Studies on freeze-withering in black tea manufacturing

In order to reduce the withering time during black tea manufacture, freeze-withering was attempted, which resulted in flaccid leaves with increased cell membrane permeability in a shorter period of time. The freeze-withered leaves had similar amounts of quality precursors as that of the conventionally withered leaves. The resultant black tea was better in quality than those manufactured without withering and after normal withering. Manufacturing of fresh leaves resulted in comparable levels of theaflavins, but the tea was not acceptable due to its harshness. Increased cell membrane permeability during freeze-withering showed that the leaf attained a sufficient degree of physical wither. The decreases in the levels of chlorophyll showed that chemical withering had also been achieved during freeze-withering, which is supported by the increased levels of caffeine.