Influence of pre-heating of food contact polypropylene cups on its physical structure and on the migration of additives

Laboratories unexpectedly carried out pre-heating of polypropylene beverage cups prior to performing a migration test in a proficiency test. Principal component analysis of the data collected showed that the preheating temperature of the cups contributed to an increased variance of the data and distinguishing pre-heating and non-pre-heating groups. This triggered to study the effect of applying such pre-heating on the physical structure of the material and on the migration of additives to food simulant D1 (ethanol 50% v/v). Several cups were pre-heated at selected temperatures and either analyzed with differential scanning calorimetry to establish the degree of crystallinity or used for the migration test. Six target additives from Regulation (EU) No 10/2011 were quantified in the food simulant using HPLC-FLD and LC–MS. Results show that pre-heating of the beverage cups led to a significant change in the degree of crystallinity, resulting in a change of analyte migration in comparison to the migration results from non-pre-heated cups.