Comparison of Waste from Different Types of Tea to Dried Butterfly Pea Flower

Abstract

At present, the bioactive compounds of teas are well established and there are more attempts to apply tea as a functional drink or food supplement. In addition, during tea processing, tea waste, including broken tea leaves, buds and stems, is generated and disposed to the environment. The present study aimed to compare the quality of tea waste generated in full fermentation (raw Pu-erh tea, ripen Pu-erh tea and Anhua dark tea) and non-fermentation (green tea) processings in comparison with dried butterfly pea flower (DBPF) (non-Camellia sinensis). The results showed that total flavonoid (TFC) was found to be the highest in raw Pu-erh tea at 474.470 ± 47.173 mg RE/g, followed by ripened Pu-erh tea, green tea, Anhua dark tea, and DBPF, respectively. Similarly, raw Pu-erh tea also had the highest total phenolic (TPC) at 608.090 ± 2.795 mg GAE/g, followed by green tea, Anhua dark tea, ripen Pu-erh tea, and DBPF, respectively. On the other hand, total polysaccharides (TPS) content in DBPF was the highest among samples, whereas that of raw Pu-erh tea was the lowest. According to the HPLC analysis, caffeine (CF) was the major catechin found in all types of tea waste and the total catechin content was in the order of raw Pu-erh > ripen Pu-erh tea > green tea > Anhua dark tea which was in agreement with the TPC results. However, the types of catechin were different in each sample. It is noteworthy that there was no CF in DBPF, and major catechin found in DBPF was catechin gallate. Likewise, antioxidant ability determined by DPPH was the most superior in raw Pu-erh tea, followed by green tea, ripen Pu-erh tea, Anhua dark tea and DBPF, respectively. ORAC antioxidant capacity was highest in the green tea, while that in raw Pu-erh tea, ripen Pu-erh tea and Anhua dark tea was lower but not significantly different, as expected, DBPF possessed the lowest ORAC antioxidant capacity. Finally, it can be said that the potential for tea waste to be a valuable source of antioxidants varies depending on the tea processing, and the plant variety also had an impact on the characteristics of the tea samples.