Effect of treatment with alkaline hydrogen peroxide associated with extrusion on color and hydration properties of oat hulls

Abstract

An incomplete factorial design with three independent variables at three levels of variation was used to evaluate the effect of the treatment with alkaline hydrogen peroxide concomitant with extrusion on some properties of oat hulls. The independent variables were hydrogen peroxide level, feed moisture and extrusion temperature. The dependent variables were water retention capacity (WRC), swollen volume (SV) and color. The analysis of variance showed that temperature was the most important variable for the hydration properties. The highest values of WRC and SV were obtained when oat hulls were processed in the condition of 7% hydrogen peroxide, 32% feed moisture and 90ºC extrusion temperature. Modified hulls had a WRC 70% higher and SV 55% higher than the untreated material. The instrumental measure of color was conducted to analyze the modifications promoted due to the treatment in this parameter. The highest value of brightness was obtained with 7% hydrogen peroxide. The modifications in the fibers were accompanied indirectly through hydration properties.<br>Um delineamento fatorial incompleto 3³ foi utilizado para estudar o efeito do tratamento com peróxido de hidrogênio alcalino associado à extrusão sobre algumas propriedades funcionais da fibra da casca de aveia. As variáveis do tratamento avaliadas incluíram teor de peróxido de hidrogênio (%), umidade da amostra (%) e temperatura de extrusão (ºC). A análise de variância (ANOVA) mostrou que a temperatura foi a variável mais importante para as propriedades de hidratação. Os maiores valores de capacidade de retenção de água (CRA) e volume de intumescimento foram obtidos na condição de 7% de peróxido de hidrogênio, 32% de umidade e 90ºC de temperatura, obtendo um incremento de 70% na CRA e 55% no volume de intumescimento. A medida instrumental de cor foi usada para analisar as modificações ocorridas neste parâmetro. O mais alto valor de luminosidade foi alcançado com maior nível de peróxido de hidrogênio (7%), obtendo-se, nessa condição, produtos mais claros. Ensaios realizados para controle mostraram que tanto a extrusão quanto o tratamento químico tiveram efeito nas propriedades avaliadas, e que o efeito conjunto foi superior ao de cada um isoladamente. As modificações ocorridas nas fibras foram acompanhadas indiretamente, através das propriedades de hidratação

Oat fibers modification by reactive extrusion with alkaline hydrogen peroxide

“…The micronized hulls (250 g) were modified by reactive extrusion with alkaline hydrogen peroxide according Galdeano and Grossmann [29] . Initially, the hulls were conditioned to 32% moisture by adding the required volume of water containing dissolved enough NaOH for the material to reach a pH of 11.5.…”

“…In a preliminary study, aiming the application in food products, our research group employed reactive extrusion with AHP to modify the fibers of oat hulls [29] . The characterization was limited to the hydration properties of the fibers.…”

Oat hulls treated with alkaline hydrogen peroxide associated with extrusion as fiber source in cookies

“…Therefore, an only one-step process was developed, with short time of reaction and without generation of residues, an oat hulls fiber with higher hydration capa-city than raw hulls [6].…”

“…The methodology described by GALDEANO & GROSS-MANN [6] was applied. The hulls were conditioned with the necessary water to attain 32% moisture and the amount of sodium hydroxide (dissolved in this water) to attain pH 11.5.…”

“…It is important to point out that the modification of gritty sensation of treated hulls was reached even without great increases on hydration properties [6] indicating that the destructuring of the fiber was enough to make this material more palatable than untreated oat hulls.…”