2 Background introduction Tea contains a variety of alkaloids including caffeine about 1%0-5%, tannic acid(tannic acid)about 11%0-12%,as well as cellulose, flavonoid pigments proteinsTea contains a variety of alkaloids, including caffeine about 1%-5%, tannic acid (tannic acid) about 11%-12%, as well as cellulose, flavonoid pigments, proteins… Background introduction