Z Lebensm Unters Forsch (1993) 197:358-362 Original paper Effects of shooting period, times within shooting periods and processing systems on the extract, caffeine and crude fiber contents of black tea Feramuz 0zdemir ~, Hiisnii Y. GOkalp 2, Sebahattin Nas 2 1 Turkish Tea Board (Cay-Kur), TR-53070 Rize, Turkey 2 Atatiirk University, Food Science and Technology Department, TR-25240 Erzurum, Turkey Received January 12, 1993 Zeitschrift fLir 9 Springer-Verlag 1993 Die Wirkungen der Sproflperiode, die Zeit innerhalb der Sproflperioden und der Verarbeitungssysteme auf den Tee-Extrakt, den Coffein- und den Rohfasergehalt yon schwarzem Tee Zusammenfassung. Die in den verschiedenen SproBperi- oden und in unterschiedlichen Zeiten innerhalb der ein- zelnen SproBperiode erhaltenen frischen Teeproben wur- den mit den fiinf verschiedenen kommerziellen Walzme- thoden zu schwarzem Tee verarbeitet. Bei diesen Teepro- ben wurden der Extrakt-, Coffein- und Rohfasergehalt bestimmt. Der Extrakt- und der Rohfasergehalt von schwarzem Tee werden durch alle Faktoren und deren Wechselwirkungen signifikant (P<0.01) beeinflul3t. Die SproBperiode und die Zeit innerhalb der SproBperioden wirkten auf den Coffeingehalt von schwarzem Tee ein. Es wurde festgestellt, dab die Verarbeitungsmethode keine signifikante Wirkung (P<0.05) auf den Coffeingehalt hatte. Der Extrakt- und der Coffeingehalt nahmen von der ersten SproBperiode bis zur dritten, und auch vom Anfang der einzelnen SproBperiode bis zum Ende ab. Der Rohfasergehalt von schwarzem Tee nahm dagegen insbesonders vom Anfang der einzelnen SproBperiode bis zum Ende der Sprogperiode zu. Abstract. The extract, caffeine and crude fibre contents of black tea, from different shooting periods, different times within each shooting period and processed by five differ- ent commercial rolling methods, were examined. The ex- tract and crude fibre contents of black tea were signifi- cantly (P < 0.01) affected by all these factors and their in- teractions. The caffeine content of black tea was affected by the shooting period and times within the shooting pe- riod. It was determined that processing methods did not have a significant (P<0.05) effect on the caffeine con- tent. The amount of extract and caffeine decreased from the first shooting period to the third, and also from the beginning of each shooting period to the end. However, the crude fibre content of the black tea increased, espe- cially from the beginning of each shooting period to the end of each shooting period. Correspondence to: H.Y. G6kalp Introduction Processed black tea quality and properties are mainly de- termined by the genetic properties of the tea bushes and by environmental conditions [1]. However, processing systems and technology also play a very important role on black tea quality criteria. Black tea is produced by a variety of methods throughout the world. The four main processes of tea manufacture are orthodox, CTC (crush- ing-tearing-curling), rotorvane and LTP (Lawrie tea pro- cessing). These methods can also be combined. At pres- ent, many different combinations of these methods are used commercially [2-7] A tea shoot of two leaves and a bud contains about 23% solid matter. About half of the solid matter is solu- ble in water and this is termed extract. Many components of the liquor influence tea quality. The amount of these components generally increases in proportion to the amount of tea extract. Thus, the percentage of extract is limited by international Standard Organization (ISO) [8]. The amount of extract decreases as the plucking intervals lengthen, and it also decreases due to coarse plucking and aging of the leaf [9]. Caffeine is an alkaloid that can constitute approxi- mately 5% of the dry matter in fine tea shoots. Tea is widely consumed all over the world, and caffeine plays a very important role in explaining why tea is used as a beverage, because it has a stimulatory effect on the hu- man body [10]. A high content of caffeine contributes to briskness, which is one of the factors indicating quality tea [1, 11]. The caffeine content of green tea increases after harvesting, particularly during the withering proc- cess. Some authors have reported that different tea rol- ling methods do not affect the caffeine content of pro- cessed black tea [1, 10] Crude fibre is the main part of the insoluble matter of black tea. The fibre content can vary and ranges between 7 and 20% in black tea products. In general, when the fibre content of tea increases, most of the quality charac- teristic components decrease [1, 9]. Coarse plucking and aged leaves result in higher levels of fibre. Coarse leaves