Sterilisation, pre-drying, and drying of raw cocoa beans and cocoa nibs

摘要

To sterilise and dry green (raw) cocoa beans, or cocoa nibs (split kernels), pref. in a single vessel (1), firstly live steam to sterilise, and then hot air to dry, is blown in. The vessel is also heated, by a steam jacket (2), assisting the drying process. Pref. the steam used has a pressure of about 2.5 bar and a temp. of 138 deg C. To pre-dry, immediately following this steam-sterilisation, the vessel and contents are also subjected to evacuation for a short time; about 1 min. suffices. A water ring pump pulls an adequate vacuum for this stage. Hot air drying then achieves the required moisture level. All this precedes the stages in which the contents are crushed and air-classified to remove the shells. Air for drying is induced through an inlet filter (18), is heated in an indirect heater (16) to 140-150 deg C before passing to the dryer (1). This air is circulated through the content to reduce their moisture to the desired residual level, which is determined from the wt. change in the prod., as measured by a vessel weighting system (3). Recirculated drying air is passed through a condenser (26), where it is partially dried.