Advancement and challenges in tea brewing: The dynamic principles, influencing factors, innovative processing technologies and pollutants

Abstract

Background

Brewing is the final stage in tea consumption, which amplifies the original flavor or embellishes defects of tea infusion, turning drinking into a life attitude and an artistic pursuit. Nevertheless, present research focused on tea brewing is majorly about chemical compositions and sensory evaluation, which lacks a systematic framework that connects apparent phenomena, underlying principles, and technical applications. Besides, the daily methods employed for tea brewing primarily rely on experience because of lacking a systematic generalization of the scientific brewing design. Simultaneously, lacking targeted tea brewing technology leads to under-expressed tea qualities and is difficult to innovate tea brewing techniques.

Scope and approach

In this review, the latest research progresses of the release principle, extraction and transformation process of tea chemical components, the effect of brewing parameters on sensory quality were summarized. Meanwhile, existing methods and potential pollutants during brewing were reviewed.

Key findings and conclusions

According to brewing kinetics, more efficient brewing would be achieved by providing enough space for tea to swell (such as reducing the single tea particle size and the height of tea bed). Meanwhile, Non-fermented and lightly-fermented teas were recommended to be brewed with low total dissolved solids (TDS) and weakly acidic water, and higher fermented teas should be brewed with higher TDS water. Temperature, time and water/tea ratio affect the overall quality of tea infusion by affecting the leaching and conversion of tea polyphenols, caffeine and theanine. Moreover, innovative CBT processing technologies have been collated, including DLC, UAE, HHP, etc. In view of the above, an interconnected framework “brewing kinetics principles - key influencing factors - brewing technologies” was proposed, which lays a foundation for the brewing technologies. Based on this framework, the possible future research orientation was also prospected in this review, especially in the aspects of healthy activity, nanoparticles and additives.