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La quitina es el biopolímero más importante de la pared celular de los hongos, la cual se degrada por la acción de quitinasas. Las plantas sintetizan estas enzimas para protegerse de factores tanto abióticos como bióticos, incluyendo a los hongos fitopatógenos, los cuales permanecen en estado de latencia hasta encontrar las condiciones adecuadas para manifestarse. Para su identificación, se podrían considerar técnicas basadas en biomarcadores y crear dispositivos que sean rápidos, simples, específicos y confiables, tal es el caso de los biosensores. Se conoce ampliamente la especificidad de las quitinasas con la quitina, por lo que, la identificación de los hongos podría llevarse a cabo mediante un biosensor que integre a las quitinasas. En este manuscrito se revisó información acerca de la síntesis de quitinasas en plantas cuando se someten a estrés, enfocándose en los patosistemas planta-patógeno. Se mencionan también las técnicas y métodos de identificación de los hongos, resaltando el uso de biosensores. Finalmente, se propone la utilización de quitinasas como biomarcadores enzimáticos para su identificación por medio de un biosensor y su aplicación en el control de hongos fitopatógenos.

Una gran cantidad de desechos se genera por la remoción de espinas en el nopal verdura con un alto contenido de fibra. Estos subproductos agrícolas son fuentes de celulosa, lignina y hemicelulosa, con potencial de uso como biomateriales en producción sustentable. Con el propósito de contribuir a la solución de un problema ambiental por el uso de plásticos convencionales, bajo la premisa de que la incorporación de harina de nopal podría integrarse a un compuesto bio polimérico para mejorar desempeño y propiedades finales como biomaterial; el objetivo de esta investigación fue realizar análisis químico proximal (AQP) y análisis térmico en harinas de subproductos de nopal del estado de Morelos, México en tres periodos de cosecha, para verificar características útiles con vistas a su adición a materiales poliméricos para envases biodegradables. En el AQP se evaluó la humedad, proteína cruda, cenizas, grasa, fibra cruda, fibra detergente ácida (FDA) y fibra detergente neutra (FDN), extracto libre de nitrógeno (ELN), celulosa, hemicelulosa y lignina. Para evaluar propiedades térmicas se realizó análisis termogravimétrico (TGA) y calorimetría diferencial de barrido (DSC). El diseño experimental fue completamente al azar, se realizó un ANDEVA con un arreglo de datos factorial y prueba de comparación de medias de Tukey. El AQP en las harinas mostró diferencias significativas (p≤0.05) en cenizas, fibra cruda, fibra detergente neutra, celulosa, hemicelulosa y lignina. Las harinas de nopal fueron similares en los tres meses de muestreo y tuvieron perfil térmico similar en TGA y DSC. Tg se obtuvo entre 46-48 °C, Tm entre 32-130 °C y temperatura de descomposición final a 455 °C. Las pruebas térmicas indicaron que la harina de nopal puede adicionarse a matrices poliméricas sin que ocurra descomposición en su uso como material bio-basado, esto es, un polímero derivado de materiales biológicos.

Actualmente se buscan nuevas alternativas amigables con el ambiente que permitan la conservación de productos agrícolas expuestos al deterioro durante la cosecha, transporte y distribución en el mercado para su venta, con la subsecuente reducción de sus atributos de calidad, fisiológicos y propiedades sensoriales, aunados a la manifestación de microorganismos patógenos. En este sentido, se presenta el estado del arte del uso de recubrimientos nanoestructurados de nanopartículas de quitosano con agentes naturales, sus beneficios y un enfoque académico, industrial y gubernamental del uso de la nanoagrotecnología, así como las perspectivas de esta técnica para la conservación de frutas y hortalizas como una solución viable.

Anthracnose compromises papaya production and is caused by the fungus Colletotrichum gloeosporioides. New natural alternatives to synthetic fungicides are necessary to control anthracnose due to health and environmental concerns. In this regard, extracts of plants from Sinaloa, Mexico, have shown activity against molds and yeasts with medical and agricultural importance; however, their protective effect on papaya fruit infected with C. gloeosporioides is still unknown. This study aimed to assess the in vitro and in vivo antifungal activities of crude methanol extracts (ME) from nine plants from Sinaloa, Mexico, and their semi-purified fractions. In vitro assays showed that C. gloeosporioides was inhibited by 7 out the 16 extracts assessed; Psidium sartorianum (pulp), Echeveria kimnachii (leaf), and Vitex mollis (VM) (pulp) had the highest antifungal activity and the lowest toxicity against Artemia salina. When these extracts were fractionated, the activity increased. Hexane (HF-VM) and ethyl acetate (EAF-VM) fractions of V. mollis were the most effective fractions (MEF), with the lowest minimum inhibitory concentration (MIC) (20 and 30 mg/mL, respectively). The in vivo results showed that HF-VM at 40 mg/mL (HF40) was the best to delay the apparition and development of anthracnose symptoms. Coumarins, alkaloids and terpenes were detected on this fraction by tube assays or thin layer chromatography (TLC). Moreover, this treatment decreased water loss and did not affect any of the quality parameters assessed. Therefore, HF40 is a natural alternative to thiabendazole (TBZ) in the protection of papaya fruit against anthracnose.

México es el principal productor y exportador mundial de aguacate ‘Hass’. Por sus características nutricionales en la salud humana, el aguacate ‘Hass’ ha ganado gran popularidad alrededor del mundo. El objetivo de esta revisión fue conocer el estado actual del manejo de la cosecha y poscosecha del aguacate, así como, revisar el proceso de infección de los hongos Colletotrichum spp. y Lasiodiplodia theobromae, causantes de las enfermedades llamadas antracnosis y pudrición peduncular, respectivamente. Estas patologías se manifiestan durante la maduración poscosecha y almacenamiento. Actualmente, el principal medio de control de estos microorganismos es un complejo de los fungicidas azoxystrobin + fludioxonil, cuya aplicación se permite sólo para exportaciones a Estados Unidos de América. En México, sólo el estado de Michoacán puede exportar aguacate a los Estados Unidos de América, pero se busca aumentar las exportaciones hacia otros mercados internacionales e integrar otras regiones productoras, por lo que es necesario buscar alternativas de control de enfermedades en poscosecha. Mediante el conocimiento de los mecanismos intrínsecos de protección del fruto se podrían sentar las bases para desarrollar y evaluar nuevos modelos de control.

Aspergillus flavus affects fresh and dry fruit and vegetable products, and its toxic metabolites, namely aflatoxins, cause serious damage in humans. The objective of this research study was to evaluate the effect of commercial natural products as well as edible and nanostructured chitosan coatings on the development of A. flavus and on the production of aflatoxins in vitro and in tomato. Treatments were as follows: chitosan 1%, chitosan coating, chitosan nanostructured coating, Citrocover 1% (citrus seed extract), Resinadher 0.5% (pine resin extract), mancozeb 2%, and water. The variables were as follows: halo inhibition, spore production, and aflatoxins content. In fruit, the following were evaluated: disease incidence, mycelial growth, and aflatoxin production. An ANOVA (Tukey: p < 0.05) was used. In vitro results showed that Citrocover and Resinadher reduced sporulation (0.2 and 0.9 × 105 spores mL−1, respectively), while chitosan inhibited the production of aflatoxins. With Resinadher and Citrocover, tomato fruit had the lowest incidence, mycelial growth, and aflatoxin production with corresponding values of 0%, 0.0 cm2, and 0.95 ppb, respectively, and 7%, 0.2 cm2, and 1.77 ppb, respectively. The use of Citrocover and Resinadher could be a viable alternative to decrease the development of A. flavus in tomato fruit.

The greatest challenge for the avocado (Persea americana Miller) industry is to maintain the quality of the fruit to meet consumer requirements. Anthracnose is considered the most important disease in this industry, and it is caused by different species of the genus Colletotrichum, although other pathogens can be equally important. The defense mechanisms that fruit naturally uses can be triggered in response to the attack of pathogenic microorganisms and also by the application of exogenous elicitors in the form of GRAS compounds. The elicitors are recognized by receptors called PRRs, which are proteins located on the avocado fruit cell surface that have high affinity and specificity for PAMPs, MAMPs, and DAMPs. The activation of defense-signaling pathways depends on ethylene, salicylic, and jasmonic acids, and it occurs hours or days after PTI activation. These defense mechanisms aim to drive the pathogen to death. The application of essential oils, antagonists, volatile compounds, chitosan and silicon has been documented in vitro and on avocado fruit, showing some of them to have elicitor and fungicidal effects that are reflected in the postharvest quality of the fruit and a lower incidence of diseases. The main focus of these studies has been on anthracnose diseases. This review presents the most relevant advances in the use of natural compounds with antifungal and elicitor effects in plant tissues.

A biofungicide is a natural product that can be derived from various sources such as, among others, microorganisms, higher plants, animal products, phytochemicals, semiochemicals, and antagonist microorganisms. One of the most important approaches for the production of biofungicides is the combination of biocontrol agents. This study showed the inhibition growth of Alternaria alternata and Fusarium solani treated with cell-free extracts of P. fluorescens. Using thin-layer chromatography and plate assays it was also demonstrated that the cell-free extracts of P. fluorescens contained siderophores and derivates of 4-diacetylphloroglucinol and phenazine. Moreover, the combination of cell-free extracts of P. fluorescens and chitosan [50–1.5% (v/v)] had a synergistic effect since they notably inhibited the mycelial growth of A. altenata and F. solani. Various morphological alterations to the mycelia and conidia of the treated fungi as a result of this combination were also observed. The present study could be a starting point to control other fungal phytopathogens using different cell-free extracts and chitosan as biocontrol agents.

Las Dalias (Dahlia spp.) son flores nativas de Mesoamérica y endémicas de México. Su consumo como alimento es una práctica antigua, en la actualidad es escasa la información y reglamentación sanitaria para su comercialización y consumo. Al respecto, el objetivo del presente estudio fue identificar morfológica, bioquímica y molecularmente, bacterias de origen entérico asociadas con flores de Dalia. Los resultados de la caracterización morfológica revelaron la predominancia de bacilos cortos Gram negativos. A partir de la observación de la morfología colonial en medios de cultivo selectivos y diferenciales se identificaron como Escherichia coli y Salmonella spp. Sin embargo, el uso de un método comercial automatizado los clasifica como Enterobacter cancerogenus. Debido a que ambas pruebas arrojaron resultados distintos en cuanto a la identidad del microorganismo aislado, no fueron concluyentes. Por lo tanto, se recurrió a la caracterización molecular para la identificación del aislado bacteriano. La bacteria predominante en flores de Dalia, correspondió a Pantoea vagans (Número de acceso CP002206). Éste es el primer reporte de Pantoea vagans aislada de flores de Dalia.

Biodegradable aliphatic polyesters are an alternative to reduce the use of synthetic plastic materials that cause severe damage to the environment. Formulations based on poly (lactic acid) (PLA) and poly (butylene adipate-co-terephthalate) (PBAT), were mixed in a 60:40 ratio, adding different concentrations of pine essential oil through the use of extrusion technology to obtain biodegradable polymer fibers. Some formulations were coated with chitosan. All the elaborated fibers were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy-Attenuated Total Reflection (FTIR-ATR), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD) and mechanical properties. The SEM studies showed that the PBAT improves the tenacity and provides greater elasticity promoting the interaction between the blends phases with fibril formation. In the FTIR-ATR analysis, compatibility between the blends was observed due to a possible interaction of the carbonyl group of PBAT with PLA. The DSC and the mechanical properties showed partial miscibility of the blends, indicating, that the plasticizing action of the essential oil gave greater mobility, flexibility, less rigidity and crystallization in the blends. A lower Young's modulus and greater elongation at break was also observed.

The aim of this work was to evaluate the structure, chemical composition and biological activity of nanoparticles composed of chitosan (CNPs) and chitosan with Byrsonima crassifolia extract (CENPs), with which two EC, edible nanochitosan coatings (ENC) and edible nanochitosan extract coatings (ENEC) were elaborated, respectively. These coatings were sprayed on bell pepper during the pre-harvest stage and microbiological activity was determined. After harvesting the quality of bell pepper was evaluated for the following variables: weight loss, firmness, color change, respiration, ethylene production, total carotenoids, phenolic content, antioxidant capacity, and microbiological activity. The result indicated that the volatile fraction of Byrsonima crassifolia extract is 94% composed of α pinene, camphene, and eucalyptol. The CNPs had a higher size distribution 420 nm than the CENPs 312 nm and a potential Zeta of −40 mV. The CNPs and CENPs decreased the in vitro growth of Alternaria alternata up to 100%. During the cultivation of the fruit, both EC reduced the microbiological activity by 80%. In the postharvest stage some changes were observed in the fruit treated with the EC, for instance: 1) the fruit showed a 30% the weight loss and 15% the change of color after 21 d of storage, 2) the phenolic content, carotenoids and reducing capacity were increased by 18% and 3) the microbiological activity was reduced by 85%. In conclusion, the application of ENC and ENEC during the cultivation and postharvest storage of bell pepper preserved the physicochemical quality, improved microbiological quality and increased their antioxidant content.

Nets in agriculture are used during crop development to provide shade and protection against the pest attack, while fruit packaging during storage is used to extend and maintain the quality of horticultural products. This study has evaluated the in vitro antifungal activity of biodegradable nets and their effect on the shelf life and control of A. alternata in tomatoes. The biodegradability of the nets was also determined. The nets were made from extruded fibres of two biodegradable polymers, poly (lactic acid) (PLA) and poly (butylene adipate-co-terephthalate) (PBAT) and cinnamon bark essential oil (CEO). The fiber with 6.1% of CEO inhibited the in vitro mycelial growth of A. alternata in 72.7% and germination in 100%. The use of nets during the development of tomatoes in the plant had no effect on weight loss, firmness, TSS; titratable acidity and carotenoid content during storage, but values of the antioxidant capacity and ethylene were notably higher in those tomatoes grown in nets with CEO. The incidence of A. alternata in tomatoes was slightly higher in non-treated fruit compared with those grown only with nets and nets with CEO. The biodegradation of nets at 24 weeks was higher in those made with PLA followed by those with CEO. Our results lead us to continue to consider this technology for further pre- and postharvest issues.

Biodegradable alternatives for the control of Aspergillus flavus in fig fruit were tested with the application of coatings based on chitosan (CS) and propolis (P). To potentiate the fungicidal effect, nanoparticles of these two (CSNPs and PNPs) were also considered. The objectives of this research were to evaluate the effect of different formulations on: (a) the ripening process of the fig, (b) the incidence of A. flavus and the production of aflatoxins, and (c) the acceptance of the treated fruit by a panel. The nanostructured coatings did not influence the ripening process of the fruit during the 12 days of storage, however, the antioxidant activity increased by approximately 30% with the coating CS + PNPs + P. The figs treated with CS + CSNPs + PNPs + P, inhibited the growth of the fungus by about 20% to 30% under laboratory and semi-commercial conditions. For all treatments, the aflatoxin production was lower than 20 ppb compared to the control with values of c.a. 250 ppb. The sensory quality was acceptable among the panel. The edible coatings can be a non-toxic alternative for post-harvest preservation and the consumption of fig fruit. The next step will be its inclusion and evaluation at a commercial level in packing houses.

"Las frutas y hortalizas frescas y mínimamente procesadas son susceptibles a la contaminación por bacterias patógenas tales como, Escherichia coli, Listeria monocytogenes y Salmonella, entre otras, las cuales causan severos daños a la salud humana y a la economía de los países en donde se detectan. Por ejemplo, anualmente, Salmonella es responsable del 30% de las muertes causadas por infecciones transmitidas por alimentos. No obstante, la problemática tiene mayor impacto, ya que, según la Organización Mundial de la Salud del 60 al 80% de los casos por salmonelosis no se reportan. En el caso particular de México, el problema es mayor ya que a pesar de que todos estos patógenos están ampliamente distribuidos en el territorio nacional no se tienen registros confiables de su incidencia. Al respecto, se ha reportado que las frutas y hortalizas frescas, son los principales hospederos de estas bacterias patógenas, sin embargo, su detección oportuna aún no se ha implementado en la cadena de producción y durante el manejo postcosechade los productos agrícolas. La mayoría de las bacterias pueden formar biopelículas en la superficie del hospedero lo que permite su sobrevivencia a pesar del método de control. En la actualidad, se utilizan métodos preventivos para el control de Salmonella, los cuales se basan en métodos químicos como los compuestos clorados y de oxígeno activo, métodos físicos como la irradiación ultravioleta y otros que aun se encuentran bajo investigación como son la aplicación del quitosano y aceites esenciales. El objetivo de esta revisión fue mostrar un visión general de la importancia de las bacterias patógenas en las frutas y hortaliza, sus mecanismos de sobrevivencia, la incidencia de Salmonella, así como, los diferentes métodos de control que a la fecha se utilizan en esta bacteria."

Biodegradable alternatives for the control of Aspergillus flavus in fig fruit were tested with the application of coatings based on chitosan (CS) and propolis (P). To potentiate the fungicidal effect, nanoparticles of these two (CSNPs and PNPs) were also considered. The objectives of this research were to evaluate the effect of different formulations on: (a) the ripening process of the fig, (b) the incidence of A. flavus and the production of aflatoxins, and (c) the acceptance of the treated fruit by a panel. The nanostructured coatings did not influence the ripening process of the fruit during the 12 days of storage, however, the antioxidant activity increased by approximately 30% with the coating CS + PNPs + P. The figs treated with CS + CSNPs + PNPs + P, inhibited the growth of the fungus by about 20% to 30% under laboratory and semi-commercial conditions. For all treatments, the aflatoxin production was lower than 20 ppb compared to the control with values of c.a. 250 ppb. The sensory quality was acceptable among the panel. The edible coatings can be a non-toxic alternative for post-harvest preservation and the consumption of fig fruit. The next step will be its inclusion and evaluation at a commercial level in packing houses.

Different formulations based on nanoparticles of chitosan-plant extracts were evaluated to detect the infection process from the earliest stage of the fungus Rhizopus stolonifer on strawberry fruit during storage. Chitosan/polyvinyl alcohol (Ch/PVA) and chitosan/polyvinylpyrrolidone (Ch/PVP) films enriched with nanoparticles (NPs) of chitosan blended with plant extracts were prepared. They were placed inside a plastic package containing inoculated fruits and stored at 25 °C for 72 h. The thickness values of the films were in the range of 0.10 to 0.25 mm. All samples showed a maximum absorbance peak of about 300-320 nm; however, the Ch/PVP films enriched with NPs of chitosan and 10% of radish extract had an evident decrease in the optical absorbance as the fungal infection progressed. Additionally, as observed by scanning electron microscopy, the cross-section and surface morphology of films were not modified during storage, and the growth of R. stolonifer was evident after 48 h. Therefore, the Ch/PVP films enriched with chitosan NPs blended with 10% radish extract could be a reliable indicator of this fungus's growth.

Worldwide, papaya is a highly consumed fruit; however, they are very susceptible to the attack of the fungus Colletotrichum gloeosporioides. The fungal cell wall has mostly chitin, which is degraded by the chitinases enzymes that are synthesized as part of the plant's defence system. For diagnose a fungal disease, it is necessary to find a biological indicator as well-referred to as biomarkers which in turn could be detected through biosensors. Until now, there was no information about the activity of the chitinases in inoculated and stored papaya, at different phenological stages (preharvest stage) of the fruit and during storage (postharvest stage). The results showed higher activity of the enzyme in those stages close to the harvest period (c.a. 42 and 113 IU mg−1 protein) and lower activity (0 IU mg−1 protein) at the senescence stage during postharvest; meanwhile, in papayas artificially inoculated with C. gloeosporioides, at both the pre and postharvest stages, the chitinolytic activity increased, although, decreased as storage days progressed. Based on these results, chitinase activity in papaya could act as an indicator of the fungal growth for further use in the design of a biosensor for the detection of this fungus.

The objective of this work was to evaluate the effect of a chitosan biodegradable coating (BC), functionalized with cinnamon essential oil and aqueous extract of Roselle calyces, on the quality, respiratory rate, anthocyanin content and antioxidant capacity using the ABTS radical. Figs ‘Black Mission’ of two maturity stages were used. The first maturity stage included purple fruits (14% SST), referred to as “ripe figs”. The second stage was unripe figs, which presented a green color in 25% of its surface (11% SST). Five treatments were applied for each fig maturity stage. 150 g of figs was kept into clamshells packaging at 5 °C for 0, 4, 10, 15 and 21 days, before being transferred to room temperature (20 °C) for 2 more days. The BC structure was evaluated with the use of SEM. Furthermore, quality of this fruits as a result of the use BC and the different storage conditions was determined. The incidence and severity of rotting caused byA. alternatawas quantified. The matrix of the BC was porous and heterogeneous. The unripe figs treated with BC and preventive treatments showed a lower weight loss, color change, respiration rate, and anthocyanin content than the control group. Meanwhile, the ripe figs receiving the preventive, curative and coated treatments, only showed the smallest color changes compared to the remaining treatments, but the remaining variables were similar to those of the control group. Finally,A. alternatadid not grow at 5 °C in unripe figs but only in the ripe ones. The BC preserved the physicochemical and microbiological quality of unripe figs at 5 °C for 21 days.

Dentro de las enzimas antimicrobianas reportadas, las lisozimas y las enzimas tipo lisozimas procedentes de diversas fuentes naturales han mostrado actividad antibacteriana y antifúngica, haciéndolas atractivas como nuevas alternativas para controlar los microorganismos patógenos. Aunque las enzimas antimicrobianas se han propuesto ampliamente en la industria alimentaria y en la protección de cultivos, su uso implica algunas desventajas, como la inactivación por inhibidores o productos químicos o condiciones de procesamiento, los altos costos de producción y purificación, y problemas de solubilidad e inestabilidad. La tecnología de inmovilización enzimática es una herramienta prometedora capaz de reducir estos inconvenientes, particularmente cuando está destinada a trabajar en medios sólidos. Esta revisión muestra el estado del arte sobre la actividad de la lisozima contra bacterias y hongos, centrándose en los mecanismos de acción involucrados. Además, también se discuten los aspectos y características más mportantes de las lisozimas y su posible aplicación tecnológica, incluida la aplicación de matrices poliméricas a base de quitosano para la inmovilización de las enzimas antimicrobianas.

Bell peppers are susceptible to postharvest diseases caused by the fungus Alternaria alternata that limit its commercialization. Nowadays, nanotechnology allows encapsulation of natural components such as terpenes. The objective of this work was to develop chitosan nanoparticles with α-pinene (P-CSNPs) and a nanostructured edible coating (EC-P-CSNPs). The P-CSNPs were characterized by TEM (Transmission Electron Microscopy), FTIR (Fourier-Transform Infrared Spectroscopy), DLS (Dynamic Light Scattering) and ζ potential. The P-CSNPs and the EC-P-CSNPs were applied to the bell peppers inoculated with A. alternata under cold storage for either 0, 7, 14 and 21 days at 12 ± 2 °C followed by a shelf-life period of 5 days at 20 ± 2 °C to assess their post-harvest quality. Nanoparticles size was 3.9 ± 0.5 nm and the ζ potential value was between 13.4 and 14.9 mV. The incorporation of α-pinene was corroborated by FTIR. Significant changes in weight loss were obtained for P-CSNPs and EC-P-CSNPs at percentage of 3 and 6% compared to the control. For firmness, color, total soluble solids, titratable acids, maturity index, total flavonoid content and antioxidant capacity, no differences were found. Total carotenes were higher in bell peppers without A. alternata. The chitosan nanoparticles and edible coating inhibited A. alternata during the cold storage period of bell pepper and preserved the physicochemical quality.

Essential oils (EOs) are volatile plant derivatives that have been evaluated in the control of phytopathogenic fungi, and whose effectiveness has been associated with the part of the plant and concentration used. Hereby we provide an overview of the role of EOs on phytopathogenic fungi agents, presenting an overview of its diversity, constituents, tests under in vivo and in vitro conditions, their mechanisms of action, and the techniques to assess its effectiveness. The antimicrobial action of EOs is attributed to their ability to penetrate through cell membranes and inhibit the functional properties of fungal cells.

Pectobacterium carotovorum is a phytopathogenic bacteria that causes significant economic loses in food crops, such as bell pepper, which is of special significance in the value of production and trade in Mexico. Therefore, a solution for fruit conservation must be sought. Due to environmental concerns, it is necessary the use of environmentally-friendly active packaging. In this article, chitosan and chitosan-thyme essential oil nanocoatings were used for the preservation of green bell pepper. Different formulations based on chitosan nanoparticles (CSNPs) and chitosan-thyme essential oil nanoparticles (15, 30, and 45%) were prepared. For uncoated and coated bell peppers, the quality and physiological variables of inoculated and uninoculated fruit with P. carotovorum during 12-day storage period were assessed. According to the results, the weight loss of the fruit remained almost constant over the storage days for the different formulations. A decrease in fruit firmness and an increase in the respiration rate and ascorbic acid content until day 8 with a decrease at the end of the storage period were observed. Of all the evaluated nanocoatings, the fruit treated with the formulation containing 15% CSNPs showed the lowest colony-forming units and disease incidence. Also, the coated bell peppers with this formulation had lower CO2 production compared to the remaining treatments, and the weight loss and firmness were maintained. Therefore, the use of CSNP coatings could represent a good alternative for the protection of bell pepper against the pathogenic bacteria P. carotovorum. PRACTICAL APPLICATION: The results of the application of nanocoatings based on chitosan and chitosan-thyme essential oil as an antibacterial agent against P. carotovorum on green bell pepper during 12-day storage period suggest that nanoparticle-based coatings can be a natural option for the preservation of fruit quality during ripening.

Strawberries have a thin epidermis and a high respiration rate. The use of edible coatings containing chitosan nanoparticles (CSNPs) and propolis (P) has been effective in preserving the shelf life and antioxidant capacity of various fruit and vegetable products. The present research evaluated the effect of coatings with CSNPs and P on the quality, antioxidant compounds, and antioxidant capacity of strawberries. The specific coatings that were evaluated were chitosan (CS), CS+CSNPs33%, CS + CSNPs + P10%, CS + CSNPs + P20%, CS + CSNPs + P30%, and a control with no coating. The variables were weight loss, firmness, total soluble solids (TSS), color, phenols, total flavonoids, antioxidant capacity, and sensory characteristics. An ANOVA and a Tukey test (p &le, 0.05) were used to analyze the data. Strawberries covered with CS + CSNPs + P10% showed the lowest weight loss (9.77%), while those covered with CS + CSNPs + P20% had the greatest firmness (4.96 N). CS + CSNPs + P coatings at 10%, 20%, and 30% concentrations maintained the antioxidant compounds and antioxidant capacity in the evaluated fruit (28.49 mg GAE g&minus, 1, 554.61 &mu, g quercetin g&minus, 1, and 92.48% DPPH, respectively). The application of nanostructured coatings did not modify the sensory characteristics of the fruit. Coatings with CSNPs and/or P could therefore be a viable alternative for preserving the quality and antioxidant capacity of strawberries.