Abstract High-intensity ultrasound irradiation proved to be an effective method for modifying tara gum by generating low molecular weight products and better water solubility. The objectives of this research were to optimize the parameters for the high-intensity ultrasonic treatment with response surface methodology and improve the tara gum solubility. The results demonstrated that after the ultrasound treatment, the solubility of the tara gum had increased (17.7%) as a result of the reduced intrinsic viscosity (70%). The molecular weight of the untreated tara gum was 1.89 x 106 Da, and after ultrasound treatment, it was reduced to 0.47 x 106 Da. Rheological analyses confirmed the reduction in molecular weight for the modified and optimized tara gum and the resulting increase in solubility. This knowledge provides a better understanding of ultrasound treatment technology and increases the scope for use of tara gum in the food industry.

Resumo O estudo comparativo de complexos coacervados entre albumina sérica bovina (BSA) e diferentes polissacarídeos, pectina (PEC) e goma acácia (GA), foi realizado avaliando-se a influência de diferentes razões (proteína:polissacarídeo) e concentrações de cloreto de sódio (NaCl) na turbidez e no potencial zeta. Os complexos BSA:PEC foram formados na proporção 10:1, enquanto os de BSA:GA, na proporção 3:1. O pH de complexação apresentou comportamento diferenciado, complexos BSA:PEC exibiram máxima turbidez em uma ampla faixa de pH (4,9 a 1,5), enquanto complexos BSA:GA tiveram turbidez máxima em pH 3,5. O aumento da concentração de NaCl influenciou negativamente a complexação, com a concentração de NaCl de 0,40 mol L-1 capaz de suprimir a interação em BSA:PEC (10:1) e reduzir a faixa de formação de BSA:GA (3:1). A espectroscopia de infravermelho com transformada de Fourier (FTIR) demonstrou a participação não apenas de interações eletrostáticas, mas também de ligações de hidrogênio na complexação. Este estudo inicial elucidou aspectos fundamentais sobre a formação de complexos coacervados entre BSA:GA/PEC que ajudam a direcionar sua aplicação em produtos alimentícios, especialmente em matrizes ácidas e com baixa concentração de sais, tendo em vista o pH máximo de formação (pH ~ 4,0) e a sensibilidade ao NaCl. Esses complexos podem ser adicionados diretamente em produtos, a fim de agregar valor nutricional ou ainda serem utilizados como uma nova matriz para o encapsulamento de compostos bioativos.

Abstract The comparative study regarding complexes coacervated between Bovine Serum Albumin (BSA) and different polysaccharides, Pectin (PEC) and Gum Acacia (GA), was carried out by evaluating the influence of different ratios (protein:polysaccharide) and sodium chloride (NaCl) concentrations on turbidity and zeta potential. The BSA:PEC complexes were formed in a 10:1 ratio whereas BSA:GA at 3:1. The complexation pH showed different behavior, BSA: PEC complexes exhibited maximum turbidity in a wide pH range (4.9 to 1.5), while BSA: GA had maximum turbidity at pH 3.5. The increase in the concentration of NaCl negatively influenced the complexation. The NaCl concentration of 0.40 mol L-1 suppressed the interaction in BSA:PEC (10:1) and reduced the range formation of BSA:GA (3:1). The Fourier Transform Infrared (FTIR) demonstrated the participation not only of electrostatic interactions, but also of hydrogen bonds in the complexation. This initial study elucidated fundamental aspects about the formation of coacervate complexes between BSA:GA/PEC that assist in directing its application in food products especially, in acidic matrices (pH~4.0) as well as with low concentration of salts, in view of the effect of pH on maximum formation and sensitivity to NaCl. These complexes can be added directly to products in order to add nutritional value or even be used as a new matrix for the encapsulation of bioactive compounds.

Abstract Due to their aqueous nature and biocompatibility, water/water emulsions are particularly advantageous in the production of low calorie functional food and bioactive carrier microparticles. The aim of this study was to investigate the stability of water/water emulsions formed by gelatin and carboxymethycelullose through the Pickering effect, by addition of whey protein particles. The effect of phase composition and pH on emulsion stability over 3 days of storage was studied and the emulsion properties were characterized. Finally, the effect of the addition of different concentrations of whey protein particles on the emulsion stability was investigated. The added protein particles contributed to reduce the rate of phase separation and higher protein concentration showed this effect more clearly. The time of complete phase separation increased 12 h after addition of 15% (w/w) protein. Emulsions at pH 5.5 with protein particles, however, showed lower stability than those at pH 7.5 without particles.

Abstract Proteins are frequently used as emulsifiers and stabilizers. In this work, two proteins with different isoelectric points were used: lactoferrin and ovalbumin. Solutions containing different proteins ratios, with different pH values, were stored for 7 days at 25 °C to analyze the system stability. Systems containing 3% w/v lactoferrin remained stable at all pH values studied, while systems containing 1% w/v ovalbumin remained stable only at a high pH value (8.0). Emulsions containing a mixture of proteins remained stable at a pH between the isoelectric points of the two proteins, which was attributed to an electrostatic bond because of the opposite charges of proteins at this pH. During the analysis of rheological properties, it was possible to observe a non-Newtonian behavior of the emulsions, using the models of Carreau and Cross to describe the pseudoplastic behavior of suspensions. This study provides important information for the use of functional ingredients.

RESUMO Géis fabricados que envolvem o uso de hidrocolóides estão ganhando polpularidade como alimentos de confeitaria/conveniência. O amido é geralmente combinado com um hidrocolóide (proteínas ou polissacarideos), particularmente na indústria de alimentos, uma vez que os amidos nativos geralmente não têm propriedades ideais para a preparação de produtos alimentares. Por conseguinte, os estudos de textura de misturas de amido-proteína podem proporcionar uma nova abordagem na produção de produtos alimentares à base de amido, sendo assim um atributo acrítico que precisa ser cuidadosamente ajustado ao gosto do consumidor. Este trabalho investigou as propriedades reológicas de textura de géis mistos de diferentes concentrações de amido de arroz (15%, 17,5% e 20%) e isolado proteico de soro (0%, 3% e 6%) com diferentes velocidades de teste (0,05, 5,0 e 10,0 mm/s) utilizando um delineamento experimental por Box-Behnken. As amostras foram submetidas a testes de compressão uniaxial com deformação de 80% para determinar os seguintes parâmetros reológicos: módulo de Young, tensão de fratura, deformação da fratura, energia recuperável e aparente viscosidade elongacional biaxial. Géis com maior concentração de amido de arroz e que foram submetidos a velocidades de teste mais altas mostraram-se mais rígidos e resistentes, enquanto que a concentração de isoldado proteico de soro teve pouca influência nessas propriedades. Os géis mostraram uma energia recuperável mais alta quando a velocidade de teste foi maior, e a viscosidade elongacional biaxial aparente também foi influenciada por este fator, exibindo propriedades diferentes dependendo da concentração de amido de arroz e da velocidade de teste.

ABSTRACT Fabricated food gels involving the use of hydrocolloids are gaining polpularity as confectionery/convenience foods. Starch is commonly combined with a hydrocolloid (protein our polyssacharides), particularly in the food industry, since native starches generally do not have ideal properties for the preparation of food products. Therefore the texture studies of starch-protein mixtures could provide a new approach in producing starch-based food products, being thus acritical attribute that needs to be carefully adjusted to the consumer liking. This work investigated the texture and rheological properties of mixed gels of different concentrations of rice starch (15%, 17.5%, and 20%) and whey protein isolate (0%, 3%, and 6%) with different crosshead velocities (0.05, 5.0, and 10.0 mm/s) using a Box-Behnken experimental design. The samples were submitted to uniaxial compression tests with 80% deformation in order to determinate the following rheological parameters: Young’s modulus, fracture stress, fracture deformation, recoverable energy, and apparent biaxial elongational viscosity. Gels with a higher rice starch concentration that were submitted to higher test velocities were more rigid and resistant, while the whey protein isolate concentration had little influence on these properties. The gels showed a higher recoverable energy when the crosshead velocity was higher, and the apparent biaxial elongational viscosity was also influenced by this factor. Therefore, mixed gels exhibit different properties depending on the rice starch concentration and crosshead velocity.

Abstract This study evaluates the stability and transport behaviors of hazardous nanoparticles into soil landfills using experimental procedures to simulate the effects of natural silica nanoparticle suspensions during their percolation into the soil layers of municipal waste landfills. For this, we prepared stabilized suspensions of nanoparticle oxides containing silicon (NPSiO2), titanium (NPTiO2), copper (NPCuO) and zinc (NPZnO), which are recognized as hazardous to the environment, and we conducted leaching experiments within the soil column by simulating landfills layers and simulating the capture and attenuation of nanomaterials into municipal waste landfills. The results demonstrated that the presence of NPSiO2 in suspensions increases the stable concentrations of copper, zinc and titanium oxides and strongly decreases soil layer effectiveness. In contrast, NPZnO improves effectiveness due to its ability to promote agglomeration and setting conditions, allowing further complexation.

Emulsões múltiplas têm sido reconhecidas como uma nova tecnologia para as indústrias de alimentos. Devido a sua estrutura diferenciada dos demais sistemas coloidais, ou seja, existência de duas fases dispersas, esse grupo de emulsão apresenta vantagens em relação às emulsões convencionais, principalmente, no que se refere ao encapsulamento, à proteção e à liberação controlada de componentes bioativos. Assim, a estabilidade e a biodisponibilidade dos encapsulados podem ser aumentadas ou otimizadas, fato que possibilita o planejamento de melhores resultados pela indústria, por meio da produção de novos alimentos. Ainda, com a perspectiva de aumentar o valor nutricional de muitos alimentos industrializados, infere-se uma maior contribuição deles para a promoção da saúde e para prevenção e tratamento de certas doenças crônico-degenerativas. A presente revisão apresenta as bases da tecnologia usual de elaboração de emulsão múltipla, os principais processos de instabilidade a que esse sistema está susceptível, e a aplicação de emulsões múltiplas como sistemas encapsuladores e transportadores de componentes bioativos.

Multiple emulsions have been recognized as a new technology for the food industry. Due to their different structure from other colloidal systems, namely the existence of two dispersed phases, this group of emulsion has advantages over conventional emulsions, especially with regard to packaging, protection and controlled release of bioactive components. Thus, the stability and bioavailability of encapsulated may be increased or optimized, a fact that enables the planning of better results by the industry through the production of new foods. Also, the prospect of increasing the nutritional value of many processed foods, infers greater contribution to the promotion of health and prevention and treatment of certain chronic diseases. This review presents the bases of the usual technology of preparation of multiple emulsion, the main processes of instability that this system is susceptible, and the application of multiple emulsions as encapsulating systems and carriers of bioactive components.

Neste trabalho, a otimização do processo de formação de complexos interpoliméricos entre lactoalbumina e os polissacarídeos goma xantana e pectina foi estudada a fim de definir as condições ótimas para a formação dos complexos. Para o planejamento experimental foi utilizada a metodologia de superfície de resposta (MSR) para três variáveis independentes. As condições ótimas para a formação dos complexos entre lactoalbumina e goma xantana foi: pH 6,6, concentração de NaCl de 0,6 mol/L e concentração de goma xantana 0,083% m/v. E para os complexos formados entre lactoalbumina e pectina foram: pH 6,6, concentração de NaCl 0,25 mol/L e concentração de pectina, 0,113% m/v. O modelo matemático que melhor se ajustou aos dados experimentais foi o correspondente ao complexo goma xantana-lactalbumina, cujo coeficiente de determinação (R²) foi de 0,97.

In this work, the optimization process of interpolymeric complexes formation between lactalbumin and the polysaccharides xanthan gum and pectin was studied in order to define the optimum conditions for the complexes formation. For the experimental design, response surface methodology (RSM) for three independent variables was used. The optimum conditions for the complexes formation between lactalbumin and xanthan gum were: pH 6.6, NaCl concentration of 0.6 mol/L and xanthan gum concentration 0.083% w/v. And for the complexes formed between pectin and lactalbumin the conditions were: pH 6.6, NaCl concentration of 0.25 mol/L and pectin concentration of 0.113% w/v. The best fitted model for the experimental data was that corresponding to the complex xanthan gum-lactalbumin, whose coefficient of determination (R²) was 0.97.

Doce de leite é uma sobremesa láctea concentrada (cerca de 70% de sólidos) muito apreciada no Brasil. Propriedades termofísicas e reológicas de duas formulações de doce de leite brasileiro (puro e adicionado de coco ralado a 1,5% em massa) foram determinadas a temperaturas compreendidas entre 28,4 e 76,4 °C. No geral, a presença de flocos de coco não acarretou diferenças significativas (p < 0,05) nestas propriedades das duas formulações. A capacidade calorífica variou entre (2633,2 e 3101,8) J/kg.°C; a condutividade térmica entre (0,383 e 0,452) W/m°C; a massa específica entre (1350,7 e 1310,7) kg/m³; e enfim, a difusividade térmica entre (1,082 × 10-7 e 1,130 × 10-7) m²/s. O modelo de Bingham descreveu adequadamente o comportamento não Newtoniano dos dois produtos, com tensão crítica de escoamento variando entre (27,3 e 17,6) Pa e a viscosidade plástica de (19,9 a 5,9) Pa.s.

Dulce de leche (DL), a dairy dessert highly appreciated in Brazil, is a concentrated product containing about 70% m/m of total solids. Thermophysical and rheological properties of two industrial Brazilian Dulce de leche formulations (classic Dulce de leche and Dulce de leche added with coconut flakes 1.5% m/m) were determined at temperatures comprised between 28.4 and 76.4 °C. In general, no significant differences (p < 0.05) were observed in the presence of coconut flakes in the two formulations. Heat capacity varied from 2633.2 to 3101.8 J/kg.°C; thermal conductivity from 0.383 to 0.452 W/m.°C; specific mass from 1350.7 to 1310.7 kg/m³; and, thermal diffusivity from (1.082 × 10-7 to 1.130 × 10-7) m²/s. The Bingham model was used to properly describe the non-Newtonian behavior of both formulations, with yielding stress values varying from 27.3 to 17.6 Pa and plastic viscosity from 19.9 to 5.9 Pa.s.