Synergistic Antioxidant and Preservative Potential of Tomato Extract–Magnetic Iron Oxide Nanoparticles in Bio-Coating and Food Applications

Abstract

This study details the synthesis of tomato extract–magnetic iron oxide nanoparticles (TEx-MIONPs), focusing on the antioxidant capacity and food preservation applications. Utilizing key reagents, including 98% iron (III) chloride hexahydrate, a controlled process yielded TEx-MIONPs. The characterization involved X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). XRD analysis revealed a predominant cubic magnetite structure. TEM and SEM depicted diverse morphologies, such as ultrasmall cubic and quasi-spherical structures. FTIR spectroscopy confirmed Fe–O bonds in a mixed phase of Fe₂O₃ and Fe₃O₄. Antioxidant activity assessment showcased the potent scavenging effects of TEx and TEx-MIONPs against DPPH free radicals, with 100% inhibition after 20 min and an IC₅₀ of about 137 µg/mL, respectively. Furthermore, TEx-MIONPs, when stabilized with banana-based bioplastic and utilized as nanocoating preservation materials, demonstrated efficacy in grape preservation by exhibiting a lower weight loss rate compared to the control group over six days. Specifically, the weight loss rate for preserved grapes was 28.6% on day 6, contrasting with 34.6% for the control. This pioneering study amalgamates the natural antioxidant properties of tomatoes with the enhanced characteristics of magnetic iron oxide nanoparticles, offering sustainable solutions for food preservation and nanopackaging. Ongoing research aims to refine the experimental conditions and explore the broader applications of TEx-MIONPs in various contexts.

1. Introduction

In the dynamic landscape of contemporary oxidation and food science, a captivating exploration unfolds, seamlessly weaving together the threads of innovative antioxidant and preservation methodologies [1,2]. This intriguing journey represents a harmonious collaboration between the forces of nature and the precision of nanotechnology, spotlighting the transformative prowess of nanomaterials, particularly the versatile magnetic iron oxide nanoparticles (MNPs) [3,4,5].

MNPs, celebrated for their various properties, transcend their origins in environmental remediation to shape various applications [6]. In the realm of biomedical contexts, MNPs play a pivotal role in targeted drug delivery, hyperthermia therapy, and magnetic resonance imaging (MRI), redefining the landscape of medical treatments. In industrial settings, their catalytic properties elevate processes, enhancing efficiency and sustainability [4,7,8,9]. The influence of MNPs extends further into technology, propelling advancements in electronic devices, magnetic data storage, and sensor technologies [10]. Their impact ripples across energy storage, bioremediation, agriculture, wastewater treatment, and the food industry, offering transformative solutions to a myriad of challenges [11,12].

The synthesis of iron-based nanoparticles traditionally involved various methods, such as inert gas condensation [13], high-energy ball milling [14], liquid-phase reduction [15,16], and reverse micelle [17]. Yet the conventional methods pose challenges related to chemical consumption, cost, and the generation of potentially harmful by-products [18,19,20,21,22,23]. Recent studies underscore the limitations of iron-based NPs, such as aggregation and oxidation. In response, green synthesis, utilizing plant extracts rich in non-toxic compounds like polyphenols and caffeine, emerges as an eco-friendly alternative [24,25,26]. In response to these limitations, the eco-friendly alternative of green synthesis has gained prominence [27]. Utilizing plant extracts rich in non-toxic compounds, this approach stands as a testament to the evolving marriage of nature and technology [20,28,29,30,31,32].

Within this green synthesis realm, tomatoes emerge as intriguing subjects. Globally renowned for their economic value and vibrant composition, tomatoes offer rich phytochemicals, including flavonoids, carotenoids, and polyphenols, showcasing robust antioxidant capabilities [33]. Tomato extracts, harnessed from this humble fruit, serve as eco-friendly precursors for the synthesis of various nanoparticles, including the noteworthy magnetic iron oxide nanoparticles (MIONPs) [34,35]. The inherent antioxidant properties of tomatoes, coupled with their compatibility in nanoparticle synthesis, open avenues for innovative applications, ranging from biomedical fields to eco-friendly packaging solutions. As researchers delve deeper into harnessing the potential of tomatoes in nanotechnology, the intrinsic qualities of this humble fruit continue to inspire novel advancements [28]. Bioplastics, a significant innovation for the chemical and plastics industry based on renewable and/or biodegradable resources, are gaining traction. They present opportunities beyond the agrifood sector, offering new markets and business prospects [36]. While various plastic-based bioresources like gelatin, chitosan, and cellulose acetate have been extensively studied, plant-based resources like banana-based bioplastics are relatively limited [37].

Expanding upon this innovative synthesis approach, this study introduces an inventive method, synthesizing tomato extract–magnetic iron oxide nanoparticles (TEx-MIONPs). This method not only focuses on the antioxidant capacity and food preservation aspect but also integrates the synergy of banana-based bioplastics into the narrative. Through comprehensive recycling, the study transforms agrowaste, including tomato by-products, into nanomaterials and banana fruit waste into bioplastic powder. This not only addresses agrowaste concerns but also aligns with the global momentum toward sustainable packaging solutions.

In pursuing sustainable food preservation and packaging, this investigation employs advanced techniques, including X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Fourier-transform infrared spectroscopy. These techniques unravel the unique characteristics of magnetite structures and diverse morphologies, deepening our understanding of novel nanocomposites. The insights from this study promise exciting possibilities for the future, resonating with the ethos of green chemistry and sustainable practices.

This comprehensive exploration not only underscores the versatility of magnetic iron oxide nanoparticles but also positions them as catalysts for a paradigm shift in sustainable food preservation. From their indispensable role in biomedical applications to their influence in eco-friendly synthesis processes, MNPs emerge as pivotal tools with far-reaching implications across scientific and industrial domains. This study not only contributes valuable insights into the synthesis and applications of TEx-MIONPs but also inspires further exploration in green chemistry and bioplastic development. Doing so marks a significant stride in the evolutionary tapestry of nanotechnology, where innovation meets sustainability, shaping the future of scientific advancements.

2. Materials and Methods

2.1. Materials

Key reagents employed in this study included 98% iron (III) chloride hexahydrate (FeCl₃·6H₂O), methanol (CH₃OH), 99.9% ethanol, NaOH, and 2,2-diphenyl-1-picrylhydrazyl (DPPH). All additional chemicals and reagents utilized met analytical grade standards.

2.2. Preparation of Agrowaste Tomato Extract (TEx)

Harvested tomatoes, deemed as agrowaste due to damage, underwent a thorough washing process to eliminate impurities. The total weight, inclusive of the pan weight (680 g) and the net weight of the damaged tomatoes (1000 g), was then determined. To facilitate drying, the tomatoes were sliced and arranged on metal trays. Subsequently, the slices were dried at 90 °C in a convection oven until a consistent weight was achieved (14 h). After this drying period, the dried slices were reweighed and ground into a fine powder (60–150 µm). The maceration process, inspired by a previous study [38], was adapted to extract bioactive compounds from tomatoes. Our modifications aimed to improve efficiency and precision, enhancing the extraction process. These adjustments, rooted in the earlier study, optimize the extraction of valuable bioactive compounds, contributing to ongoing advancements in this field. Fifty grams of fruit powder were dissolved in 100 mL of water at room temperature for 24 h to create the tomato extract. The resulting extract was filtered, and its concentration in g/mL was measured (50 g/100 mL).

2.3. Nanoparticle Synthesis

A 1 M solution of FeCl₃·6H₂O was prepared by dissolving 135.15 g of the compound in 500 mL of water. Simultaneously, a 5 M solution of NaOH was prepared by dissolving 39.997 g of NaOH in 200 mL of water. One hundred milliliters of the tomato extract were mixed with 100 mL of the FeCl₃·6H₂O solution and stirred using a magnetic stirrer. The pH was recorded and adjusted to 7.5 by adding NaOH (5 M) as necessary. The mixture was subjected to a reaction temperature of 60–80 °C for 3 h [39,40]. After the reaction, the mixture was cooled and washed, and the iron oxide nanoparticles were collected by filtration. The obtained nanoparticles were thoroughly dried using both an oven at 200 °C for 6 h and a muffle at 300 °C for 2 h, completing the synthesis process. The obtained magnetic iron oxide nanoparticles based on tomato extract were assigned the designation TEx-MIONPs.

2.4. Nanoparticle Characterization

To validate the formation of TEx-MIONPs, various advanced techniques have been employed [41,42]. XRD patterns, acquired using a Bruker D8 Advance A25 diffractometer with a Cu anode (manufactured by Bruker, sourced from Madrid, Spain), were analyzed to affirm the crystalline phase and crystal systems. Additionally, these patterns were employed to calculate the size and degree of crystallinity of the TEx-MIONPs, following the methodology outlined in a previous study [41,42]. The diffractograms were conducted within the range of 2θ = 15–70°. TEx-MIONPs’ morphology and size were investigated using a Zeiss EVO scanning electron microscope (Pleasanton, CA, USA) through scanning electron microscopy (SEM) and a Talos S200 microscope (FEI, Hillsboro, OR, USA) operating at 200 kV through transmission electron microscopy (TEM). Image analysis was conducted utilizing ImageJ software (v1.53q, NIH, Bethesda, MD, USA). The investigation was performed using FTIR spectroscopy, which was utilized to glean insights into the structure of the TEx-MIONPs by probing vibration modes in the range of 4000 to 400 cm⁻¹. The identification of Fe–O bonds in the TEx-MIONPs was specifically conducted in the fingerprint region (900–350 cm⁻¹).

2.5. Antioxidant Activity

In the process of preparing tomato extract for iron oxide synthesis, an evaluation of its antioxidant activity was conducted, using a basic technique known as Disc Diffusion, against the DPPH free radical [39]. Therefore, approximately 7 mg of the DPPH was dissolved in ethanol, and a 25 mL solution of DPPH free radical was cast onto an aluminum plate with a diameter of 10 cm. Subsequently, 1–3 mL of the tomato extract was applied to the center of the plate filled with the DPPH solution. The color immediately changed to clear yellow. Following this, the antioxidant activity was assessed by measuring the areas where the color change occurred, utilizing ImageJ software.

Briefly, the method employed for this assessment was validated by recording the area, and the following equation was used to calculate the inhibition percentage:

$$\mathrm{Inhibition}(\%)=\left(\frac{A_1-A_2}{A_1}\right)\times 100$$

(1)

Here, $A_1$ represents the total area of the inhibited DPPH with violet color, and $A_2$ represents the remaining areas without a change in color over time. When the color completely changes to yellow, it is recorded as 100% inhibition. This technique serves as a valuable tool for quantifying the antioxidant capacity of the tomato extract, providing essential insights into its potential applications in various contexts, including the synthesis of iron oxide nanoparticles. For TEx-MIONPs, the antioxidant activity was assessed using the protocol outlined in [43] with a slight variation. In summary, a series of TEx-MIONP dispersions was prepared at varying concentrations (50, 150, and 250 µg/mL in DMSO). Subsequently, 2 mL volumes of these dispersions were mixed with 2 mL of DPPH solution. The resulting mixtures were incubated for 30 min, after which their absorbance was measured at 517 nm. To establish a baseline, a control solution was created by combining 2 mL of DPPH solution with 2 mL of DMSO. The IC₅₀ was determined using an online IC₅₀ calculator [44].

2.6. Grape Preservation

Banana flour was initially obtained following the procedure outlined in [45]. In summary, the banana agrowaste, sourced from Mesa SAN R11 El Paraíso (Danli, El Paraíso, Honduras), underwent a treatment process to yield flour. Initially, the bananas were peeled, and the fruit was sliced into thin sections with a thickness of approximately 0.5 cm, utilizing a laminating machine, HLC-300 (Intertek, London, UK). This step aimed to optimize the subsequent drying process by increasing the specific surface area of the material. Subsequently, the sliced samples were subjected to a drying process in an oven set at 60 °C for 4 h. This temperature and duration were chosen to prevent the denaturation of polymers within the material. Following the drying period, the samples were allowed to temper at room temperature for 40 min. This drying procedure was crucial in maintaining the stability of the obtained flours during storage, preventing the high water content of these samples (>50%) from causing destabilization and ensuring that the flours could be stored for an extended period without succumbing to the growth of microorganisms or fungi that might alter their physicochemical characteristics. Following the drying stage, the slices underwent processing in a rotating ball mill. In this step, the particles were subjected to friction caused by the balls, progressively diminishing their size until they could traverse a 60-micron sieve (equivalent to 250 mesh). This milling process played a pivotal role in achieving the desired flour characteristics. The presented protocol unveiled the composition of the banana, showcasing specific percentages by weight for key components: moisture content at 1.50% ± 0.04, ashes at 7.81% ± 0.05, lipids at 0.22% ± 0.05, proteins at 2.25% ± 0.17, and polysaccharides at 59.2% ± 2.2.

Grapes are rich in nutrients but are susceptible to deterioration caused by microorganisms. Therefore, they were selected to assess the feasibility of using TEx-MIONPs stabilized with banana-based bioplastic as a bio-coating and food nanopackaging material. For treating the grapes, an aqueous solution of banana water (1–3) (1 g dissolved in 30 mL of water) was prepared. The mixture was then stirred for about 10 min at 100 °C. Afterward, the solution was filtered using coffee filtration paper, and the liquid-forming bioplastic was collected. Following that, approximately 7 mg of fine powder of TEx-MIONPs was introduced into the banana solution and manually shaken until a visually observed homogeneous dispersion was achieved. Finally, the grapes were immersed in the resulting solution for 3 min and left for 6 days at room temperature (28 ± 7 °C and average relative humidity (RH) of 87%) to conduct the shelf-life test.

Every 3 days, photographs were taken, and the weight loss rate (WLR, %) was calculated using the following formula [46]:

$$\mathrm{WLR}(\%)=\left(\frac{P_{Fresh}-P}{P_{Fresh}}\right)\times 100$$

(2)

where $P_{Fresh}$ and $P$ are the weights of fresh and preserved grapes, respectively.

2.7. Statistical Analysis

Statistical analyses, involving multiple software, including IBM SPSS Statistics 26 and GraphPad, (GraphPad Prism version 9.0.0 for windows, San Diego, CA, USA, www.graphpad.com) were conducted on assessed measurements at least three times. Significant differences were determined through a one-way ANOVA.

3. Results and Discussion

3.1. XRD

The XRD analysis of tomato extract–magnetic iron oxide nanoparticles (TEx-MIONPs), as depicted in Figure 1a, reveals distinctive peaks at 2θ values of 18.4°, 30.2°, 35.6°, 43.3°, 47.4°, 53.7°, 57.3°, 62.9°, 66.1°, and 67.2°. These peaks are attributed to cubic magnetite with the space group F d −3 m:2 (227) (JCPDS no. 00-900-2319) [47], constituting 85.1% of the composition. Additionally, a peak at 45.5° corresponds to the crystal system of monoclinic magnetite, contributing 7.1% (JCPDS no. 00-153-2800) [48]. Furthermore, peaks at 27.3°, 39.8°, 41.5°, and 56.5° align with the crystal system of tetragonal hematite, representing 7.8% (JCPDS no. 00-152-8612) [49].

The coexistence of peaks from both cubic and monoclinic systems underscores the magnetic response of these particles, as visually presented in Figure 1b. This observation aligns with previous studies [40,50], wherein magnetic properties were explored under various pH conditions and calcination parameters. The XRD results in this study harmonize well with their findings, highlighting a substantial percentage of the magnetic phase. This congruence can be attributed to maintaining a pH of 7.5 and calcination at 300 °C for 2 h, as justified in our experimental conditions.

Regarding the crystallinity of TEx-MIONPs, the different peaks in Figure 1a exhibit varying intensities. The total crystallinity is determined to be 96.4%. Specifically, peaks at 30.2°, 35.6°, and 62.9°, corresponding to the cubic magnetite crystalline system, demonstrate heightened crystallinity (12.45%, 17.04%, and 10.6%). Conversely, the monoclinic phase at 45.5° displays 7.5% crystallinity, while the tetragonal structure shows 3.7% at 27.3° and 6.4% at 56.5°. These findings reveal the distinct crystalline features of TEx-MIONPs, providing valuable insights for tailored applications.

The crystallite size of TEx-MIONPs was determined to be 18.6 nm. To augment these findings, further analysis using SEM and TEM techniques is warranted, promising a comprehensive insight into the structural characteristics and morphology of the synthesized nanoparticles.

3.2. TEM

Figure 2 presents a TEM image of TEx-MIONPs showcasing diverse morphologies, including ultrasmall cubic, elongated, quasi-spherical, hexagonal structures, with some exhibiting an amorphous structure (Figure 2a). The size distribution histograms were fitted using a Lorentz curve, revealing an excellent dispersion with slight aggregation (Figure 2b).

The observed dispersion characteristics can be attributed to the phenolic compound -OH⁻ in tomato extract, acting as a reducing agent, interacting with nanoparticle surfaces. This interaction induces a substantial increase in iron hydroxide seeds, Fe(OH), forming various phases of magnetic iron oxide, including magnetite and hematite. This, in turn, reduces the growth rate and interparticle reactions [51]. The competitive relationship between the phytochemical groups (phenolic compounds) of tomato extract and iron ions on the Fe₃O₄-NPs surface suggests an increased oxidation rate [52].

The nanoparticle’s diameter distribution, as illustrated in Figure 2b, reveals an average diameter of 8.9 nm.

3.3. SEM

In Figure 3, SEM images of TEx-MIONPs reveal a spectrum of morphologies, featuring diverse shapes, including cubic, plate-like, elongated, quasi-spherical, hexagonal structures, and instances of amorphous formations (Figure 3a).

Surface analysis highlights nanoscale roughness and irregularities in the SEM micrographs, with potential implications for the nanoparticles’ interactions in various applications, such as catalysis or drug delivery [40]. Further quantitative insights into surface characteristics can be gained through techniques like atomic force microscopy (AFM) or profilometry [53].

The visual examination captures the presence of grains or aggregates, aligning with the interactions observed between the phenolic compound -OH⁻ in tomato extract (acting as a reducing agent) and the nanoparticle surfaces, as discussed in the TEM analysis [51]. Additionally, SEM micrographs suggest a propensity for nanoparticle aggregation in specific regions, possibly influenced by van der Waals forces, electrostatic interactions, or solvent evaporation during sample preparation [54]. Strategies to mitigate aggregation, including surface functionalization or optimizing dispersing agents, could be explored to enhance the nanoparticles’ stability and achieve a more uniform distribution [55].

The size distribution, as illustrated in Figure 3b, highlights a considerable variation in particle size, emphasizing an average diameter of 600 nm. This SEM analysis provides valuable insights into the structural characteristics and grain size distribution of the synthesized TEx-MIONPs.

3.4. FTIR

Figure 4a,b show FTIR images of TEx-MIONPs observations in the range of 4000–400 cm⁻¹ and 1000–400 cm⁻¹, respectively.

The presence of bands at 596.31–560.23 cm⁻¹ provides evidence that hematite α–Fe₂O₃ undergoes reduction, resulting in the formation of Fe₃O₄-NPs. In addition, Fe₃O₄ FTIR spectra reveal new absorption bands around 790.69 and 890.83 cm⁻¹ and peaks at 1073.87 and 1597.53 cm⁻¹ [56,57]. The bands detected at 1130, 558.27, 538.23, and 478.11 cm⁻¹ signify the stretching vibration mode associated with the Fe–O bonds in the hematite phase (α–Fe₂O₃). Additionally, the bands around 2913.26 and 3854.71 cm ⁻¹ indicate the stretching vibration mode of Fe–O in the hematite phase (α–Fe₂O₃) [58].

The bonds at 3500–3018 cm⁻¹ signify –OH vibrational stretching in polyphenol groups in TEx-MIONPs [59]. Sharp peaks between 2913.26 and 2609.57 cm⁻¹ indicate hydrocarbon extension. At 1631 cm⁻¹, the band corresponds to aromatic ring deformation or C=C vibration in alkane groups. The band at 1774.01 cm⁻¹ is assigned to the C=O bonds of aldehydes, esters, and ketones. Also, the presence of 1427.63 cm⁻¹ in the FTIR spectra indicates the presence of C=C in lycopene, a carotenoid pigment with antioxidant properties found in tomato extract [33,60]. C–O and C–O–C asymmetric stretching vibrations, characteristic of polyphenol compounds, are observed between 1790 and 1020 cm⁻¹, respectively. Bonds in the range of 1150–1101 cm⁻¹ are assigned to C–O–H in phenolic compounds [59].

Fragmentations in peaks around 1000–400 cm⁻¹ indicate oxidation–reduction between different phases of iron oxide, justifying the magnetic response of the TEx-MIONPs, as reported in [50].

3.5. Antioxidant Activity

The evaluation of the antioxidant activity of TEx (tomato extract) through the DPPH free radical assay yields compelling results. The progression from an initial 12.29% inhibition at 5 s to a remarkable 100% inhibition at 20 min underscores the potent and time-dependent antioxidant properties of the tomato extract (

Table 1. Antioxidant capacity photographs and the inhibition percentage of tomato extract (TEx) against violet DPPH free radicals were observed over time, reaching complete color change within 20 min.

T1 = 0	T2 = 5 s	T3 = 5 min	T4 = 10 min	T5 = 20 min
0%	12.29%	38.22%	79.88%	100%

).

This observed efficacy can be attributed to the rich phytochemical composition of tomatoes, including flavonoids, carotenoids, and polyphenols, known for their antioxidant capabilities. Notably, the presence of lycopene, a powerful antioxidant, likely contributes to the observed effects [33]. The gradual increase in inhibition percentages over time reflects a sustained and evolving antioxidant activity, emphasizing the continuous scavenging of free radicals by the tomato extract components. The attainment of 100% inhibition at the final time point signifies the complete neutralization of DPPH free radicals, affirming the outstanding antioxidant potential of TEx. In comparison to Ahmed et al. (2013) [34], who assessed the antioxidant activity of tomato extract against DPPH in different solution media such as water and methanol and found 44.7% and 37.7%, respectively, after 30 min of incubation, our study showcases a more robust and prolonged antioxidant effect. While Ahmed et al. reported percentages after a fixed incubation period, our findings indicate a continuous and increasing antioxidant activity over time. These results position our TEx as a promising natural source for combating oxidative stress and promoting overall health. In contrast, the antioxidant activity of TEx-MIONPs is assessed using different concentrations (50–150 µg/mL), as shown in Figure 5.

The nanoparticle yielded excellent antioxidant activity, with an IC₅₀ value of 136.9 µg/mL, demonstrating the simultaneous activity of phytochemicals present on the surface of MIONPs [61]. Several factors contribute to this activity, as demonstrated by previous techniques, including the small size and a high proportion of magnetite in a cubic crystal system [62]. This antioxidant capacity contributes to various properties, inhibiting microbial growth and other beneficial effects [63]. Further analysis of these nanoparticles is conducted in combination with banana-based bioplastic for the conservation of grapes, as discussed in the next section.

3.6. Grape Preservation

The results of the grape preservation study, employing TEx-MIONPs stabilized with banana-based bioplastic, demonstrate promising outcomes. The preserved grapes exhibit a notably lower weight loss rate compared to the control group over the experimental period (

Table 2. Photographs depicting grape preservation using a control consisting of banana-based bioplastic (control) and banana-based bioplastic combined with TEx-MIONPs over time, along with the corresponding weight loss rate presented as a percentage.

Parameters	Day 0	Day 3	WLR1 (%)	Day 6	WLR2 (%)
Control			19.5		34.6
TEx-MIONPs			9.9		28.6

), suggesting a potential enhancement in shelf life.

However, this study acknowledges limitations, particularly uncontrolled humidity and temperature conditions in the laboratory, which may have influenced the observed effects. Efforts are underway to refine laboratory conditions and incorporate advanced techniques for more accurate assessments. Despite these challenges, this research represents a pioneering initiative, being the first to successfully assess tomato extraction and nanoparticle synthesis using basic techniques. This foundational approach holds the promise of facilitating investigations in numerous growing institutes, contributing to nanoparticle synthesis and protocol validation advancement. Ongoing improvements in experimental conditions and techniques aim to provide a more comprehensive understanding of the capabilities of TEx-MIONPs in grape preservation.

4. Conclusions

In conclusion, this study successfully synthesized tomato extract–magnetic iron oxide nanoparticles (TEx-MIONPs) and explored their potential applications in antioxidant activity and grape preservation. The comprehensive characterization using XRD, TEM, SEM, and FTIR confirmed the formation of TEx-MIONPs with diverse morphologies and a predominant cubic magnetite structure. Antioxidant activity assessments revealed the remarkable scavenging effects of both TEx and TEx-MIONPs against DPPH free radicals, with TEx-MIONPs exhibiting significant antioxidant potential at a concentration of 136.9 µg/mL.

The innovation of stabilizing TEx-MIONPs with banana-based bioplastic showcased promising results for preserving grapes, reducing the weight loss rate to 28.6% on day 6 compared to 34.6% in the control group. These findings suggested the potential of TEx-MIONPs in sustainable food preservation and nanopackaging applications.

This study contributed to the growing field of nanotechnology by providing insights into the synthesis and versatile applications of TEx-MIONPs. Future research endeavors may further optimize experimental conditions, explore broader applications, and enhance the understanding of the interactions between TEx-MIONPs and various food matrices. Overall, this work laid a foundation for the development of innovative and eco-friendly approaches in the fields of nanotechnology and food science.