The control of postharvest blue and green molds of citrus in relation with essential oil-wax formulations, adherence and viscosity.

peer reviewedThe use of wax coatings enriched with antifungals has significantly contributed to quality maintaining of harvested citrus fruit. On the other hand, interest in essential oils (EOs) as an alternative to synthetic fungicides has recently gained momentum. In this study, Cinnamomum zeylanicum EO was incorporated into a variety of commercial citrus waxes (shellac, carnauba, paraffin and polyethylene). The biological activity of these formulations against green and blue rots as well as their viscosity and adherence to the orange fruit surface were evaluated. Excellent disease control was achieved with C. zeylanicum EO incorporated in shellac and/or carnauba wax compared to other EO–wax formulations. Disease control by EO–waxes seems to depend not only on the volume that remains on the fruit skin, but also, probably on the retention of EO components on the fruit. Other factors such as formulation solubility, permeability to gases, and compatibility between EO compounds and those of waxes may also be involved in the improvement of EO efficacy. The present study may therefore allow a careful selection of ppropriate waxes for the elaboration of effective EO–wax formulations

Effect of hydroxypropylmethylcellulose and chitosan coatings with and without bergamot essential oil on quality and safety of cold-stored grapes

[EN] Biodegradable coatings based on hydroxypropylmethylcellulose (HPMC) or chitosan (CH) with and without bergamot essential oil were applied to table grapes, cv. Muscatel, in order to find environmentally friendly, healthy treatments with which to better preserve fresh fruit quality and safety during postharvest cold storage. Physicochemical properties (weight loss, °Brix, total phenols, antioxidant activity, colour and texture), respiration rates and microbial counts of samples were determined throughout cold storage. The coatings had a significant effect on the development of quality variables, with the additional effect of essential oil addition as a function of the polysaccharide matrix being especially notable. Although incorporation of essential oil resulted in smaller weight losses and a greater antimicrobial effect, it also led to browner samples when using CH. Chitosan coatings containing bergamot oil were more effective than pure CH and HPMC coatings at inhibiting respiration rates. All the coatings improved the mechanical resistance of the samples at the end of storage. The most recommended coating for Muscatel table grapes is CH containing bergamot oil since, despite only contributing slightly to the sample colour, this showed the highest antimicrobial activity and the greatest control of respiration rates with a reasonably good control of water loss during storage. © 2010 Elsevier B.V.The authors acknowledge the financial support provided by Ministerio de Educacion y Ciencia (Project AGL2007-65503).Sánchez González, L.; Pastor Navarro, C.; Vargas, M.; Chiralt, A.; González Martínez, MC.; Cháfer Nácher, MT. (2011). Effect of hydroxypropylmethylcellulose and chitosan coatings with and without bergamot essential oil on quality and safety of cold-stored grapes. Postharvest Biology and Technology. 60(1):57-63. https://doi.org/10.1016/j.postharvbio.2010.11.004S576360

Perspectives on utilization of edible coatings and nano-laminate coatings for extension of postharvest storage of fruits and vegetables

It is known that in developing countries, a large quantity of fruit and vegetable losses results at postharvest and processing stages due to poor or scarce storage technology and mishandling during harvest. The use of new and innovative technologies for reducing postharvest losses is a requirement that has not been fully covered. The use of edible coatings (mainly based on biopolymers) as a postharvest technique for agricultural commodities has offered biodegradable alternatives in order to solve problems (e.g., microbiological growth) during produce storage. However, biopolymer-based coatings can present some disadvantages such as: poor mechanical properties (e.g., lipids) or poor water vapor barrier properties (e.g., polysaccharides), thus requiring the development of new alternatives to solve these drawbacks. Recently, nanotechnology has emerged as a promising tool in the food processing industry, providing new insights about postharvest technologies on produce storage. Nanotechnological approaches can contribute through the design of functional packing materials with lower amounts of bioactive ingredients, better gas and mechanical properties and with reduced impact on the sensorial qualities of the fruits and vegetables. This work reviews some of the main factors involved in postharvest losses and new technologies for extension of postharvest storage of fruits and vegetables, focused on perspective uses of edible coatings and nano-laminate coatings.María L. Flores-López thanks Mexican Science and Technology Council (CONACYT, Mexico) for PhD fellowship support (CONACYT Grant Number: 215499/310847). Miguel A. Cerqueira (SFRH/BPD/72753/2010) is recipient of a fellowship from the Fundação para a Ciência e Tecnologia (FCT, POPH-QREN and FSE Portugal). The authors also thank the FCT Strategic Project of UID/ BIO/04469/2013 unit, the project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462) and the project ‘‘BioInd Biotechnology and Bioengineering for improved Industrial and AgroFood processes,’’ REF. NORTE-07-0124-FEDER-000028 Co-funded by the Programa Operacional Regional do Norte (ON.2 – O Novo Norte), QREN, FEDER. Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico – FUNCAP, CE Brazil (CI10080-00055.01.00/13)

ELABORACION DE RECUBRIMIENTOS COMESTIBLES FORMULADOS CON GOMA DE MEZQUITE Y CERA DE CANDELILLA PARA REDUCIR LA CINETICA DE DETERIORO EN FRESCO DEL LIMON PERSA (Citrus latifolia Tanaka)

Actualmente se dispone de muchas tecnologías que se han desarrollado para extender la vida útil en fresco de los productos hortofrutícolas después de su cosecha. Uno de los métodos con potencial para conservar la vida postcosecha de frutas y hortalizas destinadas al consumo en fresco lo constituye el uso de películas o recubrimientos comestibles, éstos se formulan con materiales naturales comestibles que funcionan como una barrera para el intercambio de gases y vapor de agua. Para la mayoría de las aplicaciones de películas en los alimentos, la característica funcional más importante de una película comestible es la resistencia que presenta contra la migración de la humedad, esto es porque deben conservarse los niveles críticos de actividad de agua para que el producto mantenga una calidad y sanidad óptimas. Sin embargo, al recubrir un fruto u hortaliza para retardar la pérdida de humedad, es necesario que exista una cierta permeabilidad al oxígeno y el dióxido de carbono para evitar una respiración anaeróbica que podría inducir desórdenes fisiológicos y una pérdida rápida de la calidad y vida útil en estos productos. Actualmente las películas y recubrimientos comestibles se elaboran a partir de una gran variedad de polisacáridos, proteínas, ceras naturales y resinas, ya sea como componentes únicos o combinados para desarrollar películas compuestas con las que se pretende crear una atmósfera modificada en el interior del fruto para retardar el proceso de maduración y senescencia de una forma similar a la de una atmósfera controlada que es mucho más costosa. Sin embargo, resulta que las formulaciones que proporcionan un adecuado intercambio gaseoso frecuentemente no son buenas barreras para la humedad y por otro lado, las que son eficientes para reducir la pérdida de agua tienden a crear condiciones de anaerobiosis en la atmósfera interna del fruto. Los retos técnicos involucrados en la elaboración de películas y recubrimientos comestibles con propiedades funcionales incluyen la selección del tipo y concentración de los materiales usados en la formulación, las técnicas de preparación, durabilidad, adherencia, entre otras. Por lo tanto, se requiere de estudios básicos para diseñar las propiedades funcionales de películas comestibles para aplicaciones específicas. El objetivo del presente trabajo fue desarrollar recubrimientos comestibles compuestos empleando dos productos naturales producidos en México como ingredientes principales: la goma de mezquite como agente estructural y la cera de candelilla sola o combinada con cera de abeja, aceite mineral o ácido oleico en una relación 2:1, como fase lipídica y determinar sus propiedades funcionales como la permeabilidad al vapor de agua, adherencia, brillo, microestructura y potencial como recubrimiento para extender la vida postcosecha y calidad de frutos de limón Persa evaluando su efecto en la pérdida fisiológica de peso, color y cambios en composición química. Los resultados obtenidos indicaron que la naturaleza de los materiales hidrofóbicos seleccionados influye en el tamaño de los glóbulos y su distribución en la emulsión, en la microestructura y propiedades de barrera de los recubrimientos obtenidos. La mezcla de cera de candelilla con el aceite mineral (formulación MCOM) mejoró significativamente la permeabilidad al vapor de agua de la formulación de cera de candelilla-goma de mezquite (50.00 g .mm. kPa¯¹. d¯¹ .m ¯² vs. 78.21 g .mm. kPa¯¹. d¯¹ .m¯²). Se encontró que hay una relación estrecha entre las propiedades de barrera al vapor de agua y la microestructura de los recubrimientos, ya que los recubrimientos con morfología superficial más uniforme y menos defectos (fracturas, poros) exhibieron valores bajos de permeabilidad al vapor de agua Los limones Persa exhibieron un 31.5% menos pérdida fisiológica de peso con respecto a los frutos sin recubrimiento, además, retuvieron su color verde y no presentaron alteración alguna en los parámetros fisicoquímicos de calidad evaluados durante 25 días de almacenamiento.Many storage techniques have been developed to preserve fresh postharvest horticultural commodities. One method for extending postharvest life of fruits and vegetables is using films or coatings made of natural edible materials that act as barriers to gases and water vapor. The most important functional characteristic of an edible coating or film for many food applications is its resistance to moisture migration. This is because critical levels of water activity must be maintained if the product is to exhibit optimum quality and acceptable safety. However, if the edible film or coating is applied on fruits or vegetables to retard moisture loss, a certain degree of oxygen and carbon dioxide permeability is necessary to avoid anaerobic respiration resulting in physiological disorders and rapid loss of quality. Films and coatings are currently being developed from a variety of polysaccharides, proteins, natural waxes and resins, either alone or in mixtures to produce composite films that attempt to create a modified atmosphere inside the fruit. These films and coatings delay ripening and senescence in a similar way to the more costly controlled atmospheres. However films or coating formulations that provide adequate gas exchange are often unsuitable barriers to water, while those efficient for reducing water loss tend to create anaerobic conditions in the internal fruit atmosphere. The technical challenges involved in producing films or coatings with functional properties include type and concentration of materials used in the formulation, film-forming techniques, durability, adhesiveness, among others. Therefore basic studies are needed to tailor the functional properties of edible films to various specific applications. The objective of this work was to develop emulsified composite edible coatings using mesquite gum as structural material and candelilla wax alone and blended with beewax, white mineral oil and oleic acid (2:1 ratios) as lipid phase; evaluating their functional properties such as water vapor permeability, gloss, microstructure as well as their potential to extend postharvest life and quality of Persian limes through their effect upon physiological weight loss, color and chemical composition changes in fruits. Results showed that the nature of the hydrophobic materials selected influenced the emulsion globule size and its distribution, as well as the microstructure and moisture barrier properties of the coatings.The blend of candelilla wax-mineral oil (MCOM) improved WVPc of candelilla wax-mesquite gum coating formulation(50.00 g .mm. kPa¯¹. d¯¹ .m ¯² vs. 78.21 g .mm. kPa¯¹. d¯¹ .m¯²). There was a close relationship between performance and coating microstructure. Coatings showing more uniformity and less defects (fissures, fractures, pinholes) surface morphology were those exhibiting the lowest WVP values. The MCOM formulation provided the lowest physiological weight loss, most adequate green color retention and unaltered physicochemical parameters in Persian limes, in comparison to the rest of coating formulations, tested during 25 days of storage at ambient temperature

Effects of mesquite gum-candelilla wax based edible coatings on the quality of guava fruit (Psidium guajava L.)

The ability of composite edible coatings to preserve the quality of guava fruit (Psidium guajava L.) at 20ºC was studied for a period of 15 days. The edible coatings were formulated with candelilla wax blended with white mineral oil as the lipid phase and mesquite gum as the structural material. The use of edible coatings prolonged the shelf life of treated fruits by retarding ethylene emission and enhancing texture as compared to control samples. At the sixth day, the ethylene produced by the control samples was fivefold higher than the ethylene produced by the coated samples. In addition, the physiological weight loss of coated fruits was nearly 30% lower than the control samples

Diseño de una red de cobre utilizando tecnología xdsl en una zona residencial para un grupo determinado de hogares

El presente proyecto consiste en diseñar una red en la zona residencial en la zona vía a la costa, escogimos la urbanización COSTALMAR que se encuentra ubicada a una distancia de 4,4 K de la central más próxima de la central ubicada por ese sector. En el estudio de la central hemos analizado los equipos que conforman una central, también el medio de transmisión que usa la misma, enfocándonos en la red de telefonía existente, por eso basándonos en los estudios realizados tanto en libros como en estándares para la tecnología ADSL hemos especificado el uso de los equipos tales como DSLAM, splitters, router, par de cobre y varios factores para llevar a cabo el diseño, también hablamos como se compone el diseño de una red usando ADSL por lo tanto estudiamos el lugar donde haremos el diseño así como la central de la operadora y la central a desarrollar, detallamos la planta externa, red primaria, cajetines, red secundaria y el bucle de abonado. El diseño de nuestra red está contemplada para una cantidad de usuarios determinada inicial de 25 usuarios, también fue diseñado para poder soportar un incremento de usuarios en las urbanizaciones aledañas a esta, y así poder sacar el máximo provecho de una infraestructura de red que está diseñada con los estándares de distancias para así poder cumplir con los límites de velocidad tanto en downstream y upstream. Fueron estudiados los estándares de xDSL para así poder llegar a la conclusión de que tecnología debería de ser la mejor elección para esta zona residencial.This project is to design a network in a residential network located via the coast, we choose COSTALMAR urbanization that is located at a distance of 4.4 km to the next central located in that sector. In the study we have analyzed the equipment that make up a central, also the transmission medium that use the central, focusing in the existing PSTN, therefore bases in the studies conducted both in books and in standard to the ADSL technology we have specified the use of the equips like that DSLAM, Splitters, Routers, Pair of copper and some factors for carrying out the design, also we speak as the design is composed of a network using ADSL, therefore study the place where will make the design, also the center of the operator and the plant to develop, we detail the outside plant, primary network, boxes, secondary networks and digital subscriber line. Our network design is provided for a certain amount of initial of 25 users, was also designed to withstand an increase in users in surrounding developments of this. So you can get the most out of a network infrastructure that is designed with standards distances in order to comply with the limits in both downstream and upstream. The standards of xDSL were studied to reach the conclusion that technology should be better choose for this residential are