The variation of acrylamide and 5-hydroxymethylfurfural in tea with different roasting degrees and the effects of tea polyphenols on their formation.

ABSTRACT

BACKGROUND: Roasting is an essential step in making roasted teas, and its role in producing flavors has been widely studied. However, the variation of potential hazardous compounds during the tea roasting process is still vague. The present study established an effective method based on liquid chromatography-triple quadrupole-tandem mass spectrometry to simultaneously determine the variation of acrylamide (AA), 5-hydroxymethylfurfural (5-HMF), and free amino acids during the tea roasting process. Meanwhile, the effects of several tea polyphenols on the formation of AA and 5-HMF were investigated by a wet-to-dry thermal model reaction. RESULTS: Medium-temperature roasted teas had the highest levels of AA and 5-HMF, with ranges of 0.13-0.15 µg g-1 and 68.72-123.98 µg g-1, respectively. Quantitative results showed that the levels of monosaccharides and amino acids decreased during roasting, which might contribute to the formation of 5-HMF and AA. Meanwhile, the decrease of epigallocatechin gallate (EGCG), epigallocatechin (EGC), and epicatechin (EC) might be related to their inhibitory effects on 5-HMF and AA. Thermal model reaction results showed that EGCG and EC significantly inhibited 5-HMF formation with a decline rate of 33.33% and 72.22%, respectively, mainly by trapping glucose. Gallic acid (GA) also had an inhibitory effect on the formation of AA (decreased by 92.86%) and 5-HMF (44.44%), mainly through impeding the preliminary reaction of asparagine and glucose. CONCLUSION: The roasting temperature determined the levels of AA and 5-HMF in teas. Catechins inhibited the formation of 5-HMF and AA mostly through trapping monosaccharides, while the inhibitory effect of GA was achieved by impeding the reaction. © 2024 Society of Chemical Industry.