Maurício de Oliveira

Oxidação dos amidos de mandioca e de milho comum fermentados: desenvolvimento da propriedade de expansão

Cassava and corn starches were fermented in the laboratory at 20 °C, and a fraction was in the sun while another fraction was oxidized with hydrogen peroxide and dried artificially to develop the expansion property. Fermentation in 0, 10, 30 and 50 days was checked and the expansion property was evaluated by the baking test and viscoamilograph behavior (RVA). Fermentation was found to cause changes that help the oxidation of cassava and corn starches, increasing the products titrable acidity. The fermented cassava starch, oxidized by exposure to sunlight or hydrogen peroxide, may develop the expansion property, but the corn starch did not display that ability under these conditions. The best results for the expansion property were obtained with cassava starch oxidized with hydrogen peroxide after 50 days of fermentation.

Efeitos de processo de secagem e tempo de armazenamento na qualidade tecnológica de trigo

Neste trabalho, objetivou-se estudar a influencia dos processos de secagem estacionario e intermitente e do tempo de armazenamento na qualidade tecnologica de graos de trigo, cultivar Embrapa 16 colhidos com teor de agua de 15% e 19%. Graos de trigo (Triticum aestivum L) foram produzidos em lavoura comercial da Granja Bretanhas, Cooperativa Arrozeira Extremo Sul, no municipio de Jaguarao, RS. O experimento foi conduzido em delineamento inteiramente casualizado, utilizando dois teores de agua de colheita (15% e 19%), dois processos de secagem (estacionario e intermitente) e quatro tempos de armazenamento. A secagem foi realizada ate o teor de agua de 13% e os graos acondicionados em embalagens de algodao, em sistema de armazenamento convencional pelo periodo de 12 meses. Nos tempos zero, 4, 8 e 12 meses foram realizadas as analises de teor de agua, peso hectolitro, cinzas, lipidios, acidez graxa, numero de queda e alveografia. Os parâmetros mais efetivos para avaliar o efeito dos processos de secagem de trigo intermitente e estacionario em funcao do tempo de armazenamento foram peso do hectolitro, lipidios e acidez graxa indicando melhor qualidade tecnologica na secagem realizada em secador intermitente. O trigo, cultivar Embrapa 16, colhido seco na planta apresentou qualidade tecnologica inferior e menor conservabilidade ao armazenamento do que o colhido de forma antecipada e seco em secador intermitente.

Effect of drying temperature on quality of β-glucan in white oat grains

Oats have received attention because of their nutritional characteristics, especially their high-quality content of β-glucan. The drying process reduces water content; therefore they can be preserved for long periods. However, high-temperature drying process may affect the physical, chemical, and functional properties of the grains. The objective of this study was to evaluate the effect of different drying temperatures on β-glucan quality in oat grains. Grains of oats (Avena sativa, L.), cultivar Albasul, harvested at harvest moisture content of 23% were submitted to stationary drying at air temperatures of 25, 50, 75, and 100 oC until they reached 13% moisture content. The β-glucan content was determined in samples of oat grains and extraction was performed using water as solvent at 90 oC. The β-glucan extract was evaluated for water holding capacity, water retention capacity, capacity of displacement, and gelation properties. Stationary of oat grains at air temperatures above 25 oC decreased the water holding capacity, whereas the content of β-glucan and the water retention capacity of β-glucan extract was affected at temperatures above 50 oC. Physical changes such as increased gelation capacity of the β-glucan extract occurred following drying at air temperature over 75 oC.

Umidade de colheita, métodos de secagem e tempo de armazenamento na qualidade tecnológica de grãos de trigo (cv. 'Embrapa 16')

The objective of this research was to study the harvest moisture and drying method systems as a function to storage period on the conservability and technological quality of wheat. Grains of wheat (Triticum aestivum L), cultivar ‘Embrapa 16’, produced in the Granja Bretanhas, in Jaguarao, RS, agricultural harvest of 1997/1998 were harvested dry in the plant (14% of moisture), with 16 and 18% of moisture. The samples harvested with moisture of 16 and 18% were submitted to artificial drying by intermittent method, with air at 70°C, stationary, with air at 45°C; and stationary, at room temperature. The grains were stored in a conventional system, during 12 months, with the realization of evaluations at 4 month intervals. Wheat grains harvested dry shown inferior technological quality and conservability in storage as compared to harvested with moisture above 14% and dry at artificial dryer.

Parâmetros operacionais na secagem intermitente de grãos de aveia branca cultivar UPFA 20 Teixeirinha

Objetivou-se, no trabalho, avaliar o desempenho energetico no processo de secagem intermitente de graos de aveia branca, realizado em diferentes temperaturas do ar e umidade final. Graos de aveia branca (Avena sativa L.) da cultivar UPFA 20 Teixeirinha, produzidos no Campo Experimental da Palma da UFPel, safra agricola de 2003/2004 foram submetidos a secagem intermitente, em tres temperaturas (60, 85, 110 oC) na relacao de intermitencia de 1:6 ate a umidade final de 11, 13 e 15%, em delineamento experimental inteiramente casualizado. A secagem foi realizada em secador piloto, de câmara cilindrica e fundo conico centrado. A taxa de secagem foi calculada pela variacao horaria do grau de umidade da massa de graos e a eficiencia energetica pela relacao entre a energia consumida para o aquecimento do ar e a variacao do grau de umidade da massa de graos. A temperatura do ar de secagem e as umidades inicial e final dos graos sao fatores determinantes para estimar o consumo energetico e a taxa de secagem de graos de aveia branca a qual aumenta com a elevacao da temperatura do ar de entrada no secador intermitente. A temperatura do ar na entrada do secador, umidade final e inicial dos graos sao fatores que influenciam no tempo de secagem intermitente de aveia branca.

Effects of moisture and temperature during grain storage on the functional properties and isoflavone profile of soy protein concentrate

The objective of this study was evaluate the effects of moisture and temperature during grain storage on the functional properties and isoflavone profile of soy protein concentrate. The protein concentrate was extracted from soybeans on the first day of storage and after 12months of storage, at 12 and 15% moisture and at temperatures of 11, 18, 25, and 32°C. The protein concentrate obtained from grains stored at 32°C showed decreased extraction yield (51.6% with 15% of moisture) and protein solubility (24.8% with 15% of moisture) with increased emulsifying capacity (52.2% with 12% of moisture) and foam formation, compared with sample obtained at the start of the storage period. The isoflavone profile showed a decrease in the concentrations of glycosylated, malonyl, and acetyl isoflavones and a corresponding increase in the concentrations of aglycone isoflavones, with the magnitude of these changes increasing with increasing storage temperature and moisture content.

Cooking quality properties and free and bound phenolics content of brown, black, and red rice grains stored at different temperatures for six months

The changes in cooking quality and phenolic composition of whole black and red rice grains stored during six months at different temperatures were evaluated. Brown rice with known cooking quality properties and low phenolic levels was used for purposes comparison. All rice genotypes were stored at 13% moisture content at temperatures of 16, 24, 32, and 40°C. Cooking time, hardness, free and bound phenolics, anthocyanins, proanthocyanidins, and free radical scavenging capacity were analysed. The traditional rice with brown pericarp exhibited an increase in cooking time and free phenolics content, while rice with black pericarp exhibited a reduction in cooking time after six months of storage at the highest studied temperature of 40°C. There as increases in ferulic acid levels occurred as a function of storage temperature. Red pericarp rice grains showed decreased antioxidant capacity against ABTS radical for the soluble phenolic fraction with increased time and storage temperature.