Bloom on chocolate chips baked in cookies

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.

► Fat migration from cookie dough to chocolate chip is essential to prevent bloom. ► A minimum of about 16% fat migration is critical to prevent bloom in cookies. ► Temperatures in chocolate chips in cookies is sufficiently high to break temper. ► Different fats in cookie dough appear to have similar effect on bloom inhibition.