Óleos e gorduras da Amazônia: produção de bases lipídicas especiais por interesterificação enzimática e predição das propriedades físicas

Abstract

The lipid modification methods can increase the potential application of the Amazonian oils and fats in the food industry. In addition, the determination of the physical properties, such as density and viscosity, are fundamental to promote the industrial application of blends of oils and fats. In this context, the first part of this study aimed to obtain blendsin different proportions of pracaxi oil/cupuaçu fat (PC) and pracaxi oil/palm stearin (PS) (% w/w) (40:60, 50 :50, 60:40 and 70:30) and use enzymatic interesterification to change their properties. Pure samples and blends, before (NIE) and after (IE) enzymatic interesterification, were characterized. Samples with the greatest potential for food applications (ratio of 70:30) were characterized by X-ray diffraction, optical microscopy and thermal analysis. The second part of this study aimed to measure the density and viscosity of passion fruit oil, pracaxi oil and palm stearin, as well as their respective binary blends(40:60, 50:50, 60:40 and 70:30), at different temperatures (303.15 to 363.15 K). And perform the fitting of experimental data to mathematical models available in the literature for the prediction of these properties. The results obtained in the first part of the study indicated that the blends with the highest proportion of pracaxi oil (70:30) had the lowest indices of atherogenicity (AI) (PC 0.21; PE 0.34) and thrombogenicity (IT) (PC 0.38; PE 0.55). The fats (cupuassu fat and palm stearin) showed good oxidative stability (> 3.0 h) and contributed to increase the stability and plasticity of the lipid bases obtained. Enzymatic interesterification increased the plastic range of PC blends and reduced the solid fat contente (SFC) of PS blends. Interesterification caused a reduction in the consistency of the blends, which shows the improvement in textural properties. The β crystalline form was reduced in the interesterified blends. The crystals found in the blends showed more stable polymorphic forms, while the interesterified blends showed a reduction in the β crystalline form and the presence of crystals in the α form, which is less stable. In relation to the experimental determination and data modeling of density and viscosity of blends of passion fruit oil, pracaxi oil and palm stearin, it was verified that the linear model used for the prediction of the density behavior presented excellent adjustment parameters, with R 2 values greater than 0.99 (0.9927 – 1.0) and low RMSE values (3.14x10-5 – 1.19x10-3) and χ 2 (1.77x10-9 – 2.56x10-6). For viscosity, the Andrade, modified Andrade and Arrhenius models were the ones that presented the best fits, with coefficients of determination (R2) greater than 0.99 (0.9939 – 0.9993), and low RMSE values (5.72x10-3 – 4.78x10- 2) and χ 2 (0.0001 – 0.0032). Based on the Arrhenius model, it was found that pracaxi oil had the highest activation energy (28.21 kJ/mol), contributing to the greater sensitivity to temperature variation of PS blends. The models that presented the best fit parameters can be reliably used to predict the behavior of the pure samples and blends studied, and thus can be used to model the operations involved in the processing of these vegetable oils and fats.