Pyrraline content in enteral formula processing and storage and model systems

Pyrraline, an advanced Maillard product, was used to evaluate heat damage from the manufacture and storage of enteral formulas and model systems. Two types of enteral formula, with the same components but different protein content, were analyzed untreated (mixture of ingredients) and after pre-sterilization, standardization, and in-bottle sterilization processing steps. The commercial formulas (in-bottle sterilization formulas) were stored at 30 degreesC for 36 weeks or 55 degreesC for 12 weeks. Model systems were prepared with similar ingredients to those used in formula manufacture (whey proteins and lactose or dextrinomaltose) and were heated at 120 degreesC for 30 min. In-bottle sterilization produced an increase in the pyrraline content of the formulas of 6.7 and 20.7%. Storage at 55 degreesC for 12 weeks produced increases in pyrraline content of 41 and 58%, and storage at 30 degreesC for 36 weeks produced increases of 44 and 52%. Pyrraline was not detected in model systems prepared with whey proteins, lactose, or dextrinomaltose when they were heated at 120 degreesC for 30 min. However, a significant increase in pyrraline content was observed after the heat treatment of commercial whey proteins.