Molecules (Nov 2020)

Binary Phase Behavior of 1,3-Distearoyl-2-oleoyl-<i>sn</i>-glycerol (SOS) and Trilaurin (LLL)

  • Shinichi Yoshikawa,
  • Shimpei Watanabe,
  • Yoshinori Yamamoto,
  • Fumitoshi Kaneko

DOI
https://doi.org/10.3390/molecules25225313
Journal volume & issue
Vol. 25, no. 22
p. 5313

Abstract

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This paper reports the precise analysis of the eutectic mixing behavior of 1,3-distearoyl-2-oleoyl-sn-glycerol (SOS) and trilaurin (LLL), as a typical model case of the mixture of cocoa butter (CB) and cocoa butter substitute (CBS). SOS was mixed with LLL at several mass fractions of LLL (wLLL); the mixtures obtained were analyzed for polymorphic phase behavior using differential scanning calorimetry (DSC) and synchrotron radiation X-ray diffractometry (SR-XRD). In melt crystallization with constant-rate cooling, SOS and LLL formed eutectics in their metastable polymorphs, allowing the occurrence of a compatible solid solution at wLLL ≥ 0.925. With subsequent heating, the resultant crystals transformed toward more stable polymorphs, then melted in a eutectic manner. For mixtures aged at 25 °C after melt crystallization, eutectics were found in the extended wLLL region, even at wLLL = 0.975. These results indicate that phase separation between SOS and LLL progressed in their solid solution under stabilization. The crystal growth of the separated SOS fraction may cause fat-bloom formation in compound chocolate containing CB and CBS. To solve this problem, the development of retardation techniques against phase separation is expected.

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