抄録
We earlier reported that glyceroglycolipid extracted from pumpkin significantly retarded the polymorphic transformation from Form V to VI of cocoa butter. We therefore investigated the effects of adding glyceroglycolipid on the fat bloom stability in dark and milk chocolates. Glycolipid fraction containing glyceroglycolipid was extracted with ethanol from pumpkin purée and partially purified on column chromatography. The apparent viscosity of dark and milk chocolates with the addition of the gained glycolipid fraction instead of lecithin significantly decreased up to 0.2% (w/w) according to a rotational viscometer at 45°C, and then decreased slightly at concentrations above that. The glycolipid fraction was then added to dark and milk chocolates up to 2% in place of lecithin. Each chocolate sample was evaluated for fat bloom resistance through two thermo-cycle tests given at an interval of 12 h between 30°C and 20°C, and between 32°C and 20°C. The accelerated tests indicated that the glycolipid fraction inhibited fat bloom compared to the control (0.4% lecithin). In dark and milk chocolates with the addition of 2.0% glycolipid fraction the polymorphic transformation from Form V to VI of cocoa butter was significantly retarded when measured by a differential scanning calorimeter. On the basis of these results, the quality of chocolate can be improved more effectively using the glycolipid fraction.
