Physicochemical stability of theabrownins-polysaccharide complexes under different environments and additives

In this study, four components of theabrownins-tea polysaccharide (TBs/TPC) complexes were isolated and purified from Pu-erh tea by column chromatography. The stability of its aqueous solution under the conditions of physical factors (light, temperature) and chemical factors (pH, food additives, oxidizers and reducing agents, metal ions) was also studied. The results indicated that TBs/TPC-1 showed minimal absorbance variation under different light conditions, with values remaining around 0.2. High temperature had the most significant effect on TBs/TPC-4, with the absorbance increasing by 39.05% as the temperature rose from 25 to 95°C. Neutral conditions (pH 6–7) were more favorable for TBs/TPC stability, where absorbance changes for all complexes did not exceed 4%. Food additives and metal ions also affected stability to varying degrees. For example, the absorbance and color difference values of TBs/TPC-2 with Mg2+ addition were 285.23 and 284.11% higher than those of the solution with Ba2+ addition. Furthermore, oxidizers reduced the stability of TBs/TPC complexes. Therefore, TBs/TPC complexes should be stored in a light, low-temperature, neutral environment to avoid contact with oxidizers. This study provided a reference for the storage and utilization of TBs/TPC complexes, and also provided a theoretical basis for its application in the development of dark tea food and drinks.