Dielectric Properties of Maillard Reaction Solutions Formed Between Different Amino Acids and Glucose Under Microwave Heating

Abstract

The dielectric properties of Maillard reaction solutions (MRSs) formed between 10 amino acids [glycine (Gly), proline (Pro), cysteine (Cys), glutamine (Gln), lysine (Lys), methionine (Met), histidine (His), arginine (Arg), tyrosine (Tyr), and tryptophan (Try)] and glucose heated for 0–5 min using microwave irradiation were studied in the frequency range of 300–3000 MHz at 25.0 ± 0.5 °C. The critical frequencies of the MRSs were in the range of 0.81–1.98 GHz and increased as the heating time increased, with the exception of the MRS formed between Gln and glucose. The color difference (ΔE) of the MRSs increased as the heating time increased; alkaline amino acids exhibited the most significant change, reaching a maximum ΔE of 12.63 compared to non-polar and neutral polar amino acids. The penetration depth of the MRSs formed between alkaline amino acids and glucose decreased at 915 and 2450 MHz upon increasing the isoelectric point (pI) (p < 0.05). However, the penetration depth of non-polar and neutral polar amino acids increased upon increasing pI (p < 0.05). Non-polar amino acids required the highest energy [20.0 (± 0.20) × 10−21 J], followed by neutral polar amino acids and alkaline amino acids [0.3 (± 0.01) × 10−21 J]. The less energy required during the Maillard reaction, the easier the reaction could start. Finally, the real and imaginary parts of the Debye model were used to calculate the dielectric constant and dielectric loss factor of the MRSs formed between the amino acids and glucose and were in good agreement with the experimental values.