In addition to containing amino acids, trace elements, protein, pectin and other rich nutrients. It also contains tea polyphenols, alkaloids, brass and other multi-functional components, which not only has the effect of quenching thirst, but also has a variety of health functions such as cancer prevention and anti-aging. Although tea polyphenols have the functions of preventing cancer and delaying aging, if the content is too high in tea drinks, it will be complexed with proteins and other proteins for a period of time, so removing part of tea polyphenols can avoid or delay the precipitation or turbidity of tea drinks, and thus improve the quality of tea drinks.
China is a big tea producing country, and vigorously developing the tea beverage industry is of great significance to the development of our national economy. Storage period is a key technical problem to be solved in the development of tea beverage. It has been reported that alum, kaolin, silica gel, etc. are used to improve the stability of tea drinks, but will affect the flavor of tea drinks. The cross-linked PVPP has good complexation, adsorption and physiological compatibility, and no residue in the beverage.
Experiments have proved that PVPP treatment of green tea extract can quantitatively adsorb part of tea polyphenols and increase the stability of tea under appropriate conditions. The mechanism of PVPP adsorption of tea polyphenols is as follows :PVPP monomer VNP is an amide with a molecular structure similar to amino acids, containing O atom to form ammonia bond. Tea polyphenol molecules contain active hydrogen (phenol hydroxyl H), which can form hydrogen bond with PVPP. Since PVPP is insoluble in water, tea polyphenol molecules are continuously precipitated to PVPP through hydrogen bond and are removed. On the other hand, the formation of hydrogen bond between PVPP and tea polyphenol molecules is a reversible process, and tea polyphenol molecules are desorbed from PVPP while being adsorbed by hydrogen bond. The use of PVPP in this process has the effect of extending the quality of tea drinks.
