CA1142022A - Direct condensation of food volatiles onto a food substrate at cryogenic temperatures - Google Patents

Abstract

DIRECT CONDENSATION OF
FOOD VOLATILES ONTO A FOOD
SUBSTRATE AT CRYOGENIC TEMPERATURES

Gordon K. Stipp Abstract A method for the direct condensation of gaseous food volatiles, such as coffee aroma, on a food substrate such as coffee, at cryogenic temperatures. A bed of particulated solid substrate is placed in a vessel cooled by a cryogenic fluid such as liquid nitrogen.
The substrate is fluidized to provide an adsorbent bed thereof. Gaseous aroma volatiles are then adsorbed onto the cooled and fluidized bed of substrate having a temperature preferably below -150°F. The aromatized substrate formed is preferably equilibrated to insure uniformity of aromatization, binding of volatiles to the substrate and storage stability. The resultant aromatized substrate can then be added to unaromatized food material for aroma and/or flavor enhancement.

Description

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DIRECT CONDENSATION Of FOOD VOLATILES ONTO A FOOD
SUBSTRAT~ ~T CRYOGENIC TE~lpERA-ruREs Gordon K. Stipp Technical Field _ _ .
The present application relates to the field of aromatization of food materials, in particular, coffee.
Background Art A frequent problem in food processing is the loss of - aroma and/or flavor volatiles. In the case of coffee, these volatiles can be lost at a number o-F points in the processing. One point is when the coffee beans are roas-ted. See U.S. Patent 2,087,602 to McCrosson, Issued July 20, 1937, which discloses a process for enrichinq the aroma and flavor of coffee by drenching roast and ground coffee with aroma-laden gases liberated during green bean roasting in a sealed coffee roa~ter.
- Roasting produces gaseous aromas which are generally -~ harsh and unpleasant-smelling but can be fractionated to recover useful aroma volatiles. See U.S. Patent

2,156,212 to Wendt et al, issued April 25, 1939, which discloses a process wherein vapors from roaster gases are collected and purified and then contacted with liquid coffee concentrate, coffee powder or roast and ground coffee.
Another point ~here aroma volatiles are lost is during the grinding of the roasted beans. Although grinding is necessary to liberate solubles for extraction, a substantial portion (about 50%) oF the -- 25 aroma volatiles are fre~uently lost. See U.S. Patent 2,3û6,061 to Johnston, issued December 12, 1942, wherein compounds or vapors released duriny grindincg of roasted coffee are brought into contact with coFfee or beverage extract, e.g. soluble coffee, in a vessel cooled to -70C (-94F) to -15C (-20F) by dry ice or brine.

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z Another point where aroma volatiles can be lost is duriny milling o f coffee to produce fla~ed coffee.
Although flaked cof~ee has increased extractability, the aroma intensity of the coffee is much less than that of 5 roast and ground coffee due to loss of aroma volatiles (about 75% of total available) liberated during milling. See U.S. Patent 3,615,667 to Joffe, issued October 26, 1971, wherein flaked low and intermediate grade coffees which are poor in aroma quality are 10 combined with high grade coffees having good aroma qualities.
T~YO principal methods are used to correct the problem of aroma volatile loss in coffee processing.
The first method involves-low temperature~grinding to 15 prevent excessi~Je release of aroma volatiles. One example is the grinding of roasted coffee beans in the presence of liquid nitrogen. See British Patent Dooument 1,424,264 to Strobel, published February 11, 1976. Another example is the co-grinding of coffee 20 beans with dry ice. See U.S. Patent 3,725,076 to Stefanucci et al, issued April :3, 1973.
Low temperature grinding to prevent excessive release of arorna volatiles has a number of disadvantages. In the case of liquid nitrogen grinding, 25 special equipment is necessary, adding to the expense of the processing. Also, the aroma character of the volatiles produced during low temperature grinding can be significantly different from aroma volatiles produced by grinding at ambient temperatures. Further, there is 30 a practical limit to the amount of volatiles which can be retained.
The other principal methad for dealing with the problem of the loss of aroma volatiles is by recovery thereof on an aroma substra te. ûne example is direct 35 c~ndensation of gaseous volatiles on a chilled aroma substrate, as suggested by the Johnson patent.
Typically,- cryogenic temperatures (below -150F) are employed See Canadian Application Serial No. 339,031 of Edmund P. Pultinas, filed November 2, 1979, conunonly .

, _ . , , ... _., . . , ,, .. . ... _ , _ _ ... . _ ..... ,_~ .. . . . . ..

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. -3-asslgned1 which discloses a method for forming highly aroMati~ed cofFee products by adsorbing grinder gas onto a packed column of coffee cooled by liquld nitrogen.
See also U.S. Patent 3,~23,2~1 to Patel e-t al, issued July 9, 1974, wherein an absorbent carrier is cooled to at least -~0F (preferably -15ûF~ and then placed in communication with roast and ground coffee under pressure conditions which transfer the roffee aroma to the absorbent carrier. Another example is aroma frost equilibration with an aroma substrate ~hich is typically a liquid glyceride such as cof-fee oil. See U.S. Patent * 3,7~3,163 to Patel, issued January 1, 1974, which discloses a method for aromatizing edible oils by adding the oil to a cryogenic fluid to form a slurry, adding an 15 aroma frost to the slurry, preferably with mixing, and then allowing the mixture to equilibrate to evaporate the cryogenic fluid, leaving behind a residue of aroma-enhanced oil.
The use of liquid nitrogen for volatile recovery, as 20 in the case of liquid nitrogen grinding, results in high capital and operational cost for large-scale processes because of the heat transfer limitations of conventional liquid nitrogen processinr~. For exarnple, in the case of ~ aroma frost ecluilibration with coffee, the standard.~ 25 equipment for -Forming the aroma frost-is a scrapped-wall heat exchanger. The wall of the exchanger generally ` serves as a heat transfer barrier, thus necessitating lirluid nitrogen as the coolant to offset this heat transfer problem. Even where liquid nitrogen is used, significant heat transfer limitations can remain. For example, in the case of direct condensation of gaseous aroma volatiles onto a packed column of coffee, thermal gradients are created because of low effective bed therma~ conductivity of the packed column which result in non-uniform adsorption of the volatiles onto the coffee.
Further, the lo~ temperatures created by liquid nitrogen processing tend to magnify the heat transfer problems. The volatile strearn used in direct .

z . -4-condensation or aroma frost formulation usually contains predominant amounts of other compounds. For example, a grinder gas stream of coffee aroma normally contains 85 air, 3% water, 12% C02 and only 0.1% aroma volatiles.
These other compounds can condense at liquid nitrogen temperatures, thus creating an additional sensible heat load ~hich necessitates the use o~ more liquid nitro~en at an additional cost.
A suitable method for direct condensation of food volatiles on a solid fo~d substrate is described in a Canadian patent application to Gordon K. Stipp and Hing C.
Tse, Serial No. 363,212, filed October 24, 1980, entitled "Method for the Collection of Aroma Volatiles Onto a Food Aroma Substrate", commonly as-signed. A
particulate mi~ture of solid coolant such as dry ice and food substrate such as coffee is rapidly agitated while in contact with food volatiles, preferably coffee aroma, which adsorb onto the mixture. The coolant is then vaporized to provide an aromatized food product. This process enables direct absorption of coffee aroma on a solid coFfee substrate at significantly higher temperatures, e.g. -110F to -80F where dry ice is the solid coolant, than are possible with liquid nitrogen processing because of improved heat transfer characteristics.
me process described in the ~x~e-mentioned Stipp et al application is an economical and e~ficient method for direct condensation of volatiles on a solid food substrate.
However, this process does have a couple of requirements which can create some inflexibility. The number of commercially available solid coolants is limited. Also, the solid coolant must be vaporized or removed from the aromatized solid food substrate which can lead to volatile stripping. Further, where dry ice is employed as the coolant, a sharp aroma is imparted to the substrate which may be undesirable for $ome food materials. In addition, lower, e.g. liquid nitrogen, temperatures are sometimes necessary for maintaining the aroma profile of certain volatile mixtures.

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Comme~cially practical methods for direct condensation oF gaseous volatlles, especially coffee aroma, on a solid aroma substrate, especially solid, particulated coffee oil, at cryogenic ternperatures are still needed.
- S It is therefore an object of the presen~ invention to provide a process ~or direct condensation of gaseous volatiles on a solid food substrate at cryogenic temperatures which has improved heat transfer characteristics during condensation/adsorption of the volatiles on the substrate.
It is a further object of the present invention to

-3~ provide a process for direct condensation of gaseous -- volatiles on a solid food substrate at cryogenic temperatures which is efficient and economical.
It is yet a further object of the present invention to provide a process for direct condensation of gaseous volatiles on a solid food substrate at cryogenic temperatures ~hich is commercially oractical.
It is yet another object of the present invention to ~, 20 provide a process for direct condensation of gaseous arorna on a solid food substrate at cryogenic ternperatures which results in an aromatized product having good fidelity arorna.
These and further objects of the present invention are disclosed hereafter.
Disclosure of the Invention A. Summary of the Invention The present invention relates to a novel method for direct condensation of food volatiles, in particular, coffee volatiles, on a food substrate, in particular, a coffee substrate at cryogenic, e.g. liquid nitrogen, ternperatures. A particulated solid food substrate is placed in a vessel. The vessel is cooled with a : cryogenic fluid. The food substrate is then fluidized to provide an adsorbent bed thereof. The fluidized, cooled bed of substrate ~Ihich has a bed temperature belo~ about -100F, preferably belo~ about -150F, is - contacted with gaseous food volatiles to condense and ~` adsorb the volatiles thereon.
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The process o~ the present invention significantlyimproves heat transfer ~rom the bed of substrate during condensation/adsorption of the volatiles. By promoting heat transfer from the bed of substrate, the volatiles adsorb more readily and uniformly onto the substrate compared to prior art liquid nitrogen recovery techniques. Further, the process of the presen-t invention is more practical and economical for volatiles recovery than prior art liquid nitrogen recovery techniques. Yet, the process of the present invention provides aromatized suostrates having good fidelity aroma.
``~` U.5. Patent 3,~23,241 to Patel ét al, issued July 9, ` 1974, does disclose a method for direct condensation of gaseous coffee aroma on a substrate such as coffee oil sprayed on instant coffee or cryofied, particulated coffee oil wherein the substrate can be "continuously agitated". However, it has been found that not all ,~ forms of agitation will work. The bed of food substrate must be fluidized, e.g. rapidly agitated, to improve heat transfer rates during condensation/adsorption of the volatiles so that the volatiles adsorb faster and more unlf`ormly on the substrate. The faster, more uniform adsorption of the volatiles makes the process of the present invention more com~ercially practlcal ~or volatiles recovery than prior art liquid nitrogen processing.
B. Food Substrates A variety of food substrates can be used in the process of the present invention. The general requirements are that the substrate be in solid form and exist either naturally, or by size reduction, as discretc units or particles. Generally, volatiles transfer to the substrate material is increased by ~.,_ decreasing the particle size thereof. Also, materials which contain edible oils, either naturally or by addition, adsorb greater amounts of volatiles. Ho~ever, it is to be understood that excessive amounts of added oil can adversely affect subsequent volatile release.

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Further, substrate materials which are porous tend to retain the volatiles more efFectively.
Materials which can be employed as food substrates include a variety of vegetables and fruits and combinations thereof, such as nuts, peanuts, cereals, and tea, or processed food materlals such as meat analog (derived from soy or other vegetable proteins). Also, - edible oils of the animal or vegetable fat variety such as soybean oil, rapeseed oil, cottonseed oil, marine or animal fats, and oils extracted from fruits can be employed. The edible oil must be solidified and particulated when forming the bed of food substrate.
The process of the present invention is particularly useful for coffee substrate materials, ~oth decaffeinated and undecaffeinated varieties. These coffee materials can include roast and ground coffee, flaked coffee, instant (soluble) coffee, expeller cake, as well as roasted arains, such as sprouted barley, rye, corn and chicory, or combinations of dif~erent coffee substrates with these roasted grains. Also, coffee substrates comprising edible oilsj i.e. an edible oil alone or an edible oil sprayed onto another coffee aroma substrate, can be employed in the process of the present invention. Coffee oiI, alone or in combination with an additional coffee substrate, as well as roast and ground and flake coffee, are preferred. The method of the ` present invention is particularly directed at-the aromatization of solid particulated edible oils, especially coffee oil.
Roast and ground coffee can be made by methods well known in the art. See, for example, "Coffee Processing Technology", Sivetz & Foote, The Avi Publishiny Co., Westport, Connecticut, 1963, Vol. I, pp. 203-239, for an illustration of grinding techniques. A variety of roast and ground coffee blends, including those which may be classif:ied for convenience and slmplification as low-grade, intermediate yrade, and high-grade coffees can be used. Suitable examples of lo~-grade coffees include the natural Robustas such as the Ivory Coast .

. -8-Robustas and Angola Robustas, and the natural Arabicas such as the natural Perus and natural Ecuadors.
Suitable intermediate-grade coffees include the natural Arabicas from Brazil such as Santos~ Paranas and ~inas, and natural Arabicas such as Ethiopians. Examples of high-grade coffees include the washed Arabicas such as Mexicans, Costa Ricans, Colombians, Kenyas and New Guineas. ûther examples and blends thereof are known in the art and illustrated in, for example, U.S. Patent 3,615,667 to Joffe, issued ûctober 26, 1971 Roast and ground coffee which has been transformed into flaked coffee by roll milling roast and ground coffee is known in the art. Processes for preparing flaked coffee are disclosed in U.S. Patent 3,615,667 to Joffe, issued Oct. 26, 1971, and in U.S. Patent 3,66û,1û6, to McS-~iggin et al, issued May 2, 1972 C. Food Volatiles A variety of food volatiles (aroma and/or flavor volatiles) derived from numerous sources can be employed in the process of the present invention. The general requirement of the volatiles is that they be gaseous when brought into contact with the food substrate. The volatiles can be derived From a variety of vegetables and fruits such as roasted beans, nuts, oranges and the like. Also, volatiles of a synthetic variety can be used in the process of the present invention. If desirable, volatiles from one food source can be adsorbed onto a food substrate from a different food source. In the case of coffee volatiles, those which are gaseous below 350F are preferred.
The food volatiles preferably adsPrbed onto the substrate are coffee volatiles. lhese coffee volatiles can be derived from a variety of sources. For example, wit~ regard to roast and ground c;offee processing, volatiles can be obtained from gases evolved during roasting, grinding, flaking, bulk handling and other processing steps. With regard to instant coffee processing, volatiles can be obtained during dry distillation or steam distillation of roast and ground coffee beans, such as Desorbate volatiles obtained from the process described in U.S. Patents 3,717,472, issued Feb. 20, 1973, and 3,997,685, issued Dec. 14, 1976 to Strobel, and U.S. 4,10n,305, issued to ~regg, July 11, 1978, or from extraction stripping condensate, stripped coffee oil and/or similar sources.
A preferred source of cof`fee volatiles is grinder 10 gas. As used in the present application, the term --"grinder gas" is defined as those aroma and flavor volatiles liberated during and after t~ grinding of the `* roasted coffee beans. Preferentially, the grinder gas is that gas drawn directly from the gr?nder but can include gas from such sources as flaking mills and coffee bins. This gas is preferred because it contains the richest and most intense source of those aroma and flavor constituents perceived by the user as most desirabl^. Also, the utilization of t.~is gas rep~e~ents the recovery of material normally lost during ; conventional roast and ~ouP~ fee proc2ssing.
D. Coolant The coolant used in the process of the preseni invention is a cryogenic fluid. As used herein, the term "cryogenic fluid" refers to those liquids haviny low temperature boiling points, i.e. below -150F, and typically on the order of about -300F. Suitable cryogenic fluids which can be used in the process of the present inven-tion include linuid nitrog2n (b.p. -320F), liquid oxygen (b.p. -297F), liquid air (b.p. -31~F), and the like. From the standpoint of cornrnercial availability, the preferred cryogenic fluid .is liquid nitrogen.
E. Description of Process - 35 1. ~y___cation of Substrate and Vessel Coolinrl It is a preferable preliminary step in the process of the present invention to precool the substrate with a cryogenic fuid. For ex3mple, the substrate can be added directly to the cryogenic fluid, prefera~ly liquid ~2~ZZ

--1 o ritrogen, in a process called l'cryofication".
Cryofication is a particularly preferable method for forming particulated edible oil substrates because the cryogenic fluid fractures the oil into very small particles (preferably 5ûû rnicrons in size or less) providin~ a large surface area and a porous structure in the particles which increases the adsorption of the volatiles. See U.S. Patent 3,783,163 to Patel, issued Jan. 1, 1974, Col. 3, lines lû-27, which describes a process for cryûfication of an edible oil such as coffee oil. Other rnethods for cryofying the substrate include grinding in the presence of a cryogenic fluid and co-spraying the substrate with a cryogenic fluid.
The vessel in which the volatiles are condensed/adsorbed onto the food substrate is cooled by a cryogenic fluid. Preferably, the vessel is insulated as much as possible from th~ surrounding environment to minimize intrusion of heat. Typically, the cryogenic fluid is circulated through the jacket of the vessel to provide the cooling. Generally, high flow rates oF
coolant and cooling of as much of the vessel surface area as possible are desirable to maintain theaverage temperature of the bed of substrate inside the vessel below about -lû0F and preferably below about -150F.
Further, greater interior vessel surface area to substrate volume ratios are preferred.
2. Fluidized beds It is irnportant to the process of the present invention that the food substrate be fluidized to provide an absorbent bed thereof. A fluidized ~ed of substrate is necessary to maintain a more uniform bep temperature, to permit a greater heat dissipation rate during condensation/adsorption of the volatiles onto the substrate and to promote faster adsorption of volatiles onto the substrate. The term "fluidi~ation" refers to a process where fine~ solid particles are made to behave in a fluid-like manner. A dense phase fluidized bed, such as a bed of particulated solid food substrate, , _ _ ... ._. . ... _ . . . . .... .. __ _ . ., ___ .. .. . . ... ... _ ~9l20;~

behaves much like that o~ a boiling l.iquid.
Fluidization normally takes place when the force of the fluidizing gas exceeds the weight and friction factors within the bed of solid particles. For example, gaseous volatiles can be passed upwardly through the food substrate at a velocity sufficient to cause a fluidized bec~ thereof. Fluidization by passing a flow of gaseous volatiles through the ~ood substra~e is referred to ~ hereinafter as "gaseous fluidization". For a gaseous ; 10 fluidization sys-tem, fluidization velocities of about 2 to S ft./sec. are usually sufficient to provide the desired fluidized bed of substrate, e.g. roast and ground coffee. See Perry~s Chemical ~ngineeris Handbook . (4th ed. 196~), pp. 20-64 to 20 74 for a further description of fluidized beds.
~ The type of fluidized bed employed in the process of - the present invention can best be defined in terms of "bed porosity". Factors which go into defining bed porosity are the volume of the bed of food substrate, the density o~ the substrate, and the amount of substrate which is fluidized. A relationship which can be used to define bed porosity is:

E _ V@ _ (Ms/Ds) ~ B

q~ 25 where E is the bed porosity, VB is the total volume occupied by the bed of substrate, M5 is the arnount of substrate in the bed and D5 is the density of the substrate. The relationship VB - (MS/Ds~ defines the amount of void space in the bed. ûther relationships for defining bed porosity can be developed based on volume expansion of the bed of substrate during fluidization. For example, the following relationship can be employed:

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~,~

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2~2Z

EF = VN~VI ENV~I

where EF is the bed porosity of the fluidized (expanded) bed, VN is the volume of the nonexpandend or nonfluidized bed, VI is the volume increase on yoing from a nonexpanded to a fluidized bed, and EN is the bed porosity of the nonexpanded bed of substrate.
The value for EN can readily be determined for a given food substrate in a particular system when ~he bed is non-expanded. Because bed porosity can change significantly during the condensation/adsorption of the volatiles, the bed porosity values reFerrd to in the present application are n~ormally determined prior to the condensation/adsorption step.
It has been found that a bed porosity value of from about 0.11 to 0.55 represents a nonexpanded or clo"fluidized system for solid coffee substra-tes, especially roast and ground coffee and particulated coffee oil. A bed porosity of at least about 0.73 has normally been found sufficient to provide an adequate fluidized bed of substrate For the process of the present invention. Preferably, the bed porosity value is at least about 0.81 to provide uniformly low temperatures in the bed oF substrate. The maxirnum bed porosity is generally determined by the size and geometry o~F the vessel where fIuidization takes place, the fluidization conditions and by the desire to avoid bubble formation in the bed which can lead to undesirable thermal gradients and nonuniform condensation/adsorption of the volatiles onto the substrate.
3. Mechanical Fluidization As indicated above, gasenus fluidization can be employed in the process of the present invention. A
preferred method for fluidizing the food substrate is mechanical fluidization~ i.e. rapid agitation with a `~` mechanical mixing system to provide the fluidized bed of ~2~

substrate. In mechanical fluidi~ation, the substrate is continuously hurled and whirled so as to create the fluidized system normally formed by gaseous fluidization. If desirable, combinations of both S mechanical arld gaseous Fluidization can be employed in the process of the present invention.
To achieve mechanical Fluidization in the process of the present invention, certain types of mixers are - usually neede~. For example, one suitable mixer employs an impeller in the form of a centrally rotating shaft having a plurality of radially extending arms attached thereto. Crescent- shaped scoops are attached to the ends of the arms. See U.S. Patent 3,273,863 to Lodige et al, issued Sept. 2û, 1966 which discloses a mixer employing an impeller having such crescent-shaped scoops. Another suitable mixer employs an impeller which has scoops in the form of a double-bladed plow.
See U.S. Patents 3,018,059, ~ssued Jan. 23, 1962, 3,027,102, issùed March 27, 1962, and 3,162,428, issued Dec. 22, 1964 to Lodige ét al, which disclose mixing devices employin~ impellers having double-bladed plow-shaped scoops.
Irnportant factors in providing the desired bed poroslties for a mechanically fluidi~ed bed of substrate in a yiven mixer are the tip speed of the impeller, i.e.
.~ the speed of the scoop, and the amount of substrate to be fluidi~ed. For exanlple, in the case of drip grind size roast and ground coffee, a bed-porosity of 0.91 is achievable where the arnount of coffee fluidi~ed is 60 lbs. in a 30û lb. capaci-ty mixer and the tip speed is 251 ft./min. By contrast, a bed porosity of 0.7~ is achievable where the amount of roast and ground cofFee ; is 18û lbs. and the tip speed is 314 f`t./min.
Generally, lower bed temperatures and better heat transFer characteristics are created as the tip speed of the mixer increases.
Typically, the mixer can be from about 209'~ to 60%
full of food substrate.

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4. Condensation and adsorption of the volatiles onto the fluidi~ed bed of_substrate While the bed of food substrate is in a cooled and fluidized state, the food volatiles are brought into contac-t therewith. It is usually desirahle to rernove any rnoisture from the volatiles prior to contact with the substrate to remove undesirable heat loads and to minimize plugg ng, i.e. ice freeze-up, of the fluidized -bed of subs-trate. The bed of substrate can be aromatized, i.e. aromatized with aroma and/or flavor volatiles, either in a batch-wise fashion or by a continuous method. The amount of contact time between the volatiles and the bed of food substrate depends on a variety of factors, including the amount of aromatization desired, the temperature of the bed, the type of substrate aromatized, etc. Generally, the length of con-tact time is preferably maximized to assure greater adsorption of the volatiles on the bed of substrate. If desirable, vola-tiles which are not adsorbed can be recycled back to the bed of substrate.
The gas loading (flow) rate of the volatiles throuyh . ~
the fluidized bed of food substrate can be very important with regard to bed temperature and heat transfer charcteristics thereo-F. Generally, it is desirable to maximize the gas loading rate of the volatiles through the bed of substrate to promote lower bed temperatures and greater heat transfer rates during condensation/adsorption of the volatiles on the substrate. For a mechanical fluidization system, a r~as loading rate of at least about 200 ft.3 of volatiles per hour per ft.3 of substrate is usually sufficient for the procesC of the present invention where the tip speed of the mixer is at least about 200 ft.irnln. For bed temperatures of from about -200 to ~300F, a gas loading rate of about 500 to 2000 ft.3 of volatiles per hour per ft.3 of substrate is usually preferred where the tip speed of the mixer is from about 400 to 1000 ft./min.

Although the volatiles can be brought into contact with the bed of food substrate at atmospheric pressure, pressurization and concentration of the volatile~ can also be employed without degradation thereof. The s volatiles can be pressurized up to about 100 psig or higher. Pressurization of the volatiles promotes adsorption of the volatiles onto the bed of food substrate. Also, because volatile transfer is promoted, pressurization of the volatiles can reduce cryogenic fluid usage, as well as increase the volatile processing capacity.
If desirable, the contacting step can be conducted under a vacuum. For example, the vacuum can be drawn on -- the vessel so as to pull the volatiles through the bed of food substrate.

5. Equilibration of Aromatized Substrate An ûptional preferable step after the volatile contacting step is equilibration. The equilibration step insures greater uniformity of aromatization of the , 20 food substrate. A variety of methods can be employed to equilibrate the aromatized food substrate. Generally, equilibration is conducted under conditions which promote uniformity of volatile adsorption on the food substrate but do not promote volatile stripping. If desirable, additional unaromatized food substrate in solid or liquid form can be added to the aromatized food substrate beFore the equilibration step~.
Two particular methods have been developed for the equilibration of coffee substrates aromatized with grinder gas volatiles. In one method, the volatile/substrate matrix is allowed to equilibrate àt temperatures above the vaporization point of C02 for at least a period of tirne sufficient to evaporate the Cû2 and leave behind a substrate enriched with volatiles. No special criticality is associated with the precise temperature employed as long as the temperature is above the vaporization point of C02.
Temperatures up to ambient can be used, although temperatures of from about -100F to about ûF are , z preferred. During the vaporization step, all undesired gases which are present can be removed, such as nitrogen, air, excess Cû2, e-tc. Preferably3 ~ to 8 days are allowed for equilibration to permit maxirnum uniforMity of aromatization on the substrate. After equilibration, the volatile-enriched substrate can be pacl<ed, or added to an unaromatized product, e.g.
instant or roast and yround coffee, to yield aroma and/or flavor enhancement for the unaromatized product and then packed.
An alternative method is pressure fixation ~here the volatile/substrate matrix is added to a pressure vessel. See U.S. Patent 3,939,291 to Katz, isued Feb. 17, 1~76; U.S. Pate~t 3,979,528 to Mahlmann, issued -~ 15 Sept. 7, 1~76, U.S. Patent 4,0û7,291 to Siedlecki et al, issued Feb. 8, 1977, which describe pressure fixation techniques for coffee aroma frost on liquid glycerides.
The contents of the vessel are gently heated by circulating a moderate heating medium (e.g. 753 to 175F
hot process water) through the jàcket o~ the vessel and agitated until the internal pressure is between 10 and 300 psig. Excess C02 is volatilized by both the agitation and heating process. Isobaric expansion of excess C02 in the venting process removes heat f`rom the vessel contents, thus maintaining the internal ternperature sufficiently low to minimize thermal `~ degradation of the volatiles. After the excess C02 has been vented, the vessel contents can be packed or - added to unaromatized product to enhance the aroma and/or flavor thereof and then packed.
In an optional method according to the present invention, the entire aromatîzation process can be conducted in a pressure vessel cooled with a cryogenic -~ fluid. For exarnple, solid particulated coffee substrate is added to the pressure vessel provided with a mechanical mixer. Coffee volatiles under pressure are continuously fed into the vessel. Generally, pressures up to 1200 psig or higher can be employed (at 75 psig, the critical point of C02, the C02 is generally -z~

-17_ present as a solid; at pressures of frorn about 75 psiy to 1200 psig, the Cû2 is present as a solid/liquid/vapor mix-ture; at pressures above 1200 psig, the C02 is generally present as-a gas). The substrate is rapidly agitated within the vessel to provide a fluidized bed thereof. After a period of time sufficien-t to allo~ adsorption of the cof~ee volatiles onto the bed, the excess C02 can be vented as in the foregoing described pressure Fixation tecnnique.

6. Advantages of the Process of the Present Invention over the Prior Art . . . ~
he process of the present invention has a number of advantages over conventional liquid nitrogen processing for volatile recovery. Because the bed of food substrate is fluidized during the contacting step, the process of the present invention tends to be better in dissipating sensible and condensation~adsorption heat loads. The process of the present invention also tends to promote the uniformity oF volatile adsorption onto the food substrate. As indicated previously, a packed bed of coffee cooled by liquid nitrogen has numerous thermal gradients which resu]t in non-uniform coating - and thus non-uniform adsorption of the volatiles on substrate. By contrast, due to fluidization of the food substrate in the process of the present invention, the bed of substrate has a fairly uniform temperature.
-~ Thus, volatiles tend to coat and thus adsorb onto the substrate more uniformly and rnore rapidly in the process of the present invention.
lhe process of the present invention also tends to be more economical than standard liquid ni-trogen processin~ for volatile recovery. Because oF the signiFicantly improved heat dissipation rates, the process of the present invention uses less cryogenic fluid than prior art liquid nitrogen processing for volatile recovery. Also? in the case of coffee aromatization, less coffee as the aroma source needs to be processed to aromatize a given amount of coFfee substrate in the process of the present inventlon.

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~18-Further, the volatiles can be adsorbed onto ~he food substrate in sufficient quantities at rela~ively higher temperaturEs in the process of the present invention compared to prior art liquid nitrogen processing.
F. Description of the Product .
It has been ~ound that the process of the present invention can be used to form aromatized food substrates, especially aromatized coffee substrates havinrJ high fidelity aroma. For example, roast and rJround coffee, flal<ed coffee and coffee oil aromatized by the process of the present invention are almost identical in aroma character and intensity to roast and ground coffee and flaked coffee aromatized by direct condensation on a.packed column, and coffee oil aromatized by aroma frost. The similarity in aroma character indicates that the chemical constituents required for good aroma character have been transferred to the coffee with minimal thermal degradation of the labile components. The aromatized coffee substrates have been found by gas chromatography to hav~ high aroma intensities, e.g. arorna intensities on the order of about 300,000 to 400,000 G.C. counts.
^ While it is possible to pacl<age the aromatized roast and ground and flaked coffee substrates made according to the process of the presen~ invention as i~, it is usually desirable to combine a minor amount, e.g~ about 20~ by weight, of the aromatized substrate with a major a~ount of non-aromatized, conventionally produced coffee materials. A method For combining the aromatized/non-aromatized blend is to first place the aromatized substrate at the bottom of the container. It is ex~remely desirable to keep this aromatized substrate below ûF in order to insure that the volatiles are not - lost unnecessarily. Next, the non-aromatized coffee material is placed on top of the aromatized substrate and the container sealed. The volatiles from the aromatizrd substrate pass throur~h the non-aromatized coffee materials and equilibrate therewith. On opening the container, the head space above the ~2~

aromatized/non-aromatized blend develops a pleasant cof~ee aroma.
In the case of aromatized oil such as coffee oil, the aromatized oil is normally added to an instant (soluble) coffee product. A preferred method is drop-wise addition of the oil to the coffee product.
See U.S. Patent 3,769,032 to Lubsen et al, issued Oct. 30 19720 The aromatized oil can typically be added to the instant coffee product at amounts of from about 0.05 to 0.8~ by weight of the coffee product.
G. G.C. Count Measurement A suitable technique for measuring actual aroma intensity of aromatized products made acCording to the process of the present invention is gas chromatography.
A flame ionization gas chromatograph analytical instrument measures the total content of organic compounds in a gas head space or void space sample from a packaged product on a scale of relative intensity.
The scale is graduated in microvolt-seconds (referred to herein as "G.C. counts") which is a measure of the area under the intensity curve, and the result is reported as an integration of the total area under the curve in total microvolt-seconds ( total counts ). The resulting G.C. count number is a measurement of the concentration of aroma volatiIes in the head or void space of the sample.
The chromatograph comprises a 36" "Chromosorb WAW *
(acid washed) 60/80 mesh column of 1/4 diameter and is housed in an oven section for isothermal temperature control. The column is packed with a uniform-sized solid called the solid support, but is not coated with a non-volatile liquid (called the substrate~ because the gas is not to be separated into individual compounds as is commonly done in this type of analysis. A hydrogen flame detector is used at the outlet port. An electrometer receives the output signal from the flame detector and amplifies it into a working input signal for an integration. The integrator both sends a display * Trademark for a brand of closely graded flux-calcined diatomite aggregates, used in gas chromatography.

.. . . . .. _. . .

,f2~

signal to a recorder to print out the response curve and electronically integrates the area under the curve.
The gas sample is injected into a heated injection port, and is immediately swept into the packed column by a carrier gas flow. The non-separated gas mixture is swept as a compact band through the colurnn and into the detector. The detector tnen ionizes the sample and generates an electrical signal proportional to the concentration of the materials in the carrier gas. The lo ionized gases and carrier gas are then vented from the unit.
... A Hewlett Packard gas chromatograph (Model 7ûO), electrometer (Model 5771A), integrator (Model 337û~), and recorder (Model 7127D), range 0-5 mv. and temperature controller (Model 220) are used. Nitrogen pressure in the column is approximately 16 psig. Air pressure of 24 psig is used to flush out the detector.
An oven temperature of 100C is used and maintained to r~f keep the volatiles vaporized. The hydrogen is supplied from a gas cylinder regulated at 30 pslg.
Each peak is measured in counts, the counts being - first measured by the flame detectûr and then both integrated and recorded. The number of counts for a particular component is directly proportional to the 2s number of milligrams of` that component in the vapor sample.
:~ The recorder is synchronized with the integrator as follo~ls:
1. _libration A standard methane gas is used to precisely set the flarne ionization response. Prior to analyzing the samples, a 1 cc. sample of gas is obtained from a gas cylinder (0.5% by weight of CH4). The pressure of the _ gas as it is obtained is 4 psi. The gas sample is syringed into the inlet port oF the gas chromatograph.
The attenuation of the recorder is set at 8 while the range is lû. The total counts when the procedure is repeated three times average between 145,000 to 150,000 total counts. If the average is not .within thæ

" ' `

specified ran~e, the carrier gas flow rate is adjusted.
2. Sample Analysis The sample is vacuum packed for at least 3 days at 75u + 5F before sarnpling. The amount of coFFee packed and the pressure within the canister is evaluated to insure that the sample will give a representative measurernent. The vacuum-sealed canis-ter of coffee is punctured to remove the vacuum, then resealed and allowed to equilibrate at least one hour at 75 + 5F to allow vapor phase equilibration.
AFter equilibration, a 1 cc. sample of the aromatic --.. ``~! atmosphere of the canister headspace/voidspace is taken again using the same type of syringe as used for the : standard methane sample. The gas sample is then injected into the inlet port of the gas chromatograph.
For roas~t and ground and flaked coffee products, the sample is normally taken from a 13 oz. or 16 oz. size can packed under normal coffee packing conditions.
However, differences in the can size or the amount of coffee packed do not generally create significant differences in G.C. count measurements unless the can is grûssly underfilled.
;~ Best Mode The following examples are intended to exemplify the present invention and are not limitinq thereof:

Sixty lbs. oF flaked coFfee having the following particle size distribution was added to a 10 ft3 capacity paddle mixer (3 ft. in length with 1.8 ft.
diame-ter impeller):
% Retalned on Screen Screen Size (U.S. Mesh ~!o.) 4 +12 ; 16 ~16 3523 ~20 16 ~30 41 Pan Approximately 80 lbs. of liquid nitrogen was slowly added to the coffee. The resultant mixture was agitated .~
~, :;

~1~2~

_22-at 188 ft./min. tip spee~ to reach an equilibrium bed temperature of -235f. Additional cooling was provided by -Fnrcing liquld nitrogen through the mixer jacket from a supply tank operating at 2û psig.
Grinder gases were yenerated by grinding a commercial coffee blend roasted to a color of 68-78 photovolts (see Sivetz, Ibid, Vol. II, at pp. 132-138 for measurirly the color of coffee by photoelectric devices) in a Model 56 Gump~grinder. The grinder was equipped with grinder gas take-off ports mounted beneath the grinder rolls and on the normalizer. The coffee -~ blend was ground at a rate of 636 lbs./hr. to a fine grind particle size distribution. Grinder gas was drawn ~' off at a rate of 9.1 ft.3/min. via a compressor operating at about 1 psig discharge pressure. The grinder gas was passed through the rapidly agitated (approx. 402 ft./min. tip speed) bed of particulated flaked coffee. Under static non-expanded conditions, the coffee bed fillecl about 20% of the total volurne of . !20 the mixer. Under agitation, the bed of coffee expanded -to the total mixer volume, yieldin~ a bed porosity uf about 0.91 . Grinder gas was drawn throu~h the expanded coffee bed at a gas loading (flow) rate of 273 ft.3/hr. per ft.3 of coffee. The gas entered below `25 the impeller at one elid of the mixer and was drawn out the otller end at the top of the mixer. Under these conditions, coffee bed temperatures ranged from -151 to -173F during the 4-1/4 hours of the aromatization run.
The intensity of aroma measured in the gas stream averaged 21,400 G.C. countsJcc. for the grinder gas feed into the mixer and 1700 G.C. counts /cc. on exiting the mixer, thus indicating that 92% of the volatiles were recovered.
-~t the completion of the aromatizatlon run, approximately 2,640 lbs. of coffee i-ad been ~round to aromatize the flaked coffee. The aromatized coffee was -removed from the mixer and stored at -80F in bulk containers. The aromatized coffee was held for 5 days -at -80F to separate residual carbon dioxide. The ~ .
~ ~r~ e ~

~2~Z

intensity of the aromatized coffee was determined by first blencling about lOo of the aromatized f`laked coffee with 9o~0 non-arorna-tized flaked coffee and then sealing the blend in a 1 lb. can under vacuum. Af-ter allowing the olend to equilibrate for at least 12 hours, the aroma headspace intensity wa measured by gas chromatography. The intensity of the 10% aromatized/90O
non-aromatized flaked coffee blend ~las found to be 49,980 ~.C. counts/cc. The intensity of the aromatized flaked coffee was determined to be 384,100 G.C.
counts/cc.
`~

Expelled and filtered coffee oil, having a total solid content of less than 1% by weight, was cryofied in a liquid nitrogen slurry. Oil was metered batchwise into a lir~uid nitrogen filled tank agitated by a 6 inch diameter, high dispersion mixer. About a 2:1 by weight ratio of liquid nitrogen/oil WaS present at the start of -j cryofication. After addition of the oil, the liquid 2C nitrogen/oil mixture was continuously agitated at about 900 ft./min. tip speed for 5 minutes. A total of 450 lbs. of particulated cryo~ied oil was formed in three 150 lbs. batches. A representative particle size distribution was as follows:

Screen Size % Retention (U.S. Mesh No.) . . . _ . . .
~6 8 +8 12 -~12 30 19 +20 +30 - 61 ~50 Oil temperature was -320F due to the presence of residual liquid nitrogen. Physic~lly, the oil existed 3s as discrete particles having a "puffed" appearance.
Four hundred and fifty lbs. of cryofied oil was added to a chillecl 30 ft. paddle mixer (4 ft. in ~l ~Z~'hZ

lengtn with a 2.8 ft. diameter impeller). Liquid nitrogen at 15 psi~ pressure was force circulated through the jacket at about 80 gal./min. flow rate. The cryofied oil was continuously agitated at 828 ft./min.
tip speed to flash residual liquid nitrogen. An equilibrium bed temperature of -303F was reached after two hours o-F agitation.
Grinder gases were generated by grinding a commercial coffee blend roasted to a color of 77-79 photovolts in a Model 88 Gump grinder. Grinder gas was drawn from 6-10 grinders equipped with grinder gas take-off ports mounted beneath the grinder rolls and on the normalizer. The coffee blend was ground at a nominal rate of 2900 lbs;/hr. to an electric perk particle size distribution. Grinder gas was drawn off at the rate of` 10-12 ft.3/min. from the grinders Yia a `` compressor operating at about 2 psig discharge pressure.
The cumulative grinder gas, which was dra~vn at a flowrate averaging 98 ft.3/min. from each grinder, was cooled to 75F via a gaséous nitrogen chilled tube ancl shell heat exchanger. ~he cooled grinder gas stream ~as passed through the rapidly a~itated ~approx. 940 ft./min. tip speed) bed of particuiated cryofied coffee cil. The oil bed temperature ranged from -3û7F to -2a9~F (average of -247F) during the 17 hours of the aromatization run. The amount of aroma measured in the gas stream averaged 26,400 G.C. counts/cc. for the grinder gas feed into the mixer and 1900 G.C. counts~cc.
on exiting from the mixer, thus indicating g3% of the Yolatiles were recovered.
The 45û lbs. of cryofied oil occupied approximately 30~ of the mixer volume. Under the agitation and gas loading conditions described above, the bed porosity at the beginning of the aromatization run increased to 0.73 (expanded) relative to 0.11 under static (nonexpanded3 conditions.
Due to condensation of C02 and H20, as well as - aroma volatiles, the batch ~Yeight in the mixer increased ` to 793 lbs. at the end of the aromatization run.

. . .~, .

~2~2~

At the completion of the run, approximately 62,700 ft.3 of grinder gas was processed. This gas was collected from about 384,ûO0 lbs. of ground coffee. The aromatized oil was removed from the mixer and stored at - 5 -80F in 14 ft.3 rectangular equilibration cells. The aromatized oil was held for 7 days at -80~F to separate residual C02 and to allow further aroma enrichment of oil. Following completion of equili~ration, the residual oil was heated yently with an electrically heated perforated plate. The melted oil was batch ; centrifuged in a lab unit at 3200 rpm for 30 minutes to separate water from the oil. Approximately 385 lbs. of refined oil and 52 lbs. of oil~H~0 sludge were ~ obtained, indicating an overall aromatized oil yield of ~6%.
The intensity of the aromatized oil was determined by placins one gram of oil in a 125 ml. glass septum bottle. The bottle was sealed with a rubber stopper and allowed to equilibrate at ambient temperatures ~or at 1 20 least one hour, prior to measurement of the~aroma - neadspace intensity by gas chromatography. The intensity of the aromatized oil was found to be 361,800 G.C. courlts/cc.
Approximately 0.11 grams of the aromatized oil was added drop-wise to 56 grarns of soluble instant coffee in a 2-ounce jar. The jar was then sealed with a glasine `~ liner. The instant coffee/aromatized oil mixture was allo~Yed to equilibra-te for at least 12 hours at ambient temperatures prior to gas chromatographic analysis. The headspace arorna intensity averaged 80,000 G.C.
counts/cc. and yielded good fidelity coffee aroma upon opening as determined by expert panelists.

.
~ EXAMPLE 3 ``- An alternative residual C02 separation technique 3s involv.ing pressure fixation of aroma volatiles onto the substrate was evaluated. The arornatized oil prepared in Example 2 was placed in a 2-liter batch pressure bornb.
The initial C02 content of the oil was estimated at . ~ .

about 40%-50%. The bomb was sealed and placed in an ayitated hot water bath. The pressure in the bornb was permitted to build up to 2û5 psig over an hour time period. The bomb was then slowly vented to atmospheric pressure at the rate of 0.25 ft.3/min. f~r an additional one-hour time period. The bo~b was then opened and the contents sealed in containers with gasketed tight-fi-tting lids.
The aroma intensity of a one gram oil sample in a 125 ml. septum bottle was determined by gas chromatography to be 322,600 G.C. counts~cc. The ~; drop-wise addition of 0.13 grams of this oil to 56 grams of soluble instant coffee yielded a 2-ounce jar - headspace intensity of 84,500 G.C. counts/cc. The j~r - 15 aroma was recognized as being good fidelity cofFee aroma by exper-t panelists.

The aroma volatile profile of aromatized coffee oil prepared in Example 2 (~irect), and coffee oil , 20 aromatized via the addition of aroma frost (Frost) were / determined by gas chromatography and compared.
The Frost oil was prepared as follows: A commercial blend of roasted coffee (77-79 photovolts) was ground in a Model 88 Gump grinder equipped with take-off ports below each side port and the normalizer. Grinder gas was pulled by a vacuum from the grinder a-t a rate of 7-9 ft.3~min. The nominal grinding rate was 3800 lbs./hr.
(average across all grinds ranging from drip to electric perk grind size). The nominal physical aroma intensity of the grinder gas stream averaged 35,00û to 40,000 G.C.
counts/cc. across all grind sizes. The grinder gas stream was condensed in a liquid nitrogen cooled 9 ft. scraped-wall heat exchanger at the rate of about ~ 10 lbs./hr. (9 ~t.3/min. gas loading rate and -3~0F
condensing temperature).
Clarified coffee oil (less than 1% solids content) was chilled to -320F by the addition of about a 3:1 by weight ratio of liquid nitrogen to coffee oil in a high : shear mixer. The resultant frozen mixture was rapidly ~l~Z~2~

-27~
mixerl to yield a finely particulated cryofied oil.
Sixty lbs. of this cryofied oil was added to ~10 lbs. of condensed aroma Frost frorn the scraped-~all heat exchanger and thoroughly mixed in a paddle mixer. T~e resultant mixture ~las transferred to 14 ft,3 rectangular equilibration cells and stored for 6 days at -80F. Following the melting/centrifuga-tion procedure described in Example 2, residual C02 and water ~ere evaporatr,~d from the aroma enriched cof-fee oil.
Approximately û.ll 9. of the Direct oil and 0.12 9.
of the Frost oil were added dropwise to 56 9. o~ solu~le coffee in a 2 oz. ~jar. The jar was then sealed with a glasine liner. The soluble coffee/oil mixtures were allowed to equilibrate for at least 12 hours at ambient temperatures prior to gas chromatographic analysis. The headspace aroma intensities averaged about 80,000 G.C.
counts/cc. for both Direct oil and Frost oil.
To determine the volatile profile for'Direct oil and Frost oil, a Perkin-Elmer Model 990 gas chromatograph equipped with temperature programming, flame ionization detector and Varian Integrator Model CDS 111 was used.
A 60 ft. lon~, 0.0~ inch diameter glass capillary column coat~d ~lith a thin layer of Carbo~ax 20R and heated in an oven in which the temperature can be controlled and increased according to a specified pattern by the temperature programmer was employed. T'ne hydrogen flame `` ionization detector was attached to the outlet port of the colurnn. The signal generated by the detector was amplified by an electrometer into a workin~ input signal for the integrator. The integrator sent a display signal to a recorder to print out the response curve and to electronically integrate the area under the curve, The sample preparation and experirnental conditions for measurlng the aroma volatiles of the aromati~ed coffee oil products were as follows: Ten grams of coffee oil ~ere taken out and put into a 125 ml. glass vial covered by a Mininert~valve, manufactured by Pierce ; Chemical Company of Rockford, Illinois. The vial ~as held at arnbient temperature (72f) ~or at least an hour :`
...~

to reach equilibrium. One hundred rnicroliters of headspace aroma were taken from the vial by a yas-tight syringe and injected into the sample port of the gas chrornatograph by a;~ automatic plunger. Inside the sample port, the aroma volatiles were condensed onto a small cold -trap chilled by liquid nitrogen to -135C
(-211F). After all the aroma volatile components condensed, the trap was quickly ~larmed up to 300C and swept by a nitrogen carrier gas to push the aroma volatiles into the column. The column was held ~t a temperature of 80C (176F) ~or 4 minutes and was then .~:` heated up to 135C (572F) at a rate of 4~C(39F)/min.
Flow rate of the nitrogen carrier gas was 6 ml.fmin.
The results from the chroma-tograph, i.e. peak nunnber, time (in minutes) at which the volatile `` component was recorded, and the percentage of the total area under the gas chromatograph curve which the peak ~epresented, were recorded as follo~s:
DIRECT FRûST
Time Area Tirne Area Peak (#) (min.) _%) (min.) (%) 1 0~80.06 2 û.730.03 ` 3 1.700.75 ].73 0.46 - 25 4 1.7~4.04 1.77 3.22 ;` 5 1.781~.87 1.81 11.24 6 1.834.93 1.85 6.57

7 1.8510.78 1.88 11.41

8 1.9034.43 1.93 35.90 30 9 1.957.32 1.98 7.62 1.990.79 2.02 0.95 - 2.07 1.92 12 2.~715.65 2.11 1~.94 13 2.190.01 -- --35 14 2.233.49 2.27 3.21 2.3~0.32 2.38 0.32 16 2.420.07 2.46 0.05 17 2.460.06 2.50 0.06 18 2.562.05 2.60 1.88 40 19 2.810.02 2.86 0.02 ? 2.990.01 3.04 0.01 21 3.050.05 3.10 0.04 22 3.110.02 3.15 0.01 23 3.330.02 -- --~ 45 24 4.700.02 - ---~ 25 4.830.12 4.80 0.11 26 5.030.01 4.97 0.01 27 6.130.01 6.05 0.02 28 6.210.03 -- --50 29 8.130.02 -- ---- -- 9.09 0 01 31 lO.Gl0.02 -- -Difference in Area Peak (~ ) *Colrlments 1 Air Peak (NS) 2 Air Peak (NS) 5 3 0.46 Increase 4 0.82 Increase 3.63 Increase 6 -1.64 Decrease 7 -0.63 Decrease lo 8 -1.47 Decrease

9 -0.30 Decrease -0.16 Decrease 12 )1.21 Combined 15 13 0.01 No change 14 0.28 Increase 0 No change 16 0.02 No Change (NS) 17 0 No Change 20 18 0.17 Increase 19 0 No Change 0 No Change 21 0.01 No Change 22 0.01 No Change 25 23 0.02 No Change (NS) 24 0.02 No Change (NS) 0.01 No Change 26 0 No Change 27 -0.01 No Change 30 28 0.03 No Change (NS) 29 0.02 No Change (NS) -0.01 No Change (NS) 31 ~.02 No ~hange (NS) *NS = No significant difference Peaks which were recorded at approximately the same -time for both Direct and Frost aromatized coffee oils are believed to represent the same volatile component.
Thereffore, the resul-ts from Direct and Frost coffee oil have been lined up accordingly. Peak-by-peak comparison shows that the general features are the same; however, there are slight differences in relative amounts of some components. These differences appear in the most volatile components having retention times less than 2 minutes. There are also sorne extra peaks in the Direct -- 45 aromatized coffee oil after 2 minutes retention time.
However, the magnitude of these peaks~ less than 2 x

10 lû gralns in all cases, is below the effect~ive sensitivity of the gas chromatograph detector.
Therefore, it cannot be concluded that these are real ~ .~

differences in the componen-ts due to the exceedingl~ lo:~
amounts detected. Thus, lt can be seen tha,t the Uirect volatile pro-file is virtually identical to that of the Frost prûfile, indicating capture and retention of the keg ~/olatile components.

: EXAMPLE 5 The effect of tip speed~ gas loading and amount of food substrate on bed temperature and heat transfer characteristics of a mechanically fluidized system was tested as follows: Various amounts of drip grind particle-size roast and ground coffee were added to a 10 ft.3 capacity chilled paddle mixer (see Example 1).
The tip speed of the mlxer was adjusted to achieve an expanded, mechanically fluidized bed o~ coffee. The tip speed was progressively increased with the degree of bed expansion llmited by the vessel geometry and initial fill level of the coffee. The mixer was chilled by forcing liquid nitrogen through the jacket thereof from ! a supply tank operated at 15-20 psig. Air containing ` 2G approximately 1% moisture by volume at ambient temperature ~las forced at various flo~ rates through the beds G f cof-fee to approximate 80% of the heat of condensation/adsorptiûn of a grinder gas feedstock. For a given fill volume-of coffee, tip speed and gas loading rate, sufficient time was allowed until steady state bed ,i temperatures ~ere reached.
The results of the above test are presented in the follo~ing table:
Substrate Tip Speed Gas Loading Run Batch Size of Mixer Rate 8ed No. (lbs.) (ft./min.) (ft.3/hr./ft.3) Condition 1 60 157 90 Not e~panded 2 60 439 90 Expanded 3 60 Z51 ll44 Expanded 35 4 60 502 444 Expanded 690 444 Expanded .` 6 130 157 42 Not expanded 7 13û 251 42 Expanded - 8 130 465 42 Expanded . , .

z 9 130 213 lg6 Expanded 13n ~08 196 Expancled

11 130 690 196 Expanded

12 180 314 483 Not expanded

13 180 439 483 Expanded

14 180 628 483 Expanded 180 753 483 Expanded 16 300 188 18 No-t expanded 17 300 377 54 Not expanded Increase Bed in Overall Run Bed Temperature Heat Transfer No.Porosity (F) (%) 1 0.55 -50 Base 2 0.91 -150 110 : 3 0.91 -122 230 4 0.91 -140 288 0.91 -147 437 6 0.55 -100 51 7 0.81 -160 190 9 0.81 -12~ 219 0.81 138 315 11 0.~1 -143 ~07 12 0.55 -87 472 13 0.74 -107 630 14 0.74 -116 802 0.74 -116 847 16 0.55 28 41 17 0.~5 23 152 As can be seen from the above table, for fill volumes up to about 60% of total vessel capacity, bed expansion was achieved with tip speeds exceeding 157 to 314 ft./min. Below this point mechanical fluidization was not obtainable. In the non-expanded beds, the bed 35 temperature ranged frorn 23F to -100F. for conditions typical of a mixer system having high fill volumes of coffee/lo~ tip speeds, bed temperatures of only 23 to 28F were achieved. These temperature ranges are not sufficiently cold enough for effective grinder gas volatile recovery. For tip speeds suf~icient to achieve .

_ _ . . _._ . ... _. .. __ _ _ _ _ . ._ . _ _ . . .. ,.. .. ~ .. . .... _ . ._ Z~22 bed porosities of from 0.74 to 0.91 (fluldized beds), bed temperatures ~anged from -100 to -16ûF. ûptimum bed temperatures were achieved with coffee fill volumes of up to 40% of the vessel capacity with tip speeds in the range of 4û8 to 690 ft./min. and hlgh gas loading (fLow) rates. Further reduction of bed temperature be:Lnw those indicated in the above table are possible by forced liquid nitrogen circulation through the mixer jackèt and by great heat transfer surface area to subs-trate volume ratios.

: EXAMPLE 6 ``J
The quantity of coffee processed to aromatize flaked coffee products by three alternati~/e recovery techni~ues was compared. These three methods were frost aromatization, direct condensation on a packed column and the process of the present invention.
For frost aromatization, grinder gas was pulled via a vacuum from a commercial blend of coffee roasted tû
77-79 photovolts at a rate oF 7 ft.3~min. from a Model 88 Gump grinder equipped with take-off ports below each side port and the normalizer. The nominal grinding rate was ~8~0 lbs.~hr. (average across all grinds ranging from drip to electric perk grind size). The nominal intensity of the grinder gas stream averaged 39,700 G.C.
counts/cc. across all grind sizes. The grinder gas was condensed in a liquid nitrogen cooled DeLaval 9 ft.2 scraped-wall heat exchanger at the rate of about lû
lbs./hr. (9 ft.3/min. gas loading rate and -320F
condensing temperature). Flaked coffee was chilled to 30- about -200F by the addition of a 0.5:1 by weight ratio of liquid nitrogen to coffee. Twenty-fiYe lbs. of condensed aroma frost from the scraped-~all heat exchanger was added to 75 lbs. of flaked coffee and ~` thoroughly mixed. The resultant mixture was stored in dry ice to slowly sublime the carbon dioxide and to allow volatile adsorption by the flaked coffee. The mixture was held for six days at an average temperature of -75F. The intensity of the aromatized flaked coffee _ _ . . , . , . . ., ... __. _ . , _ ._ ., ., .... _ ... ... ~_ ~, . . . ... ,, .. ~

~2~3~

was determined to be 646,200 G.C. counts.
For direct condensation on a packed column, 19 lbs.
of flaked coffee were added to a stainless steel adsorption column 4 f`t. long and 6 in. in diameter. The column was immersed in a bath of liquid nitrogen which cooled the top of the colutnn to -30F, the middle of the column to -287F and the base of the column to -301F.
Grinder gases were generated From a commercial coffee blend roasted to a color of 78 photovolts yround in a Model 66 Gump grinder. The grinder was equipped with grinder gas take-off ports mounted beneath the grinder rolls and on the normalizer. The roasted coffee was ground at a rate of 780 lbs./hr. The grinder gas was drawn off at a rate of 2.2 ft.3/min. by a vacuum pump. The grinder gas was drawn through the absorption column where the aroma volatiles were adsorbed onto the cold, flaked coffee. During the adsorption run, the temperatures averaged -171F throughout the entire co:Lumn with a range of -3U to +25F at the top of the column, -287 to -170F at the center of the column, and ; -301 to -288F at the base o-f the column. At the completion of a 2 hour aromatization run, approximately 175û lbs. of roasted coffee had been ground to aromatize the flaked coffee in the column. Following - ~5 equilibration for 4 days at -80F, the aromatized flaked coffee was determined to have an aroma intensity of _~ 484,20n G.C. counts.
For the process of the present invention, 60 lbs. of flaked coffee, see Example 1, was aromatized in a mechanically fluidized system. About 2640 lbs. of coffee was ground to yield an aromatized flaked coffee havin~J an intensity of 384,100 G.C. counts.
The results from the foregoing three aroma-tization methods are presented in the following table:

. .

- ~

Arnount of roast &
8atch Conden- Aroma gas ground size sation processed processed Method (Lbs.) Temp.(F) (ft.3/lb.) (lbs.) Fros-t 100 -320 55.8 12,670 Aroma- (25%
tization frost/
75% chilled coffee) Direct 19 -171 12.1 1,750 condensa-tion on packed

15 column Process 60 -166 37.8 2,640 of present invention 4Stoichometry 3Amount of (lbs.
Aromatized 2Arornatized aromatized of R~G
substrate substrate coffee processed per intensity addition produced lbs. aroma-Method (E.C.counts) level (%~ (lbs~) tized coffee 25 Frost 646,200 7.2 1042 12.2 ~ Arorna-tization Direct 484,200 9.6 198 11.3 condensa-tion on packed column Process 384,100 12.2 490 4.6 of present invention Measured from 10% by weight addition of aromatized flaked coffee substrate to 90% by weight non-aromatized flal<ed coffee (see Example 1).
2Calculated on basis of linear addition of aromatized flaked coffee substrate necessary to raise flaked coffee havinq an aroma intensity of 15,0ûO G.C. counts to 60,000 G.C. counts.
3Calculated from batch size and weight fraction of aromatized flaked coffee substrate required to raise ; 45 aroma intensity from 15,000 to 60,000 G.C. counts 4Amount of ~&G coffee required to form aromatized flaked coffee product of 60,000 G.C. counts.
.. .
.~

As shown ln the above table, the amount o~ processed roast and ground coffee needed to form aroma-tized flaked coFfee products of similar intensity greatly di-ffers in these three methods. In the case of condensed aroma frost and direct condensation on a packed column, about 12.2 and 11.3 lbs. of processed roast and ground coffee, lo respectively, was needed to increase the aroma intensity of 1 lb. of flaked coffee from lS,OûO to 60,0ûO G.C.
counts. By contrast, only 4.6 lbs. of processed roast and ground coffee was needed in the process of the present invention.

' ' , .

. ~ ~

Claims (19)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method for aromatizing a food substrate, comprising the steps of:
placing a particulate solid food substrate in a vessel;
cooling the vessel with a cryogenic fluid;
mechanically fluidizing the food substrate by mixing at a tip speed of at least about 200 ft./min., to provide an absorbent bed thereof having a porosity of at least about 0.73; and contacting the fluidized, cooled bed of food substrate at a temperature below about -100°F with gaseous food volatiles at a rate of at least about 42 ft.3/hr. per ft.3 of food substrate, whereby the food volatiles condense on and are absorbed by the food substrate.

2. A method according to claim 1 wherein the fluidized bed of food substrate has a porosity of at least about 0.81.

3. A method according to claim 1 wherein the tip speed is from about 400 to 1000 ft./min. and wherein the volatiles are flowing at a rate of from about 500 to 2000 ft.3/
hr. per ft.3 of food substrate.

4. A method according to claim 1 wherein the temperature during said contacting step is below about -150°F.

5. A method according to claim 4 further comprising the step of cryofying the food substrate prior to said cooling and fluidization steps.

6. A method according to claim 4 further comprising the step of equilibrating the aromatized food substrate after said contacting step.

7. A method according to claim 6 further comprising the step of adding unaromatized food substrate after said contacting step and prior to said equilibration step.

8. A method according to claim 1 wherein the food substrate comprises a coffee substrate.

9. A method according to claim 1 wherein the cryogenic fluid is liquid nitrogen.

10. A method for aromatizing a coffee substrate, comprising the steps of:

placing a particulate solid coffee substrate in a vessel;
cooling the vessel with a cryogenic fluid;
mechanically fluidizing the coffee substrate by mixing at a tip speed of at least about 200 ft./min. to provide an absorbent bed thereof having a porosity of at least about 0.73; and contacting the fluidized, cooled bed of coffee substrate at a temperature below about -150°F with gaseous coffee volatiles at a rate of at least about 42 ft.3/hr. per ft.3 of coffee substrate, whereby the coffee volatiles condense on and are absorbed by the coffee substrate.

11. A method according to claim 10 wherein the coffee substrate is selected from the group consisting of roast and ground coffee, flaked coffee and mixtures thereof.

12. A method according to claim 10 wherein the coffee substrate comprises an edible oil.

13. A method according to claim 12 further comprising the step of cryofying the edible oil prior to said cooling and fluidization steps.

14. A method according to claim 13 wherein the edible oil is coffee oil.

15. A method according to claim 10 wherein the volatiles comprise grinder gas.

16. A method according to claim 10 further comprising the step of adding unaromatized coffee substrate after said contacting step.

17. A method according to claim 10 further comprising the step of cryofying the coffee substrate prior to said cooling and fluidization steps.

18. A method according to claim 10 wherein the cryogenic fluid is liquid nitrogen.

19. A method according to claim 10 wherein the coffee substrate is soluble coffee.