Furosine and 5-hydroxymethylfurfural as chemical markers of tea processing and storage

One of the most consumed beverages around the world is tea, but little is known about how tea quality can be monitored during storage and processing. Thus, the objective of this research was to study the usefulness of furosine and 5-hydroxymethylfurfural (HMF) content-two Maillard reaction markers-as quantitative parameters that control tea processing and storage. Two different experiments were carried out: one using green and black teas (processed at laboratory scale) and another one using commercial green, white, black and red teas that were under storage for one year (shelf life) and under accelerated conditions (55 degrees C at 40% of humidity for 3 months). The samples were analyzed for the content of furosine, HMF, and free and total lysine. The combination of HMF and furosine was useful as an indicator to control tea processing and storage regardless the type of tea. HMF and furosine are useful chemical indicators (when combined) to monitor tea quality during processing and storage. Furosine analysis is especially sensitive to control the first drying steps, while HMF reflects those changes occurred in the last tea processing steps.