Description
Author: Dr. Richard Hartel & Amelia Frazier
University of Wisconsin-Madison
PMCA GIA Recipient 2008-2009
It is somewhat surprising that chocolate chips baked in cookies do not exhibit bloom despite what seems to be sufficient heat to melt and break temper of the chocolate. We hypothesize that fat migration from the cookie dough into the molten chocolate chip during baking disrupts cocoa butter crystallization upon cooling and is responsible for this bloom inhibition. To test this hypothesis, both chocolate chip cookies and a sand– fat model system were baked with different types and levels of fat in the matrix. Bloom was evaluated 10 days after baking by image analysis of stereomicroscope images to quantify white areas on the flat bottom surface of oriented chips in sample cookies. All fats used in the dough, except cocoa butter, were shown to inhibit bloom when fat levels were sufficiently high. For palm oil and olive oil, a minimum degree of fat migration of about 16% was required to inhibit bloom. Below this critical level, bloom was observed on chocolate chips. A sand model system was also studied with palm oil. Since a higher level of fat migration was required to inhibit bloom for the sand model system than for cookies, other ingredients in the cookie dough must also play a role in bloom inhibition.
