CRUDE FIBRE, WATER EXTRACTS, TOTAL ASH, CAFFEINE AND MOISTURE CONTENTS AS DIAGNOSTIC FACTORS IN EVALUATING GREEN TEA QUALITY

摘要

Purpose - This experiment was carried out to diagnose the qualities of green tea form Nigeria using quality markers including crude fibre, water extracts, total ash, caffeine and moisture content respectively. Design/methodology/approach - Green tea was processed from seven different tea clones from Mambilla Highland located 1840m above mean sea level. The clon-al materials used for green tea followed standard Chinese methods viz: plucking, fixing (pan firing), rolling and drying. The green teas produced were analyzed for moisture content, MC; crude fibre, CF; water extracts, WE; total ash, TA; water-soluble ash, WSA; alkaline-insoluble ash, ALIA and acid-insoluble ash, AIA. The quality of the green tea produced was compared to the recommended ISO standard for tea. Findings - Our findings showed that there were significant differences (p＜0.05) in the chemical components studied as a result of clonal variations, which made the quality characteristics of the green tea vary accordingly. Of all the tea clones examined except clone 236, WE were within values recommended for good quality green tea as speculated by ISO 3720, and percentage MC was between 4.11-12.5 per cent, with an average of 10.2 per cent. The high MC was due to the high humidity of the processing environment, where sunlight was inadequate and farmers were not patient enough to dry the tea samples to the recommended moisture level of 6.5 per cent The percentage CF ranged between 4.37-20.8 per cent; the ALIA 0.90-1.30 per cent; TA, 4.2-6.5 per cent; WSA, 50-67 per cent; WE 21.7-43.6 per cent and the caffeine content was widiin 1.29-2.56 per cent. Originality/value - The materials used in this study were obtained locally. Practical implications - The study showed that the determination of quality markers for green tea can be done routinely with reduced costs.