Qualitative and quantitative changes of nonvolatile compounds and taste profiles in Wuyi rock tea during the manufacturing processes

Wuyi rock tea (WRT), a type of oolong tea, is famous for ‘rock flavor’ with characteristic taste and aroma. The qualitative and quantitative changes of the nonvolatile constituents and taste profiles were investigated during the WRT production process by analyzing of polyphenols, caffeine, amino acids, L-theanine and total sugar, coupled with sensory evaluation and determination of dose-over-threshold values. The contents of L-theanine, total sugar, amino acids and some catechins varied considerably except for GA, GCG and GC that increased significantly during the process, while the amount of caffeine was relatively stable. Astringent, bitter, sweet and umami taste properties were predicted. In accordance with the sensory evaluation, there was no umami-like taste in the finished tea that underwent full fire processing, which is essential for WRT to enhance the mellow, heavy taste, and weaken the bitter taste. EGCG and caffeine contributed the most to the astringent, bitter taste of WRT. This study provides a comprehensive profile of the changes in taste characteristics during the WRT manufacturing process.