1992 Volume 39 Issue 2 Pages 178-182
In order to establish suitable production conditions of canned tea drinks, first of all, caffeine, catechins and L-ascorbic acid in commercial canned tea drinks were quantitatively determined as indicative substances of quality change by high performance liquid chromatography and colorimetric analysis. Secondly, canned green tea drink was prepared as a trial to examine the influence of pH of extraction media and of heat processing on the stability of caffeine, catechins and L-ascorbic acid. From the analysis of various kinds of commercial canned tea drinks including oolong tea, black tea and green tea, it was found that the concentrations of caffeine and catechins in commercial canned tea drinks were 1/2-2/3 of those in normal tea infusion. The drinks kept at lower pH had higher retention of catechins From the test production of canned green tea, it was found that, (1) catechins were less stable than caffeine in heat processing, (2) L-ascorbic acid was considerably stable in heal processing, (3) most catechins decreased by heat processing but (+)-catechin was remarkably increased, (4) the increase of (+)-catechin was possibly caused by isomerization of(-)-epicatechin, (5) the isomerization of(-)-epicatechin was remarkably depressed in slightly acidic extraction media containing citric acid. In conclusion, the most dominant factor affecting the stability of catechins in tea drinks was pH of extraction media.
