Document Type : Full Paper
Authors
Tea Research Center, Horticultural Science Research Institute, Agricultural Research Education and Extension Organization (AREEO), Lahijan, Iran
Abstract
Keywords
Main Subjects
Extended Abstract
Introduction
Tea is one of the strategic products in Iran agriculture, which has wide and daily consumption. Increasing the production and improving the quality of tea are important in the national economy of the country. Based on recently official reports the production of green tea leaves in Iran is 135,000 tons per year, which is only enough for the consumption of 30% of Iran population. Increasing the yield and improving the quality of tea are known as important strategies in tea production and trading. Superiority of modified cultivars in performance and uniform quality are among the advantages that can be effective in increasing the economic efficiency of tea gardens. In this study, the properties of teas made from two cultivars of tea, Kashef and Lahij, which were introduced by the Iran tea research institute in 2019 were studied in order to complet breeding investigations. This study was designed considering the variety of chemical compounds in tea of different cultivars and their importance for improving qualitative characteristics in different types of dry tea.
Materials and Methods
Tea shoots of Kashef and Lahij cultivars were plucked from tea shrubs of Lahijan Fajr research station in three seasons (spring, summer, and autumn), and four methods on the laboratory scale (green Orthodox, green CTC, black Orthodox, and black CTC) were used to make the tea. This study was conducted in a factorial split plot experiment based on a completely randomized design with three replications. The main factor was harvest time and sub-factors were the cultivar (in two levels) and tea-making method (in four levels). The chemical properties of tea samples, including the amounts of total polyphenols, antioxidant activity, theaflavin, thearubigins, and organoleptic score, were determined.
Results
The results showed that qualitative characteristics (sensory score, amount of theaflavin, ratio of theaflavin to thearubigin, antioxidant activity, and polyphenol) in all of the made teas were observed in the Kashef cultivar more than the Lahij cultivar. In addition to the cultivar, the harvesting season and the type of tea production are also important factors affecting the changes in theaflavin, which is one of the important indicators of tea quality. In summer, with the increase in lighting hours, the synthesis of polyphenols increases in tea green leaves, which has an effect on increasing the amount of theaflavin in tea. Of the two types of the made teas, black CTC tea was better than Orthodox tea in both cultivars in terms of quality characteristics, especially the ratio of theaflavin to thearubigin. But orthodox tea obtained a higher overall sensory score than CTC tea, the difference was only due to the unpleasant appearance of CTC tea. However, CTC black tea got a higher score in terms of the characteristics of the color and taste of the brewed drink. The antioxidant activity of green tea was not significantly different between cultivars (p≤0.05). In both cultivars, Orthodox green tea had a higher score than CTC green tea due to differences in the color of brewed beverage.
Conclusion
Kashef and Lahij cultivars can be used to produce black tea by both orthodox and CTC methods, and to achieve the product of the highest quality, which has a desirable appearance and beverage properties, following the correct principles of tea making. The high amount of polyphenol in the Kashef cultivar tea confirms the appropriateness of this variety for producing black tea, especially by CTC method. CTC and orthodox black teas, in Kafesh variety, showed outstanding characteristics in terms of sensory score, theaflavin content, theaflavin to thearubigin ratio, antioxidant and polyphenol activity. Due to the high amounts of chlorophyll, consumption of Lahig green tea made through orthodox method is preferred to another method.
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