with reference to the drawings , an aromatized coffee oil is gasified by injection of an inert gas to cause foaming and the resulting foamed aromatized coffee oil is pumped through the central aperture 11 of a co - extrusion nozzle 10 . at the same time , an aqueous coffee extract is pumped through an annular aperture 12 which surrounds central aperture 11 . flow rates and pressures in the nozzle are controlled to form droplets 13 , each droplet having a core of gasified aromatized coffee oil surrounded by a substantially spherical wall of the aqueous coffee extract . the droplets fall into a body 14 of a liquid desiccant , such as anhydrous alcohol , in container 15 . the anhydrous alcohol dehydrates the shells of the droplets , causing the shells to harden . the dehydrated droplets are removed from the tank and the alcohol removed , preferably by gently heating the dehydrated droplets at temperatures not exceeding about 50 ° c . the water content of the main body of alcohol 14 is preferably maintained at a low level by continuously removing and dehydrating a stream of alcohol 16 taken from tank 15 and then recycling the dehydrated alcohol to tank 15 . dehydration of the alcohol is preferably achieved by passing the stream of alcohol 16 through a bed 17 of drying agent , such as calcium sulphate crystals . the dehydrated alcohol is then recycled via conduit 18 to tank 15 . the water content of the main body 14 of alcohol is preferably not more than 5 %, and more preferably not more than 4 % by weight . the process may be made essentially continuous by employing a plurality of alcohol tanks and causing the droplets to fall into one tank while removing dehydrated droplets from another . co - extrusion nozzle 10 is preferably constructed of stainless steel . the gasified aromatized coffee oil enters a first port 19 of the nozzle and is forced through inner chamber 20 to central outlet aperture 11 . the aqueous coffee extract enters a second port 21 of the nozzle and is forced through peripheral chamber 22 to annular outlet aperture 12 which surrounds aperture 11 . central aperture 11 is preferably circular annular aperture 12 preferably closely surrounds central aperture 11 such that its inner diameter only slightly exceeds the diameter of central aperture 11 . this is preferably accomplished by tapering to a point the cylindrical outer end 23 of wall 24 surrounding inner chamber 20 . it is an advantage of the invention that the aqueous coffee extract is not required to be of high viscosity as to require pumping the extract through the nozzle at high pressures . it is preferred that the solids content of the aqueous extract is not more than 75 % by weight , more preferably not more than 70 % by weight , and most preferably not more than 65 % by weight based on the weight of the extract . if the solids concentration is too low , however , the integrity of the extracted droplets will be impaired . a minimum coffee solids content of the extract is about 50 % by weight and more preferably 55 % by weight , and most preferably about 60 % by weight the aqueous coffee extract can be obtained in any conventional way such as by aqueous extraction of roast and ground coffee or by dissolving instant coffee in water . it is an advantage of the invention that the capsules can be made entirely of coffee - derived materials and it is therefore preferred that the solids content of the extract is 100 % coffee - derived . it is also preferred that the aqueous liquid employed to prepare the extract is water the flow rate and pressure of the gasified aromatized coffee oil and of the aqueous coffee extract in the co - extrusion nozzle are controlled to form droplets having a shell of the coffee extract encapsulating a core of encapsulated oil . suitable flow rates and pressure will , of course , depend on the design of the co - extrusion nozzle including the size and configuration of the nozzle outlet orifices . it is preferred , however , that the size of the dried capsule products is about 0 . 5 to 5 mm in diameter . accordingly , for a nozzle configuration such as shown in fig2 an outer diameter of annular aperture 12 of about 0 . 5 to 5 mm is suitable . in examples below , a co - extrusion nozzle is employed which has a central circular aperture of 1 mm and an annular aperture which surrounds the central aperture and has an inside diameter of substantially 1 mm and an outer diameter of 2 mm . for this nozzle , a flow rate of from 1 to 100 ml / minute at a pressure of up to 30 or 40 psi is suitable for both the coffee extract and the gasified oil . variable speed pumps are preferably employed to force the extract and gasified oil components through the co - extrusion nozzle . controlling the pump speed will control the flow rate and pressure , and pump speeds can be easily set to cause the formation of the droplets . gasification of the aromatized oil is preferably conducted with co 2 or with any other inert gas such as nitrogen which does not adversely affect coffee aroma . gas injection is preferably accomplished with a sparger and at a gas pressure which causes the oil to foam . a gas pressure in the range of 10 - 50 psi is suitable . anhydrous alcohol is preferred as the liquid desiccant in tank 15 , and it is preferred to position tank 15 such that the droplets do not impact the upper surface of the liquid at a velocity that would cause significant distortion . it is preferred that the aromatized coffee oil both before and after being gasified , is maintained at a temperature of from 0 to 50 ° c ., and more preferably not more than 25 ° c . it is preferred to maintain the coffee extract at a temperature of from 0 to 70 ° c ., and preferably not more than 40 ° c . the liquid desiccant is preferably maintained at a temperature of from 10 to 80 ° c ., and more preferably from 35 to 50 ° c . the amount of the aromatized oil fed to the co - extrusion nozzle is preferably from 20 to 80 %, and more preferably from 40 to 60 % by weight , based on the weight of the combination of aqueous extract and oil fed to the nozzle . the product particles are substantially spherical and preferably have a particle size ( diameter ) of from 0 . 5 to 5 mm . wall thickness of the product particles is preferably from about 20 to 80 % of the particle diameter . the content of aromatized oil is the product particles is preferably from 20 to 80 %, and more preferably from 40 to 60 % by weight , based on the weight of the product particles . moisture content of the product particles is generally from 0 . 5 to 5 % by weight , and preferably from 2 to 4 % by weight , based on the weight of the particles . the entire content of the particles is preferably 100 % coffee derived . scanning election microscope ( sem ) examination of sections of the encapsulated product particles shows that the solid wall is porous and that the porosity is substantially all of the closed cell type , with very little channeling and open pore porosity that would permit rapid loss of encapsulated aroma , examination of sem of product particles encapsulated with coffee extracts having a solids content of from 50 to 75 % in accordance with the invention shows that the total pore volume of the open cell porosity or channeling in the walls of the product particles does not exceed about 25 % of the total pore volume . product particle density is preferably about 0 . 1 to 0 . 8 g / cc and more preferably about 0 . 2 to 0 . 4 g / cc . it is a distinct advantage of the invention that the relatively low density of the product particles will cause the particles to float and remain on or near the surface of hot water . the porous nature of the shell of the capsule facilitates its dissolution at a rate comparable to that of spray dried coffee , and the aroma will tend to be released at or near the surface of the hot water which will minimize the loss of aroma due to dissolution in the water and maximize a burst of cup aroma . the coffee oil and coffee aroma employed in the invention can be any coffee oil or aroma derived from coffee such as those described in the u . s . patents identified above , the disclosures of each of which are herein incorporated by reference . it is preferred to employ from 0 . 01 to 20 % by weight and more preferably from 0 . 2 to 2 % by weight coffee aroma , based on the weight of the aromatized coffee oil . the aromatized product capsules are preferably utilized in instant coffee products , such as spray dried or freeze dried instant coffee products , preferably in an amount of from 0 . 01 to 20 %, and more preferably 0 . 1 to 1 % by weight , based on the weight of the instant coffee to which the capsules are added . the capsules are preferably homogeneously blended with the instant coffee and it is an advantage of the invention that the process can be easily controlled to produce capsules having a density which closely matches a target density of an instant coffee product to which the capsules are intended to be added . in order to minimize particle segregation , it is preferable that the capsule density is not more than 10 - 350 % different than that of the particulate instant coffee product with which the capsules are blended , which is primarily determined by the level of substitution . dehydrated aromatized coffee oil containing 20 % by weight of coffee aroma obtained from cryogenically condensed aroma frost is gasified by injecting carbon dioxide at a pressure of 20 psi . the gasified aromatized coffee oil is pumped through the central 1 mm aperture of a stainless steel co - extrusion nozzle . an aqueous coffee extract having a soluble coffee solids content of 65 % by weight is simultaneously pumped through an annular aperture which surrounds the central aperture . the annular aperture has an inside diameter slightly greater than 1 mm , an outside diameter of 2 mm , and an annular width of ½ mm . the extract is pumped at a flow rate of 20 ml / minute and at a pressure of 30 psi . the gasified aromatized coffee oil is pumped at a flow rate of 20 ml / minute and at a pressure of 30 psi . the co - extruded material forms droplets of gasified aromatized coffee oil encapsulated in the aqueous coffee extract . the droplets fall into a tank containing anhydrous alcohol having a water content of not more than 3 % by weight . a stream of alcohol is continuously pumped from the tank through a calcium sulphate drying tower to remove water , and the dehydrated alcohol is recycled to the tank . the liquid coffee extract droplets become dehydrated in the anhydrous alcohol , causing the formation of soluble coffee particles having a solidified shell of soluble coffee encapsulating the aromatized coffee oil . the dried particles are separated from the alcohol and gently heated at 20 - 50 ° c . to completely remove alcohol form the particles . scanning electron microscope examination of sections of the particles shows that the solidified shell has many fine closed cell pores . the amount of open porosity in the shell is estimated to be about & lt ; 25 % based on the total shell porosity . the size of the particles is 1 - 3 mm . density of the particles is 0 . 15 - 0 . 3 g / cc . example 1 is followed , except that the solids concentration of the aqueous extract , and the pumping pressure and flow rates are as shown in table i . table i gasified extract coffee oil solids pumping flow pumping flow ex - conc . pressure rate pressure rate ample ( wt . %) ( psig ) ( ml / min ) ( psig ) ( ml / mm ) 2 60 30 20 40 80 3 70 40 40 30 10 particle size , density and porosity results are as reported in table ii . table ii particle open cell size density porosity example ( mm ) ( g / cc ) (% of total porosity ) 2 1 - 2 0 . 25 - 0 . 25 & lt ; 10 3 1 - 4 0 . 15 - 0 . 25 & lt ; 25 the aroma produced on dissolving the capsule particles of examples 1 - 3 is evaluated by blending the particles with a fresh portion of maxwell house ® coffee , a commercially available spray dried instant coffee . the blend contains 1 % by weight of the capsule particles based on the weight of the blend . a coffee beverage is prepared by spooning 1 grams of the blend into a coffee cup containing 100 ml . of water at 80 ° c . comparison beverages are prepared in the same manner , employing the same amount of the commercial instant coffee employed to make the blends . a sensory panel of twenty persons is employed to evaluate the perception of aroma . the sensory panel evaluates the perception of aroma burst on preparation of the coffee beverage and the perception of aroma over the cup after the beverage is prepared . results are as shown in table iii . table iii perception of aroma at time of beverage beverage preparation over - the - cup commercial soluble none very little coffee with capsules of significant some example 1 with capsules of very significant fairly significant example 2 with capsules of some some example 3 gc count was total count analyzed over 2 minutes of preparation time . the cup after preparation was placed under closed container from which released aroma + air were pumped to gc for analysis . from table iv it is clearly evident that capsules loaded with higher aroma dosage show higher gc count and higher aroma is perceived . table iv at time of beverage preparation beverage sensory - perception chemistry - gc count commercial soluble coffee none 235 , 350 with capsules of significant 2 , 539 , 430 example 1 with capsules of very significant 8 , 467 , 830 example 2 with capsules of some 700 , 450 example 3 type of aroma carrier oil and water soluble encapsulant material can be changed utilizing exactly the same conditions . table v lists different materials used . aqueous solution of 65 % concentration of the various water soluble encapsulant materials are co - extruded with aroma fixed with different carrier oil as core material . table v example aroma oil shell material 4 coffee palm oil coffee 5 coffee coffee oil gelatin 6 coffee coffee oil cyclodextrin 7 coffee coffee oil maltodextrin 8 artificial coffee coffee oil coffee aroma ( supplied by givaudan *) code : 10283 - 73 9 mint ( supplied by palm oil gelatin givaudan *) code : 10732 - 76 dehydrated aromatized palm oil containing 20 % by weight of coffee aroma obtained from cryogenically condensed aroma frost is gasified by injecting carbon dioxide at a pressure of 20 psi . the gasified aromatized palm oil is pumped through the central 1 mm aperture of a stainless steel co - extrusion nozzle . an extract of coffee having solids content of 65 % by weight is simultaneously pumped through an annular aperture which surrounds the central aperture . the coffee extract and gasified aromatized palm oil are pumped at a flow rate of 20 ml / minute and at a pressure of 30 psi . the co - extruded material forms droplets of gasified aromatized palm oil encapsulated in the coffee extract which are dried in anhydrous alcohol having a water content of not more than 3 % by weight . the dried particles are separated from the alcohol and gently heated at 20 - 50 ° c . to completely remove alcohol form the particles . the amount of open porosity in the shell is estimated to be about & lt ; 25 % based on the total shell porosity . the size of the particles is 1 - 3 mm . density of the particles is 0 . 15 - 0 . 3 g / cc . dehydrated aromatized coffee oil containing 20 % by weight of coffee aroma obtained from cryogenically condensed aroma frost is gasified by injecting carbon dioxide at a pressure of 20 psi . the gasified aromatized coffee oil is pumped through the central 1 mm aperture of a stainless steel co - extrusion nozzle . an aqueous solution of cyclodextrin 65 % concentration is simultaneously pumped through an annular aperture which surrounds the central aperture . the aqueous cyclodextrin solution and gasified aromatized coffee oil are pumped at a flow rate of 20 ml / minute and at a pressure of 30 psi . the co - extruded material forms droplets of gasified aromatized coffee oil or aromatized oil encapsulated in the aqueous cyclodextrin which are dried in anhydrous alcohol having a water content of not more than 3 % by weight . the dried particles are separated from the alcohol and gently heated at 20 - 50 ° c . to completely remove alcohol from the particles . the amount of open porosity in the shell is estimated to be about & lt ; 25 % based on the total shell porosity . the size of the particles is 1 - 3 mm . density of the particles is 0 . 15 - 0 . 3 g / cc . dehydrated aromatized coffee oil containing 20 % by weight of coffee aroma obtained from cryogenically condensed aroma frost is formed by injecting carbon dioxide at a pressure of 20 psi . the gasified aromatized coffee oil is pumped through the central 1 mm aperture of a stainless steel co - extrusion nozzle . an aqueous solution of gelatin having 65 % concentration is simultaneously pumped through an annular aperture which surrounds the central aperture . the aqueous solution and gasified aromatized coffee oil are s pumped at a flow rate of 20 ml / minute and at a pressure of 30 psi . the co - extruded material forms droplets of gasified aromatized coffee oil or aromatized oil encapsulated in the aqueous gelatin which are dried in anhydrous alcohol having a water content of not more than 3 % by weight . the dried particles are separated from the alcohol and gently heated at 20 - 50 ° c . to completely remove alcohol form the particles . the amount of open porosity in the shell is estimated to be about & lt ; 25 % based on the total shell porosity . the size of the particles is 1 - 3 mm . density of the particles is 0 . 15 - 0 . 3 g / cc . dehydrated aromatized coffee oil containing 20 % by weight of coffee aroma obtained from cryogenically condensed aroma frost is gasified by injecting carbon dioxide at a pressure of 20 psi . the gasified aromatized coffee oil is pumped through the central 1 mm aperture of a stainless steel co - extrusion nozzle . an aqueous solution of maltodextrin having 65 % concentration is simultaneously pumped through an annular aperture which surrounds the central aperture . the aqueous solution and gasified aromatized coffee oil are s pumped at a flow rate of 20 ml / minute and at a pressure of 30 psi . the co - extruded material forms droplets of gasified aromatized coffee oil or aromatized oil encapsulated in the aqueous maltodextrin which are dried in anhydrous alcohol having a water content of not more than 3 % by weight . the dried particles are separated from the alcohol and gently heated at 20 - 50 ° c . to completely remove alcohol from the particles . the amount of open porosity in the shell is estimated to be about & lt ; 25 % based on the total shell porosity . the size of the particles is 1 - 3 mm . density of the particles is 0 . 15 - 0 . 3 g / cc . dehydrated coffee oil is aromatized with artificial coffee flavour supplied by givaudan ( code : 10283 - 73 ) by adding 20 % flavour by weight and the combination is gasified by injecting carbon dioxide at a pressure of 20 psi . the gasified aromatized coffee oil is pumped through the central 1 mm aperture of a stainless steel co - extrusion nozzle . an extract of coffee having solids content of 65 % by weight is simultaneously pumped through an annular aperture which surrounds the central aperture . the coffee extract and gasified aromatized oil are pumped at a flow rate of 20 ml / minute and at a pressure of 30 psi . the co - extruded material forms droplets of gasified aromatized coffee oil encapsulated in the coffee extract which are dried in anhydrous alcohol having a water content of not more than 3 % by weight . the dried particles are separated from the alcohol and gently heated at 20 - 50 ° c . to completely remove alcohol form the particles . the amount of open porosity in the shell is estimated to be about & lt ; 25 % based on the total shell porosity . the size of the particles is 1 - 3 mm . density of the particles is 0 . 15 - 0 . 3 g / cc . mint flavour supplied by givaudan ( code : 10732 - 76 ) is added to palm oil at 25 % by weight which is gasified by injecting carbon dioxide at a pressure of 20 psi . the gasified aromatized palm oil is pumped through the central 1 mm aperture of a stainless steel co - extrusion nozzle . an aqueous solution of gelatin having 65 % concentration is simultaneously pumped through an annular aperture which surrounds the central aperture . the aqueous solution and gasified aromatized palm oil are pumped at a flow rate of 20 ml / minute and at a pressure of 30 psi . the co - extruded material forms droplets of gasified aromatized oil encapsulated in the aqueous gelatin which are dried in anhydrous alcohol having a water content of not more than 3 % by weight . the dried particles are separated from the alcohol and gently heated at 20 - 50 ° c . to completely remove alcohol form the particles . the amount of open porosity in the shell is estimated to be about & lt ; 25 % based on the total shell porosity . the size of the particles is 1 - 3 mm . density of the particles is 0 . 15 - 0 . 3 g / cc .
the present invention describes aromatized particles containing aromatized vegetable oil contained within a shell of a water soluble encapsulant such that upon dissolution with hot water a burst of aroma will be released . the process to produce the aromatized particles is also set forth .