This study presents the synthesis of agro-waste banana peel extract-based magnetic iron oxide nanoparticles (BPEx-MIONPs), emphasizing antioxidant capacity and food preservation. Using iron (III) chloride hexahydrate (FeCl₃ · 6 H₂O) as a precursor and a reducing agent from agro-waste peel extract, a precisely controlled process yielded BPEx-MIONPs. Characterization involved X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). XRD revealed tetragonal Fe₂O₃, cubic magnetite structure, and monoclinic Fe_xO_y-NPs with an average size of 14.8 nm. TEM and SEM revealed diverse morphologies. TEM displayed both spherical and elongated nanoparticles, with some appearing as thin fibrils. In contrast, SEM images depicted an array primarily consisting of spherical nanoparticles, resembling coral reef formations. FTIR confirmed Fe–O bonds (1000 –400 cm^-1). The antioxidant assessment showed robust DPPH free radical scavenging; BPEx achieved 100% inhibition at 18 min, and BPEx-MIONPs had an IC₅₀ of ~ 136 µg/mL. BPEx-MIONPs, stabilized with banana-based bioplastic, effectively preserved grapes, reducing weight loss to 6.2% on day 3, compared to the control (19.0%). This pioneering study combines banana peel antioxidants with magnetic iron oxide nanoparticles, providing sustainable solutions for food preservation and nano-packaging. Ongoing research aims to refine conditions and explore broader applications of BPEx-MIONPs. Graphical Abstract

The development of biodegradable plastics and eco-friendly biomaterials derived from renewable resources is crucial for reducing environmental damage. Agro-industrial waste and rejected food can be polymerized into bioplastics, offering a sustainable solution. Bioplastics find use in various industries, including for food, cosmetics, and the biomedical sector. This research investigated the fabrication and characterization of bioplastics using three types of Honduran agro-wastes: taro, yucca, and banana. The agro-wastes were stabilized and characterized (physicochemically and thermically). Taro flour presented the highest protein content (around 4.7%) and banana flour showed the highest moisture content (around 2%). Furthermore, bioplastics were produced and characterized (mechanically and functionally). Banana bioplastics had the best mechanical properties, with a Young’s modulus around 300 MPa, while taro bioplastics had the highest water-uptake capacity (200%). In general, the results showed the potential of these Honduran agro-wastes for producing bioplastics with different characteristics that could add value to these wastes, promoting the circular economy.

This study synthesizes magnetic iron oxide nanoparticles from agro-waste sweet pepper extract, exploring their potential as antioxidant additives and in food preservation. Iron (III) chloride hexahydrate is the precursor, with sweet pepper extract as both a reducing and capping agent at pH 7.5. Characterization techniques, including microscopy and spectroscopy, analyze the sweet pepper extract-magnetic iron oxide nanoparticles. Antioxidant capacities against 2,2-diphenyl-1-picrylhydrazyl are assessed, incorporating nanoparticles into banana-based bioplastic for grape preservation. Microscopy reveals cubic and quasi-spherical structures, and spectroscopy confirms functional groups, including Fe–O bonds. X-ray diffraction identifies cubic and monoclinic magnetite with a monoclinic hematite presence. Sweet pepper extract exhibits 100% inhibitory activity in 20 min, while sweet pepper extract-magnetic iron oxide nanoparticles show an IC₅₀ of 128.1 µg/mL. Furthermore, these nanoparticles, stabilized with banana-based bioplastic, effectively preserve grapes, resulting in a 27.4% lower weight loss rate after 144 h compared to the control group (34.6%). This pioneering study encourages institutional research into the natural antioxidant properties of agro-waste sweet pepper combined with magnetic iron and other metal oxide nanoparticles, offering sustainable solutions for nanopackaging and food preservation. Current research focuses on refining experimental parameters and investigating diverse applications for sweet pepper extract-magnetic iron oxide nanoparticles in varied contexts.

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.

This study aimed to determine the physicochemical, hydration, and rheological characteristics of flours derived from different crop residues (taro, cassava, maize, and banana) affected by climate change in Honduras and to investigate their potential application in food processes. The physicochemical (moisture content, ash, protein, crude fat, starch, amylose content, and color), hydration (water absorption capacity (WAC), water absorption index (WAI), water solubility index (WSI), swelling power (SP), true and bulk density), pasting (pasting temperature, peak, trough, breakdown, setback, and final viscosity), and rheological properties of the flours were evaluated. Taro flour had the highest values of ash content, WAI and SP and the lowest for crude fat, amylose content, bulk density and peak, breakdown, setback viscosity and consistency index. Cassava flour had the highest breakdown viscosity and flow behavior index values and the lowest for protein content, hysteresis loop area, yield stress, and consistency index. Maize flour had the highest crude fat, protein, and amylose content, bulk density, WAC, setback viscosity, hysteresis loop area, and yield stress, and the lowest values were for ash, protein content, WSI, pasting temperature, breakdown viscosity, and flow behavior index. Banana flour had the highest starch, carbohydrate, WSI, pasting temperature, peak viscosity and consistency index, and the lowest value for protein content, WAI and SP. The study's results have determined the compositional value and functionality of the flours obtained from the agro-residues studied for their potential use in different food products. Keywords: Crop residues flour; Food security; Change climatic; physicochemical characterization; steady shear