Carlos Wanderlei Piler de Carvalho

Effect of soybean hull, screw speed and temperature on expanded maize extrudates

Summary Brazil is one of the biggest producers and exporters of soybean grains and also produces large amounts of soy for animal feed. However the amount of soy based products for human consumption is surprisingly low in Brazil, due, in part, to the limited preference for soy based products. During the processing of soybeans, a considerable quantity of soybean hull is discarded, but this could be used as an source of insoluble fibre in food products, for example, in extruded expanded products. The objective of this work was to study the effects of soybean hull, moisture content and temperature on the production of expanded maize extrudates. Mixtures of maize grits and soybean hull were extruded in a single screw extruder to produce directly expanded extrudates, and the effects of three independent variables, screw speed (100-200 rpm), temperature (100-200 °C) and soybean hull content (0-40%) were investigated using a central composite rotatable design and response surface methodology. The response variables used in this study were: specific mechanical energy (SME), sectional expansion index (SEI) and the paste viscosity readings (cold viscosity, peak value, breakdown and setback). All the response variables were affected significantly (p < 0.05) by the addition of soybean hull. The interaction between soybean hull and temperature increased breakdown and reduced setback. SME and SEI decreased as the addition of soybean hull and the temperature increased. No significant effect of increasing screw speed on SME and SEI was observed in this study. The sensory evaluation showed that no statistical difference was found between extrudates containing 10, 20 and 30% soybean hull, indicating that maize extrudates containing added soybean hull could be used as a rich source of insoluble fibre.

Determinação da cor, imagem superficial topográfica e ângulo de contato de biofilmes de diferentes fontes de amido

Atualmente, um dos problemas que acometem o meio ambiente e a poluicao ocasionada pelo descarte de filmes plasticos de polimeros sinteticos sem nenhum controle. Uma das alternativas para minimizar este problema e a utilizacao de amido na elaboracao de materiais biodegradaveis que possuem alta degradabilidade quando lancados no meio ambiente. Apesar do numero crescente de trabalhos de pesquisas utilizando diferentes materiais biodegradaveis, o conhecimento das propriedades fisicas de biofilmes elaborados com amido ainda e bastante reduzido. Objetivou-se com este trabalho determinar a diferenca de cor, a imagem superficial topografica por microscopia eletronica de varredura e o ângulo de contato de biofilmes elaborados com tres diferentes tipos de amido: filme de fecula de batata (FFB), filme de fecula de mandioca (FFM) e filme de amido de milho (FAM) com tres concentracoes: 1, 2 e 3% empregando-se um delineamento inteiramente casualizado com tres repeticoes. A interacao concentracao e tipo de amido foi estatisticamente significativa para ângulo de contato e nao significativa para a diferenca de cor. A diferenca de cor foi afetada pela fonte de amido e o maior valor observado para filme de fecula de mandioca. Com o aumento da concentracao de amido, o ângulo de contato diminuiu para filmes de fecula de mandioca e de batata, diferentemente para os biofilmes de milho, onde esta relacao foi constante.

Efeito da extrusão sobre a adsorção de água de farinhas mistas pré-gelatinizadas de arroz e bagaço de jabuticaba

It was studied the effect of extrusion variables on the water absorption characteristics of pre-gelatinized flours (FME) resulting from the extrusion of white rice (FAP) and jabuticaba (Myrciaria jaboticaba) dried bagasse flour (FBJ). Response surface methodology (RSM) type 23 was used as a predictive mathematical model to evaluate the flour stability. The experimental design was used to study the effect of two levels of FBJ replacement as a fiber source (15 and 25%), two levels of screw speed (100 and 200 rpm) and two temperatures of the 3rd heating zone (120 and 180oC) resulting in eight treatments. The water absorption of FME, FAP and FBJ were compared by analysing the absorption isotherms water activity (Aw), which varied from 0.113 to 0.973 at 25oC. The isotherms experimental data were adjusted to GAB mathematical model, which generated the Xm (equilibrium moisture of the monolayer) coefficient applied to RSM as a variable response to evaluate the stability of the pre-gelatinized flours. The results showed the importance of the three variables during the extrusion process. The isotherms curves presented a typical surface hydrophilic characteristic having a sigmoidal type II shape. The region of intermediate moisture revealed that FAP adsorbed higher water content per unit of Aw, followed by FME. FBJ showed the lowest hygroscopic character. Concerning the stability of pre-gelatinized flour, the three extrusion variables were statiscally significant. The stability increased with the increase of FBJ flour content and also with the extruder temperature, whereas it decreased as the screw speed reduced, although with lower effect. The combination of high temperature and FBJ content improves the stability of the extruded flours.

Tocochromanols and carotenoids in sorghum (Sorghum bicolor L.): diversity and stability to the heat treatment.

The content and stability (retention) to dry heat in a conventional oven (DHCO) and extrusion of tocochromanols and carotenoids in sorghum genotypes were evaluated. One hundred sorghum genotypes showed high variability in tocochromanol content (280.7-2962.4 μg/100g in wet basis) and 23% of the genotypes were classified as source of vitamin E. The total carotenoid varied from 2.12 to 85.46 μg/100g in one hundred sorghum genotypes. According to the genetic variability for carotenoids and tocochromanols, the 100 genotypes were grouped into 7 groups. The retention of the total tocochromanols and α-tocopherol equivalent decreased after extrusion (69.1-84.8% and 52.4-85.0%, respectively) but increased after DHCO (106.8-114.7% and 109.9-115.8%, respectively). Sorghum carotenoids were sensitive to extrusion (30.7-37.1%) and DHCO (58.6-79.2%). In conclusion, the tocochromanols profile in sorghum varied widely and the genotypes presented high genetic variability for carotenoids and tocochromanols. Sorghum was a source of tocochromanols, which increased after DHCO and decreased after extrusion. The carotenoid content in sorghum decreased after DHCO and extrusion.

Effect of sugar and water contents on non-expanded cassava flour extrudates

Foram estudados os efeitos da sacarose e da agua de mistura no processamento de farinha de mandioca por extrusao. As variacoes de sacarose (0-20% p/p) e agua (28-42% p/p) foram estudadas empregando-se metodologia de superficie de resposta. O processo de extrusao foi conduzido em uma extrusora de dupla rosca acoplado a um reometro de torque. A energia mecânica especifica (SME) dissipada no final da extrusora foi calculada. As amostras extrusadas foram analisadas quanto aos indices de absorcao de agua (WAI) e de solubilidade em agua (WSI), e quanto as propriedades de pasta durante o ciclo de gelatinizacao/retrogradacao usando-se um analisador rapido de viscosidade (viscosidade a frio (CV), pico de viscosidade (PV), breakdown e setback). SME e WSI diminuiram em funcao dos teores de agua e acucar. WAI e as propriedades de pasta foram influenciadas pelo teor de agua. Nao foi observado o efeito antiplastificante da sacarose nas propriedades de pasta, indicando que a adicao de acucar na mistura de farinha de mandioca nao reduziu a capacidade da agua em gelatinizar o amido durante o processo de extrusao. A natureza do ponto otimo para o WAI, PV e BD foi uma sela, enquanto que para SME foi maximo e para CV e SB foi minimo. Estes resultados podem ser usados na fabricacao de produtos extrusados nao expandidos de farinha de mandioca contendo acucar com desejaveis propriedades funcionais para fins especificos.

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

The effects of water and sucrose contents on the physicochemical properties of non-directly expanded rice flour extrudates

Rice flour was processed by extrusion cooking in the presence of variable contents of water and sucrose. The process was carried out in a twin-screw extruder under the conditions given by a centre rotational experimental design of second order. The effects of the independent variables, water content (27.9 to 42.1%), and sucrose content (0.1 to 19.9%) on the physicochemical properties of the extrudates were investigated. The water absorption index (WAI), water solubility index (WSI), volumetric expansion index (VEI), and bulk density (BD) were determined as dependent variables. BD was determined for samples before and after frying. An increase in water contents resulted in higher WAI and VEI, and lower WSI and BD for extrudates before and after frying. Higher sucrose levels led to increased values of WAI and VEI and to reduced values of WSI and BD. Both independent variables had significant influence on the physicochemical properties of rice flour extrudates. However, the sucrose content was the most significant. The interaction between these two independent variables and their quadratic effect were also important for the responses studied.

Caracterização físico-química de filmes comestíveis de amido adicionado de acerola (Malphigia emarginata D.C.)

Edibles films are an alternative to synthetic materials used for packing food products. Barbados cherry is rich in vitamin C and carotenoids. The aim of this study was to characterize and develop films by casting from cassava starch, lyophilized Barbados cherry pulp and glycerol. The films were characterized with respect to thickness, water vapor permeability (WVP), water solubility, vitamin C, carotene and mechanical properties. The interaction of pulp and glycerol reduced film thickness. An increase in pulp concentration up to 60% increased WVP but beyond this concentration reduced both WVP and solubility leading to an increased level of vitamin C and β carotene in the films.

Food powder delivery through a feeder system: effect of physicochemical properties.

Understanding the differences in delivery by feeders as affected by the powder properties is important for control but not much is written about this in the scientific literature. A regression analysis was undertaken to determine how to quantitatively integrate the effects of powder physicochemical properties on delivery through a twin-screw feeder. There was a linear relationship between powder delivery and screw speed over the entire operating range of the commercial twin-screw feeder test platform with the slope varying with the material delivered. Apparent particle density and particle size represented by both D50 and mode of a volume weighted particle size distribution (PSD) were found to have the most influence on delivery rate. Their effects could be quantitatively accounted for through a multiple regression equation for predicting the slope of the linear powder delivery curves.

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.