Changes in phenolics and antioxidant capacity during short storage of ready-to-drink green tea (Camellia sinensis) beverage at commercial conditions
ABSTRACT The objective of this research was to evaluate the changes of phenolics and antioxidant capacity of a ready-to-drinkgreen tea beverage during short storage at commercial conditions. The total phenols (Folin-Ciocalteu), total catechins (4-dimethylaminocinnamaldehyde) and total non-catechins (difference between total phenols and total catechins) were evaluated as part of phenolic analysis, while antioxidant capacity was evaluated by using DPPH (2,2-diphenyl-1-picrylhydrazyl) radical. At the beginning of the experiment, the levels of total phenols, total catechins and total non-catechins were 1220.69 ± 29.73, 636.94 ± 14.60and 584.75 ± 15.12 milligrams of catechin per liter of sample, respectively; these values decreased to 674.38 ± 26.52, 424.54 ± 11.29and 251.83 ± 37.81 milligrams of catechin per liter of sample, respectively, after nine days of storage. The losses of phenolics at the final day of the experiment were 44.67% in total phenols, 33.40% in total catechins and 56.93% in total non-catechins. The initial values of the DPPH antioxidant capacity were 3116.43 ± 90.91 micromoles oftrolox equivalents per liter of sample and 66.09 ± 1.82 percentage of radical scavenging. These values decreased to 1288.86 ± 70.71 micromoles of trolox equivalents per liter of sample and 31.90 ± 2.44percentage of radical scavenging after nine days of storage, which means a loss of 58.62% and 53.24%, respectively. The data obtained in this work give information to the ready-to-drink green tea consumers, manufacturers and food researchers about loss of compounds with beneficial health effects during short storage of greentea at commercial conditions.