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Method for producing fat and/or solids from beans and compositions containing cocoa polyphenols

Reference is made to copending U.S. application Ser. No. 08/317,226, filed Oct. 3, 1994 (allowed, now U.S. Pat. No. 5,554,645), and Ser. No. 08/631,661, filed Apr. 2, 1996, incorporated herein by reference.

The present invention relates to a versatile process for extracting fat from fat-containing beans and/or processing fat-containing beans to yield a solid product having a conserved level of polyphenols, preferably polyphenols with active procyanidins. More specifically, the invention provides a method of producing cocoa butter and/or cocoa solids having conserved levels of polyphenols from cocoa beans using a unique combination of processing steps which does not require separate bean roasting or liquor milling equipment. The method of the present invention allows for the option of processing cocoa beans without exposure to severe thermal treatment for extended periods of time and/or the use of solvent extraction of fat. The invention provides a significantly less complex process regarding total cost of assets, maintenance, energy and labor, with the concomitant benefit of obtaining solids having conserved concentrations of polyphenols relative to the starting materials.

Documents are cited in this disclosure with a full citation for each appearing thereat. These documents relate to the state-of-the-art to which this invention pertains, and each document cited herein is hereby incorporated by reference.

Cocoa beans are produced by cocoa trees which are found in warm, moist climates in areas about 20 degrees latitude north and south of the Equator. In general, the seeds of the Theobroma cacao (of the order Sterculiacae) are known chiefly in two varieties: Criollo and Forastero, with Forastero divided into several varieties. A third group, called Trinitario, is essentially a cross between Criollo and Forastero and is not found in the wild. Criollo beans are pale brown in color while Forastero beans are a purple hue. The cocoa tree produces leaves, flowers and fruit throughout the year, and the ripe fruit or pod resembles a long cantaloupe, typically containing from about 20 to 40 almond-shaped cocoa beans.

The cocoa bean is comprised of an inner nib portion covered by an outer shell. On a dry basis, the shell of the bean comprises about 12 to 15% of the weight of the bean, while the nib and residual moisture amounts to approximately 85 to 88%. Typical analytical data ranges for chemical components of cocoa nib are: fat content of 48 to 57%; theobromine content of 0.8 to 1.3%; caffeine content of 0.1 to 0.7%; total nitrogen content of 2.2 to 2.5%; ash content of 2.6 to 4.2%, and water content of 2.3 to 3.2% (see Pearson's Composition and Analysis of Foods, 9th Edition, 1991).

Various processes are traditionally employed to extract cocoa butter and cocoa solids from commercial cocoa beans. Typical methods of processing cocoa beans include the steps of (a) bean cleaning; (b) bean roasting; (c) bean winnowing; (d) nib grinding; (e) liquor pressing to produce cocoa butter and cocoa cake; (f) cake alkalizing; and (d) cake milling.

The initial step of typical cocoa bean processing methods consists of cleaning the beans to remove extraneous non-cocoa materials. Conventional bean cleaning separates beans from extraneous non-cocoa materials by either size or density using a cleaning machine which is a gravity, vibratory or aspiration table (See Chocolate, Cocoa and Confectionery: Science and Technology, 3rd Ed., by Bernard W. Minifie, page 35; Chocolate Production and Use, 3rd Ed., by L. Russell Cook, page 144-146; and Industrial Chocolate Manufacture and Use, 2nd Ed., by S. T. Beckett, page 55, hereby incorporated by reference).

Current cleaning technology is typically limited in separation ability to a minimum density difference of 10-15%. This reduces the efficiency of achieving an accurate separation of bean and extraneous non-cocoa materials and subsequently reduces the clean bean yield of the process. Additionally, conventional cleaning machines become easily clogged and require frequent cleaning. This also reduces the cleaning efficiency and the clean bean yield of the process.

Moreover, cleaning machines have a tendency to fracture the beans during cleaning which reduces the percentage of whole beans available after cleaning. These broken bean pieces can later give rise to problems during roasting and winnowing. For instance, small bean pieces will burn readily at the elevated temperatures used during roasting and may result in burnt and ashy flavored liquors which are unacceptable from a flavor viewpoint. Small bean pieces may also decrease the efficiency of the winnowing process because they can be lost during the aspiration of the shells and result in overall yield efficiency losses.

In most conventional processes, roasting of the whole bean or nib is an essential step in the manufacture of chocolate or cocoa. Roasting develops the natural flavor and aroma of the cocoa beans, and also loosens the shell so that it can be readily removed during the winnowing process. The degree of cocoa roast is a time/temperature dependent relationship, where the time can vary from 5 to 120 minutes and the temperature of the whole bean can typically vary from 125° C. to 150° C., and with respect to the roasting of nibs, an initial drying process step can be at just below 100° C. to remove the shell, with second stage roasting of nibs alone being at elevated temperatures up to about 130° C.; all of which depend on the construction of the machine, size of the batch and final product desired (See Chocolate, Cocoa and Confectionery: Science and Technology 3rd Ed., by Bernard W. Minifie, incorporated herein by reference, especially page 37, 45-46; Chocolate Production and Use, 3rd Ed., by L. Russell Cook, page 146-152; and Industrial Chocolate Manufacture and Use, 2nd Ed., by S. T. Beckett, page 55-64, hereby incorporated by reference). U.S. Pat. No. 5,252,349 to Carter, Jr., hereby incorporated by reference, involves heating the bean to a temperature of about 152° C. to 160° C. for about 5 to 8 minutes.

The winnowing operation serves to separate the beans into the desired inner portion of the bean (nib) and the outer portion of the bean (shell). The principle of separation by a winnowing process depends on the difference in the apparent density of the nib and of the shell. Standard winnowing machines make use of the combined action of sieving and air aspiration. As discussed earlier, the shell is loosened during the conventional roasting step and/or other heating or drying steps. After loosening, the beans are typically broken between rollers or such devices to shatter the cocoa beans along natural fracture lines of the cocoa nib to facilitate shell removal during winnowing (see U.S. Pat. No. 2,417,078 to Jones, U.S. Pat. No. 5,252,349 to Carter, Jr., Chocolate, Cocoa and Confectionery: Science and Technology, 3rd Ed., by Bernard W. Minifie, page 47-51; Chocolate Production and Use, 3rd Ed., by L. Russell Cook, page 152-153; and Industrial Chocolate Manufacture and Use, 2nd Ed., by S. T. Beckett, page 67-68, hereby incorporated by reference).

Some cocoa bean processing techniques include the use of thermal pre-treatment equipment to aid in the separation of the shell from the nib. This involves giving the beans a thermal shock by hot air, steam or infra-red heat (see U.S. Pat. No. 4,322,444 to Zuilichem et al., and British Patent No. 1,379,116 to Newton, Chocolate, Cocoa and Confectionery: Science and Technology, 3rd Ed., by Bernard W. Minifie, page 44-43; Chocolate Production and Use, 3rd Ed., by L. Russell Cook, page 155; and Industrial Chocolate Manufacture and Use, 2nd Ed., by S. T. Beckett, page 60-62, hereby incorporated by reference).

Infra-red pre-treatment uses infra-red heating to rapidly heat and expand the beans which assists in loosening the shells. The method consists of treating the beans with infra-red radiation for a period between one half and two minutes, during which time the beans are typically heated to a temperature of about 100 to 110° C. The infra-red radiation used has a wavelength between 2 and 6 microns which corresponds to a frequency in the range of 0.7 to 1.2×108 megacycles per second. This energy penetrates and excites the molecules of the bean which causes them to vibrate at their own frequency and results in rapid heating of the beans. However, there is no teaching or suggestion in the art of any processing technique involving heating, such as by infra-red, without a subsequent roasting.

The next step in most conventional cocoa processing, after winnowing, involves nib grinding. Nib grinding is typically performed in two stages, an initial grinding stage to convert the solid nibs into a fluid paste and a finish grinding stage to achieve the desired particle size. Both of these stages are asset, maintenance, and energy intensive.

The cleaned roasted cocoa nibs typically vary in cocoa butter content from 50-58% by weight. During the grinding, the nib is ground, for instance by milling, into a fluid, dark brown “liquor”. The fluidity is due to the breakdown of the cell walls and the release of the cocoa butter during the processing. Ground particles of cocoa solids are suspended in the cocoa butter. This liquor is sometimes commercially sold as a product useful in the confectionery and baking industries where machinery for processing the cocoa beans is not available.

Most conventional cocoa processing includes separating cocoa butter from liquor. This is accomplished by using a batch hydraulic pot press (“hydraulic press”) to separate the cocoa butter from the cocoa solids. The resultant cocoa butter is subsequently filtered to result in clear, solid-free cocoa butter. Butter can also be produced by utilizing a continuous screw press to extract the butter from whole bean with shell or less frequently, from nibs (see U.S. Pat. No. 5,252,349 to Carter, Jr.; and Chocolate, Cocoa and Confectionery: Science and Technology, 3rd Edition, by Bernard W. Minifie, hereby incorporated by reference, see especially pages 71-72 of Minifie).

The resulting cocoa cake from either hydraulic presses or screw presses may be milled into cocoa powder. Cocoa cake typically contains either 10-12% cocoa fat or 20-22% cocoa fat. (See Chocolate, Cocoa and Confectionery: Science and Technology, 3rd Ed., by Bernard W. Minifie, page 72-76; Chocolate Production and Use, 3rd Ed., by L. Russell Cook, page 169-172; and Industrial Chocolate Manufacture and Use, 2nd Ed., by S. T. Beckett, page 78-82, hereby incorporated by reference). Cocoa powder from cocoa cake obtained by hydraulic pressing is usually produced by milling the cocoa cake. If natural cocoa powder is desired, cocoa cake is fed directly to the cocoa cake mill. If alkalized cocoa powder is desired, the cake from an alkalizing process is fed to the mill. Hydraulic pressing produces a cocoa cake which is an agglomerate of previously milled cocoa particles. Cocoa cake mills for cocoa cake from hydraulic pressing are therefore designed to reduce the size of these agglomerates. Conventional particle size reduction of cocoa cake from hydraulic pressing is typically performed by either hammer or disc mills in conjunction with particle size classification and separation. The classification and separation retains and returns particles larger than the size desired for further grinding. After milling, the powder is cooled and packaged.

The natural cocoa cake or natural cocoa powder can be further processed by alkalizing to improve the color and flavor qualities of the cake (see U.S. Pat. No. 3,997,680 to Chalin; U.S. Pat. No. 5,009,917 to Wiant, et al., Chocolate, Cocoa and Confectionery: Science and Technology, 3rd Ed., by Bernard W. Minifie, page 61-67; Chocolate Production and Use, 3rd Ed., by L. Russell Cook, page 162-165; and Industrial Chocolate Manufacture and Use, 2nd Ed., by S. T. Beckett, page 71-72, hereby incorporated by reference). The alkalizing process can be used at any of several different stages of processing and includes the treatment of either the beans, liquor, nib, cake or powder with solutions or suspensions of alkali, usually, but not limited to, sodium or potassium carbonate. After alkalizing, the cocoa solids are dried and cooled. The dried cocoa solids are subsequently milled to produce alkalized cocoa powder, and thereafter cooled and packaged.