The Effect of Rotational Speed and Applied Pressure During the Rubbing Process on Some Physical Properties of Black Tea

Mahdavi, Mostafa; Azadbakht, Mohsen; Abbaszadeh Mayvan, Ahmad

doi:10.22104/ift.2025.7867.2237

The Effect of Rotational Speed and Applied Pressure During the Rubbing Process on Some Physical Properties of Black Tea

Articles in Press

Document Type : Research Article

Authors

¹ Department of Biosystem Engineering, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran

² Department of Bio-System Mechanical Engineering, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran.

³ Department of Biosystems Engineering, Faculty of Water and Soil Engineering, Gorgan University of Agricultural Sciences and Natural Resources

10.22104/ift.2025.7867.2237

Abstract

In this research, an attempt was made to design and evaluate a semi-industrial tea rolling machine. The study investigated the effect of roller rotational speed and the pressure applied to the green tea leaves on the quality of the rolled tea. First, prepared and weighed tea samples were rolled using the semi-industrial rolling machine with a capacity of 10 kg. The independent parameters were chosen at three pressure levels: 170, 340, and 680 kg/m², and three rotational speeds: 20, 30, and 40 RPM. Finally, the percentage of breakage, rolling time, and sensory quality were measured. The analysis of the percentage of breakage in samples due to the roller speed and pressure showed that as both speed and pressure increased, the percentage of breakage also increased. For the rolling time, it was concluded that only the independent factor of pressure had a significant effect on the required rolling time. By increasing the pressure of the roller, the time needed for the samples to roll decreased significantly. Ultimately, it was concluded that the best levels for the effective independent factors on the percentage of breakage were a pressure factor of 170 N and a rotational speed of 20 RPM. In the sensory test, the best aroma and flavor were related to the samples under a pressure of 340 N and a rotational speed of 30 RPM.

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