Research on the release of theanine in the exist of metal ions in natural water

Theanine is a main component in tea leaf, it is the key factor to influence the nutrition value and flavor when the tea leaf is brewing. Natural water is the most-used extractant to dissolve out the theanine. It is recorded in ancient books that dissolution rate is quite different in different kinds of natural water. Recent study shows its correlation with the complexing abilities of metal ions. The thesis is trying to explain the law between the release of theanine and metal ions through designed model test. Response surface experiments showed that in the mixed solution of 1.74 mg/L Ca2+, 21.63 mg/L Na+, 5.55 mg/L Mg2+ and 4.86 mg/L Al3+., the release of theanine reaches the peak value 0.88 mg/mL. It is also found that in the exist of Ca2+, free theanine is increasing with total metal ions while free theanine is decreasing with the increasement of total metal ions in the absence of Ca2+. © Maxwell Scientific Organization, 2014.