CA1063864A - Process for producing roasted and ground coffee - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
This invention relates to a process for roasting and grinding coffee beans. The beans are roasted under normal conditions except for quenching. The hot beans are quenched with a non-aqueous cooling medium to bring them down to an extremely low temperature. Cold water is contacted with these low temperature beans, and they are ground: The ground product is then immediately vacuum packed.

Description

: ~63~364 In the past, many attempts have been made to prepare ~ -roasted and ground coffee which is characterized by strong aroma retention and a freshness resembling that of brewed coffee. Most of these attempts have been primarily geared towards separation or isolation of essential coffee oils or other aromatic constituents from the roasted and/or ground coffee. These isolated coffee oils or other aroma constituents have been added back to the coffee utilizing many diversified techniques. However, the desideratum in the art was to effect a means for maximizing the retention of freshness and aroma without the necessity of initially separating essential coffee oils and other aroma constituents for ultimate addition back to the coffee after grinding (or in the case of soluble coffee after the extract is dried).
Aroma retention ca~ be greatly enhanced by freeze grinding the roasted coffee beans as described in U.S. Patent No. 3,725,076 (See Canadian Patent No. 975,214). This prevents volatilization of oleaginous materials as well as flavors and aromas which may evolve during grinding. Grinding, while the -i bean is in the frozen state, minimizes liquefaction of the oils ~- -: . .
by absorbing frictional heat generated during grinding. Also, aromatic and flavor retaining oils will not be evolved to the atmosphere but will instead remain relatively solidified within the coffee particles.
As conventionally practiced, green coffee beans having a moisture content in the range of about 7 to 17% by weight are heated in a roaster such as a JABEZ BURNS* roaster for a period of about 5 to 10 minutes to about 20 or 30 minutes.
At the end of the roast period, it is necessary to quickly cool ,, '' .' .
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,, ': , 1~63~4 . ' ' the beans so that exothermic reactions do not take place that burn or otherwise degrade the roasted beans. While air is --suitable, it is customary to quench the beans with a water spray. It is desirable to quench the beans as rapidly as possible in order to reduce the shrinkage (loss) associated with the roasting process. The disadvantage of quenching by water is that a considerable amount of steam is generated. The formation of this steam is also accompanied by the volatiliza-tion of portions of the roasted coffee beans such as oils and other aromatic constituents. Thus, these desirable components ;~
are lost to the atmosphere.
The roasting of the beans reduces their moisture content to about 1~ to 2%o Typically, quenching adds moisture back to the roasted beans at levels of about 3% to about 5~ by weight. In conventional coffee processing, the grinding step releases desirable flavors and aromatic constituents from the coffee beans. ~s the moisture of the beans are increased, more of these elements are released.
Thus, it would be highly desirable if a simple method were devised whereby the moisture lost during the roasting of the beans could be added back as free water and not as quench water in a manner that would not cause any loss of flavor volatiles or aromatic constituents.
It has now been discovered that novel means are available for retaining aroma retention and preserving freshness of roasted and regularly ground coffee. Accordingly, whole roasted beans are cooled to a temperature below 32F., say about -30F. using a non-aquebus cooling medium. Next, the frozen beans are contacted with water such that the water 3~69L ~:~

freezes as it contacts the surface of the frozen beans and is ~
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not absorbed by them. The beans are subjected to grinding.
The product is immediateIy vacuum packed.
The present invention is a process for producing roasted and ground coffee comprising the steps of roasting the coffee, coolin~ the roasted coffee with an non-aqueous cooling medium to a temperature below 32F., applying water to the cooled coffee so that as the water contacts the surface of the coffee it ;-freezes on said surface, grinding the cooled coffee, and there-after packing the coffee. Throughout these steps all of the coffee bean material is kept at a low temperature. Further, it is preferred that the grinding apparatus be maintained at a temperature below 32F., preferably about -30F. or below.
This will insure that the heat normally generated during :
grinding is removed so that the temperature of the beans ~ -remains well below their freezing te~peratures.
The water added to the frozen beans in amounts of

2% to 4~ is preferably applied by means of a spray nozzle or , nozzles so the water is uniformly distributed. The temperature of the water is preferably about 32F. As the water is ; sprayed onto the beans, i~ freezes when it contacts the outer `;`
surface of the frozen coffee and is not absorbed. Thus, the water co-exists with the beans during and for a period of time after grinding in a solid state. In one embodiment of this invention, the water is applied to the frozen beans before they are ground. In another embodiment, the water is added concur- `
rently with the grinding. Still another embodiment of this ``
- invention is the addition of the water immediately after the frozen beans are`ground.
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~63~36~

In accordance with one embodiment of this invention, only high grade coffee fractions such as high grown milds of coffee blends rich in high grown milds are subjected to non-aqueous quenching to a temperature below 32F and subsequent water addition. Low grade coffee fractions, preferably consist-ing of only low and intermediate type coffees such as Robusta, ~
natural Arabicas and possibly Brazilian coffees, may be con- -ventionally quenched and ground. In this manner, the high grade fractions which contain mostly desirable coffee aromatics are processed in such a manner as to retain these aromatics, and the low grade coffee fractions which may contain quantities of undesirable aromatics are processed in a manner which will permit significant quantities of aromatics to escape from the coffee. High and low grade coffee fractions processed in accordance with the procedures set forth above may be combined into a composite roasted and subdivided coffee product.
Immediately after grinding, the product is vacuum packed. It is contemplated that the added water will not equilibrate with the coffee beans for a period of time after grinding. Preferably, the coffee product would be vacuum `~ packed before this time period has run out.
` Grind settings for the beans should be adjusted to provide conventional grind size distributions employed for regular coffee products and conventional percolation for soluble, i.e., the grind distribution should typically contain at least 90% larger than lQO mesh ~.S. Standard Sieve screen, preferably based on U.S. Standard Sieve screen. The grind distribution should be such that less than about 5% remains on a No. 12 screen, about 5 to 30% remains on a No. 16 screen, ~3864 ; :

about 30 to 60% remains on a No. 20 screen and the remainder is deposited in the pan.
If desired, the roasted and ground coffee may be extracted by conventional techniques to form a soluble coffee product. In this embodiment, the frozen beans would be packed in a percolator column immediately after the grinding step.
The invention will now be described by reference to a specific example:
EXAMPLE
A 2 pound charge of whole green coffee beans is roasted until the bean temperature reaches its exothermic reaction point, between about 270F. and 375F. The beans are then quenched and cooled to about minus 40F., using liquid `
nitrogen. Next, they are ground in a pre-cooled HO~R~ coffee grinder. Then the beans are placed in a pre-cooled rotary candy coater and are sprayed with 36 milliliters of 32F.
water mist. The product is immediately vacuum packed.

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Claims (8)

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

1. A process for producing roasted and ground coffee comprising the steps of a) roasting the coffee, b) cooling the roasted coffee with an non-aqueous cooling medium to a temperature below 32°F., c) applying water to the cooled coffee so that as the water contacts the surface of the coffee it freezes on said surface, d) grinding the cooled coffee, and thereafter e) packing the coffee.

2. The process of claim 1 wherein the water is applied before grinding the coffee.

3. The process of claim 1 wherein the water is applied concurrently with the grinding of the coffee.

4. The process of claim 1 wherein the water is applied after grinding the coffee.

5. The process of claim 1 wherein the cooling medium is liquid nitrogen or dry ice.

6. The process of claim 5 wherein the water is sprayed onto the coffee surface.

7. The process of claim 6 wherein the coffee is vacuum packed while the water which is applied to the cooled coffee is still in a frozen state.

8. The process of claim 6 wherein the coffee is packed in a percolator column while the water which is applied to the cooled coffee is still in a frozen state.