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Films and edible coatings of natural polymers have been proposed as an attractive alternative for conventional plastic packaging because of their excellent biodegradability and biocompatibility. However, natural polymers, like chitosan, are hydrophilic and present poor water barrier properties. The addition of wax or other hydrophobic substances decreases water permeability of natural polymers but can increases their opacity.The objective of this work was to produce biofilms based on chitosan and different concentrations of carnauba wax and analyze their optical and barrier properties. The films were obtained by dissolving chitosan in acetic acid. Carnauba wax was incorporated into filmforming solutions at0, 15, 30, 40 and 50% (w/w). The opacity increased with higher concentrations of wax, the film with 50% of wax showed the highest value with an increase of 10.5% compared to the control film. The water vapor permeability decreased from 2.73 g.mm/kPa.m 2 .h (0% of wax) to 0.77 g.mm/h.kPa.m 2 (40% of wax). The solubility decreased to about 60% over the control films, and the contact angle increased from 53º to 83º, in film with 0 and 50% of wax, respectively.

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Biopolymer films have several industrial applications because they are environmentally sustainable. Cassava starch is a biopolymer that is easily available, but has limitations: it is hydrophilic, poorly resistant and degradable. The improvement of these properties was proposed in this research from the use of bentonite clay (BT) as a filling material. The compatibilization of this in the polymer matrix was obtained by ion exchange with an organic anionic surfactant. The formation of intercalated or exfoliated starch nanocomposites in the presence of natural or modified clay was characterized by XRD, FTIR, AFM and SEM. The improvement of water vapor, thermal and mechanical properties was investigated by WVP, solubility, TGA and tensile test. The starch nanocomposites in the presence of modified clay showed a better result than those of natural clay. There was no significant difference in the color of the starch film in the presence of the natural or modified clay.

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<p>O objetivo deste trabalho foi avaliar a Conservação pós-colheita de carambola com recobrimento de gelatina e PVC. Para isto, carambolas da cultivar ‘Gigante doce’ foram colhidas na maturidade fisiológica, transportadas para o Laboratório de Pós-colheita da Universidade Federal Rural do Semiárido sendo selecionadas quanto a maturação, sanificadas, secas e separadas em três grupos para a aplicação dos recobrimentos: os frutos foram recobertos  individualmente com uma solução filmogênica de gelatina a 10% com 1% de glicerol como agente plastificante, recobertos 4 frutos com filme flexível de policloreto de vinila (PVC) de 15μm por bandeja e testemunha (sem recobrimento). Os frutos foram armazenados a 10±1 ºC e 85-90% de UR, avaliados em intervalo de cinco dias durante 20 dias quanto a perda de massa, coloração da casca, firmeza de polpa, sólidos solúveis, acidez titulável, pH e ácido ascórbico. O delineamento experimental utilizado foi inteiramente casualizados, em esquema fatorial 3 x 5, com  quatro  repetições de três frutos. O recobrimento de PVC foi mais eficiente em minimizar a perda de massa dos frutos de carambola durante o armazenamento refrigerado. Enquanto, o biofilme propiciou a manutenção da coloração verde do fruto por maior período de tempo. Verificou-se aumento no teor de ácido ascórbico e decréscimo na firmeza de polpa dos frutos com o tempo de armazenamento.</p><p align="center"><strong><em>Postharvest conservation Star fruit refrigerated with biofilm coating gelatin and PVC</em></strong></p><p><strong>Abstract</strong><strong>: </strong>The objective of this study was to evaluate the Star fruit post-harvest preservation with coating of gelatin and PVC. For this, starfruit cultivar 'sweet Giant' were harvested at physiological maturity, transported to the Postharvest Laboratory of the Federal Rural University of the Semi-Arid being selected as maturation, sanitized, dried and separated into three groups for the implementation of coatings: the fruits were coanting individually with a film solution of gelatin to 10% with 1% glycerol as plasticizer, covered four fruits with flexible film of polyvinyl chloride (PVC) of 15μm per tray and control (without coating). The fruits were stored at 10 ± 1 ° C and 85-90% RH, valued at five-day intervals for 20 days as the mass loss, peel color, flesh firmness, soluble solids, titratable acidity, pH and ascorbic acid. The experimental design was completely randomized in a factorial 3 x 5, with four replications of three fruits. The PVC coating was more efficient in minimizing the mass loss of Star fruit fruit during cold storage. While the biofilm provided the maintenance of green color of the fruit for a longer period of time. An increase in the ascorbic acid content and decrease in firmness of fruit with storage time.</p>