Farshad Soheili-Fard, Hamid Reza Ghassemzadeh, Seyed Babak Salvatian
Department of Biosystem Engineering, Faculty of Agriculture, University of Tabriz, Tabriz, Iran
Tea Research Institute, Lahijan, Guilan Province, Iran
Key words: Duration, Green leaf, Trough, Tea processing, Withering.
Withering is the first step in tea processing and has a significant impact on final product quality. During the tea green leaf withering and its preparation for the next stage of processing (curling), reduction in moisture content of the leaf is accompanied by occurrence of biochemical interactions that play an important role in product quality; its aroma in particular. Air flow rate and withering time are two important parameters that affect withered tea leaves. In the present study, impact of withering on the quality of black tea product was examined based on environmental conditions and green tea quality through sensory evaluation method. A laboratory scale trough was used for withering operation. Two factors of air flow rate and withering time duration were considered with three and five levels respectively. Results showed that the impact of the air flow rate on dry tea appearance, liquor color, taste, aroma, infused leaves and final product quality (black tea) is significant at the 1% level. The interaction between air flow rate and withering time was also significant on dry tea appearance, liquor color, infused leaves and final product quality at 1%, and aroma at 5% probability levels respectively.
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