Investigation of Maillard reaction involvement in the steam processing of Panax Notoginseng root
Purpose: To explore the possible mechanism of Maillard reaction (MR) involvement in the steam processing of Panax notoginseng (PN) root.
Methods: PN root was soaked in water for 24 h and then steamed at 100 °C using an autoclave for 1, 2, 3, 4, 5 and 6 h, respectively. Several indicators associated with MR during steam processing were measured. The pH and absorbance at 420 nm (A420) of samples were measured using a pH meter and an ultraviolet-visible spectrophotometer, respectively. The contents of 5-hydroxy-methyl-furfural (5-HMF) and sugars were determined by high performance liquid chromatography (HPLC) while amino acids were evaluated using an automatic amino acid analyzer.
Results: During PN root steam processing (0 - 6 h), pH value gradually decreased from 6.35 ± 0.02 to 5.88 ± 0.03 while A420 value gradually increased from 0.23 ± 0.01 to 0.44 ± 0.02. The levels of reducing sugars (maltose and glucose) and amino acids (aspartic acid, glutamate, cysteine, lysine and arginine) in PN root decreased after steaming for 6 h. However, the content of 5-HMF in PN root increased with increase in steaming time.
Conclusion: The results indicate that MR occurs during steam processing of PN root, and the reaction mechanism might be closely related to the reaction between the reducing sugars and amino acids.
Keywords: Panax notoginseng, Steaming, Reducing sugars, Amino acids, Maillard reaction