Effect of Sucrose Fatty Acid Ester on Fat Crystallization in O/W Emulsion
S. Arima1, T. Deguchi2, A. Ogawa1, H. Hondoh2, S. Ueno2
 1. Mitsubishi-kagaku Foods Co., Yokohama, Japan
2. Graduate School of Biosphere Sciences, Hiroshima University, Hiroshima, Japan

Fat crystallization in O/W emulsion is a key process in food production. For example, partial coalescence of emulsion which is occurred by fat crystallization makes air bubbles stable, forms smooth whipping cream.　By contrast partial coalescence sometimes leads to a destabilization of emulsion. Therefore, controlling of the fat crystallization in O/W emulsion is one of the most important subjects in emulsion food industry. We have already reported the sucrose palmitic acid polyester (P-170, Mitsubishi Kagaku Foods Co.) makes the emulsion with polyoxyethylene sorbitan monolaurate (Polysorbate 20) stable. However, it is not clear whether the effect of P-170 is dependent on the types of fatty acid chain of polysorbates or not. Hence the purpose of this study is to find out the effect of combination of P-170 and polysorbate 40, polysorbate 80 on the stability of the emulsion.
We used palm mid fraction as oil phase. The P-170 added to control fat crystallization in emulsion which was emulsified by polysorbate 40 and polysorbate 80. We performed gelation test and observed fat crystallization under polarized optical microscope. As a result, we found the functions of P-170 in the polysorbate O/W emulsion.
(i) emulsion stability with the polysorbate 40 was improved, while that with polysorbate 80 was not improved because of the partial coalescence, coalescence between oil droplets and  the occurrence of the phase transition from a to b’ polymorph. (ii) growth of the needle like crystals in polysorbate 40 emulsion was controlled, however those crystals were observed in polysorbate 80 emulsion.
From these results, we concluded that the functions of  P-170 was depended on the type of polysorbate. We propose the role of P-170 that P-170 retards partial coalescence and coalescence in the case of the emulsion emulsified by saturated fatty acid emulsifiers, on the other hand, P-170 promotes partial coalescence and coalescence in the emulsion with unsaturated fatty acid emulsifiers.