Figure 3- Peak melting temperature (oC) of mixtures of fractionated pequi oil and fractionated Kpangnan butter at different proportions (w/w) after static crystallization in 4, 12, and 60 days of storage at room temperature (22oC)
Molecular composition and phase behavior
The TAG composition of fractionated pequi oil mixed with fractionated Kpangnan butter (w/w) is shown in Table 5. The main TAGs in 100% dry fractionated pequi oil were POP (37%) and POO (21%), while SOS (90%) was the major TAG in 100% solvent fractionated Kpangnan butter. Multi-step solvent fractionation was more efficient for increasing the amount of symmetrical TAG (SOS) in fractionated Kpangnan butter (increasing from 52% before fractionation to 90% after fractionation). In contrast, the single-step dry fractionation of pequi oil at 20oC only resulted in an increase in the amount of POP from 33.7% to 36.7% but did significantly decrease POO content from 38.7% to 21.9%.
The amount of POS (the main TAG in cocoa butter) in all fractionated pequi oil-fractionated Kpangnan butter mixtures remained constant (~ 5%). While SOS was the main TAG in mixtures containing 10% to 70% fractionated pequi oil, POP was the major symmetrical TAG for the rest of the mixtures (80% and 90%). van Malssen, Peschar, Brito & Schenk (1996) showed that symmetrical mono-unsaturated triacylglycerols (POP, POS, and SOS) comprised 70% to 88% of total TAGs present in cocoa butter. In our study, we found the total amount of symmetrical TAGs only in fractionated blends containing 10% to 60% (w/w) fractionated pequi oil was in the range of total symmetrical TAGs of cocoa butter. The high melting point of binary blends containing 10% to 60% (w/w) fractionated pequi oilcan be explained by the high amount of SOS in these mixtures (84% to 43%, respectively). These mixtures have a great potential to be categorized as cocoa butter improvers (CBIs). Cocoa butter mixed with CBIs had better heat resistance and bloom development properties at temperatures higher than ambient temperature (Lipp and Anklam,1998); Timms, 2003). For the binary mixtures containing 70% to 100% fractionated pequi oil, the high amount of low melting TAGs (OOO, POO, and SOO) resulted in a lower melting point at all storage times (4, 12, and 60 days).
Timms (2003) reported a blend of solvent fractionated palm oil and illipe butter was successfully used to produce cocoa butter equivalent (CBE). For the past 75 years, commercial CBEs in the market continue to be made in the same way, namely by blending palm mid-fraction (PMF) as a source of POP, with a high SOS fat such as shea butter, shea stearin, sal fat, or kokum butter (De Clercq, Kadivar, Van de Walle, De Pelsmaeker, Ghellynck & Dewettinck, 2017).
Table 5- The main triacylglycerol composition of fractionated pequi oil (FPO) and fractionated Kpangnan butter (FKB) and their mixtures (%)