UPLC-Q-TOF-MS/MS analysis on the chemical composition of malts under different germination cycles and prepared with different processing methods

Objective: To investigate changes in the chemical composition of malts under different germination cycles and prepared with different processing methods, thus providing a reference for the clinical application of malt in disease treatment. Methods: Nine malt samples were analyzed by ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS), and the MS fragmentation pathway of 4 compounds (including hordenine, gramine, N-methyltyramine and catechin) were also analyzed. Results: By database comparison and literature search, we detected 31 compounds in raw barley and 33 compounds in both raw malt and roasted malt. Nonetheless, the most of these 33 compounds were detected higher contents in raw malt than in roasted malt. Besides, we detected 15 compounds in brown malt. At Day1 of germination, 31 compounds were detected in malt, without two alkaloids (representative: hordenine). At Day2-5, 33 compounds were detected, with different contents as shown by the peak area comparison; hordenine had a gradually increasing abundance; and nearly one third of the chemical components in barley increased gradually, one third decreased gradually, and one third tended to be stable. Conclusion: Malts under different germination cycles and prepared with different processing methods have varying active ingredients, and especially brown malt exhibits a serious loss of compounds. The tight association between the chemical composition and clinical application of malt offers a basis to the clinically scientific and reasonable selection of Chinese medicinal materials for treatment purposes.