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 da qualidade de óleos e gorduras de fritura em bares, restaurantes e lanchonetes / Assessment of used frying oils and fats in bars, restaurants and snack bars

Com o objetivo de avaliar a qualidade de óleos e/ou gorduras utilizados para fritura por imersão em bares, restaurantes e lanchonetes, foram coletadas 180 amostras de óleo e/ou gordura, sendo 90 antes e 90 após fritura. Aplicou-se um questionário para avaliar as técnicas de fritura e a infra estrutura dos estabelecimentos. Foram realizados os métodos analíticos para avaliar a alteração dos óleos e gorduras a saber, compostos polares totais (%), acidez (mgKOH/g) e índice de peróxido (mEq/kg). Das 90 amostras coletadas antes da fritura, 18,18 % demonstraram valores de compostos polares superiores ao limite estabelecido (5%), predominantemente nas amostras coletadas de lanchonetes. Quanto aos compostos polares totais, acidez e índice de peróxidos para óleos e gordura de fritura, 7,78%, 12,22 % e 2,22 % das amostras, respectivamente, apresentaram valores acima dos limites estabelecidos para efetuar o descarte. A avaliação das técnicas de fritura demonstrou dados insatisfatórios, tais como falta de controle da temperatura, tipo de óleo e equipamentos empregados. Os resultados obtidos indicam a necessidade de ações educativas no setor, assim como efetiva fiscalização por parte dos órgãos competentes.

Aiming at assessing the quality of oils and fats employed for frying food in bars, restaurants and snack bars, 180 samples were analyzed, from which 90 were collected before use and 90 after the frying process. A questionnaire was used in order to collect information on food frying procedures and on the respective food-serving places infrastructure. The analysis on alterations in oil and fat samples was performed by using the following analytical methods: total polar compounds (%), free fatty acid (mg KOH/g) and peroxide index (meq/kg). Among the 90 samples collectedbefore the frying procedure, 18.18% showed higher values of polar compounds over the established limit (5%), predominantly in samples collected from snack bars. In 7.78%, 12.22% and 2.22% of the analyzed frying oil and fat samples, the total polar compounds, free fatty acids and peroxide indices, respectively, were in a higher rate than those limit values established for discarding them. The inadequacy on the employed frying procedure was observed as this process was performed without control over the frying temperature, type of oil, and employed equipment.These findings indicate that the food-service locations require close surveillance supervisions.