Estudo do comportamento do oleo de girassol e do efeito do dimetil polisiloxano em termoxidação e frituras

AUTOR(ES)
DATA DE PUBLICAÇÃO

1996

RESUMO

Experiments were carried out in the absence of food to define the influence of significant variables of the frying process, Le., oi! unsaturation, temperature, surface-to-oi/ volume ratio, type of heating and dimethylpolysiloxane (DMPS) addition. Special emphasis was placed on clarifying the action of the addition of low concentrations of DMPS to frying oils. The analytical methods applied for direct evaluation of alteration included determination of polar compounds and quantification of minor glyceridic compounds. Additionally, induction time at 100°C and a-tocopherol levels were determined. The quantitative analyses were carried out by techniques as Gas Liquid Chromatography (GLC), combination of Adsorption and High Performance Size Exclusion Chromatography (CC/HPSEC), Thin Layer Chromatography (TLC) and High Performance Liquid Chromatography (HPLC). From statistical evaluation based on the content of polar compounds, the strong influence of the variables surface-to-oil volume ratio, DMPS addition and oil unsaturation was observed. However, changes due to 10°C difference in frying temperature were not significant. Analysis of two-way interactions demonstrated that interactions between type of heating/DMPS addition, type of heating/oil unsaturation, surface-to-oil volume ratio/DMPS addition and surface-to-oil volume ratio/oil unsaturation were significant, thus indicating the complexity of the frying process. It was also found that increase in specific groups of compounds formed through oxidative polymerization as well as loss of natural antioxidants mainly depended on the total content of polar compounds and, in a second level, on the oil unsaturation. Then, conventional and high oleíc sunflower oils were used to study the influence of DMPS (2 mg/kg) on discontinuous and simulated contínuous laboratory and industrial frying using potatoes as food. Results indicated that DMPS has a strong positive action in discontinuous frying since differences between samples with and without DMPS were very high and much more pronounced than those attributed to oil unsaturation. However, DMPS was not effective in simulated continuous and industrial frying.

ASSUNTO(S)

dimetil polisiloxano analise cromatografica fritura

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