Abstract
The objective of this work was to study the changes in chlorophyll contents in green teas stored under different conditions and to suggest the most suitable way and length of green tea storage. A secondary aim was to evaluate the possibility of using the chlorophyll content as an indicator of tea freshness. Samples for analysis were obtained from a range of tea-growing regions. Chlorophyll contents were measured using UV-vis spectrophotometry. Chlorophyll absorbance was measured at 642.5 and 660 nm. Prior to storage, chlorophyll concentration in teas ranged from 1.12 to 1.89 mg per 1 g of tea, which corresponded to data given by other authors. Storage was found to lead to a decline in chlorophyll concentration. From the 6th month of storage onwards, a significant decrease (P < 0.05) was observed in all samples, irrespective of storage conditions. Based on the findings of this study, original and metal packaging can be considered the most chlorophyll-friendly. On the other hand, glass and paper packaging stored in direct daylight were found to have the strongest impact on chlorophyll concentration. Overall, it can be concluded that the storage time can have a strong influence on oolong green tea colour as an important qualitative variable. Thus, the shelf-life of tea should be shorter than the 12 months claimed by most manufacturers. Once the relationship between changes in chlorophyll concentration and length of the storage period had been established, the chlorophyll content was suggested as an indicator of the storage time (freshness) of a tea substance.
Highlights
The objective of this work was to study the changes in chlorophyll contents in green teas stored under different conditions and to suggest the most suitable way and length of green tea storage
The findings obtained by the present study correspond to the results of other studies focusing on chlorophyll content in green teas
A significant difference (P < 0.05) in chlorophyll contents was observed in three samples of teas from high-mountain teagrowing regions
Summary
The objective of this work was to study the changes in chlorophyll contents in green teas stored under different conditions and to suggest the most suitable way and length of green tea storage. In Europe, green tea comes with no unified “guidelines” regarding preparation and storage; rather, these exist in the form of supposedly all-purpose recommendations, with discrepancies between them It has not been established for how long tea can be stored or under what conditions and form. Neither the duration of storage nor its most suitable conditions have been suggested yet, whether concerning tea-selling shops or consumers’ homes It has not been determined, either, how the shelf-life of tea from different tea-growing regions can be estimated. In tea leaves and non-fermented teas, chlorophyll is a highly important pigment as its amount determines the final colour of green tea infusion. Pheophorbides and pheophytins are the main products of chlorophyll degradation (Cartaxana et al 2003)
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