Melicia Cintia Galdeano

Filmes compostos biodegradáveis a base de amido de mandioca e proteína de soja

–1 m –2 kPa –1 ) foi obtida com maximo teor de EPS (47%) e 13% de glicerol em pH 12. A forca de perfuracao variou de 0,08 a 2,78 N, sendo os maiores valores com adicao de EPS e glicerol em nivel intermediario (30%) em pH neutro. A maior deformacao na perfuracao (31,9%) ocorreu no teor de EPS mais baixo (13%) e de glicerol mais alto (47%). Considerando-se os fatores desejaveis: baixa PVA, baixa solubilidade e boa resistencia mecânica, os filmes produzidos com 15,2% de EPS, 29,2% de glicerol em pH 6,1 foram os que mais bem atenderam a estas caracteristicas. Palavras-chave: glicerol, pH, perfuracao, permeabilidade ao vapor de agua. Biodegradable Composite Films Based on Cassava Starch and Soy Protein

Influence of thickness on properties of plasticized oat starch films

The aim of this study was to investigate the effect of thickness (between 80 and 120 µm) on apparent opacity, water vapor permeability and mechanical properties (tensile and puncture) of oat starch films plasticized with glycerol, sorbitol, glycerol:sorbitol mixture, urea and sucrose. Films were stored under 11, 57, 76 and 90% relative humidity (RH) to study the mechanical properties. It was observed that the higher the thickness, the higher was the opacity values. Films without the plasticizer were more opaque in comparison with the plasticized ones. Glycerol:sorbitol films presented increased elongation with increasing thickness at all RH. Puncture force showed a strong dependence on the film thickness, except for the films plasticized with sucrose. In general, thickness did not affect the water permeability.

Comparing sorghum and wheat whole grain breakfast cereals: Sensorial acceptance and bioactive compound content

The sensory acceptance and the content of bioactive compounds of whole-sorghum and whole-wheat breakfast cereals were compared. Sensory acceptance was assessed using the Food Action RatingScale. 3-Deoxyanthocyanidins, flavones and flavanones were determined by high-performance liquid chromatography (HPLC) with diode array detection, and vitamin E by HPLC with fluorescence detection. Total phenolics and antioxidant activity were determined by spectrophotometry. The sorghum breakfast cereal had better sensory acceptance (70.6%) than wheat breakfast cereal (41.18%). Sorghum had higher 3-deoxyanthocyanidin content (100% higher), total phenolic compounds (98.2% higher) and antioxidant activity (87.9% higher) than wheat breakfast cereal. Flavones and flavanones were not detected in both breakfast cereals. Total vitamin E content was 78.6% higher in wheat than in sorghum breakfast cereal. Thus, consumption of whole sorghum breakfast cereal should be encouraged, since it had good sensory acceptance and is a source of bioactive compounds that can promote benefits to human health.

Length-scale Specific Crystalline Structural Changes Induced by Molecular Randomization of Pequi Oil

Pequi fruit (Caryocar brasiliense Camb) is considered important since its pulp has a high content of oil and carotenoids. The oils triacylglycerols (TAGs) contain mainly oleic (~57%) and palmitic (~36%) fatty acids, distributed primarily among POO, POP/PPO, and OOO TAGs. It displays a tendency to fractionate upon storage and has a relatively low melting temperature (SFC of 4% at 25°C). Pequi oil was modified through chemical interesterification, which increased the PPP content to ~6%. This caused a flattening in the SFC-temperature profile, raising the end of melt temperature significantly (SFC of 4% at 39°C). The interesterified oil does not fractionate and is thermally stable up to 40°C, with an SFC-temperature profile resembling that of roll-in shortening (SFC of 31% at 16°C) despite containing high amounts of oleic acid. Crystallization and melting behavior changed. Crystal packing became more disorganized as evidenced by a significant decrease in crystalline domain size in the [001] direction from 42.3 nm to 32.1 nm. Polymorphism remained of the triclinic (β) subcell type but polytypism changed from the 3L to the 2L type. Polarized light microscopy demonstrated that interesterification dramatically decreased crystal size, consistent with a higher rate of nucleation in the material. Moreover, the dramatic improvement in physical stability and functionality was not accompanied by a significant decrease in total carotenoid content (~390 mg/kg).

Influence of milling and extrusion on the sorption properties of sorghum

The processing to which a material is subjected can affect its physical or chemical structures, resulting in products with different hygroscopic behaviours. The present work studied the water adsorption properties of sorghum subjected to different types of processing: raw flour (produced by milling whole grain), extrudates (obtained using a double screw extruder) and extruded flour (obtained by milling the extrudates). The isotherms were obtained using an automated instrumental method. The tests were run in duplicate at 25 °C with relative humidity values ranging between 11 and 84%. The water adsorption data fitted the GAB model well, showing high coefficients of determination. The estimated water contents of the adsorption monolayer ranged from 5.3 to 6.9 g of water per 100 g of dry material. The sorption isotherms were affected by the type of processing, extrusion cooking resulting in products with less water in the monolayer (less hygroscopic). The milling process yielded high water contents in the monolayer, probably due to the breakdown of some polymer-polymer interactions, which exposed the binding sites. To ensure microbiological stability, the water contents in the materials should not exceed 6.9 g of water per 100 g of dry material for raw sorghum flour, 5.3 g of water per 100 g for sorghum extrudates and 6.7 g of water per 100 g for extruded sorghum flour.

Effect of water temperature and pH on the concentration and time of ozone saturation

Ozone has been used for many years to disinfect water due to its oxidizing potential. Since it decomposes quickly into molecular oxygen, leaving no residue, it has important advantages for use. The decomposition of ozone is affected by the temperature and pH of the medium, low pH values and temperatures increasing its half-life, which can result in more efficient disinfection. With the objective of increasing the effectiveness of ozonation, this study investigated the effect of temperature (8 oC and 25 °C) and pH (3.0 and 6.0) of the water on the saturation time and gas concentration, employing two initial gas concentrations (13.3 and 22.3 mg L-1). The concentration of ozone saturation increased as the temperature and pH of the medium decreased, as also with the higher initial gas concentration (C). The highest saturation concentrations were obtained at pH 3.0 and 8 °C (4.50 and 8.03 mg L-1 with C of 13.3 and 22.3 mg L-1, respectively). This higher ozone content could result in greater decontamination efficiency of the food products washed with this water.

OBTENÇÃO E CARACTERIZAÇÃO DE MATERIAL DE REFERÊNCIA EM BLENDS DE COFFEA. ARABICA E C. CANEPHORA

Não há no Brasil uma legislação para características mínimas de qualidade e autenticidade para blends de Coffea arabica e C. canephora robusta torrados e moídos. A fim de obter padrão de identidade para rotulagem, faz-se necessária a elaboração de material de referência (MR) que permita a identificação e ratificação da composição percentual dos blends de café, para dar suporte a uma possível legislação. Atualmente os MR disponíveis para comercialização que utilizam o café como matriz, foram desenvolvidos para identificação de alguns analitos, tais como, ocratoxina A, cafeína, acrilamida, entre outros. No entanto, ainda não existe nenhum MR de C. arabica e C. canephora para verificação dos teores dessas espécies nos blends. O objetivo do trabalho foi elaborar e caracterizar um candidato a MR de C. arabica, C. canephora e mesclas das duas espécies. O café verde foi torrado a 240 °C por 14 minutos, moído e peneirado na granulometria < 600 μm. O MR consistiu dos percentuais: 100:0; 95:5; 75:25; 50:50, 25:75, 5:95 e 0:100 de C. arabica e C. canephora, respectivamente. Foram avaliados a perda de massa durante a torra, a cor instrumental, o tamanho e a distribuição de partículas por difratometria laser. Os resultados indicaram que o MR apresentou homogeneidade quanto ao tamanho e a distribuição de partícula e perda de massa. A análise de cor instrumental mostrou maior luminosidade para espécie C. canephora comparado ao C. arabica, segundo o parâmetro CIEL*. O MR apresentou tendência ao amarelo conforme aumentava a proporção de C. canephora no blend, de acordo com o parâmetro CIEb* e o ângulo Hue, e uma tendência a tonalidade vermelha, segundo os valores de CIEa*. Concluiu-se que as condições estabelecidas para a produção do MR de blend de café apresentou uniformidade e homogeneidade adequadas e podem ser utilizadas como parâmetro para novos MR que utilizam café torrado e moído, bem como contribuir para avaliação da garantia de qualidade e identidade do produto e para fins de rotulagem onde constem os percentuais de C. arabica e C. canephora no blend.