Determination and Prediction of Partition Coefficient Values (Kp) for Printing Ink Solvents on Cookie from the Kp of Each Cookie Ingredient

The partitioning behavior of five printing ink solvents was studied in cookie ingredients and cookies to examine migration behavior, and to determine if one could predict Kp of a cookie from summing the Kp of each ingredient multiplied by its weight factor in the cookie formula. Solvents were ethyl acetate, hexane, isopropanol, methyl ethyl ketone, and toluene. Gas chromatography was used to measure Kp values on each raw and baked ($260^{\circ}C$ for 10 min) cookie ingredients, and lab-made cookies. The baking process-decreases in water content in each sample generally affected Kp of polar solvents, but did not affect that of the non-polar solvents. Structural changes in cookie ingredients during the baking process also caused some change of migration behavior. While the prediction of Kp of lab-made cookies using the Kp of raw ingredients showed significant differences between calculated and experimentally found values, predictions with baked ingredients showed much smaller differences. This suggests that loss of water and changes of crystallinity in cookies and cookie ingredients due to the baking process are important and affect the Kp.