Efecto de cocción en horno convencional y microondas sobre rancidez, pérdida por cocción y diferencia sensorial de hamburguesas / Effect of conventional oven versus microwave cooking on rancidity, cooking loss and sensory difference of hamburger patties

El uso de microondas está muy extendido a nivel doméstico gracias a su rapidez y facilidad de uso. El objetivo del presente trabajo es comparar el efecto de cocción de hamburguesas de distintos tipos de carne, en microondas y en horno convencional, sobre la pérdida de peso y estabilidad oxidativa. Además, determinar si existen diferencias desde el punto de vista sensorial aplicando una prueba triangular, comparando 2 productos presentados en tríos, uno que corresponde a hamburguesa cocida en microondas y otro a hamburguesa cocida en horno convencional. Se adquirieron hamburguesas de pollo, pavo, cerdo y vacuno en el comercio, se cocinaron en horno convencional y en microondas. Se calculó pérdida por cocción, se evaluó la rancidez y diferencias sensoriales entre hamburguesas del mismo tipo de carne, cocidas en distinto tipo de horno. La pérdida por cocción fue menor en hamburguesas cocidas en microondas. La acidez e índice de peróxido aumentaron en las muestras cocidas en ambos tipos de hornos respecto a hamburguesas crudas. La acidez fue mayor en hamburguesas cocidas en horno convencional, y el índice de peróxido fue mayor en hamburguesas cocidas en microondas, llegando a 10,6 meq O2/kg. En el análisis sensorial se encontraron diferencias significativas (p<0,05) entre las hamburguesas cocidas en horno convencional y en microondas. Resulta mejor opción cocinar hamburguesas en horno convencional, ya que el índice de peróxidos es menor que al cocinar en microondas; dentro del tipo de hamburguesas, son más estables las de vacuno y cerdo frente a la oxidación.

The use of microwaves is very widespread at the domestic level thanks to its speed and ease of use. The aim of this study was to compare cooking loss, rancidity and sensory differences for hamburger patties cooked in conventional versus microwave ovens. We also determined sensorial differences with the triangular test, comparing two products presented in threesomes, one that corresponded to a patty cooked in the microwave and the other in a conventional oven. Chicken, turkey, pork and beef patties were purchased commercially, cooked in a conventional oven and in microwaves. Cooking loss was calculated, rancidity and sensory differences were evaluated between patties of the same type of meat and cooked in the different oven types. Cooking loss was lower in patties cooked in microwaves compared to those cooked in conventional ovens. For both oven types, acidity and peroxide index increased with respect to raw ones. Acidity was higher in hamburgers cooked in conventional ovens and the peroxide index was higher in burgers cooked in microwaves, reaching 10.6 meq O2/kg. In sensory analysis, significant differences were found (p<0.05) between patties cooked in a conventional oven and in microwaves. It is a better option to cook patties in a conventional oven, because the peroxide index is smaller than in microwaves; and within types of patties, beef and pork are more stable against oxidation.

Avaliação das características físico-químicas de óleo de café torrado (Coffea arabica) durante armazenamento em diferentes temperaturas / Evaluation of physico-chemical characteristics of roasted coffee oil (Coffea arabica) stored at different temperatures

O óleo extraído de café torrado é um produto de altíssimo valor agregado, uma vez que seu valor de mercado é muito superior que a matéria-prima principal, o café. Desse modo, o objetivo deste trabalho foi avaliar as características físico-químicas do óleo de café torrado (Coffea arabica) armazenados sob refrigeração e temperatura ambiente por um período de 12 meses. A acidez não apresentou grande variação devido à degradação da lipase durante o processo de torra dos grãos de café, o índice de peróxidos apresentou um resultado crescente durante o armazenamento, porém, mantendo-se dentro do limite estabelecido pela legislação atual (máximo 15 mEq kg-1). Durante o período de um ano, o óleo de café apresentou qualidade de utilização de acordo com a legislação vigente, independente das condições de armazenamento (6 °C ± 2 °C e 25 °C ± 2 °C).

Avaliação do estado oxidação dos óleos de abacate, azeite e arroz / Oxidation state evaluation of the avocado, olive and rice oils

O estado de oxidação é um importante aspecto relacionado à qualidade nutricional e sensorial dos óleos vegetais, que pode limitar a utilização dos mesmos. Assim, objetivou-se com este estudo avaliar o estado oxidação de óleo de abacate produzido nacionalmente, comparativamente a azeite de oliva extra virgem e a óleo de arroz refinado. Avaliaram-se nos produtos os índices de peróxidos, p-anisidina e coeficiente de extinção específica (K232 e K270). Os resultados indicaram que, de um modo geral, as amostras lipídicas mostravam bom estado de conservação, tanto em relação a produtos primários quanto secundários de oxidação. Entretanto, com base na legislação para azeite de oliva, pode-se inferir que o óleo de arroz apresentava elevado valor para produtos de oxidação secundários, expressos pelo K270. O óleo de abacate mostrou os mais baixos valores em todas as determinações realizadas, portanto, indicando estar em ótimo estado de conservação em relação à presença de produtos de oxidação.

Antioxidant effect of 4-nerolidylcatechol and -tocopherol in erythrocyte ghost membranes and phospholipid bilayers

4-Nerolidylcatechol (4-NC) is found in Pothomorphe umbellata root extracts and is reported to have a topical protective effect against UVB radiation-induced skin damage, toxicity in melanoma cell lines, and antimalarial activity. We report a comparative study of the antioxidant activity of 4-NC and α-tocopherol against lipid peroxidation initiated by two free radical-generating systems: 2,2′-azobis(2-aminopropane) hydrochloride (AAPH) and FeSO4/H2O2, in red blood cell ghost membranes and in egg phosphatidylcholine (PC) vesicles. Lipid peroxidation was monitored by membrane fluidity changes assessed by electron paramagnetic resonance spectroscopy of a spin-labeled lipid and by the formation of thiobarbituric acid-reactive substances. When lipoperoxidation was initiated by the hydroxyl radical in erythrocyte ghost membranes, both 4-NC and α-tocopherol acted in a very efficient manner. However, lower activities were observed when lipoperoxidation was initiated by the peroxyl radical; and, in this case, the protective effect of α-tocopherol was lower than that of 4-NC. In egg PC vesicles, malondialdehyde formation indicated that 4-NC was effective against lipoperoxidation initiated by both AAPH and FeSO4/H2O2, whereas α-tocopherol was less efficient in protecting against lipoperoxidation by AAPH, and behaved as a pro-oxidant for FeSO4/H2O2. The DPPH (2,2-diphenyl-1-picrylhydrazyl) free-radical assay indicated that two free radicals were scavenged per 4-NC molecule, and one free radical was scavenged per α-tocopherol molecule. These data provide new insights into the antioxidant capacity of 4-NC, which may have therapeutic applications for formulations designed to protect the skin from sunlight irradiation.

Study of hepatocellular function in the murine model following hepatic artery selective clamping

PURPOSE: To investigate the impact of selective hepatic artery clamping (SHAC) in hepatocellular function. METHODS: Three groups of Wistar male rats were subjected to SHAC ischemia period of 60min: Group A continuous SHAC were subjected to SHAC ischemia period of 60min, Group B intermittent SHAC of 30min with 5min of reperfusion and Group C intermittent SHAC of 15min with 5min of reperfusion. Animals without SHAC were included-Group D. To evaluate hepatocellular function blood markers and hepatic extraction function (HEF) using 99mTc-mebrofenin were performed before and after surgery. Flow cytometry was used to analyze oxidative stress and cell viability. RESULTS: A mortality rate of 7.6% in Group A was observed. HEF maintained normal values between the groups. Flow cytometry demonstrated no significant differences between the groups in viability, type of cell death as well as in the production of reactive oxygen species. CONCLUSIONS: The selective hepatic artery clamping compared to other clamping techniques results on increased cell viability and decreased hepatocyte death. The SHAC is a potential alternative to decrease per-operative bleeding while maintaining hepatocellular function.

Análisis in vitro de la micro dureza del esmalte dental humano expuesto al peróxido carbamida y sometido a la acción del flureto / In vitro analysis of the micro hardness of human enamel exposed to carbamide peroxide under the action of flureto

Este estudio analizó la micro dureza del esmalte dental humano expuesto al agente blanqueador peróxido de carbamida a 16%, con posterior aplicación, o no, de fluoreto de sodio a 2%. La muestra fue constituida por 20 dientes humanos, terceros molares inclusos de los cuales fueron confeccionados 20 especímenes divididos en 2 grupos: Grupo A compuesto por 10 especímenes que fueron clareados, Grupo B compuesto por 10 especímenes clareados y sometidos a la aplicación de fluoreto. Fueron tomadas las medidas iniciales y finales de micro dureza para los dos grupos. Después del análisis estadístico, los resultados demostraron que, para el Grupo A, el agente blanqueador no presentó una reducción estadísticamente significativa (p < 0,05) en la micro dureza del esmalte dental, ya para el Grupo B, el uso de fluoreto de sodio a 2% restauró completamente la micro dureza del esmalte. Se concluye que la técnica de blanqueamiento vital mediato con peróxido de carbamida a 16% es un tratamiento recomendado, pues aunque altere la micro dureza del esmalte, esa pérdida es revertida probablemente debido al efecto tapón de la saliva y al uso de fluoretos pos blanqueamiento

This study analyzed the microhardness of the human dental enamel exposed the brighten agent 16% carbamide peroxide, with and without application of 2% sodium flouride. The sample was established by twenty human tooth, intact third molars from which have been obtained twenty fractions of enamel and were made the specimens, these have been divided in two groups : Group A - composed by 10 specimens which were only brighten, Group B - composed by ten specimens brighten and submitted on the application of flouride. After the initial results of microhardness of the dental enamel, were made the final measures of microhardness from the specimens from the Groups A and B. After statistical analysis, the results demonstrating that to the Group A, the brighten agent it didn´t present a reduction significant estatistical (p < 0,05) on microhardness of the dental enamel, about the group B the use of 2% sodium flouride revamped entirely the microhardness of the enamel. We concluded that the technique of mediate vital bleaching with 16% carbamide peroxide is a recommended treatment, because even it affects the microhardness of the enamel, this waste is probably reverted due the tampon effect from saliva and the use of flouride after bleaching

Antioxidant isolated from Schisandra propinqua (Wall. ) Baill

Schisandra propinqua (Wall.) Baill.(Schisandraceae) is widely used as a Chinese folk medicine. In this study, activity-guided fractionation of the ethanol extract from the stem of Schisandra propinqua led to the isolation of four extracts. Subsequently, a neolignan 4,4-di(4-hydroxy-3-methoxyphenly)-2,3-dimethylbutanol was isolated from the EtOAc part of the stem of Schisandra propinqua, the free radical scavenging activities of which were researched in vitro. The present work demonstrated that extracts and pure compound possessed scavenging activities to DPPH, superoxide anions and hydroxy radical, and could depress lipid peroxidation reaction induced by oxygen radical produced by the Fe2+/cysteine system in vitro. This suggests that the traditional application of Schisandra propinqua in China may be related to its antioxidant activities, and the EtOAc part of the stems of Schisandra propinqua can be utilized as an effective source of antioxidants.

Specific concentration evaluation of 16 percent carbamide peroxide compounded at dispensing pharmacies

The aim of this work was to evaluate the concentration of carbamide peroxide compounded at different dispensing pharmacies. Immediate concentration analysis was made of bleaching gels dispensed by specialized pharmacies, and of a commercially available gel (control group) (n = 20). The carbamide peroxide concentration was determined by titration and the results were analyzed statistically by the Kruskal-Wallis test. The commercial bleaching agent (control group) and one of the gels from the pharmacies presented the best mean concentration values, close to 16 percent. In conclusion, the concentration of the manipulated and industrialized carbamide peroxide gels presented concentration values differing from 16 percent.

O objetivo deste trabalho foi avaliar a concentração do peróxido de carbamida manipulado em diferentes farmácias de manipulação. Foram utilizados géis clareadores manipulados em farmácias especializadas e um industrializado (grupo controle) (n = 20) com análise de concentração imediata. A concentração do peróxido de carbamida foi obtida por titulometria e os resultados foram submetidos a análise estatística pelo teste de Kruskal-Wallis. Como resultado, o agente clareador (controle) e um dos produtos manipulados em farmácia apresentaram as melhores médias de concentração, próximas a 16 por cento. Pode-se concluir que a concentração do peróxido de carbamida manipulado e dos industrializados apresentaram valores de concentração diferentes de 16 por cento.

Evaluación nutricional y almacenamiento acelerado a 37 degrees C de mezclas de frejol y maíz fritos / Nutritional evaluation and accelerated storage at 37 degrees C of fried bean and corn mixtures

Nutritive value of corn and beans is limited by the deficiency in some aminoacids; so, the combination of both of them might be very advantageous from a nutritional point of view. A research with the following purposes was done: to improve the biological value of corn and bean through the formulation of mixes of fried kernels; and, to know the shelf life of the mixes during an accelerated storage period. Fried kernels mixes, in a ratio of 50:50 per cent, from three varieties of bean (Pinto 114, Suave 85 and Tortola Inia) and dent yellow corn were made; protein value of the mixes was evaluated. Mixes were store at 37 degrees C during 15 days, determining every five days, their peroxides and moisture content and their water activity. All the mixes got values of NPR-Rel higher than 80 per cent; the best one was Suave 85/corn with a value of 88.2 per cent which indicates an improving of the protein quality. The stored products showed along the whole period, low values for peroxides (3.25-6.12 meq/kg oil) which might allow a shelf life of 90 days at room temperature; also, moisture content and water activity were low assuring microbial stability.

Screening of Brazilian plants for the presence of peroxides

Chloroform or dichloromethane extracts of 357 southern Brazilian plant species were tested for the presence of peroxides by thin-layer chromatography, using the spray reagent from Huber & Fröhlke. >From the species tested, 71 (20 por cento) showed positive results and most of them (56 por cento) are Asteraceae species. The species tested were mainly from Asteraceae, but 55 more families were screened, in a total of 77 genera surveyed...

Teores de acidez e peróxido em óleo de soja reutilizado em múltiplas frituras / Acidity and peroxide levels in soybean oil reused in multiple fritter

Foram analisados os teores de acidez (ácido oléico por cento) e peróxido (meq/Kg), em amostras de óleo de soja refinado reutilizado em múltiplas frituras (160 graus Celsius), no Restaurante do Hospital Universitário da UFPB, durante 35 dias. Quanto aos teores de acidez, verificou-se um aumento significativo de 0,20 a 1,86 e 0,20 a 1,75 por cento de ácido oléico ao final do 35( dia, para os óleos nao filtrado e filtrado respectivamente; em relaçao aos teores de peróxido observou-se um aumento de 2,13 a 6,76 até o 14( dia, caindo para 0,81 meq/Kg no 35( dia e 2,13 a 6,42 até o 14( dia, caindo para 1,22 meq/Kg no 35( dia do experimento, para o óleo nao filtrado e filtrado respectivamente. O estudo demonstrou um comportamento influenciado pela temperatura elevada, sugerindo a nao reutilizaçao do óleo por tempo prolongado.