Formation of Maillard reaction products in parenteral alimentation solutions

Terminal heat sterilization of glucose-amino acid solutions produces Maillard reaction products. Since deleterious effects are associated with the ingestion of these compounds, their presence in parenteral nutrition solutions should be avoided. We measured the extent of Maillard product formation in 25% glucose + 4.25% amino acid solutions (+/- added electrolytes) sterilized by membrane filtration. Maillard product formation increased with time and temperature of storage. In the absence of added electrolytes, the average loss of amino acids to Maillard products at 4 degrees after 1, 7 and 30 days storage was 0.35, 0.62, and 1.51%, respectively. Losses of 0.74, 1.07 and 2.88% were noted at 4 degrees in the presence of added electrolytes. The average loss of amino acids in mixtures stored for 1, 7 and 30 days at 25 degrees in the absence of electrolytes was 0.83, 2.99 and 4.63%, respectively, and 1.52, 3.36 and 7.43 in the presence of added electrolytes, Mixtures stored at 60 degrees for 24 hours without added electrolytes showed an average loss of 8.03% of amino acids, whereas an 11.5% loss was noted in the presence of added electrolytes. Proline and amino acids with hydrophobic side chains reacted more slowly than other amino acids, while tryptophan and amino acids with aliphatic hydroxy side chains reacted most rapidly. The addition of electrolytes increased the rate of Maillard product formation at all temperatures. The data indicated that 25% glucose + 4.25% amino acid solutions should be stored for only a minimal period of time, preferably at 4 degrees, prior to use.