Resumo A queimadura solar é responsável por uma parcela significativa de perdas pós-colheita e tem motivado estudos para mitigar seu efeito em diversos tipos de cultivares. Desta forma, o presente estudo propõe um protocolo rápido para avaliar o efeito fotoprotetor de formulações supressoras. O experimento consistiu em posicionar frutos (manga) recobertos com diferentes formulações supressoras acerca de 7 centímetros de uma fonte incandescente e medir a variação da temperatura superficial por meio de termômetro e de câmera térmica. As formulações foram baseadas em polissacarídeo filmogênico (galactomanana) e aditivos reflexivos (argilas montmorilonita, bentonita e hidroxiapatita). O melhor resultado foi alcançado com revestimento, tendo a bentonita como aditivo, o qual apresentou diferença estatística de temperatura (43,3±2,1 °C) em relação ao controle (52,1±3,0 °C) e ao revestimento padrão caulinita (39,4±1,7 °C). Assim, ficou comprovada a viabilidade do protocolo bem como de formulações alternativas para diminuir o efeito da queimadura solar. Isto contribui como soluções para o estabelecimento da Agricultura Tropical.

Abstract Sunburn is responsible for significant losses in post-harvest and has motivated studies to diminish its effect on different types of cultivars. Thus, the present study proposes a rapid protocol to evaluate the photoprotective effect of suppressive formulations. The experiment consisted in placing fruits (mango) covered with different suppressor formulations about 7 centimeters from an incandescent source and measuring the surface temperature variation employing a thermometer and thermal camera. The formulations were based on a filmogenic polysaccharide (galactomannan) and reflective additives (hydroxyapatite, montmorillonite and bentonite clays). The best result was achieved with a coating with bentonite as an additive, which showed a statistical difference in temperature (43.3±2.1 °C) compared with the control (52.1±3.0 °C) and the standard kaolinite coating (39.4±1.7 °C). Thus, it was proven the viability of the protocol as well as of the alternative formulations in to reduce the sunburn effect. This contributes to solution for the establishment of the Tropical Agriculture.

Abstract The increasing use of natural biodegradable polymers to preserve foods is a consequence of the concern of society with sustainability. Starch stands out amongst the natural polymers due to its great availability on a worldwide scale, high extraction yield and nutritional value, low cost, biodegradability and biocompatibility. Apart from the traditional sources, various others exist with extraction potential. The objective of this study was to identify films from different non-traditional starch sources with properties revealing their potential to be applied as coating for fruits and vegetables. The biodegradable films were prepared with three starch concentrations (2, 3 and 3.5%) for each of the following sources: cassava, yam, jackfruit seed and mango kernel. The starches from the sources studied are promising ingredients for the formulation of films, presenting good physical, optical (such as transparency) and mechanical characteristics, principally tensile strength whose maximum value was 36.63 MPa. Increases in starch concentration directly influenced the thickness, water vapor permeability, tensile strength and puncture force. The films with the greatest potentials for use according to their characteristics were 3% cassava, 3% yam, 3.5% jackfruit seed and 2% mango.

RESUMO Dada a potencialidade das nanopartículas (NP) de serem empregadas como vetores para administração de drogas, cosméticos e alimentos, tem-se procurado aumentar a sua produção. Particularmente no setor agroindustrial, os subprodutos são fontes de compostos ativos que precisam ser estabilizados para garantir sua aplicação. No entanto, dado o volume de subproduto gerado, é preciso estudar o encapsulamento em escalas maiores. Assim, visando determinar a influência do escalonamento nas propriedades da NP, a vitamina C (extraída do resíduo do processamento de acerola) e polifenóis (obtido do resíduo do processamento de uva) foram nanoencapsulados em NP de quitosana a partir de três volumes reacionais diferentes: 0,1; 1,0 e 10,0 dm3. As NP foram caracterizadas em relação ao rendimento, tamanho de partícula, morfologia e perfil de liberação. De forma geral, o aumento de escala não influenciou os parâmetros estudados. Assim, os valores de tamanho das NP entre os volumes reacionais de 0,1 e 10,0 dm3 foram muito similares. Por exemplo, para o controle (não encapsulado), o tamanho foi 155±6 e 227±118 nm, respectivamente, para os volumes reacionais de 0,1 e 10,0 dm3. O mesmo padrão foi observado para o extrato do subproduto de acerola encapsulado (373±44 e 400±83 nm) e o ácido ascórbico (279±29 e 217±29 nm). Para o extrato da casca de uva encapsulado, houve um decréscimo de tamanho, variando de 1040 a 308 nm. A razão rendimento por volume ficou em torno de 1,3 mg cm-3. Análises adicionais para NP com extrato da casca de uva encapsulado, por Microscopia Eletrônica de Varredura, mostrou estruturas esféricas uniformemente distribuídas e o perfil de liberação foi independente do volume reacional. Desta forma, o sistema é adequado para o escalonamento.

ABSTRACT Given the potentiality of nanoparticles (NP) to load substances as active principle of drugs, cosmetics and food, there is interest in increasing its production. Particularly in the agroindustrial area, the byproducts are source of functional compounds that must be stabilized by encapsulation, for example, to allow its application. Considering the amount of generated byproducts, it is necessary to understand the encapsulation synthesis in a high scale dimension. In this way, the active compounds vitamin C (from the byproduct of the acerola processing) and polyphenols (from the byproduct of grape processing) were nanoencapsulated into chitosan NP at three reactional volumes: 0.1; 1.0 and 10.0 dm3. The NP were characterized for yield, particle size, morphology, encapsulation efficiency and release profile. In general, the increase in scale did not influence these parameters. It is found a close similarity for NP size value between the 0.1 and 10.0 dm3 reactional volumes. For example, for the blank control, the size was 155±6 and 227±118 nm respectively for 0.1 and 10.0 dm3 reactional volumes. Similarly for the encapsulated acerola byproduct extract (373±44 and 400±83 nm) and ascorbic acid (279±29 and 217±29 nm). For the encapsulated skin grape extract, the size decreased sharply from 1040 to 308 nm. The yield per volume ratio was about 1.3 mg cm-3. Additional analysis for NP with encapsulated skin grape extract, by Scanning Electronic Microscopy, showed uniformly distributed spherical structures and the release profile was similar for all reactional volumes. Thus, the system is suitable for scale-up for NP production.

The agroindustrial residue from the production of acerola pulp is rich in residual vitamin C. Thus, aiming its extraction and stabilization, this work proposed the nanoparticle (NP) encapsulation via ionic gelation with subsequent preparation of nanocomposites (NC) film based on galactomannan matrix. NP were characterized and their stabilities were evaluated under different storage conditions (incidence of light, temperature and oxidizing atmosphere). The results by Dynamic Light Scattering (DLS) and Scanning Electron Microscopy (SEM) indicated homogeneous morphology, spherical shape and size of ~220 nm. Regarding the stability, the UV-visible spectrophotometric analysis showed a much lower degradation rate for encapsulated vitamin C, resulting in more than 30% of preservation compared with the non-encapsulated systems at the end of 15th day of storage. In agreement, the NC films also resulted in preservation of vitamin C mainly for the test in high temperature, which maintained about 80% of the initial concentration, whereas in the non-encapsulated condition this value fell to 45%. The morphological analysis of these films by SEM indicated good distribution of the NP in the galactomannan matrix. Thus, the results indicate the feasibility of using the encapsulation method to stabilize vitamin C extracted from the agroindustrial residue of acerola.

The food nutritional content is reduced as result of vitamins degradation. In order to minimize such losses, the encapsulation technique into polymeric nanoparticles (NPs) could offer an additional protection, extending the stability. The crosslinking formed by the ionic gelation process of chitosan and tripolyphosphate (Chi-TPP) has been widely used as an encapsulating matrix for several chemical compounds. In this way, Chi-TPP was used for encapsulation of C, B9 and B12 vitamins. The stability of the vitamins in NPs was evaluated in aqueous suspension by UV-Visible spectroscopy under different conditions: stored in dark, light exposure and effect of oxygen bubbling. The results indicated that encapsulation had a positive effect in preserving the vitamins, mainly vitamin C. The encapsulation preserved 47% of the initial concentration of vitamin C by the tenth day and around 28% after 17 days. Conversely, in non-encapsulated controls (neutral and acidic medium) the losses were higher, reaching 13% by the tenth day and almost 3% after 17 days of storage in both medium. When exposed to light and O2 the protection provided by the encapsulation was even greater. By thermogravimetric analysis, the pure and the encapsulated vitamins showed distinct thermal behavior confirming Chi-TPP as a potential encapsulation material.

O emprego de coberturas comestíveis na conservação de frutas na condição pós-colheita, sejam intactas ou minimamente processadas, tem sido preconizado como uma tecnologia emergente e de grande potencial, principalmente para aplicações sobre frutas de origem tropical. Diversos biopolímeros têm sido avaliados na formulação dessas coberturas e, neste texto, apresentamos, de forma geral, os principais conceitos físico-químicos envolvidos no processo, com o objetivo de subsidiar uma escolha que possa gerar uma maior eficiência da cobertura formada. Alguns exemplos de aplicação, com base na literatura, são apresentados a título ilustrativo. É importante notar que não há uma cobertura "universal", ou seja, uma formulação que possa ser aplicada a qualquer fruta indiscriminadamente. A escolha do material apropriado dependerá das características da fruta, do biopolímero e dos objetivos almejados para o revestimento.

The use of edible coatings to preserve post-harvest fruits in the intact or slightly processed forms, has been advocated as an emerging technology with great potential for application in fruits, especially those of tropical origin. Several biopolymers have been evaluated in formulating these coatings and this review presents the main physicochemical concepts related to the coating formed in a general way. Some examples of their applications, available in the literature, are also presented for illustrative purposes. It is important to note the absence of a "universal" coating, that is, a formulation suitable for application to any fruit indiscriminately. The ideal choice depends on the fruit, the biopolymer and the aims targeted for the coating.

Zeínas são proteínas de reserva do milho (prolaminas), que podem ser extraídas através de solubilização em meio alcoólico. Essas proteínas são altamente hidrofóbicas, com elevado grau de polimerização. Neste estudo, zeínas do tipo a (massa molecular entre 10 e 22 kDa) foram extraídas do glúten do milho e caracterizadas com respeito às suas principais bandas de absorção espectroscópica na região do infravermelho. Blendas de zeínas com ácido oléico (AO) como plastificante foram avaliadas em diversas proporções e filmes processados por casting sobre superfície apolar. Filmes de zeínas sem plastificante mostraram-se inviáveis para manipulação e medidas, mas a adição de 1 e 2% em massa de AO proporcionou um significativo aumento do módulo de elasticidade, segundo análise realizada por DMA. A presença de plastificante introduz também irregularidades superficiais e leva a uma perda das características hidrofóbicas dessas proteínas.

Zeins comprise a group of maize storage proteins (prolamines) that can be extracted via solubization in alcoholic media. Such proteins are highly hydrophobic with elevated degree of polymerization. In the present study, zein type a (molecular mass between 19 and 22 kDa) was extracted from corn gluten meal and characterized concerning the main spectroscopy absorption bands in the infrared region. Cast films were processed by blending zein and oleic acid (OA) as plasticizer. Films with no plasticizer were extremely brittle, and thus impossible to handle or used for mechanical analysis. The addition of 1 or 2% wt OA resulted in significant increase in the elongation length, according to DMA analysis. The presence of the plasticizer led to microscopic surface irregularities and to a reduction in the original hydrophobic characteristics.

A biocompatibilidade de revestimentos baseados em quitosana e seus sais quaternários foi estudada visando seu emprego como revestimentos comestíveis de maçãs fatiadas. Medidas de perda de água, mudança de coloração e desenvolvimento de fungos foram monitoradas em função do tempo de estocagem. O efeito de escurecimento enzimático para fatias de maçãs recobertas com solução de quitosana foi bastante pronunciado, variando de L* = 76,5 e Ângulo de Hue = 95,9° (t = 0) a L* = 45,3 e Ângulo de Hue = 69,8° (t = 3 dias), ao passo que, para as amostras revestidas com TMC, a variação foi bem menor no mesmo período (L* = 74,1; Ângulo de Hue = 95,0°) a (L* = 67,0; Ângulo de Hue = 83,8°). O derivado hidrossolúvel N,N,N-trimetilquitosana apresentou ótima atividade antifúngica contra P. expansum, mas muito dependente das propriedades do polímero como o grau de quaternização. A formulação mais eficiente foi a preparada a partir do derivado com grau de quaternização de 45% com altas solubilidade e viscosidade. Neste caso, o avanço do fungo ficou restrito a cerca de 30%, enquanto que para o controle atingiu-se cerca de 80% da superfície analisada para um período de 7 dias de armazenamento.

The biocompatibility of chitosan and chitosan quaternary salt coatings was evaluated for use as edible coatings for sliced apple. Measurement of water loss, color change, and fungal growth appearance were monitored as a function of time. A significant brownish effect was observed on chitosan coated slices, varying greatly from L* = 76.5 and Hue angle = 95.9° (t = 0) to L* = 45.3 and Hue angle = 69.8° (t = 3 days), whilst for TMC coated samples the variation was considerable lower (L* = 74.1; Hue angle = 95.0°) to (L* = 67.0; Hue angle = 83.8°) within the same period. The hydrosoluble derivative N,N,N-trimethylchitosan demonstrated good antifungal activity against P. expansum although highly dependent on the polymer properties such as degree of quaternization. The most efficient formulation was that prepared from derivative having a degree of quaternization of 45%, high solubility, and high viscosity. This formulation restrained fungus spreading up to 30%, while for the control it reached almost 80% of the total assessed surfaces during 7 days of storage.

The polyelectrolyte complex (PEC) resulting from the reaction of sodium carboxymethylcellulose (CMC) and N,N,N-trimethylchitosan hydrochloride (TMQ) was prepared and then characterized by infrared spectroscopy and energy dispersive X rays analysis. The interactions involving the PEC and Cu2+ ions, humic acid and atrazine in aqueous medium were studied. From the adsorption isotherms the maximum amount adsorbed (Xmax) was determined as 61 mg Cu2+/g PEC, 171 mg humic acid/g PEC and 5 mg atrazine/g PEC. The results show that the CMC/TMQ complex has a high affinity for the studied species, indicating its potential application to remove them from aqueous media.

Chitosan, a versatile hydrophilic polysaccharide derived from chitin, has a broad antimicrobial spectrum to which gram-negative, gram-positive bacteria and fungi are highly susceptible. In the current review, three possible and accepted antimicrobial mechanisms for chitosan are presented and briefly discussed. The activity dependence on polymeric molecular weight (MW) and degree of acetylation (DA) are described. The chitosan minimum inhibitory concentrations (MIC) are summarized according to recent data found in the literature. The potential to improve inhibitory growth of bacteria by using water soluble chitosan derivatives is also discussed. The data indicate that the effectiveness of chitosan varies and is dependent on species of target microorganisms.

The fact that alpha- and beta-chitin adopt different arrays in the solid state is explored to emphasize their different properties and distinct spectral characteristics and X ray diffraction patterns. The methods for their extraction from the biomass in view of the preservation of their native structures and aiming to fulfill the claims of purity and uniformity for potential applications are discussed. The different arrays adopted by alpha- and beta-chitin also result in distinct reactivities toward the deacetylation reaction. Thus, the deacetylation of beta-chitin is more efficient owing to the better accessibility to amide groups due to the lower crystallinity of this polymorph.

Films of chitosan and N,N,N-trimethylchitosan were cast from aqueous solutions. Chitosan was dissolved in 1% acetic acid while deionized water was the solvent for N,N,N-trimethylchitosan chloride. The resulting films presented different mechanical behaviors as evaluated by DMTA. The film of chitosan exhibited an elastic-type behavior while that of N,N,N-trimethylchitosan was typically viscous. No glass transition temperatures were observed; however, a discrete thermal transition was detected at 25 °C in the case of the N,N,N-trimethylchitosan.