Effect of enzymatic hydrolysis on some physicochemical properties of root and tuber granular starches

A hidrólise enzimática do amido pode fornecer informações importantes sobre sua estrutura granular. Amidos de mandioca, batata-doce, mandioquinha-salsa e batata foram hidrolisados por α-amilase bacteriana a 37 °C durante 48 horas, e algumas propriedades físico-químicas dos resíduos da hidrólise foram determinadas. O amido de mandioca foi o mais suscetível à enzima com 20,9% de hidrólise, enquanto o amido de batata foi o mais resistente com 5,9%. O tamanho médio dos grânulos variou de 10,8 a 23,4 μm para os amidos de mandioquinha-salsa e batata, respectivamente. Amidos de mandioca e batata-doce apresentaram um padrão de difração de raio-X tipo A, enquanto os amidos de mandioquinha-salsa e batata mostraram padrão tipo B. Todos os amidos nativos mostraram superfície granular lisa e, após hidrólise, os amidos de mandioca, batata-doce e mandioquinha-salsa mostraram alguns grânulos bastante degradados, enquanto o amido de batata apresentou sutil sinal de degradação. O teor de amilose dos amidos diminuiu com a hidrólise para os amidos de mandioca, batata-doce e mandioquinha-salsa, permanecendo inalterado para o amido de batata. Como esperado, a viscosidade intrínseca e as propriedades de pasta diminuíram para todos os amidos hidrolisados. Não houve diferença significativa entre as propriedades térmicas dos amidos nativos e hidrolisados. Estes resultados sugeriram que a hidrólise ocorreu nas áreas cristalinas e amorfas dos grânulos. O padrão de difração do tipo B e o grande tamanho dos grânulos do amido de batata podem ter contribuído para a maior resistência deste amido à hidrólise.

Enzymatic toxins from snake venom: structural characterization and mechanism of catalysis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Macromolecular properties of cepacian in water and in dimethylsulfoxide

Cepacian is the exopolysaccharide produced by the majority of the so far investigated clinical strains of the Burkholderia cepacia complex. This is a group of nine closely related bacterial species that might cause serious lung infections in cystic fibrosis patients, in some cases leading to death. In this paper the aggregation ability and the conformational properties of cepacian chain were investigated to understand its role in biofilm formation. Viscosity and atomic force microscopy studies in water and in mixed (dimethylsulfoxide/water) solvent indicated the formation of double stranded molecular structures in aqueous solutions. Inter-residue short distances along cepacian chain were investigated by NOE NMR, which showed that two side chains of cepacian were not conformation ally free due to strong interactions with the polymer backbone. These interactions were attributed to hydrogen bonding and contributed to structure rigidity. (c) 2007 Elsevier Ltd. All rights reserved.

A general treatment for the conductivity of electrolytes in the whole concentration range in aqueous and nonaqueous solutions

Despite the great importance of ion transport, most of the widely accepted models and theories are valid only in the not very practical limit of low concentrations. Aiming to extend the range of applicability to moderate concentrations, a number of modified models and equations (some approximate, some fundamented on different assumptions, and some just empirical) have been reported. In this work, a general treatment for the electrical conductivity of ionic solutions has been developed, considering the electrical conductivity as a transport phenomenon governed by dissipation and feedback. A general expression for the dependence of the specific conductivity on the solution viscosity (and indirectly on concentration), from which the whole conductivity curve can be obtained, has been derived. The validity of this general approach is demonstrated with experimental results taken from the literature for aqueous and nonaqueous solutions of electrolytes.

The characteristics of a test liquid formulation for use in evaluating the performance of handling and metering systems

Injection metering systems are an important option for the development of pesticide application equipment, with advantages relating to minimising the need for disposal of unused pesticide, improving the ease of cleaning and optimising the accuracy of chemical application. For all injection systems, characteristics such as the steady-state accuracy of delivered dose, dose stability and the time response for dose step changes are related to the ability of the system to operate with different chemical formulations. A system designed to inject liquids should be able to accommodate changes in viscosity and density. The aim of this study was to develop a methodology for testing chemical injection systems using liquids with different viscosities. The experimental arrangement simulating applications with injection metering systems used dye and salt solutions as tracers. Tests were conducted to analyse the influence of salt on the characteristics of the water and a viscous solution. Results showed that the salt interfered with the dye stability in the water solution. In tests with a viscous test liquid, the salt was introduced at different steps during the mixing process, providing four different liquids to be analysed in terms of viscosity, density and pH. Some differences in liquid characteristics were found which could influence the performance of the injection systems.

Influence of low and high levels of grain defects on maize wet milling

Yields and starch pasting characteristics obtained from wet milling of maize samples with low and high levels of defect grains were compared to those from sound samples. Defect grain groups ere established taking into account the defect degree. Thus the first group consisted of fermented, molded, heated and sprouted grains and the second of insect damaged. hollow, fermented (up to 1/4) grains and those injured by other causes. The grain groups, if present at low levels in the samples, 10% for first group and 17% for second group did not affect the chemical composition of starch and its pasting properties. obtained by the rapid visco analyser. Samples with high levels of grain groups (up to 100%). affected wet milling yields and starch viscosity. Samples with 100% of grains in the first group decreased starch, germ yield and peak viscosity and increased gluten yield. Samples with 100% of grains in the second group decreased germ and fiber yield but increased starch yield. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Effect of lithium doping on the evolution of rheological and structural properties during gelation of siloxane-poly(oxypropylene) nanocomposites

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of pectin extracted from citrus pulp on digesta characteristics and nutrient digestibility in broilers chickens

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of the concentration of polyols on the rheological and spectral characteristics of guar gum

Polyols are widely used as sugar substitutes and provide texture to foods. Guar gum has many applications in food industry such as increasing product viscosity and improving texture. Knowledge of rheological properties of gum/polyol systems is important to permit replacing sugar while maintaining product texture. In this work, rheological properties of 0.1, 0.5 and 1 g/100 g guar solutions containing 10 and 40 g/100 g of maltitol, sorbitol, or xylitol were studied. The behavior of these mixtures was evaluated by steady and oscillatory shear measurements, and after a freezing/thawing cycle. Apparent viscosity of guar solutions increased with addition of polyols and with the increase in their concentrations, except for 40 g/100 g sorbitol addition to 1 g/100 g guar gum, in which the apparent viscosity decreased. Addition of polyols also increased the dynamic moduli of the systems. In mixtures of guar with 40 g/100 g polyol, the phase angle (δ) was below unity, but was dependent on frequency, which is characteristic of concentrated solutions with a certain degree of structuring. FTIR spectroscopy was studied to provide information on possible interactions between guar gum and polyols. Analyses carried out after freezing/thawing showed no changes in the viscoelastic behavior of the solutions. © 2013 Elsevier Ltd.

Statistical and dynamical properties of a dissipative kicked rotator

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of acetylation and acetylation-hydroxypropylation (dual-modification) on the properties of starch from Carioca bean (Phaseolus vulgaris L.)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Production of exopolysaccharide from rhizobia with potential biotechnological and bioremediation applications

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Potentially synbiotic fermented beverage with aqueous extracts of quinoa (Chenopodium quinoa Willd) and soy

The aim of this study was to develop a potentially synbiotic beverage fermented with Lactobacillus casei LC-1 based on aqueous extracts of soy and quinoa with added fructooligosaccharides (FOS). Five formulations with differing proportions of soy and quinoa extracts were tested. The viability of the microorganism, the pH, and the acidity of all formulations were monitored until the 28th day of storage at 5 ℃. The chemical composition of the extracts and beverages and the rheological and sensory properties of the final products were analyzed. Although an increase in acidity and a decrease in pH were observed during the 28 days of storage, the viability of the probiotic microorganism was maintained at 10(8) CFU·mL(-1) in all formulated beverages throughout the storage period. An increase in viscosity and consistency in the formulations with higher concentrations of quinoa (F1 and F2) was observed. Formulation F4 (70% soy and 30% quinoa extracts) showed the least hysteresis. Formulations F4 and F5 (100% soy extract) had the best sensory acceptance while F4 resulted in the highest intention to purchase from a group of 80 volunteers. For chemical composition, F3 (50% soy and 50% quinoa extracts) and F4 showed the best results compared to similar fermented beverages. The formulation F4 was considered the best beverage overall.

Amylase utilization for the extrusion of dog diets

Effects of amylase addition on extruder parameters, cost of extrusion, kibble quality and digestibility of dog food were measured in two separate experiments. In experiment 1, 120 kilo-novo-alpha-amilase-unit (KNU)/kg of heat stable alpha-amylase produced by Bacillus licheniformis was added in liquid form during a preconditioning period. In experiment 23684 KNU/kg of heat stable alpha-amylase produced by Aspergillus oryzae was mixed with the ingredients before extrusion. The diets were processed in a single screw extruder and submitted to digestibility and on experiment 1 also to palatability tests. Digestibility was tested using 12 dogs, six per diet. Data were submitted to analysis of variance followed by F-test. Amylase addition altered extrusion parameters in both experiments (P<0.05), with higher output (kg of dry matter [DM]/h: 28% and 43% higher in experiments 1 and 2) and less electric energy consumption (kW to produce 100 kg DM: 22% and 29% lower in experiments 1 and 2). Kibble appearance and quality [density (g/L), cutting force (g), and starch gelatinization degree (%)] did not change with enzyme treatment (P>0.05). Likewise, enzyme addition did not change nutrient digestibility, fecal dry matter or food palatability (P<0.05). Taken together our results suggest that amylase promoted the breakdown of amylose chains, thereby reducing the dough viscosity and resistance inside the extruder which allowed for higher product flow and less electricity energy consumption without altering food quality. (C) 2012 Elsevier B.V. All rights reserved.

Influência da técnica de pressão expiratória positiva oscilante utilizando pressões expiratórias pré-determinadas na viscosidade e na transportabilidade do escarro em pacientes com bronquiectasia

OBJETIVO: Verificar a efetividade da técnica de pressão expiratória positiva oscilante (PEPO) utilizando pressões expiratórias pré-determinadas sobre a viscosidade e a transportabilidade do escarro em pacientes com bronquiectasia. MÉTODOS: Foram incluídos no estudo 15 pacientes estáveis com bronquiectasia (7 homens; média de idade = 53 ± 16 anos), submetidos a duas intervenções PEPO consecutivas, com 24 h de intervalo entre si, utilizando pressões expiratórias de 15 cmH2O (P15) e 25 cmH2O (P25). O protocolo consistiu de tosse voluntária; nova expectoração voluntária após 20 min, denominado tempo zero (T0); repouso de 10 min; e utilização da técnica em duas séries de 10 min (S1 e S2) de PEPO em P15 e P25, com intervalo de 10 min entre si. A viscosidade e transportabilidade do escarro foram avaliadas pela viscosimetria, velocidade relativa de transporte no palato de rã, deslocamento em máquina simuladora de tosse e ângulo de adesão. As amostras de escarro foram coletadas em T0, após S1 e após S2. Testes estatísticos específicos foram aplicados de acordo com a distribuição dos dados. RESULTADOS: Houve diminuição significante da viscosidade do escarro após S1 em P15 e após S2 em P25. Não houve diferenças significantes entre todas as amostras para a transportabilidade. CONCLUSÕES: Houve diminuição da viscosidade do escarro quando a PEPO foi realizada em P15 e P25, o que sugere que não seja necessário gerar alta pressão expiratória para obter o resultado desejado.