Unilever’

s Lipton subsidiary has been awarded a US patent relating to its method for processing whole leaf tea by exploiting the thermodynamic properties of carbon dioxide as a means to initiate the fermentation reactions that occur in black tea manufacture.

Protected under US patent number 6,254,902, the abstract reads:

A method for processing whole leaf tea that involves impregnating tea leaves with liquid carbon dioxide within a pressure vessel, depressurising the vessel at a rate that is sufficient to freeze the liquid carbon dioxide, applying sufficient heat to cause the frozen carbon dioxide to sublime and consequently initiate fermentation within the leaves, allowing the tea to ferment for a time that is sufficient to achieve desired liquor properties, and drying the fermented product to yield the whole leaf tea. An apparatus for manufacturing such a leaf tea is also described.

The first claim (of 9) is for:

A method for processing whole leaf tea comprising the steps of impregnating tea leaves with liquid carbon dioxide within a pressure vessel, depressurising the vessel at a rate that is sufficient to freeze the liquid carbon dioxide, applying sufficient heat to cause the frozen carbon dioxide to sublime and consequently initiate fermentation within the leaves, allowing the tea to ferment for a time that is sufficient to achieve desired liquor properties, and drying the fermented product to yield the whole leaf tea.

To see full details of the patent, please click here.