Improvement of the UV Barrier and Antibacterial Properties of Crosslinked Pectin/Zinc Oxide Bionanocomposite Films

Humidity-responsive pectin/AgNPs/ZnO composite films with high antimicrobial and UV-proof functions

ZnO nanoparticles and Ag nanoparticles (AgNPs) tend to agglomerate when used individually, and high Ag+concentrations can cause cytotoxicity. To address these issues, we synthesized carboxymethyl cellulose (CMC)-based antimicrobial mimetic peptides (AMPMs) by introducing amphiphilic cations on the surface of CMC using a chemical grafting method. Bis-formaldehyde-formylated AMPMs were prepared through the directional oxidation of AMPMs with periodate and used as the reducing agent to synthesize AgNPs on the surface of pectin in situ for the preparation of a pectin/AgNPs/ZnO composite film. The physical and chemical properties of the films were characterized and analyzed by SEM (EDS), TEM, XRD, and UV spectroscopy. The results showed that the film's surface was smooth and flat, with small, well-stabilized AgNPs and uniformly dispersed ZnO. The film retained the original crystalline form of pectin, but exhibited altered crystallinity, indicating that the method employed was very mild. A systematic evaluation of the film's antimicrobial performance using the dynamic growth curve, inhibition zone, and colony counting methods showed that AgNPs and ZnO imparted excellent, long-lasting antimicrobial activity to the film (98 %). Additionally, the films exhibited good flexibility, excellent ultraviolet protection (99.9 %), biocompatibility, and biodegradability. Notably, the film was sensitive to humidity, as demonstrated by its humidity-responsive bionic application. This study provides a promising reference and strategy for advancing the development of multifunctional polysaccharide-based nanocomposites.

Natural Food Components as Biocompatible Carriers: A Novel Approach to Glioblastoma Drug Delivery

Efficient drug delivery methods are crucial in modern pharmacotherapy to enhance treatment efficacy, minimize adverse effects, and improve patient compliance. Particularly in the context of glioblastoma treatment, there has been a recent surge in interest in using natural dietary components as innovative carriers for drug delivery. These food-derived carriers, known for their safety, biocompatibility, and multifunctional properties, offer significant potential in overcoming the limitations of conventional drug delivery systems. This article thoroughly overviews numerous natural dietary components, such as polysaccharides, proteins, and lipids, used as drug carriers. Their mechanisms of action, applications in different drug delivery systems, and specific benefits in targeting glioblastoma are examined. Additionally, the safety, biocompatibility, and regulatory considerations of employing food components in drug formulations are discussed, highlighting their viability and future prospects in the pharmaceutical field.

Development of Hematite Nano Ellipsoids/Pectin Composite Films for Green Packaging Applications

Synthetic packaging materials are known to cause serious environmental and human health problems. Among the eco-friendly biopolymers from nonfood sources that are suitable for packaging applications, pectin is a promising candidate. However, native pectin films (NPF) exhibit poor mechanical strength, high hydrophilicity, and poor gas diffusion barrier properties. These shortcomings offset the advantages of pectin as a potential packaging material. To address these limitations, in this study, hematite nano ellipsoids (HNEs) were incorporated as fillers to reinforce native pectin films. This reinforcement resulted in substantial improvements in the mechanical properties, hydrophobicity, thermal stability, barrier properties, and optical attributes of pectin films. Compared to NPF, the pectin-hematite composite film exhibited a 35% increase in tensile strength, a 30° increase in contact angle, a 6-fold increase in the oxygen diffusion barrier properties, and a 20% increase in the water vapor barrier properties. This study presents a sustainable, biocompatible, and biodegradable packaging solution by capitalizing on eco-friendly biopolymer and nanoparticle engineering.

A comprehensive review on crosslinked network systems of zinc oxide-organic polymer composites

In recent years, the synergistic crosslinked networks formed by zinc oxide (ZnO) particles and organic polymers have gained significant attention. This importance is ascribed due to the valuable combination of low band gap containing ZnO particles with responsive behavior containing organic polymers. These properties of both ZnO and organic polymers make a suitable system of crosslinked ZnO-organic polymer composite (CZOPC) for various applications in the fields of biomedicine, catalysis, and environmental perspectives. The literature extensively provided the diverse morphologies and structures of CZOPC, and these architectural structures play a crucial role in determining their efficiency across various applications. Consequently, the careful design of CZOPC shapes tailored to specific purposes has become a focal point. This comprehensive review provides insights into the classifications, synthetic approaches, characterizations, and applications of ZnO particles decorated in organic polymers with crosslinked network. The exploration extends to the adsorption, environmental, catalytic, and biomedical applications of ZnO-organic polymer composites. Adopting a tutorial approach, the review systematically investigates and elucidates the applications of CZOPC with a comprehensive understanding of their diverse capabilities and uses.

Nanofillers in Novel Food Packaging Systems and Their Toxicity Issues

Background: Environmental concerns about petroleum-based plastic packaging materials and the growing demand for food have inspired researchers and the food industry to develop food packaging with better food preservation and biodegradability. Nanocomposites consisting of nanofillers, and synthetic/biopolymers can be applied to improve the physiochemical and antimicrobial properties and sustainability of food packaging. Scope and approach: This review summarized the recent advances in nanofiller and their applications in improved food packaging systems (e.g., nanoclay, carbon nanotubes), active food packaging (e.g., silver nanoparticles (Ag NPs), zinc oxide nanoparticles (ZnO NPs)), intelligent food packaging, and degradable packaging (e.g., titanium dioxide nanoparticles (e.g., TiO2 NPs)). Additionally, the migration processes and related assessment methods for nanofillers were considered, as well as the use of nanofillers to reduce migration. The potential cytotoxicity and ecotoxicity of nanofillers were also reviewed. Key findings: The incorporation of nanofillers may increase Young's modulus (YM) while decreasing the elongation at break (EAB) (y = -1.55x + 1.38, R2 = 0.128, r = -0.358, p = 0.018) and decreasing the water vapor (WVP) and oxygen permeability (OP) (y = 0.30x - 0.57, R2 = 0.039, r = 0.197, p = 0.065). Meanwhile, the addition of metal-based NPs could also extend the shelf-life of food products by lowering lipid oxidation by an average of approx. 350.74% and weight loss by approx. 28.39% during the longest storage period, and significantly increasing antibacterial efficacy against S. aureus compared to the neat polymer films (p = 0.034). Moreover, the migration process of nanofillers may be negligible but still requires further research. Additionally, the ecotoxicity of nanofillers is unclear, as the final distribution of nanocomposites in the environment is unknown. Conclusions: Nanotechnology helps to overcome the challenges associated with traditional packaging materials. Strong regulatory frameworks and safety standards are needed to ensure the appropriate use of nanocomposites. There is also a need to explore how to realize the economic and technical requirements for large-scale implementation of nanocomposite technologies.

Preparation of Poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide)/Zinc Oxide Nanocomposite Bioplastics for Potential Use as Flexible and Antibacterial Food Packaging

High-molecular-weight poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) (PLLA-PEG-PLLA) is a flexible and biodegradable bioplastic that has promising potential in flexible food packaging but it has no antibacterial ability. Thus, in this work, the effect of zinc oxide nanoparticles (nano-ZnOs) which have antimicrobial activity on various properties of PLLA-PEG-PLLA was determined. The addition of nano-ZnOs enhanced the crystallization, tensile, UV-barrier, and antibacterial properties of PLLA-PEG-PLLA. However, the crystallization and tensile properties of nanocomposite films decreased again as the nano-ZnO increased beyond 2 wt%. The nano-ZnO was well distributed in the PLLA-PEG-PLLA matrix when the nano-ZnO content did not exceed 2 wt% and exhibited some nano-ZnO agglomerates when the nano-ZnO content was higher than 2 wt%. The thermal stability and moisture uptake of the PLLA-PEG-PLLA matrix decreased and the film's opacity increased as the nano-ZnO content increased. The PLLA-PEG-PLLA/ZnO nanocomposite films showed good antibacterial activity against bacteria such as Escherichia coli and Staphylococcus aureus. It can be concluded that nano-ZnOs can be used as a multi-functional filler of the flexible PLLA-PEG-PLLA. As a result, the addition of nano-ZnOs as a nucleating, reinforcing, UV-screening, and antibacterial agent in the flexible PLLA-PEG-PLLA matrix may provide protection for both the food and the packaging during transportation and storage.

Moisture loss inhibition with biopolymer films for preservation of fruits and vegetables: A review

In cold storage, fruits and vegetables still keep a low respiratory rate. Although cold storage is beneficial to maintain the quality of some fruits and vegetables, several factors (temperature and humidity fluctuations, heat inflow, air velocity, light, etc.) will accelerate moisture loss. Biopolymer films have attracted great attention for fruits and vegetables preservation because of their biodegradable and barrier properties. However, there is still a certain amount of water transfer occurring between storage environment/biopolymer films/fruits and vegetables (EFF). The effect of biopolymer films to inhibit moisture loss of fruits and vegetables and the water transfer mechanism in EFF system need to be studied systematically. Therefore, the moisture loss of fruits and vegetables, crucial properties, major components, fabrication methods, and formation mechanisms of biopolymer films were reviewed. Further, this study highlights the EFF system, responses of fruits and vegetables, and water transfer in EFF. This work aims to clarify the characteristics of EFF members, their influence on each other, and water transfer, which is conducive to improving the preservation efficiency of fruits and vegetables purposefully in future studies. In addition, the prospects of studies in EFF systems are shown.

Development and characterization of films from Campomanesia xanthocarpa and commercial citrus pectins with different degrees of methyl-esterification

In this study, pectins from commercial citrus and isolated from gabiroba (Campomanesia xanthocarpa) fruits, were obtained with different degrees of methyl-esterification (DM) and applied in the films. The DM ranged from 0 % to 62.5 % and the gradual de-esterification process was confirmed by mono-dimensional analysis (1H NMR). In order to investigate the influence of DM values in pectin film properties, PCP (DM: 62.5 %); PCP-5 (DM: 37.4 %); PCP-15 (DM: 19.1 %), and a fully de-esterified sample PCP-35 (DM: 0 %) were selected. The functional properties of the films clearly showed that the DM and cross-linking process are necessary to obtain a material with water resistance. Furthermore, pectin isolated from the fruits of gabiroba was purified (GW-Na, DM: 51.9 %) and partially de-esterified (GW-Na-5, DM: 37.1 %). These pectins were used, for the first time, in development of films and the physical and mechanical properties were compared with films made with PCP and PCP-5 samples. GW-Na and GW-Na-5 films presented suitable properties, with reduced solubility reduced (57.1 and 26.2 %), high degree of swelling (2.14 and 2.26), low flexibility (18.05 and 6.11 MPa), respectively. High strength and rigidity (99.36 and 1040.9 MPa), for both films (GW-Na and GW-Na-5) were demonstrated, similar to that obtained by analyzed citrus pectin.

Zinc oxide nanoparticle-reinforced pectin/starch functionalized films: A sustainable solution for biodegradable packaging

Environmental pollution caused by non-biodegradable plastic pollutants adversely affects various ecosystems. This study proposes the development of novel functional and biodegradable films based on corn starch (CST) and pectin (PEC) containing zinc oxide nanoparticles (ZnONPs) from the casting method. The films exhibited processability, transparency, low water vapor permeation, and desirable mechanical properties for food packaging and coating applications. The ZnONPs acted as a plasticizer, enhancing the film elongation at the break, increasing the pec25-1 (PEC 25 wt% and ZnONPs 1 wt%) elongation from 79.85 to 162.32 %. The improved film elasticity supported by ZnONPs reduced the material stiffness. However, the films still demonstrated an average tensile strength (0.69 MPa) 17-fold higher than the tensile strength (0.04 MPa) of the non-biodegradable commercial film based on poly(vinyl chloride). Furthermore, the ZnONPs enhanced the UV-blocking capabilities of the films, leading to wettable materials with water contact angles lower than 90°. The films showed high biodegradation rates under natural disposal conditions. The results indicated that the pec25-1/ZnONPs film is a promising eco-friendly coating in food preservation due to its biodegradability, suitable mechanical properties, low water vapor permeability, and UV-blocking properties.

Plant-Based, Hydrogel-like Microfibers as an Antioxidant Platform for Skin Burn Healing

Natural polymers from organic wastes have gained increasing attention in the biomedical field as resourceful second raw materials for the design of biomedical devices which can perform a specific bioactive function and eventually degrade without liberating toxic residues in the surroundings. In this context, patches and bandages, that need to support the skin wound healing process for a short amount of time to be then discarded, certainly constitute good candidates in our quest for a more environmentally friendly management. Here, we propose a plant-based microfibrous scaffold, loaded with vitamin C (VitC), a bioactive molecule which acts as a protecting agent against UV damages and as a wound healing promoter. Fibers were fabricated via electrospinning from various zein/pectin formulations, and subsequently cross-linked in the presence of Ca2+ to confer them a hydrogel-like behavior, which we exploited to tune both the drug release profile and the scaffold degradation. A comprehensive characterization of the physico-chemical properties of the zein/pectin/VitC scaffolds, either pristine or cross-linked, has been carried out, together with the bioactivity assessment with two representative skin cell populations (human dermal fibroblast cells and skin keratinocytes, HaCaT cells). Interestingly, col-1a gene expression of dermal fibroblasts increased after 3 days of growth in the presence of the microfiber extraction media, indicating that the released VitC was able to stimulate collagen mRNA production overtime. Antioxidant activity was analyzed on HaCaT cells via DCFH-DA assay, highlighting a fluorescence intensity decrease proportional to the amount of loaded VitC (down to 50 and 30%), confirming the protective effect of the matrices against oxidative stress. Finally, the most performing samples were selected for the in vivo test on a skin UVB-burn mouse model, where our constructs demonstrated to significantly reduce the inflammatory cytokines expression in the injured area (50% lower than the control), thus constituting a promising, environmentally sustainable alternative to skin patches.

Metal-Based Nanoparticles in Food Packaging and Coating Technologies: A Review

Food security has continued to be a topic of interest in our world due to the increasing demand for food. Many technologies have been adopted to enhance food supply and narrow the demand gap. Thus, the attempt to use nanotechnology to improve food security and increase supply has emerged due to the severe shortcomings of conventional technologies, which have made them insufficient to cater to the continuous demand for food products. Hence, nanoparticles have been identified to play a major role in areas involving food production, protection, and shelf-life extensions. Specifically, metal-based nanoparticles have been singled out to play an important role in manufacturing materials with outstanding properties, which can help increase the shelf-life of different food materials. The physicochemical and biological properties of metal-based nanoparticles, such as the large surface area and antimicrobial properties, have made them suitable and adequately useful, not just as a regular packaging material but as a functional material upon incorporation into biopolymer matrices. These, amongst many other reasons, have led to their wide synthesis and applications, even though their methods of preparation and risk evaluation remain a topic of concern. This review, therefore, briefly explores the available synthetic methods, physicochemical properties, roles, and biological properties of metal-based nanoparticles for food packaging. Furthermore, the associated limitations, alongside quality and safety considerations, of these materials were summarily explored. Although this area of research continues to garner attention, this review showed that metal-based nanoparticles possess great potential to be a leading material for food packaging if the problem of migration and toxicity can be effectively modulated.

Recent progress in pectin extraction, characterization, and pectin-based films for active food packaging applications: A review

Pectin is an abundant complex polysaccharide obtained from various plants. Safe, biodegradable, and edible pectin has been extensively utilized in the food industry as a gelling agent, thickener, and colloid stabilizer. Pectin can be extracted in a variety of ways, thus affecting its structure and properties. Pectin's excellent physicochemical properties make it suitable for many applications, including food packaging. Recently, pectin has been spotlighted as a promising biomaterial for manufacturing bio-based sustainable packaging films and coatings. Functional pectin-based composite films and coatings are useful for active food packaging applications. This review discusses pectin and its use in active food packaging applications. First, basic information and characteristics of pectin, such as the source, extraction method, and structural characteristics, were described. Then, various methods of pectin modification were discussed, and the following section briefly described pectin's physicochemical properties and applications in the food sector. Finally, the recent development of pectin-based food packaging films and coatings and their use in food packaging were comprehensively discussed.

Optimization of citron peel pectin and glycerol concentration in the production of edible film using response surface methodology

Pectin-based edible film plasticized with glycerol has been developed, and the effect of pectin and glycerol concentration was optimized using response surface methodology for better mechanical properties and transparency. The upper and lower concentration of pectin (3-5 g) and glycerol (15%-25%) concentration ranges were considered in this study based on the preliminary experiment. The responses of the edible film determined were tensile strength, elongation at break and elastic modulus and opacity. The interaction effects of glycerol and pectin concentrations on edible film properties significantly affected the film properties. Tensile strength and opacity were positively affected by pectin concentrations; however, elastic modulus and elongation at break were negatively affected. Glycerol concentration negatively affected the edible film's tensile strength and elastic modulus. The decrease in the opacity of the biofilm was observed as the pectin concentration increased; however, glycerol had not shown a significant influence on opacity. The numerical optimization provided 4 g of pectin, and 20% of glycerol showed a strong and transparent edible film. The TGA curve showed that the maximum weight loss occurred between the temperatures 250-400 °C due to the loss of polysaccharides. From FTIR analysis, observed peaks around 1037 cm-1 represented the C-O-C stretching vibrations of the saccharide found in pectin and glycerol.

High performance biopolymeric packaging films containing zinc oxide nanoparticles for fresh food preservation: A review

Biodegradable food packaging films (FPFs) assembled from sustainable biopolymeric materials are of increasing interest to the food industry due to pollution and health risks resulting from the use of conventional plastic packaging. However, the functional performance of these FPFs is often poorer than that of plastic films, which limits their commercial application. This problem may be partly overcome by incorporating nano-additives like zinc oxide nanoparticles (ZNPs) into the films. The incorporation of ZNPs into FPFs can improve their functional performance. The properties of these films depends on the concentration, dispersion state, and interactions of ZNPs with the biopolymeric matrix in the films. ZNPs-loaded films and coatings are highly effective at preserving a variety of fresh foods. Studies of ZNPs migration through FPFs have shown that the zinc is mainly transported in an ionic form and the amount entering foods is below safety standards. This article reviews recent developments in the design, fabrication, and application of ZNPs-loaded FPFs based on biopolymers, focusing on the impacts of ZNPs on the optical, barrier, mechanical, water sensitivity, and antimicrobial properties of the films. The potential applications of ZNPs-loaded FPFs for fresh food preservation is also discussed.

Influence of the Alcohols on the ZnO Synthesis and Its Properties: The Photocatalytic and Antimicrobial Activities

Zinc oxide (ZnO) nanomaterials are used in various health-related applications, from antimicrobial textiles to wound dressing composites and from sunscreens to antimicrobial packaging. Purity, surface defects, size, and morphology of the nanoparticles are the main factors that influence the antimicrobial properties. In this study, we are comparing the properties of the ZnO nanoparticles obtained by solvolysis using a series of alcohols: primary from methanol to 1-hexanol, secondary (2-propanol and 2-butanol), and tertiary (tert-butanol). While the synthesis of ZnO nanoparticles is successfully accomplished in all primary alcohols, the use of secondary or tertiary alcohols does not lead to ZnO as final product, underlining the importance of the used solvent. The shape of the obtained nanoparticles depends on the alcohol used, from quasi-spherical to rods, and consequently, different properties are reported, including photocatalytic and antimicrobial activities. In the photocatalytic study, the ZnO obtained in 1-butanol exhibited the best performance against methylene blue (MB) dye solution, attaining a degradation efficiency of 98.24%. The comparative study among a series of usual model dyes revealed that triarylmethane dyes are less susceptible to photo-degradation. The obtained ZnO nanoparticles present a strong antimicrobial activity on a broad range of microorganisms (bacterial and fungal strains), the size and shape being the important factors. This permits further tailoring for use in medical applications.

Novel pectin-based nanocomposite film for active food packaging applications

Novel pectin-based films reinforced with crystalline nanocellulose (CNC) and activated with zinc oxide nanoparticles (ZnO NPs) were prepared by solvent-casting method. Film ingredients enhanced UV-blocking, thermal, and antibacterial properties of active films against well-known foodborne pathogens. Optimal active films exhibited higher mechanical, water vapor barrier properties compared to pristine pectin films. SEM confirmed the even distribution of CNC and ZnO NPs in pectin matrix and their interactions were proven using FTIR. Wrapping hard cheese samples artificially contaminated with Staphylococcus aureus and Salmonella enterica with the ternary nanocomposite film at 7 °C for 5 days significantly reduced the total population counts by at least 1.02 log CFU/g. Zn2+ migrating to wrapped cheese samples was below the specific limit (5 mg/kg), confirming their safety for food contact. Overall, ZnO/CNC/pectin nanocomposite films represent promising candidates for active food packaging as safe, eco-friendly alternatives for synthetic packaging materials.

3D-Printed Pectin/Carboxymethyl Cellulose/ZnO Bio-Inks: Comparative Analysis with the Solution Casting Method

Bio-inks consisting of pectin (Pec), carboxymethyl cellulose (CMC), and ZnO nanoparticles (ZnO) were used to prepare films by solution casting and 3D-printing methods. Field emission scanning electron microscopy (FE-SEM) was conducted to observe that the surface of samples made by 3D bioprinter was denser and more compact than the solution cast samples. In addition, Pec/CMC/ZnO made by 3D-bioprinter (Pec/CMC/ZnO-3D) revealed enhanced water vapor barrier, hydrophobicity, and mechanical properties. Pec/CMC/ZnO-3D also showed strong antimicrobial activity within 12 h against S. aureus and E. coli O157: H7 bacterial strains compared to the solution cast films. Further, the nanocomposite bio-inks used for 3D printing did not show cytotoxicity towards normal human dermal fibroblast (NDFB) cells but enhanced the fibroblast proliferation with increasing exposure concentration of the sample. The study provided two important inferences. Firstly, the 3D bioprinting method can be an alternative, better, and more practical method for fabricating biopolymer film instead of solution casting, which is the main finding of this work defining its novelty. Secondly, the Pec/CMC/ZnO can potentially be used as 3D bio-inks to fabricate functional films or scaffolds and biomedical applications.

Development of chitosan-based biodegradable films enriched with thyme essential oil and additives for potential applications in packaging of fresh collard greens

In the present study, chitosan (CH) based biodegradable films were developed enriched with thyme essential oil (TEO) incorporated with different additives including zinc oxide (ZnO), polyethylene glycol (PEG), nano clay (NC), and calcium chloride (CaCl₂) and characterize the postharvest quality of 'collard greens' during refrigerated storage. The results indicated that the incorporation of ZnO/PEG/NC/CaCl₂ in CH-based films significantly decreased water vapor transmission rate, increased tensile strength, and were water soluble and biodegradable in nature. Moreover, CH-TEO based films incorporated with ZnO/PEG/NC/CaCl₂ were significantly effective in reducing physiological weight loss, retained total soluble solids, titratable acidity, and preserved chlorophyll contents as well as showed lesser a* values, suppressed microbial growth, and preserving appearance/sensory quality of collard greens for 24 days than LDPE and other biodegradable films. Our results suggest that CH-based films enriched with TEO and additives such as ZnO/CaCl₂/NC/PEG are an ecological, environmental friendly, and effective alternative approach to retain shelf life of collard greens during refrigerated storage.

Gelatin/Cellulose Nanofiber-Based Functional Nanocomposite Film Incorporated with Zinc Oxide Nanoparticles

A novel bio-based nanocomposite film was developed using the combination of gelatine and cellulose nanofiber (CNF) as a polymer matrix and zinc oxide nanoparticles (ZnONP) as nanofillers. The nanocomposite film solution was developed using simple solution mixing and film prepared by the following casting methods. The fabricated nanocomposite film containing 2 wt% of ZnONP shows excellent UV-light barrier properties (>95%) and high transparency (>75%). The presence of ZnONP also improves the mechanical strength of the film by ~30% compared to pristine gelatin/CNF-based film, while the flexibility and rigidity of the nanocomposite film were also slightly improved. The addition of ZnONP slightly increased (~10%) the hydrophobicity while the water vapor barrier properties remain unaltered. The hydrodynamic properties of the bio-based film were also changed in the presence of ZnONP, moisture content and the swelling ratio slightly enhanced, whereas water solubility was decreased. Moreover, the integration of ZnONP introduced antibacterial activity toward foodborne pathogens. The fabricated bio-based nanocomposite film could be useful in active packaging applications.

Preparation of a biodegradable chitosan packaging film based on zinc oxide, calcium chloride, nano clay and poly ethylene glycol incorporated with thyme oil for shelf-life prolongation of sweet cherry

This study includes development of chitosan-based films with incorporated essential thyme oil and different combinations of cross-linkers viz., ZnO, CaCl₂, NC, and PEG for the safe storage of sweet cherries. The resulting films stored with sweet cherries were analyzed for different physicochemical and antimicrobial properties. Incorporation of ZnO, CaCl₂, NC, and PEG in chitosan-based films maintained fruit quality by conserving higher total soluble solids, titratable acidity, and reduced weight loss. The combined ZnO + CaCl₂ + NC + PEG in chitosan-based films also suppressed microbial activity. The sensorial quality of fruits stored with CH + ZnO + CaCl₂ + NC + PEG treatment was also stable during storage. In conclusion, the combined CH + ZnO + CaCl₂ + NC + PEG with added thyme oil application is an effective approach to maintain the postharvest quality and could be an alternative to increase the shelf life of sweet cherries, besides decreasing environmental impacts of non-biodegradable packages.

Ultrasensitive detection of pectin based on the decarboxylation reaction and surface-enhanced Raman spectroscopy

In the present study, a novel simple and sensitive method was developed for the determination of pectin based on the decarboxylation derivatization reaction and surface-enhanced Raman scattering (SERS) without complicated separation steps. The derivatization reaction can be controlled by the experimental parameters such as reaction time, temperature and the amount of hydrochloric acid. Additionally, the method was used to accurately and reliably detect pectin added in honey or apple, which can be detected at levels as low as 0.5 or 0.01 ppm, respectively. Based on the conventional decarboxylation reaction, a simple and sensitive SERS method was proposed for the detection of pectin, which shows potential for practical application.

Antibacterial and Antifungal Properties of Electrospun Recycled PET Polymeric Fibers Functionalized with Zinc Oxide Nanoparticles

Currently, to reduce the environmental problems associated with plastic waste, methods are being sought to use this waste as raw materials in different applications, such as fibers. In addition, to improve these materials and provide different properties, nanoparticles (NPs) are incorporated. In the present work, polymeric fibers made of recycled polyethylene terephthalate (r-PET) from post-consumer water bottles, functionalized with 0%, 1.5%, 3% and 6% zinc oxide nanoparticles (ZnO-NPs) in function of r-PET weight, were elaborated to evaluate their antibacterial and antifungal characteristics. The ZnO-NPs were synthesized by the solvothermal method, obtaining particles with a mean diameter of 38.15 nm, while the fibers were obtained by electrospinning with a diameter range between 200-5000 nm. The functionalized fibers were carried out against Escherichia coli and Bacillus subtilis through the agar diffusion method, obtaining the highest inhibition halo at 6% w/w ZnO-NPs, being 26.5 mm and 34.25 mm, respectively. In addition, the same method was used to evaluate the antifungal activity of Penicillium s.p. and Fusarium graminearum, observing antifungal properties due to the presence of nanoparticles in the fibers.

A New Method for Determination of Pectin Content Using Spectrophotometry

The study aimed at developing a new spectrophotometric method for determining the pectin content. Take commercial pectin as an example, and the method is based on the reaction of copper ions with pectin to produce copper pectate. The spectrophotometer was used to measure the remaining content of copper ions so as to calculate the pectin content. This method eliminated the weight step and avoided the error associated with it. Effects of reaction time, temperature, and pH on absorbance were also studied. Additionally, the accuracy of this method was verified. It indicated excellent repeatability and accuracy with the relative standard deviation of 2.09%. In addition, three different plant types were used to demonstrate the reliability of the method. To summarize, this method can be widely used for the determination of pectin content in many materials.