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Search Results: 1 - 10 of 480848 matches for " LIRENY A. GUARALDO GON??ALVES "
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QUANTIFICA O DE TOCOFER “IS EM OL ‰OS DE MILHO, SOJA, CASTANHA-DO-PAR E CASTANHA DE CAJU POR CROMATOGRAFIA L QUIDA DE ALTA EFICI NCIA EM FASE REVERSA
JANICE RIBEIRO LIMA,LIRENY A. GUARALDO GON??ALVES
Alimentos e Nutri??o , 2009,
Abstract: RESUMO: Este trabalho foi realizado com o objetivo de se padronizar a t cnica da CLAE-FR, com detector de ultravioleta, para determinar tocofer 3is em alguns 3leos vegetais. Comparou-se a t cnica de inje § £o direta da amostra no cromat 3grafo ap 3s dilui § £o em hexano, e a t cnica de saponifica § £o para posterior extra § £o dos insaponific veis e inje § £o destes no cromat 3grafo. Os resultados mostraram que as etapas de saponifica § £o e extra § £o dos insaponific veis provocam perdas de 12% a 40% dos tocofer 3is nos 3leos testados (soja, milho, castanha-do-par e am andoa de castanha de caju). Comparou-se ainda a extra § £o a frio e a quente da fra § £o lip -dica de am andoas de castanha de caju. Constatou-se que a extra § £o a frio conserva melhor os tocofer 3is, enquanto a composi § £o em cidos graxos permanece a mesma nos 3leos obtidos pelos dois m todos de extra § £o. PALAVRAS-CHAVE: Tocoferol; CLAE; 3leo de soja; 3leo de milho; 3leo de castanha-do-par ; 3leo de castanha de caju.
COMPORTAMENTO DO óLEO DE GIRASSOL COM ALTO TEOR DE áCIDO OLéICO EM TERMOXIDA??O E FRITURA
JORGE, Neuza;GONALVES, Lireny Aparecida Guaraldo;
Ciência e Tecnologia de Alimentos , 1998, DOI: 10.1590/S0101-20611998000300015
Abstract: sunflower seed oils with different levels of oleic acid were investigated under temperature of frying conditions to evaluate their thermal and oxidative stability. the behavior of the oils was analysed on their contents of polar compounds, minor glyceridic compounds, triglyceride composition, induction time at 100oc and a -tocopherol levels. the results indicated lower polar compounds contents in high oleic sunflower oil than in normal sunflower oil. the results also showed an increase on total polar compounds mainly related on high molecular weight compounds, polymers, dimers and oxidized triglycerides monomers as thermal and oxidative reaction products. in contrast, the contents of diglycerides and free fatty acids, indicatives of the hydrolytic alteration, remain constant, once there was no moisture in the medium. the quantitative loss of the triglyceride composition was dependent on their insaturation degree and it was higher in triglycerides that contain two or three molecules of linoleic acid. the normal sunflower oil showed, in all experiments, a higher tendency to the polymerization, a higher degree of total alteration and a higher loss on its major triglycerides that on high oleic sunflower oil. in general, the results showed an excellent behavior of the high oleic sunflower oil related to the thermoxidation, independently of the heating type and to the discontinuous frying. such results demonstrated that its thermal and oxidative stability was related on its low content of polyunsaturated fatty acids and high contents of oleic acid and triolein.
COMPORTAMENTO DO óLEO DE GIRASSOL COM ALTO TEOR DE áCIDO OLéICO EM TERMOXIDA O E FRITURA
JORGE Neuza,GONALVES Lireny Aparecida Guaraldo
Ciência e Tecnologia de Alimentos , 1998,
Abstract: óleos de sementes de girassol com diferentes níveis de ácido oléico foram utilizados sob condi es de termoxida o e fritura para avaliar o comportamento do óleo de girassol com alto teor de ácido oléico quanto ao seu grau de insatura o quando comparado com o óleo de girassol convencional. Os métodos analíticos aplicados incluíram a determina o de compostos polares totais, quantifica o de compostos glicerídicos menores, quantifica o da composi o triglicerídica, período de indu o a 100oC e níveis de a -tocoferol. Os resultados para compostos polares totais apresentaram menores valores em óleo de girassol com alto teor de ácido oléico quando comparados com óleo de girassol convencional. Quanto à distribui o dos compostos glicerídicos menores, verificou-se, de modo geral, que o aumento dos compostos polares totais estava relacionado essencialmente aos compostos de maior peso molecular, isto é, polímeros, dímeros e triglicerídios oxidados, os quais s o representantes das altera es térmica e oxidativa. Já os diglicerídios e ácidos graxos, indicativos da altera o hidrolítica, permaneceram praticamente nos níveis originais; uma vez que a umidade n o se encontrava presente no meio. A perda quantitativa da composi o triglicerídica dependeu do grau de insatura o do triglicerídio, sendo mais elevada em triglicerídios que contêm duas ou três moléculas de ácido linoléico. Em todos os casos, o óleo de girassol convencional teve uma maior tendência à polimeriza o, um maior grau de altera o total e uma maior perda de triglicerídios majoritários que o óleo de girassol com alto teor de ácido oléico. Assim, dentre os óleos utilizados neste estudo, os resultados mostraram um excelente comportamento do óleo de girassol com alto teor de ácido oléico em rela o à termoxida o, independente do tipo de aquecimento e à fritura descontínua. Tais resultados demonstraram que sua resistência à altera o termoxidativa estava relacionada com seu baixo teor em ácidos graxos polinsaturados e alto teor em ácido oléico e trioleína.
Evaluation of the quality of pet foods using fast techniques and official methods
Osawa, Cibele Cristina;Gonalves, Lireny Aparecida Guaraldo;Ragazzi, Sidnei;
Ciência e Tecnologia de Alimentos , 2008, DOI: 10.1590/S0101-20612008000500034
Abstract: this paper was designed to evaluate the rancidity of 18 pet food samples using the diamed fats kits and official aocs methods for the quantification of free fatty acids, peroxide value and concentrations of malonaldehyde and alkenal in the lipid extracted. although expiration dates have passed, the samples presented good quality evidencing little oxidative rancidity. the results of this study suggest that the brazilian pet food market is replete with products of excellent quality due to the competitiveness of this market sector.
Otimiza??o da rea??o de interesterifica??o química do óleo de palma
Grimaldi, Renato;Gonalves, Lireny Aparecida Guaraldo;Ando, Marlene Yumi;
Química Nova , 2005, DOI: 10.1590/S0100-40422005000400015
Abstract: the brazilian market has been showing a growing concern with nutritional values of oil components of foods. chemical interesterification is a promising alternative to the current processes of modifying the consistency of oils. chemical interesterification of deodorized palm oil was studied on a laboratory scale. the best results were obtained with 0.4% meona and heating for 20 min at 100 °c. these conditions are based on the largest variation in triacylglycerols as compared to a control. the trisaturated values varied from 6.2 to 9.9%, showing that the consistency of the oil improved for it to be used in margarines, without the formation of trans isomers.
Titula??o potenciométrica aplicada na determina??o de ácidos graxos livres de óleos e gorduras comestíveis
Osawa, Cibele Cristina;Gonalves, Lireny Ap. Guaraldo;Ragazzi, Sidnei;
Química Nova , 2006, DOI: 10.1590/S0100-40422006000300031
Abstract: free fatty acids are a measure of evaluating fats and oils, submitted to abusive conditions, besides being a quality characteristic of edible vegetable oils. the official method of determination (aocs ca 5a-40, 2004) is based on titration, using phenolphthalein as an indicator. for crude and degummed oils, the titration end point is difficult to be observed due to the high level of pigments, resulting in dark solutions. in this case and others, such as self-life studies, in which sample quantities are limited, potentiometric titration may be a very good alternative.
Determination of melting point of vegetable oils and fats by differential scanning calorimetry (DSC) technique.
Nassu, Renata Tieko,Guaraldo Gonalves, Lireny Aparecida
Grasas y Aceites , 1999,
Abstract: Melting point of fats is used to characterize oils and fats and is related to their physical properties, such as hardness and thermal behaviour. The present work shows the utilization of DSC technique on the determination of melting point of fats. In a comparison with softening point (AOCS method Cc 3-25), DSC values were higher than those obtained by AOCS method. It has occurred due to the fact that values obtained by DSC technique were taken when the fat had melted completely. DSC was also useful for determining melting point of liquid oils, such as soybean and cottonseed ones. El punto de fusión de grasas es usado para caracterizar aceites y grasas, y está relacionado con sus propiedades físicas, tales como dureza y comportamiento térmico. El presente trabajo muestra la utilización de la técnica de Calorimetría Diferencial de Barrido (DSC) en la determinación del punto de fusión de grasas. En comparación con el punto de ablandamiento (AOCS método Cc 3-25), los valores de DSC fueron más altos que los obtenidos por los métodos de AOCS. Esto ha ocurrido debido al hecho que los valores obtenidos por la técnica de DSC fueron tomados cuando la grasa había fundido completamente. DSC fue también útil para determinar puntos de fusión de aceites líquidos, tales como los de soya y algodón.
Titula o potenciométrica aplicada na determina o de ácidos graxos livres de óleos e gorduras comestíveis
Osawa Cibele Cristina,Gonalves Lireny Ap. Guaraldo,Ragazzi Sidnei
Química Nova , 2006,
Abstract: Free fatty acids are a measure of evaluating fats and oils, submitted to abusive conditions, besides being a quality characteristic of edible vegetable oils. The official method of determination (AOCS Ca 5a-40, 2004) is based on titration, using phenolphthalein as an indicator. For crude and degummed oils, the titration end point is difficult to be observed due to the high level of pigments, resulting in dark solutions. In this case and others, such as self-life studies, in which sample quantities are limited, potentiometric titration may be a very good alternative.
Utiliza??o de diferentes culturas starter no processamento de embutido fermentado de carne de caprinos
Nassu, Renata Tieko;Gonalves, Lireny Aparecida Guaraldo;Beserra, Frederico José;
Ciência Rural , 2002, DOI: 10.1590/S0103-84782002000600021
Abstract: the effect of different starter cultures in the processing of goat meat fermented sausages was evaluated by using ph, water activity and lactic acid production besides sensory acceptance and safety of final products were determined. commercial starter cultures containing 1. staphylococcus xylosus and pediococcus pentosaceus; 2. a mixture (50:50) of two strains of pediococcus sp 3. lactobacillus farciminis, staphylococcus xylosus and staphylococcus carnosus were tested. during processing, fermented sausages containing the different starter cultures showed distinct behaviour in relation to ph, water activity and lactic acid production, although sensory acceptance did not present significative differences. the safety of products evaluated by calculation of hours-degree in obtaining the products indicated that all tested cultures resulted in safe products in relation to staphylococcus aureus growth. results showed that all tested cultures can be used for processing of goat meat fermented sausages.
Efeito do teor de gordura nas características químicas e sensoriais de embutido fermentado de carne de caprinos
Nassu, Renata Tieko;Gonalves, Lireny Aparecida Guaraldo;Beserra, Frederico José;
Pesquisa Agropecuária Brasileira , 2002, DOI: 10.1590/S0100-204X2002000800015
Abstract: the objective of this study was to verify the effect of the addition of different fat contents (5, 10 and 20%) in the processing, chemical characteristics and sensory acceptance of a goat meat fermented sausage. during processing, ph and water activity were measured. moisture, protein and fat contents were determined in final products, as well as sensory acceptance by hedonic scale. final average values of ph and water activity, which ranged from 5.07 to 5.14 and 0.897 to 0.923 respectively, showed no significant difference (p>0.05) among any of all treatments. there were no significant differences (p>0.05) for any of all measured sensory attributes. no different percentage of fat in manufacturing of goat meat fermented sausage significantly affected its processing and sensory acceptance. due to low fat content in goat meat, 10 to 20% of fat level were considered as the most adequate.
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