Effects of repeated deep-frying on fatty acid profiles of potato fries and frying oils: soybean oil, canola oil and their 1:1 blend

@#Introduction: This study looked at the fatty acid composition changes in potato fries fried in three different types of oils, namely soybean oil (SO), canola oil (CO), and a 1:1 blend of soybean oil and canola oil (SCO), throughout an intermittent frying process of 80 batches in five consecutive days. The study also examined the fatty acid composition changes in SO, CO and SCO during the frying process. Methods: Fat from potato fries (extracted by Soxtec system) and oil samples from the corresponding frying oil were analysed by gas chromatography-mass spectrometer (GC-MS) to examine the fatty acid profile changes during the deep-frying process. Results: Linoleic acid (LA) and a-linolenic acid (ALA) in all three oils decreased, while oleic acid (C18:1), stearic acid (C18:0), palmitic acid (C16:0) and octanoic acid (C8:0) increased. Formation of C18:1 trans fatty acid was observed as the frying time increased. The fatty acid composition of the potato fries was consistent with the fatty acid composition of the corresponding frying oils. Conclusion: Our results showed that blending soybean oil and canola oil did not significantly improve the frying stability of the resulting oil in terms of fatty acid profile. Due to the formation of trans fatty acids and the decrease in polyunsaturated fatty acids, our study also recommends not to use the same frying oil repeatedly and not to consume food products cooked in reused oil.

Oxidative stability of crude palm oil after deep frying akara (Fried Bean Paste)

Abstract For this study 47 samples of crude palm oil (CPO) were collected, consisted of what had been used for 4 hours around the city of Salvador-Bahia. To evaluate the quality of CPO were analyzed: Total Polar Compound (TPC; %) by Adsorption Chromatography (AC), Testo 270 and Fricheck; Free fatty acids (FFA; % oleic acid), Color (CIELab); Total Carotenoids (TC; ppm), induction time (IT, h) and fatty acids composition (g 100 g-1). The TPC analysis by Testo 270 and Fricheck showed a poor linear correlation with AC (0.69 and 0.60 respectively). Otherwise 44.70% and 36.95% of samples were completely oxidized, according to CA and IT methods. All samples presented TC (11.01-331.45 ppm) and yellow color predominance. Trans fatty acids, C18:1t in 17.02% and C18:3t in 65.65% of the samples were identified. The results demonstrate the need in the deep frying control, respect to techniques used during process. As well the improvement of the quality of palm oil fresh, can minimize the degradation process during th deep frying.

Effect of process variables in the production of fried green plantain in vacuum / Efecto de las variables de proceso en la obtención de plátano verde frito en condiciones de vacío

Background: This article technology deep frying green plantain was evaluated. Objectives: To optimize the process of deep frying in the production of green banana slices and set the association in terms of the quality parameter: texture; from the point of sensory and instrumental view. Methods: Was used as a raw material banana green maturity, variety (Dominico Harton) and a mixture of refined vegetable oils from soybeans and palm olein with antioxidant (TBHQ). For the evaluation of the process we worked with various pressure ranges, driving force (∆T) and time; selecting maximum and minimum for these process variables (10-79kPa) values (13-113°C) and (57-663s) respectively. For the analysis of the response variables (moisture content, fat content and texture "hardness") officially sanctioned AOAC methods and protocols in the case of the texture were used. Looking for the best frying conditions, an analysis of response surface optimization process was performed. Results: saddle points were obtained on optimization analysis of the three response variables. A higher time of 550s and between 40 and 80°C, and times 200 to 500s and ∆T 80 to 100°C, zones of influence of moisture content with a value of 0.25% occurred. For the fat content was observed that values below about 20°C and 200s of time and pressures greater than 55kPa, begin to generate relatively low values. Regarding the hardness, treatments 7 and 11 were the most accepted sensorially. Conclusions: The moisture content did not depend on the pressure variable in the process, only the driving force and time altered the outcome of this variable. Considering the sensory evaluation, it was concluded that the desired value for the moisture content was 0.25%, to the fat content values were between 31 and 36%, and hardness between 6.4 and 9.2N.

Antecedentes: En este artículo se evalúo la tecnología de fritura por inmersión en plátano verde. Objetivos: Optimizar el proceso de la fritura por inmersión en la producción de rodajas de plátano verde y establecer la asociación existente en cuanto al parámetro de calidad: textura; desde el punto de vista sensorial e instrumental. Métodos: Se empleó como materia prima plátano en estado de madurez verde, variedad (Dominico Hartón) y una mezcla de aceites vegetales refinados de soya y oleína de palma con antioxidante (TBHQ). Para la evaluación del proceso se trabajó con varios rangos de presión, fuerza im pulsora (∆T) y tiempo; seleccionando unos valores máximos y mínimos para estas variables de proceso (10-79kPa), (13-113ºC) y (57-663s) respectivamente. Para el análisis de las variables de respuesta (contenido de humedad, contenido de grasa y textura "dureza") se utilizaron métodos oficiales de la AOAC y protocolos en el caso de la textura. En busca de las mejores condiciones de fritura, se realizó un análisis de superficie de respuesta para la optimización del proceso. Resultados: Se obtuvieron puntos de silla en el análisis de optimización de las tres variables de respuesta. A tiempos superiores de 550s y ∆T entre 40 y 80°C, y a tiempos entre 200 y 500s y ∆T entre 80 y 100°C, se presentaron zonas de incidencia del contenido de humedad con un valor del 0.25%. Para el contenido de grasa se observó que a valores por debajo de aproximadamente 20°C de ∆T y 200s de tiempo y presiones mayores a 55kPa, se empiezan a generar valores relativamente bajos. En cuanto a la dureza, los tratamientos 7 y 11 fueron los más aceptados sensorialmente. Conclusiones: El contenido de humedad no dependió de la variable presión en el proceso, sólo la fuerza impulsora y el tiempo alteraron el resultado de esta variable. Teniendo en cuenta la evaluación sensorial, se concluyó que el valor deseable para el contenido de humedad fue de 0.25%, para el contenido de grasa los valores estuvieron entre 31 y 36%, y para la dureza entre 6.4 y 9.2 N.

Deep-fried Keropok Lekors Increase Oxidative Instability in Cooking Oils

Background: This study was performed to compare the oxidative quality of repeatedly heated palm and soybean oils, which were used to fry keropok lekors and potato chips. Method: A kilogramme of keropok lekors or potato chips was fried in 2.5 L of palm or soybean oil at 180 °C for 10 minutes. The frying process was repeated once and four times to obtain twice-heated and five-times-heated oils. The peroxide value and fatty acid composition of the oils were measured. Results: Frequent heating significantly increased the peroxide values in both oils, with the five-times-heated oils having the highest peroxide values [five-times-heated palm: 14.26 ± 0.41 and 11.29 ± 0.58 meq/kg vs fresh: 2.13 ± 0.00, F (3,12) = 346.80, P < 0.001; five-times-heated soybean: 16.95 ± 0.39 and 12.90 ± 0.21 meq/kg vs fresh: 2.53 ± 0.00 oils, F (3,12) = 1755, P < 0.001, when used to fry keropok lekors and potato chips, respectively]. Overall, both oils showed significantly higher peroxide values when keropok lekors were fried in them compared with when potato chips were fried. In general, the heated soybean oil had significantly higher peroxide values than the heated palm oil. Fatty acid composition in the oils remained mostly unaltered by the heating frequency. Conclusion: Keropok lekors, when used as the frying material, increased the peroxide values of the palm and soybean oils. Fatty acid composition was not much affected by the frequency of frying or the fried item used.

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.

La fritura de los alimentos: el aceite de fritura: [revisión] / Deep frying: [review]

Durante el proceso de fritura todos los aceites, sin importar la fuente, presentan cambios en el contenido de nutrientes que pueden generar compuestos tóxicos que pasan al alimento. Las transformaciones se presentan de manera lenta o rápida, según el manejo durante el proceso de cocción, de las cuales las más críticas son: la temperatura; el tipo de alimento a freír, la relación aceite/alimento, el material de fabricación del equipo utilizado, la adición de aceite nuevo como reposición del que se pierde por el proceso; la limpieza y el almacenamiento del aceite. Este artículo de revisión proporciona un marco de las investigaciones que evalúan el uso de los aceite de fritura como medio de cocción, las prácticas de manejo y los efectos del proceso sobre la composición de los ácidos grasos, tocoferoles, carotenoides y polifenoles, los indicadores de calidad y las formas rápidas para determinarlos, mejorando la evidencia con relación a la calidad de los aceites de fritura.

The oil changes during deep-frying independent of kind. The change can be reduction of nutrients or formation of toxic component that through to food and then can be consumption. The transformation can be slow or fast depend of care during cooking, of parameter like as the control of temperature, kind of food, relation oil: food, equipment, addition of new oil as reposition, clean of oil and storage, something else. To know that the polar components and the monomer and polymers of cyclic acid fatty are the parameters internationals of quality and how can be identificated easy and quietly, it’s important because when an oil for deep-frying is no good it won’t be used and this way prevent risk for health of people like fried food.