Phase behavior of symmetrical monounsaturated triacylglycerols


Correspondence: Kevin W. Smith, Fat Science Consulting Ltd., 16 Arundel Drive, Bedford MK41 8HP, UK



The unique properties of cocoa butter (CB) are due to the fact that it is composed, for the most part, of just three TAGs, 1,3-dipalmitoyl-2-oleoylglycerol (POP), 1,3-distearoyl-2-oleoylglycerol (StOSt), and rac-1-palmitoyl-2-oleoyl-3-stearoylglycerol (POSt). In this study we have examined blends, at 10% intervals, across the ternary of these three TAG by stabilizing them during a lengthy temperature regime designed to induce the most stable polymorph at the point of melting. The liquidus observed is in good agreement with that predicted using the Hildebrand model. A eutectic is seen in each binary system, with a possible ternary eutectic present at about POP:POSt 1:1 and <10% StOSt. CB stabilized following the same regime exhibits solid fat contents much greater than those obtained following the standard IUPAC 2.150(b) stabilization, likely to be due to the presence of the βVI polymorph rather than the βV form.

Practical applications: The processing characteristics and final properties of fat based products depend greatly on the composition, crystallization, and melting properties of the fat or fats involved. In the case of chocolate and confectionery, this fat is CB. The present study confirms many of the relevant published phase diagrams and emphasizes the compositional areas having similar melting behavior to that of CB and, hence, suitable for cocoa butter equivalents.