Purification of a β-Primeverosidase Concerned with Alcoholic Aroma Formation in Tea Leaves (Cv. Shuixian) To Be Processed to Oolong Tea

β-Primeverosidase, which is concerned with the alcoholic aroma formation in tea leaves, was purified from fresh tea leaves ( Camellia sinensis var. sinensis cv. Shuixian) to be processed to oolong tea by successive precipitation with acetone and ammonium sulfate followed by column chromatography on CM-Toyopearl and Mono S-HR. The molecular mass was shown to be 61 and 60.3 kDa by SDS−PAGE and TOFMS, respectively. Its p I, optimum temperature, and pH are 9.5, 45 °C, and 4, respectively. The enzyme is stable below 45 °C and between pH 3 and 5. The enzyme hydrolyzes β-primeveroside into primeverose and an aglycon without further hydrolysis. These enzymic characteristics were found to be quite similar to those of the β-primeverosidase from cv. Yabukita exclusively processed to green tea. As most of the alcoholic tea aroma precursors have been isolated as β-primeverosides, the main route of the aroma formation in oolong tea has been elucidated on a molecular basis. Keywords: β-Primeverosidase; oolong tea; Camellia sinensis; aroma formation; glycosidase; tea aroma