Efeito do binômio Tempo/Temperatura sobre a fração lipídica de óleos vegetais submetidos a processos de fritura

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Studies show that the frying process causes changes in the physical and chemical aspects of oils which affect their chemical, sensorial and nutritional quality. This study aimed to evaluate the effect of the time/temperature pair on the lipid fraction of vegetable oils used in the frying process. Four Meal Production Units (MPU) were selected which served on average 1000 meals per day. Samples of the frying oils were collected from November 2006 to August 2007 every two days until the oil disposal. The study was carried out in a fully random design with six treatments (T0, T1, T2, T3, T4 and T5) and data was collected on the indices of acidity, peroxide and iodine according to the Analytical Norms of the Instituto Adolfo Lutz (BRASIL, 2005). On each treatment a sample was collected and analyses were carried out in triplicate, with 69 fractions of soy oil samples. Parameters studied included: 0.3g acidity in oleic acid /100g of oil, 10meq/kg of peroxide and 120% 143% iodine (Brasil, 1999). At the same time, a part of each oil sample was esterified to analyze lipid composition using gas chromatography (CG). The esterified samples were stored in amber flasks at -18C. Statistical analyses were carried out using SAS Enterprise Guide version 2.0. The significance level of 5% (P=0.05) was used in the analysis of variance (Proc GLM) to determine significant effect. As significant differences were found in each UPR a regression analysis was carried out using PROC REG. Those traits which did not show a significant regression were analyzed using the Tukey test (P=0.05). The treatments significantly influenced the physical-chemical characteristics of the frying oil samples collected in the UPRs and completing the oil in the fryer with virgin oil favored the maintenance of oil quality. The acidity index was the most appropriate indicator to evaluate the hydrolytic and oxidative stabilities of the samples studied. With reference to the effect of heat stress on the lipid fraction of the oils sampled, it was observed that the type and quantity of the food that was fried influenced the alterations in composition of saturated fatty acids, both monosaturated and poly saturated. Despite the tendency of saturated fatty acids levels to decline at the end of the treatments (T5) in the UPRs, it was noted that the curves varied between UPRs. During the frying process, linoleic and linolenic acids showed greatest changes and during the treatments only the linolelaidic fatty acid (C18:2t) showed an increase of up to 0.03%. It is recommended that the usage of oils for frying should be reduced to six (6) days, (T3), as well as monitor the frying process including: the nature of the food to fried, temperature (180C to 200C) and foods of animal and vegetable origins should be fried separately.

ASSUNTO(S)

ácidos graxos essenciais acidity index in frying oils essential fatty acids óleo de fritura frying oil lipid oxidation nutricao ácidos graxos oxidação lipídica índice de acidez em óleos de fritura fatty acids

ACESSO AO ARTIGO

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