GB687175A - Improvements in or relating to the preparation of an aromatized soluble beverage - Google Patents

Abstract

An aromatic fraction is obtained from roasted coffee by dry distillation within the temperature range of 25 DEG -80 DEG C. under reduced pressure to remove said fraction which is then condensed. By heating roasted ground coffee containing less than 2 per cent moisture for under three hours, preferably about one hour, at 50 DEG -70 DEG C. and at an absolute pressure of less than 20 mm. of mercury, a highly aromatic distillate is obtained. Preferably the condensation of the entire distillate is effected at -180 DEG C., but if the moisture content of the distillate is relatively high the latter is first condensed at 0 DEG to -30 DEG C.; alternatively it may, particularly if the moisture content is below 2 per cent, be condensed at -80 DEG C. before the condensation at -180 DEG C., the latter being essential for the condensation of the most volatile constituents. Roasted ground coffee containing about 2 per cent moisture is placed in a steam-jacketed autoclave which is then closed by a hatch carrying a thermocouple, a manometer or the p like, and steel piping leading to two condensers. The latter comprise two closed cylinders connected to evacuating apparatus, e.g. an oil pump, and each having inserted in the top thereof a pipe closed at the bottom and forming a "cold finger." The cylinders are connected in series but could be in parallel. The cold fingers are filled with liquid air or liquid nitrogen, and evacuation of the system is started. When the absolute pressure is reduced to 30 mm. of mercury steam is introduced into the jacket of the autoclave, and the coffee is heated for about one hour until it reaches a temperature of about 70 DEG C., the absolute pressure then being about 13 mm. The pump is then disconnected and the pressure is allowed to rise to atmospheric; the condensers are taken apart and the condensate in the form of a loose solid is scraped from the cold fingers. The condensate is left at room temperature for an hour to melt and is then incorporated in dry soluble coffee powder by tumbling the latter in a revolving drum and slowly spraying the condensate on to it. The whole is then stood overnight for tempering, and then screened and packed. The carbon dioxide evolved as the condensate warms up to room temperature may be passed through a chamber containing tumbled coffee powder which will absorb the aromatic constituents in the gas. The condensate may, however, be incorporated into coffee powder by condensing it on to a chilled mass of such powder. The fraction may be added to cup coffee, or incorporated into a soluble coffee powder, a concentrated coffee infusion or syrup, a soluble aerial beverage powder or other foodstuffs. The amount of the fraction introduced into a soluble coffee powder should be such that the moisture content of the resulting aromatized powder does not exceed 4.5 per cent, i.e. such that the powder will not cake on storing. If coffee containing more than 2 per cent moisture is treated, the more dilute distillate' obtained may be used for flavouring e.g. ice cream. Due to the mild heating the fraction is obtained without causing deterioration of the roasted coffee which may then be used to prepare a soluble coffee powder.