Composition of a biodegradable film based on sodium alginate, containing essential Pelargonium graveolens oil

Abstract

Composition of a biodegradable sodium alginate-based film containing Pelargonium graveolens essential oil, wherein the film comprises a) Sodium alginate as a primary film-forming biopolymer, b) Glycerin as a plasticizer to improve flexibility, c) geranium essential oil in an amount sufficient to enhance the antioxidant and hydrophobic properties, d) wherein the film has improved physicochemical properties, including improved surface hydrophobicity, antioxidant activity and UV-blocking capabilities, making it suitable for active packaging applications.

Description

[0001] The present invention relates to a biodegradable film composition containing sodium alginate (SA) as the primary polymer matrix, Pelargonium graveolens essential oil (GEO) as a bioactive additive, and glycerin as a plasticizer. This composition improves the mechanical strength, optical properties, surface hydrophobicity, and antioxidant activity of the film for packaging applications.

[0002] Plastic packaging has become an integral part of modern life due to its durability, flexibility, and cost-effectiveness. However, its widespread use has led to serious environmental problems, primarily due to its non-biodegradability and long degradation time, often several hundred years. The accumulation of plastic waste in ecosystems contributes to pollution, disrupts marine and terrestrial life, and leads to the formation of microplastics, which have been detected in soils and waterways. For these reasons, there is an urgent need for sustainable and biodegradable alternatives that can reduce environmental impact while retaining the essential functions of conventional plastic packaging.

[0003] A promising solution to address these challenges is the use of sodium alginate (SA), a naturally occurring polysaccharide derived from brown algae. SA is known for its biodegradability, biocompatibility, and excellent film-forming properties, making it a viable replacement for synthetic plastics in food and pharmaceutical packaging. Despite their advantages, SA-based films have several limitations, including low mechanical strength and the lack of antioxidant and antimicrobial properties, which are critical for extending the shelf life of packaged goods. These disadvantages limit the widespread use of SA films for commercial packaging applications and necessitate further enhancement through functional additives.

[0004] To overcome these limitations, this study focuses on the incorporation of geranium essential oil (GEO), extracted from Pelargonium graveolens, into SA-based films. GEO is known for its antioxidant and antimicrobial properties, making it a valuable bioactive agent for improving film performance. While essential oils have been previously used to enhance biopolymer films, the specific effects of GEO on the mechanical, optical, and antioxidant properties of SA films are still understudied. By incorporating GEO into SA films, this research aims to develop a multifunctional, environmentally friendly packaging material with improved physicochemical and bioactive properties, providing a sustainable alternative to conventional plastic packaging.

[0005] An aim of the present disclosure is to develop biodegradable sodium alginate-based films as an environmentally friendly alternative to synthetic plastics.

[0006] Another object of the present disclosure is the improvement of the functionality of films by incorporating Pelargonium graveolens essential oil (GEO).

[0007] Another object of the present disclosure is to improve the antioxidant activity in biopolymer films to extend the shelf life of packaged products.

[0008] Another object of the present disclosure is to modify the optical properties, reduce transparency and increase UV blocking potential.

[0009] Another object of the present disclosure is to increase surface hydrophobicity, thereby making the films for food packaging more moisture resistant.

[0010] Another objective of the present disclosure is to evaluate mechanical properties to ensure adequate flexibility and structural integrity.

[0011] Another objective of the present disclosure is to analyze the chemical composition of geranium essential oil using GC-MS for quality validation.

[0012] Another objective of the present disclosure is to ensure the statistical reliability of the results through ANOVA and post-hoc analysis.

[0013] Other objects and advantages of the present disclosure will become more apparent from the following description, which is not intended to limit the scope of the present disclosure. The present invention relates to a biodegradable film composition containing sodium alginate (SA) as the primary polymer matrix, Pelargonium graveolens essential oil (GEO) as a bioactive additive, and glycerin as a plasticizer.

[0014] Another embodiment of the present invention is that GEO is incorporated into the sodium alginate matrix to improve the antioxidant and potentially antimicrobial properties of the film.

[0015] Another embodiment of the present invention is the addition of glycerin to improve the flexibility and mechanical properties of the sodium alginate-based film.

[0016] Another embodiment of the present invention is the formulation of a uniform dispersion method for GEO within the SA matrix to ensure a homogeneous film structure and stability.

[0017] Another embodiment of the present invention is the optimization of the optical properties of the film by controlling transparency and haze through the interaction between SA and GEO.

[0018] Another embodiment of the present invention includes modifying the surface properties by increasing hydrophobicity using essential oils to improve moisture resistance.

[0019] Another embodiment of the present invention is the controlled variation of film thickness and mechanical strength to balance structural integrity with functional performance.

[0020] Another embodiment of the present invention is the evaluation of the bioactivity of the film composition, particularly its antioxidant potential, for improving shelf life and packaging applications.

[0021] The present invention relates to a biodegradable film composition containing sodium alginate (SA) as the primary polymer matrix, Pelargonium graveolens essential oil (GEO) as a functional bioactive additive, and glycerin as a plasticizer. Sodium alginate, a naturally occurring polysaccharide, forms the basic structure of the film due to its excellent film-forming ability and biodegradability. To increase the flexibility of the film, glycerin is used as a plasticizer, improving mechanical properties and reducing brittleness. To impart antioxidant and potentially antimicrobial properties, geranium essential oil (GEO) is added at a controlled concentration. The essential oil, rich in bioactive compounds, is dispersed in the sodium alginate matrix, forming a functional composite material suitable for food and pharmaceutical packaging.

[0022] The composition is carefully formulated to achieve an optimal balance between mechanical strength, optical properties, surface hydrophobicity, and bioactivity. The incorporation of GEO into the sodium alginate matrix alters the structural integrity, thereby changing the film's transparency and light-scattering properties. Furthermore, the surface properties are improved by improving water resistance and reducing hydrophilicity. The bioactive compounds contained in GEO contribute to the film's functional properties and offer antioxidant potential, which can help extend the shelf life of packaged goods. This biodegradable film composition offers an environmentally friendly alternative to synthetic plastic packaging, making it a sustainable solution for industries seeking renewable and functional packaging materials. EXAMPLE 1: COMPOSITION

[0023] A biodegradable sodium alginate-based film containing Pelargonium graveolens essential oil, the film comprising: - Sodium alginate (SA) as a primary film-forming biopolymer, - Glycerin as a plasticizer to improve flexibility, - Geranium essential oil (GEO) in an amount sufficient to enhance antioxidant, antimicrobial and hydrophobic properties, - The film exhibits improved physicochemical properties, including improved surface hydrophobicity, antioxidant activity and UV-blocking capabilities, making it suitable for active packaging applications. EXAMPLE 2: GCMS analysis of geranium essential oil

[0024] A gas chromatograph-mass spectrometer was used to analyze the chemical composition of geranium essential oil. A tiny 1 µL sample of the oil was injected with a split ratio of 1:115. The column was first heated to 50 °C for 2 minutes, then gradually to 210 °C at 3 °C per minute, and finally to 280 °C at 6 °C per minute. Helium gas flowed through the system at 1.0 mL per minute while the injector and ion source were maintained at 260 °C and 220 °C, respectively. The major compounds in geranium essential oil were identified by comparing their retention indices and retention times (RT) with known reference standards.

[0025] GC-MS analysis of Pelargonium graveolens (GEO) essential oil confirmed its main constituents as citronellol (28.62%), geraniol (20.25%), linalool (5.68%), L-menthone (3.27%), and phenylethyl alcohol (3.11%). Citronellol and geraniol are the main bioactive compounds, contributing to its characteristic fragrance, antimicrobial potency, and therapeutic properties. Slight variations in chemical composition can be attributed to factors such as geographical origin, extraction method, and seasonal variations.

[0026] Furthermore, the presence of linalool, menthone, and phenylethyl alcohol supports the distinct fragrance and bioactivity of geranium essential oil. Linalool is known for its soothing and antimicrobial effects, L-menthone contributes to the minty and cooling sensation, while phenylethyl alcohol enhances the floral aroma and antibacterial efficacy. The combined effect of these components makes geranium essential oil a versatile additive for bio-based films, capable of improving both the preservation and functional properties of biopolymer-based packaging materials. EXAMPLE 3: Production of sodium alginate-based films

[0027] To prepare the films, 1.5% SA was dissolved in distilled water and stirred at 50°C for two hours to obtain a homogeneous solution. Glycerol (1%) was added as a plasticizer to improve flexibility. The solution was then divided into two beakers: SA1 (control) and SA2 containing GEO (0.5%). After ensuring that the geranium essential oil was fully dispersed, 20 ml of each solution was poured into previously leveled and coded Petri dishes and allowed to dry at controlled room temperature. Once completely dry, the films were carefully removed and stored in a desiccator for further analysis.

[0028] The results show that the SA films (SA1 and SA2) exhibited significant differences in transparency and appearance, as revealed by visual assessment. The control film (SA1) had a transparent and uniform texture, while the GEO-loaded film (SA2) was slightly opaque. The lower transparency of SA2 is likely due to the presence of essential oil droplets that scatter light and make the film appear opaque. EXAMPLE 4: Analysis of optical and surface properties

[0029] The transparency and light scattering behavior of the SA1 and SA2 films were analyzed using a haze meter, ensuring correct alignment to avoid measurement errors. Surface hydrophobicity was determined by measuring the water contact angle. A 2 × 2 cm film sample was placed on a flat surface, and a 1 µl water droplet was carefully placed in the center. The contact angle was measured using an OCA11 goniometer and evaluated using the dpiMAX software.

[0030] The results show that the transmittance of the SA1 film (86.72%) was higher than that of the SA2 film (68.76%), indicating that the addition of GEO reduced transparency. However, haze values ​​were higher for SA2 (90.27%) than for SA1 (83.31%), indicating an increase in light scattering within the film structure. The increase in haze and the reduction in transmittance could be beneficial for packaging applications where UV protection is required to extend shelf life.

[0031] The results show that the control film (SA1) exhibited a lower water contact angle of 42.74°, indicating higher wettability and hydrophilic properties due to the inherent nature of the SA matrix. In contrast, the GEO-incorporated film (SA2) exhibited a higher contact angle of 58.84°, indicating increased surface hydrophobicity. Such an increase in hydrophobicity is beneficial for food packaging, where moisture resistance is critical for product integrity. EXAMPLE 5: Physical and mechanical properties

[0032] The film thickness was measured with a digital micrometer by randomly selecting five points per sample and recording the average thickness. Mechanical strength was determined using a texture analyzer with a 5 kg load cell. Before testing, the films were conditioned for 40 hours at 25 °C and 50% relative humidity. They were then cut into 7 × 60 mm strips and subjected to a tensile test at 30 mm / min to determine the tensile strength (TS, MPa) and elongation at break (EAB, %). The results were processed and evaluated using Exponent Connect software.

[0033] The results show that the films had a relatively lower thickness than the control film (SA1) (∼0.074 mm), while the germanium oil-infused film (SA2) (∼0.108 mm) was thicker. This increase was due to the presence of droplets of germanium essential oil in the sodium alginate matrix, which altered the film structure and potentially broadened the polymer matrix and made it more heterogeneous.

[0034] The results show that the tensile strength of SA1 was measured at 0.041 MPa, while SA2 showed a significant decrease to 0.014 MPa. This decrease suggests that the addition of germanium essential oil disrupted the sodium alginate polynetwork, resulting in weaker intermolecular interaction.

[0035] Similarly, the % elongation at break, which measures film flexibility, decreased from 99.63% in SA1 to 82.57% in SA2. This reduction may be related to the incompatibility between the hydrophilic sodium alginate matrix and the hydrophobic essential oil, likely resulting in poor cohesion within the film structure. EXAMPLE 6: Antioxidant activity

[0036] The antioxidant potential of the films was evaluated using the DPPH radical scavenging assay. The reaction mixture was analyzed using an ONDA Vis spectrophotometer at 517 nm, and the percent inhibition was calculated based on three independent measurements per sample.

[0037] The results show that the control film (SA1) exhibited a low antioxidant inhibition of 4.69%, while SA2 showed a significant increase to 31.87%. This improvement is due to the presence of bioactive compounds in the germanium essential oil, such as citronellol, geraniol, and linalool. The improved antioxidant capacity suggests that the germanium oil-containing films could extend the shelf life of perishable foods by reducing oxidative degradation. EXAMPLE 7: Statistical analysis

[0038] All results were expressed as mean ± standard deviation (SD) of triplicate measurements. Statistical differences between samples were determined using one-way ANOVA followed by Fisher's post-hoc test. Examples

[0039] 1. Composition of a biodegradable sodium alginate-based film containing Pelargonium graveolens essential oil, the film comprising a) Sodium alginate as a primary film-forming biopolymer, b) Glycerin as a plasticizer to improve flexibility, c) geranium essential oil in an amount sufficient to improve the antioxidant and hydrophobic properties, d) wherein the film has improved physicochemical properties, including improved surface hydrophobicity, antioxidant activity and UV-blocking capabilities, making it suitable for active packaging applications.

Claims

[1] A composition of a biodegradable sodium alginate-based film containing Pelargonium graveolens essential oil, the film comprising a) Sodium alginate as a primary film-forming biopolymer, b) Glycerin as a plasticizer to improve flexibility, c) geranium essential oil in an amount sufficient to improve the antioxidant and hydrophobic properties, d) wherein the film has improved physicochemical properties, including improved surface hydrophobicity, antioxidant activity and UV-blocking capabilities, making it suitable for active packaging applications. [2] A biodegradable sodium alginate-based film composition according to claim 1, wherein the geranium essential oil (GEO) comprises citronellol (28.62%) and geraniol (20.25%) as primary bioactive components contributing to its antimicrobial and antioxidant properties. [3] A biodegradable sodium alginate-based film composition according to claim 1, wherein the addition of geranium essential oil increases the thickness of the film from about 0.074 mm to 0.108 mm, thereby altering the structural integrity and distribution of the film matrix. [4] A sodium alginate-based biodegradable film composition according to claim 1, wherein the incorporation of geranium essential oil reduces the film transparency from 86.72% to 68.76% and increases the haze from 83.31% to 90.27%, thereby improving UV-blocking properties beneficial for food packaging applications. [5] A sodium alginate-based biodegradable film composition according to claim 1, wherein the tensile strength decreases from 0.041 MPa to 0.014 MPa and the elongation at break decreases from 99.63% to 82.57% due to the hydrophobic nature of GEO disturbing the polymer matrix. [6] A biodegradable sodium alginate-based film composition according to claim 1, wherein the DPPH radical scavenging activity increases from 4.69% in control films to 31.87% in geranium oil-added films, indicating increased antioxidant potential for extended shelf life of packaged goods.