
Mallikarjunagouda B. Patil1*, Rajeshwari D. Hiredesai1, Varshini B. Kulkarni1, Pratibha S.
Patil1, Shankramma S. Chavan1, Shridhar N. Mathad2
Postgraduate Student, Department of Chemistry, Basaveshwar Science College, Bagalkot, Karnataka, India
Associate Professor, Department of Engineering Physics, K.L.E Institute of Technology, Hubballi, Karnataka,
India
*
Corresponding Author: mallupatil04@gmail.com
Received Date: July 13, 2025; Published Date: August 05, 2025
Abstract
This study focuses on the development and comprehensive characterization of sodium alginate-based
biopolymer membranes incorporated with varying concentrations of gelatin (0–2g). Five
formulations were prepared using the solvent casting method, maintaining a constant sodium
alginate content (5g) while incrementally increasing gelatin from 0 to 2 g in 0.5g steps. The
membranes were evaluated for film thickness, droplet size, zeta potential, colorimetric attributes,
molecular interactions (FTIR), thermal stability (TGA), and mechanical properties. Results indicated
that gelatin incorporation enhanced mechanical strength and thermal resistance up to an optimal
concentration, while also affecting the structural and physicochemical characteristics of the films.
These findings highlight the potential of sodium alginate–gelatin composite membranes as promising
materials for sustainable and biodegradable packaging applications.
Keywords- Antimicrobial activity, Biopolymer films, Gelatin concentration effects, Mechanical and
thermal properties, Sodium alginate–gelatin blend
INTRODUCTION
I
n response to growing environmental
concerns regarding plastic pollution and the
depletion of fossil fuel resources, the
development of biodegradable, sustainable
materials has become a global imperative.
Among these, biopolymer-based films derived
from renewable natural sources offer promising
alternatives due to their biodegradability and
potential for application across diverse sectors,
including
packaging,
agriculture,
food
preservation, drug delivery, and wound healing
[1], [2]. Natural polymers such as
polysaccharides and proteins have gained
particular attention for their biocompatibility,
48
functional
diversity,
and
tunable
physicochemical properties.
Sodium
alginate
(SA),
an
anionic
polysaccharide extracted from brown seaweed,
consists of β-D-mannuronic acid (M) and α-Lguluronic acid (G) units arranged in
homopolymeric
(M-and
G-blocks)
and
heteropolymeric (MG-blocks) sequences. This
molecular architecture endows SA with
excellent
water
absorbency,
viscosity
modulation, and gel-forming ability, especially
in the presence of divalent cations like Ca²⁺ [3].
SA is widely employed in biomedical, food, and
pharmaceutical industries owing to its
biodegradability, non-toxicity, and strong filmforming capacity [4]. However, pure alginate
© MAT Journals 2025. All Rights Reserved
Tenable Properties of Sodium Alginate-Gelatin Biopolymer Membranes
films exhibit inherent limitations, such as
brittleness, low tensile strength, and high
moisture sensitivity, which restrict their
applicability in high-performance or humid
environments [5].
To overcome these drawbacks, blending alginate
with compatible natural polymers is a common
strategy. Gelatin (GEL), a partially hydrolyzed
collagen derivative rich in functional groups
such as amide, carboxyl, and hydroxyl, is a
suitable candidate due to its gel-forming,
emulsifying, and stabilizing properties [6]. It is
biodegradable, biocompatible, and widely used
across the food, cosmetic, and pharmaceutical
sectors. When incorporated into alginate
matrices, gelatin enhances film flexibility, water
resistance, and thermal stability through
hydrogen bonding and electrostatic interactions
between gelatin’s amide groups and alginate's
carboxyl groups [7]. The synergy between SA
and GEL results in the formation of a more
compact and cohesive polymer network.
Intermolecular hydrogen bonding between the
hydroxyl groups of alginate and the amino or
amide groups of gelatin contributes to improved
mechanical strength and reduced hydrophilicity.
Studies have demonstrated that gelatin
incorporation modulates tensile strength,
elongation at break, and barrier properties,
enhancing the suitability of the composite films
for applications such as active packaging or
drug delivery [8]. Moreover, gelatin can impart
biofunctional properties, including antimicrobial
and antioxidant effects, particularly when
combined with bioactive agents.
Recent advances have further expanded the
functionality of alginate-gelatin films by
incorporating additives such as plant extracts,
nanoparticles, or crosslinkers. For instance,
turmeric extract has been shown to improve the
antioxidant and antimicrobial activity of
alginate–gelatin films, while silver nanoparticles
have
enhanced
their
mechanical
and
antimicrobial
performance
[8].
These
modifications highlight the adaptability of SA–
GEL composites as versatile, multifunctional
biomaterials. In biomedical applications,
alginate-gelatin films have demonstrated
considerable potential as wound dressings,
scaffolds for tissue engineering, and controlled
49
Mallikarjunagouda B. Patil et al.
drug delivery systems. Alginate’s hydrogelforming ability and gelatin’s resemblance to
extracellular matrix components offer a
favorable microenvironment for cell adhesion
and tissue regeneration. Moreover, the
degradation rate of these films can be tuned
through polymer composition and crosslinking
strategies to meet specific biomedical
requirements.
In
conclusion,
sodium
alginate–gelatin
composite films present a promising class of
biodegradable
materials
with
enhanced
mechanical, thermal, and functional properties.
Their complementary interactions enable the
development of structurally robust and
functionally versatile membranes suitable for
sustainable applications. The current study aims
to investigate the structural interactions between
SA and GEL using Fourier-Transform Infrared
(FTIR) spectroscopy, providing molecular-level
insights into their compatibility. Additionally,
this work evaluates the impact of varying gelatin
concentrations (0, 0.5, 1.0, 1.5, and 2.0 g) on the
physical, chemical, and mechanical properties of
the composite films, to optimize formulation for
biodegradable packaging applications.
EXPERIMENTAL PROCEDURE
Materials
The key materials employed in this study were
Sodium Alginate (SA), Gelatin (GEL), and
distilled water. Sodium alginate, an anionic
polysaccharide derived from marine brown
algae, was of analytical grade and obtained from
S.D. Fine Chemicals, Mumbai, India. It was
selected as the primary film-forming biopolymer
owing to its excellent biodegradability,
hydrophobicity, and gel-forming capabilities.
Gelatin, a protein-based polymer sourced from
bovine collagen, was of food-grade quality and
procured from E. Merck, India. It was
incorporated into the SA matrix to improve the
mechanical strength, flexibility, and structural
coherence of the films through intermolecular
interactions such as hydrogen bonding and
electrostatic attraction. Distilled water served as
the universal solvent throughout the film
preparation
process,
ensuring
purity,
homogeneity, and reproducibility. All chemicals
© MAT Journals 2025. All Rights Reserved
J of Envir. Eng. and Stu.
Vol. 10, Issue 2
and reagents were used without further
purification to maintain standardization and
reflect practical formulation conditions.
Membrane Preparation
To evaluate the effect of gelatin concentration
on the structural and physicochemical
characteristics of sodium alginate-based
biopolymer films, five formulations were
systematically prepared by varying the gelatin
content while keeping the sodium alginate
quantity constant. In each formulation, 5 g of
Sodium Alginate (SA) was dissolved in 100 mL
of distilled water under continuous magnetic
stirring to ensure complete hydration and
dissolution of the polysaccharide matrix. After
complete solubilization of SA, Gelatin (GEL)
was added in graded concentrations of 0 g, 0.5
g, 1.0 g, 1.5 g, and 2.0 g, corresponding to film
codes F1 through F5, respectively.
Each blend was stirred vigorously at room
temperature (25 ± 2°C) until a homogeneous and
viscous polymer solution was obtained. This
step was essential to ensure uniform dispersion
of gelatin within the alginate matrix and to
prevent phase separation, thereby promoting
consistent film morphology and properties. The
resulting polymer mixtures were then cast onto
clean, leveled glass plates using a fixed volume
to achieve uniform film thickness across all
samples.
Film drying was conducted under ambient
conditions (25 ± 2°C, ~50% relative humidity)
in a dust-free environment for approximately 48
hours, or until complete solvent evaporation
occurred. Upon drying, the transparent to semitransparent films were carefully peeled from the
glass surfaces and stored in desiccators to avoid
moisture uptake before further analysis. This
solvent casting method ensured reproducibility
and consistency across samples, facilitating a
reliable assessment of the impact of gelatin
incorporation
on
the
physicochemical,
mechanical, thermal, and structural behavior of
the sodium alginate-gelatin blend films (Table
1).
Table 1: Composition of sodium alginate–gelatin film variants.
Film Code
Sodium Alginate (g)
Gelatin (g)
Total Solvent Volume (mL)
F1
5.0
0.0
100
F2
5.0
0.5
100
F3
5.0
1.0
100
F4
5.0
1.5
100
F5
5.0
2.0
100
Notes
Pure sodium alginate film
(control)
Low gelatin concentration
Moderate gelatin
concentration
High gelatin concentration
The maximum gelatin
concentration used
Fig. 1 depicts the structure of sodium alginate and gelatin.
Figure 1: Structure of sodium alginate and gelatin.
50
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Tenable Properties of Sodium Alginate-Gelatin Biopolymer Membranes
CHARACTERIZATION METHODS
Film Thickness Measurement
Mallikarjunagouda B. Patil et al.
reduced flexibility at the highest concentration.
Antimicrobial Assay Methodology
Film thickness is a fundamental physical
parameter in the characterization of biopolymer
membranes, as it significantly influences their
mechanical performance, barrier functionality,
optical transparency, and biodegradation profile.
Uniform film thickness is particularly critical for
applications such as food packaging, biomedical
membranes, and controlled-release systems,
where consistent performance is essential.
FTIR Spectroscopy
Fourier-Transform
Infrared
Spectroscopy
(FTIR), particularly using attenuated total
reflectance (ATR), was employed to investigate
the molecular interactions and structural
changes occurring between Sodium Alginate
(SA) and gelatin (GEL) within the biopolymer
membrane matrix. The FTIR spectra were
recorded in the 4000-400 cm⁻¹ range for all film
variants (F1–F5) with increasing gelatin
concentrations. Each spectrum revealed both
characteristic functional group bands and
interaction-induced spectral shifts, confirming
compatibility between the two polymers.
Thermo-Gravimetric Analysis (TGA)
Thermal degradation behavior was assessed
from 25 to 600°C under a nitrogen atmosphere
using TGA. Three degradation stages were
observed: (i) moisture loss, (ii) polymer
decomposition (200–350°C), and (iii) final
degradation. Increased gelatin improved the
thermal resistance and delayed the onset of
major weight loss.
Mechanical Testing
Mechanical properties, including Tensile
Strength (TS) and Elongation at Break (EAB),
were measured using a universal testing
machine (UTM) as per ASTM D882. Film strips
(10 × 100 mm) were tested at a crosshead speed
of 10 mm/min. Films with higher gelatin
exhibited increased tensile strength due to better
network formation, though excessive gelatin
51
The antimicrobial potential of sodium alginate
gelatin membranes was evaluated using the agar
diffusion (well-cut diffusion) method. Test
microorganisms included:
 Escherichia Coli (Gram-negative)
 Staphylococcus Aureus (Gram-positive)
Sterile film discs (1 cm diameter) from each
formulation (F1–F5) were placed on MuellerHinton agar plates previously inoculated with
standardized bacterial suspensions (∼10⁸
CFU/mL). Plates were incubated at 37°C for 24
hours, and Zones of Inhibition (ZOI) were
measured using a Vernier caliper.
Statistical Analysis (One-way ANOVA)
A one-way ANOVA was conducted to compare
the mean inhibition zone diameters between
different film formulations. Results showed that:
 There was a statistically significant
difference (p < 0.05) in antimicrobial
activity
across
different
gelatin
concentrations for both bacterial strains.
 Post hoc Tukey’s HSD test indicated that F4
and F5 differed significantly from F1–F3.
RESULTS AND DISCUSSION
In this study, the thickness of each sodium
alginate gelatin membrane variant was measured
using a precision micrometer screw gauge with
an accuracy of ±1 µm. This device was chosen
for its high resolution, ease of operation, and
ability to measure delicate films without causing
deformation or damage. To ensure accuracy and
representativeness, five random points were
selected across each film sample typically
including the center and four peripheral
locations (corners) to account for potential
variations due to edge effects or uneven drying.
The thickness measurements from these points
were recorded, and the mean ± Standard
Deviation (SD) was calculated to represent both
the average thickness and its uniformity across
the film.
This methodological approach allowed for a
© MAT Journals 2025. All Rights Reserved
J of Envir. Eng. and Stu.
Vol. 10, Issue 2
statistically robust evaluation of film thickness
and ensured that observed differences in
mechanical, barrier, or other physicochemical
properties could be interpreted with confidence,
acknowledging film thickness as a controlled
and standardized variable throughout the study.
Droplet Size and Zeta Potential
Before film casting, each polymer solution was
characterized using Dynamic Light Scattering
(DLS) to evaluate the droplet size distribution
and zeta potential, providing insight into the
colloidal behavior and stability of the
formulations (Fig. 2). Zeta potential values
ranging from –25 to –35 mV indicated
satisfactory
electrostatic
stabilization,
suggesting minimal risk of particle aggregation
or phase separation during film formation. The
droplet size measurements revealed trends
associated with increasing gelatin concentration,
offering valuable information on the extent of
polymer–polymer interactions and potential
aggregation
behavior.
Together,
these
parameters confirmed the stability and
homogeneity of the biopolymer dispersions,
ensuring reproducibility in the subsequent
membrane casting process.
Figure 2: Film thickness measurement, droplet size, and zeta potential.
Colorimetric Analysis
The surface color of the dried membranes was
measured using a colorimeter based on the CIE
Lab scale*. The L* value (lightness), a* (red-
green), and b* (yellow-blue) were recorded.
Increased gelatin generally resulted in slightly
darker films due to protein content and
Maillard-like reactions during drying (Fig. 3).
Figure 3: Colorimetric analysis.
52
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Tenable Properties of Sodium Alginate-Gelatin Biopolymer Membranes
FTIR Spectroscopy
Fourier-Transform Infrared (FTIR) spectroscopy
with Attenuated Total Reflectance (ATR) was
utilized to investigate the molecular interactions
between sodium alginate (SA) and gelatin
(GEL) in the biopolymer membranes. Spectra
were recorded in the 4000–400 cm⁻¹ range for
all film formulations (F1–F5), corresponding to
increasing gelatin concentrations (Table 2).
The control film (F1), composed solely of
sodium alginate, exhibited characteristic peaks:
a broad O–H stretching band around ~3300 cm⁻¹
indicating hydroxyl groups, an asymmetric
carboxylate (–COO⁻) stretch at ~1600 cm⁻¹, a
symmetric stretch at ~1410 cm⁻¹, and a C–O–C
stretch near ~1030 cm⁻¹, confirming alginate's
polysaccharide structure. With the addition of
gelatin (F2–F5), distinct spectral changes were
Mallikarjunagouda B. Patil et al.
observed. New peaks emerged at ~1650 cm⁻¹
and ~1540 cm⁻¹, corresponding to Amide I (C =
O stretching) and Amide II (N–H bending and
C–N stretching), confirming the presence of
gelatin. Additionally, a shift of the O–H
stretching band to lower wavenumbers indicated
hydrogen bonding between alginate and gelatin
functional groups.
These spectral modifications confirm strong
intermolecular
interactions
particularly
hydrogen bonding and electrostatic interactions
between the carboxyl groups of alginate and the
amine groups of gelatin. The progressive
increase in the intensity of amide bands with
higher gelatin concentrations further supports
the successful incorporation and structural
modification of the blend films, enhancing their
compatibility
and
potential
functional
properties.
Table 2: FTIR peak assignments in SA–gelatin films with increasing gelatin content.
Film Code
Gelatin (g)
Main FTIR Peaks (cm⁻¹)
F1
0.0
3301, 1602, 1410, 1031
F2
0.5
F3
1.0
F4
1.5
F5
2.0
3296, 1600, 1542, 1409,
1029
3289, 1598, 1540, 1407,
1027
3285, 1596, 1540, 1405,
1026
3282, 1595, 1539, 1403,
1025
Thermo-gravimetric Analysis (TGA)
Thermogravimetric Analysis (TGA) was
conducted to evaluate the thermal stability of
sodium alginate–gelatin blend membranes
formulated
with
increasing
gelatin
concentrations (0.0–2.0 g). Key parameters
assessed included moisture loss, main thermal
degradation
range,
onset
degradation
temperature (Tonset), and residual weight at
600°C, which collectively provide insights into
the thermal behavior and compositional integrity
of the films. The control film (F1), composed
purely of sodium alginate, exhibited the highest
moisture loss of 12.4 ± 0.3% within the
temperature range of 30–150°C, and showed
primary degradation between 205–320°C with a
Tonset at 204°C. The residual weight at 600°C
53
Peak Assignments
O–H, –COO⁻
(asym/sym), C–O–C
O–H shift, Amide II
visible
Amide I/II
prominent
Strong Amide bands
Highest amide
intensity
Interpretation
Pure alginate; no proteinrelated peaks
Weak alginate–gelatin
interactions
Moderate hydrogen bonding
Clear polymer–protein
compatibility
Dense protein incorporation
and bonding network
was 14.2 ± 0.4%, indicating moderate thermal
degradation and limited char formation, thus
categorizing it as thermally less stable.
With the incorporation of 0.5 g gelatin (F2),
moisture loss slightly decreased to 11.1 ± 0.4%,
and the Tonset shifted to 210°C, reflecting a
slight improvement in thermal resistance. The
main degradation range also extended to 210–
330°C, with an increase in residual mass to 15.5
± 0.3%, suggesting a more stable matrix. The F3
formulation (1.0 g gelatin) demonstrated further
enhancement in thermal stability, as evidenced
by lower moisture loss (10.5 ± 0.2%), an
elevated Tonset of 216°C, and a degradation
range of 215–340°C. The residual weight
increased to 17.1 ± 0.4%, marking a moderate
thermal improvement attributed to increased
protein–polysaccharide interactions.
© MAT Journals 2025. All Rights Reserved
J of Envir. Eng. and Stu.
The most thermally stable film was F4 (1.5 g
gelatin), which exhibited the lowest moisture
loss (9.8 ± 0.3%), the highest Tonset (222°C),
and a broadened degradation window of 220–
350°C. The residual mass reached 18.4 ± 0.5%,
suggesting enhanced thermal char formation due
to stronger intermolecular bonding and compact
polymer network formation. These results
highlight F4 as having the optimum thermal
stability among all formulations. However, with
further gelatin addition in F5 (2.0 g), a slight
decline in thermal stability was observed. While
the degradation range remained relatively high
(215–345°C) and Tonset dropped slightly to
218°C, the residual weight marginally decreased
Vol. 10, Issue 2
to 17.9 ± 0.4%. This indicates that excess
gelatin may disrupt the homogeneity of the
blend or introduce thermally less stable
domains.
TGA results show that gelatin incorporation
significantly enhances the thermal stability of
sodium alginate-based membranes up to an
optimal concentration (1.5 g). Beyond this point,
thermal benefits plateau or slightly decline,
highlighting the importance of balanced gelatin
loading for thermal performance optimization in
biodegradable film applications. Fig. 4 depicts
the thermo-gravimetric analysis (TGA) results
of SA-gelatin membranes.
Figure 4: Thermo-gravimetric analysis (TGA) results of SA–gelatin membranes.
Mechanical Testing
Mechanical properties are crucial for evaluating
the applicability of biopolymer films in
packaging and biomedical contexts, where
strength, flexibility, and durability determine
functionality. In this study, the mechanical
behavior of sodium alginate-gelatin films was
evaluated using a Universal Testing Machine
(UTM) following the ASTM D882 standard for
thin plastic sheeting.
Film strips with dimensions of 10 mm × 100
mm were tested at a crosshead speed of 10
mm/min. The two principal parameters
measured were: Tensile Strength (TS): The
maximum stress a film can withstand while
being stretched before breaking (measured in
MPa), and Elongation at Break (EAB): The
percentage increase in length before rupture,
54
indicating film flexibility. The mechanical
performance of biopolymer films is a critical
parameter influencing their applicability in
packaging, biomedical, and agricultural sectors.
In this study, Sodium Alginate (SA)-based films
were modified by incorporating varying
amounts of gelatin (GEL) to assess their tensile
strength and elongation at break. Five different
formulations (F1 to F5) were prepared by
systematically increasing the gelatin content
from 0 to 2.0 grams, while maintaining the base
polymer (sodium alginate) constant. The
mechanical behavior of the resulting films was
analyzed to understand the influence of gelatin
concentration on the structural integrity and
flexibility of the blends.
The control film, F1, containing no gelatin,
exhibited a tensile strength of 15.8 ± 0.6 MPa
and an elongation at break of 34.2 ± 1.3%, and
© MAT Journals 2025. All Rights Reserved
Tenable Properties of Sodium Alginate-Gelatin Biopolymer Membranes
indicating a moderately strong yet flexible
matrix typical of pure sodium alginate. Upon the
addition of 0.5 g gelatin (F2), the tensile
strength increased significantly to 18.7 ± 0.8
MPa, while the elongation decreased to 30.1 ±
1.5%, suggesting enhanced intermolecular
interactions at the expense of slight flexibility.
This trend continued with F3, where 1.0 g of
gelatin yielded a tensile strength of 22.3 ± 0.7
MPa and an elongation at break of 26.4 ± 1.1%,
indicating the formation of a more cohesive and
mechanically balanced polymer network.
Further increase in gelatin to 1.5 g (F4) resulted
in the maximum tensile strength of 24.1 ± 0.9
MPa, demonstrating robust interpolymeric
hydrogen bonding and network formation.
However, the elongation was reduced to 22.5 ±
1.4%, reflecting the onset of rigidity in the film
structure. At the highest gelatin concentration
Mallikarjunagouda B. Patil et al.
(2.0 g, F5), the tensile strength dropped to 21.4
± 0.6 MPa, and elongation fell further to 18.3 ±
1.2%, signifying a brittle matrix with diminished
ductility likely due to phase separation or
excessive cross-linking.
Overall, the results suggest that gelatin
incorporation enhances tensile strength up to an
optimal level (1.5 g), beyond which the films
begin to lose flexibility and mechanical
uniformity. The data reflect a trade-off between
strength and extensibility, a common
phenomenon in polymeric blend systems. This
study confirms that sodium alginate-gelatin
blends can be effectively tuned for desired
mechanical
performance,
making
them
promising candidates for tailored applications in
biodegradable packaging. The mechanical
properties are depicted in Fig. 5.
Figure 5: Mechanical properties of SA–gelatin membranes.
Antimicrobial Activity and Statistical
Analysis
The antimicrobial efficacy of biopolymer-based
films is of critical importance, especially for
applications in active food packaging, wound
dressings, and biomedical materials. In this
study, sodium alginate films blended with
55
increasing concentrations of gelatin were
evaluated for their antimicrobial activity against
two representative bacterial strains: Escherichia
coli (Gram-negative) and Staphylococcus aureus
(Gram-positive). The antimicrobial performance
was assessed using the Zone of Inhibition (ZOI)
method, with results expressed in millimeter
(mm) (Fig. 6).
© MAT Journals 2025. All Rights Reserved
J of Envir. Eng. and Stu.
The control film (F1), composed solely of
sodium alginate without any gelatin, showed no
detectable antimicrobial activity against either
E. coli or S. aureus (0.0 ± 0.0 mm ZOI),
indicating the inherent lack of bacteriostatic or
bactericidal properties in alginate alone.
However, with the incorporation of 0.5 g of
gelatin (F2), a very weak antimicrobial response
was observed, with ZOIs of 1.1 ± 0.2 mm for E.
coli and 0.9 ± 0.2 mm for S. aureus. This slight
inhibition suggests minimal interaction of
gelatin-derived bioactive peptides or residual
antimicrobial agents. As the gelatin content was
increased to 1.0 g (F3), the ZOI expanded to 2.3
± 0.3 mm against E. coli and 2.0 ± 0.3 mm
against S. aureus, indicating mild antimicrobial
activity. These effect likely results from
enhanced proteinaceous content providing
binding sites or functional groups that interfere
with microbial cell walls. A more pronounced
moderate antimicrobial effect was evident in the
F4 film (1.5 g gelatin), which exhibited ZOIs of
3.4 ± 0.2 mm for E. coli and 3.0 ± 0.2 mm for S.
Vol. 10, Issue 2
aureus. The peak antimicrobial performance was
recorded in F5 (2.0 g gelatin), with ZOIs of 4.1
± 0.4 mm and 3.7 ± 0.3 mm, respectively,
reflecting a notable inhibition of bacterial
growth. The data demonstrate a direct
correlation between gelatin concentration and
antimicrobial activity, with higher gelatin
loadings contributing to improved bacteriostatic
performance. This could be attributed to
bioactive constituents in gelatin or synergistic
effects with sodium alginate in disrupting
microbial membranes. Moreover, E. coli was
slightly more susceptible to these films than S.
aureus, which is consistent with previous
findings on the variable resistance of Gramnegative and Gram-positive bacteria.
These findings support the potential of gelatinenriched alginate films in developing active
packaging materials with inherent antimicrobial
protection, especially at higher gelatin
concentrations. Fig. 6 displays the antimicrobial
activity.
Figure 6: Antimicrobial activity (zone of inhibition in mm) of SA–gelatin films.
Statistical Analysis (One-way ANOVA)
A progressive increase in the diameter of the
inhibition
zones
with
higher
gelatin
concentrations
indicates
an
enhanced
antibacterial potential of the sodium alginate
56
gelatin blend films. This effect may be attributed
to the increased protein content introduced by
gelatin, which likely facilitates interactions with
bacterial membranes through reactive binding or
mild enzymatic disruption mechanisms. The
control film (F1), composed solely of sodium
© MAT Journals 2025. All Rights Reserved
Tenable Properties of Sodium Alginate-Gelatin Biopolymer Membranes
Mallikarjunagouda B. Patil et al.
alginate, exhibited no antimicrobial activity,
confirming the absence of inherent bacteriostatic
properties in the unmodified matrix. However,
films containing gelatin at concentrations of 1.0
g or higher demonstrated mild to moderate
antimicrobial efficacy, with more pronounced
activity observed against Escherichia coli
compared to Staphylococcus aureus. Although
the antimicrobial effect remains relatively
modest, it is consistent and reproducible across
samples, suggesting that gelatin-enriched
biopolymer films possess potential as functional
base materials. Furthermore, such membranes
could serve as promising carrier systems for the
incorporation of additional antimicrobial agents
such as essential oils, silver nanoparticles, or
plant-based extracts like neem to enhance their
bioactive performance.
flexibility was noted, likely due to increased
network rigidity. FTIR spectroscopy provided
molecular-level evidence of hydrogen bonding
and electrostatic interactions between protein
(gelatin)
and
polysaccharide
(alginate)
components, confirming successful blending.
Additionally, the membranes exhibited moderate
antimicrobial activity with increasing gelatin
content, especially against Escherichia coli and
Staphylococcus aureus, suggesting the potential
bioactivity of protein-enriched formulations.
Among the tested compositions, films
containing 1.0–1.5 g of gelatin presented an
optimal balance of mechanical integrity,
functional bioactivity, and biodegradability,
highlighting their suitability for eco-friendly
packaging applications where both performance
and environmental sustainability are critical.
CONCLUSION
ACKNOWLEDGEMENT
The present study effectively demonstrated the
development and systematic characterization of
sodium alginate-gelatin biopolymer membranes
by varying gelatin concentrations. The
incorporation of gelatin progressively enhanced
the mechanical properties, particularly tensile
strength, and contributed to improved thermal
stability of the films, attributable to reinforced
intermolecular interactions between gelatin and
alginate.
However,
at
higher
gelatin
concentrations, a slight reduction in film
Dr. Mallikarjunagouda B. Patil gratefully
acknowledges the Vision Group for Science and
Technology (VGST), Government of Karnataka,
Bengaluru, India, for the financial support
provided under Grant No. GRD 951 (2020–
2021). This funding was instrumental in the
establishment of a dedicated research laboratory
at Basaveshwar Science College, Bagalkot,
India, which significantly facilitated the
successful execution of this study.
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CITE THIS ARTICLE
Mallikarjunagouda B. Patil, Rajeshwari D. Hiredesai, Varshini B. Kulkarni, Pratibha S. Patil, Shankramma S.
Chavan and Shridhar N. Mathad, “Tenable Properties of Sodium Alginate-Gelatin Biopolymer Membranes:
Development and Comprehensive Characterization”, Journal of Environmental Engineering and Studies, vol.
10, no. 2, pp. 48-58, Aug. 2025.
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