State Diagrams of Binary Mixtures of Saturated Monoglycerides in Vegetable and Mineral Oil and their Impact in the Oleogels Rheology

Abstract

State diagrams of binary mixtures of 1-stearoyl glycerol (C18) with 1-myristoyl glycerol (C14), 1-palmitoyl glycerol (C16) or 1-monobehenin glycerol (C22) in vegetable and mineral oil were obtained using different molar fractions of the monoglycerides (MGs) keeping the MG concentration constant (8% wt/wt). We observed that, independent of the MG mixture (C18:C14, C18:C16, C18:C22) and the type of oil, the MGs developed a mixed Lα phase with a transition temperature practically independent of the C18 molar fraction. In contrast, the transition temperature for the sub-α phase showed a eutectic point that, for the same MG mixture, occurred in both oils at the same MG molar fraction. At the MG molar composition corresponding to the eutectic point, the difference in length between the aliphatic chains in the mixed lamella resulted in a sub-α phase with the least efficient chain packing compared to that developed by any other MG molar fraction. Independent of the MG mixture and the type of oil, the oleogels developed by cooling (80 °C to 5 °C) followed by 180 min at 5 °C achieved the highest elasticity (G’_5 °C) at the MG molar fraction composition associated with the eutectic point. Tentatively the least efficient aliphatic chains packing developed by the sub-α phase at the eutectic point, favored the incorporation and retention of higher amounts of oil. Thus, for a particular MG binary mixture, the oleogels at the eutectic point had the highest G’_5 °C in comparison with the G’_5 °C of oleogels formulated at any other MG proportion.