Effect Of Chlorogenic Acid On HMF Formation In Fructose-Sugar Reaction Model And The Underlying Mechanism

Hydroxymethylfurfural(HMF), identified as one of the main contaminants in heat-processing foods, aroused a extensive attention among the researchers. Accoring to investigation and statistics, there was a positive correlation between the concentration of chlorogenic acid in fresh fruit and HMF content in dried products. In this research, a model reaction system in low-temperature processing condition containing fructose and citric acid buffer solution was employed to test the effect of chlorogenic acid on formation of HMF and 3-deoxyglucosulose(3-DG). A RP-HPLC quantitative method for simultaneous determination of four α-dicarbonyls, including 3-DG, glyoxal(GO), methylglyoxal(MGO), and 2,3-butanedione(2,3-BD), was established. The main results were as follows: 1. Effect of chlorogenic acid on the formation of HMF in fructose-acid reaction systemsChlorogenic acid influenced the formation of HMF and 3-DG dependent on p H. When p H was kept at 2.80 and 3.70, the addition of chlorogenic acid inhibited the formation of HMF and 3-DG; the lower the p H value, the higher the inhibition rate. When p H was kept at 4.70 and 5.70, the addition of chlorogenic acid significantly increased the formation of HMF, but showed no significant effect 3-DG formation. After reaction at 90℃, p H 6.0 for 48 h, 2.14 times of HMF was produced when 42 mmol/m L of chlorogenic acid was added into the model reaction system. It can be concluded that, when p H was kept at 2.80 and 3.70, fructose inclined to form HMF by the pathway of fructofuranosyl cation.Chlorogenic acid may inhibit the transformation of fructose to 3-DG. While at 4.70 and 5.70, fructose inclined to form HMF through the pathway of 3-DG, and chlorogenic acid may promote the transformation of 3-DG to HMF. At both low and high p H conditions, chlorogenic acid plays its role mainly depending on the moiety of caffeic acid 2: Simultaneous determination of four α-dicarbonyls in foods by RP-HPLCFour species of α-dicarbonyl compounds were optimally reacted with phenylenediamine to form quinoxaline derivative at 60℃, p H 9.00 for 4h. The derivatives were separated on an Agilent column ZORBAX SB-Aq(4.6mm×250mm,5μm) using 0.1%acetic acid aqueous solution(A) and methanol(B) as mobile phase for the following stepwise gradient elution : 35~70%(B) in 0-35 min,70-35%(B)in 35-40 min,35-35%(B) in 40-50 min; the flow rate was 0.7 m L/min. The results showed that the four quinoxaline derivatives were well separated within 30 min.This method can meet the quantitative analysis because of its good reproducibility and accuracy confirmed by methodology. It is also well applied in the determination of four α-dicarbonyls in honey, vinegar, preserved fruit, and coffee.The content of 3-DG in honey and preserved fruit is far higher than that in vinegar. The content of 2,3-BD in vinegar is 8.53 times than that in the preserved fruits. The content of 3-DG, 2,3-BD in coffee and 2,3-BD in honey is below the limit of detection.