Chocolate Chips in Cookies Do Not Bloom Fat migration appears to be the primary factor controlling bloom on chips baked in cookies.

Amelia Frazier; Rich W. Hartel University of Wisconsin –Madison

hocolate bloom is of major concern for these particles that are responsible for the Canyone who uses chocolate. Many fac- whitish appearance of untempered-choco- tors can cause chocolate bloom, including late bloom. Chocolate that is allowed to improper tempering, temperature cycling solidify without tempering will usually during storage and mixing of incompatible bloom within one to two days. fats. Tempering is the process of precrystal- This, surprisingly, does not appear to hap- pen in all cases. For example, bloom does lizing to seed the chocolate Amelia Frazier is with the proper number, size and polymor- not occur on chocolate chips baked in cook- currently pursuing a ies, even though they melt completely during phic form of seed crystals. Untempered master’s degree in baking. When the cookies are cooled, the food science at chocolate blooms rapidly because the cocoa chocolate chips solidify without tempering. UW – Madison butter crystallizes in uncontrollable fashion. Despite this, bloom is not a under Dr. Rich Har- Bloom on untempered chocolate occurs tel, studying fat common problem and is rarely observed on shortly after solidification. This is also true migration and ordinary chocolate chip cookies. for tempered chocolate that has been chocolate bloom. Our initial studies demonstrated that the exposed to temperatures high enough to fat content of cookie dough is directly related completely melt cocoa butter. Initially, cocoa to the amount of bloom that forms on choco- butter crystals will crystallize in an unsta- late chips after baking. The higher the fat ble form. These cocoa butter crystals rap- content of the cookie dough, the less bloom idly transform to the more stable βV and will form on the chocolate chip. At some βVI forms. This polymorphic transforma- level, which can vary somewhat depending tion results in a contraction effect of the on the type of fat used, bloom can be com- cocoa butter crystalline matrix. The shift- pletely inhibited. From these results, fat ing to a more compact cocoa butter struc- migration appears to be the primary factor ture produces cavities in which controlling bloom on chocolate chips baked and sugar particles become entrapped. It is in cookies, although there may be other ➤

The Manufacturing Confectioner • June 2010 69