ABSTRACT This study aimed to optimize the tea rolling process by investigating the effects of roller rotation speed (20, 30, and 40 rpm) and applied pressure (170, 340, and 680 kg/m 2 ) using a semi‐industrial machine. The aim of the research was to investigate how key operational parameters affect the biochemical properties of tea, including caffeine, theaflavins, thearubigin, and soluble solids content. All experiments were performed in three replications and the results were analyzed using factorial experiments and in a completely randomized design using SAS statistical software. With regard to caffeine, the results showed a significant decrease in its amount with increasing pressure. Among the samples at constant pressure, those rolled at 40 rpm had the highest caffeine content. Statistical analysis indicated that none of the independent factors had a significant effect on the amount of theaflavins. Conversely, both rotation speed and pressure had a significant effect on thearubigin content, with their increase leading to a decrease in thearubigin. Finally, it was observed that increasing the rotation speed and pressure applied during tea processing resulted in a significant increase in the soluble solids content. In conclusion, the optimum levels of the independent factors for the key biochemical parameters were determined to be a pressure of 170 kg/m 2 and a rotation speed of 40 rpm.
Mahdavi et al. (2026) studied this question.