3.4.2. Blends of fats and oils
In order to match the more adequate melting profile for product formulation, such as for margarine, modified butter, and cocoa replacers, fats with a high melting point can be blended with oils (Oliveira, Rodrigues, Bezerra, & Silva, 2017). Taking into account that MUFA, PUFA, and SFA are present in different ratios in Amazon crude fats and oils, particular FA profiles can be obtained with their blends.
Table S2 (Supplementary Material) shows the calculated FA compositions, atherogenicity, and thrombogenicity indexes for the blends prepared during the course of this study. As expected, addition of oils to the solid fats reduced AI and TI. Tucuma kernel oil, for instance, had its AI reduced from 14.31 to 7.97 with the addition of 10% patawa oil and to 1.89 at 50:50 ratio. Similar results were obtained for murumuru fat and pracaxi oil blends, in which AI/TI were reduced from 14.60/6.69 to 2.40/1.21 at 50:50 ratio blend. These results are quite important since the use of these blends in replacement of partially hydrogenated oils in formulations of spreads, shortenings or margarines, for example, might present not only technological advantages but also improved nutrition values.
Figures S1 to S3 (Supplementary Material) show melting curves of the blends. All blends showed multiple endothermic peaks related to the variety of TAGs in their compositions. The melting curve of tucuma kernel oil/patawa oil blend presented two main endothermic peaks in all ratios. The first probably corresponded to the melting of OOO and OOP fractions from patawa oil, and the second was probably related to the melting points of LLL, LLM, and MML fractions, the main saturated TAGs of tucuma kernel oil. As expected, the enthalpy of the first peak decreased as the content of patawa oil decreased. The murumuru fat/pracaxi oil blends at the ratios of 50:50 and 60:40 exhibited two main peaks. The first was related to the melting of OOBe fractions, found in pracaxi oil, and the second (around 30 °C) probably corresponded to the melting of TAG fractions rich in lauric and myristic acids from murumuru fat. Notably, at ratios from 70:30 to 90:10 only one main peak was found. This is probably due to the fact that the decreasing in pracaxi oil content decreased the melting enthalpy of fractions rich in unsaturated TAGs, promoting an overlapping of the two main peaks. This could be interesting if one desires a blend without phase separation considering storage conditions.
The melting behavior of Bacuri fat/Brazil nut oil blend was very close to the Bacuri fat melting profile. Indeed, one of the TAG fractions of bacuri fat is rich in oleic acid and presented melting temperatures very close those of Brazil nut oil fractions. However, when compared to Bacuri fat, the last melting peak of the blend was slightly decreased, especially at 50:50 ratio. This means that the fraction which melted around 53 °C in the pure bacuri fat sample, when blended with Brazil nut oil tended to melt around 46 °C. These results showed that one might decrease the melting temperature of bacuri fat and alter its melting profile by blending it to low melting TAGs, such as those observed in Brazil nut oil, broadening its range of industrial application.