Studies on the Colored Components in Black Tea Infusion

Among the high, middle and low grade black teas, the concentration levels of theaflavin, thearubigin and water-soluble oxidized matter were surveyed by using the photometric method shown in previous paper.The high grade teas showed high concentration levels of theaflavin and thearubigin, while the reversed result was obtained from the low grade one.Each adjoining groups between high and middle or middle and low grade teas were discriminated by the discriminant functions made from both values of theaflavin and thearubigin or theaflavin plus thearubigin and water.soluble oxidized matter, respectively.The distributed areas of the infusion colors of respective three grade teas were fixed by the quality control diagrams made from above-mentioned coupled two variables.