Elimination of Glycidyl Palmitate in Diolein by Treatment with Activated Bleaching Earth

In this study, activated bleaching earth (ABE) was used to eliminate glycidyl esters from both triacyl- and diacylglycerol oils. To investigate the mechanism, glycerol dioleate containing glycidyl palmitate (GP) was treated with ABE and the fate of the GP was monitored by analyzing the feed, treated, and ABE-absorbed oils using a gas-liquid chromatograph equipped with a flame-ionized detector. GP was completely removed from both the treated and absorbed oils. This indicates that this treatment is useful for GE removal from diacylglycerol oil, although it was not achieved by absorption of GE on ABE but rather by modification of GP. The results of composition analysis demonstrate that GP is transformed to glycerol monopalmitate, glycerol palmitate oleate, and glycerol dipalmitate at a recovery rate of 99.1 ± 1.3 %. An increase in glycerol monooleate and trace amounts of free glycerol and fatty acids were also observed after treatment. The transformation is proposed to involve a ring-opening reaction of GP with water contained in the ABE and in the bulk oil followed by an interesterification reaction among the resultant monopalmitate and the glycerol dioleate of the bulk oil. All the generated compounds were simple acylglycerols and glycerol. Therefore, ABE treatment could be useful for GE removal during the manufacture of edible oils.