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about the chocolate liquor flavors favored by the European roasters and the US roasters. Europe tends to favor a light roast and the American processors favor a dark roast. This has led to European chocolate liquor (cocoa mass) being described as green in the USA and the US material described as burnt by European producers.

In summary, there is not a right or wrong roast level nor is there a correct way or an incorrect way to obtain the target roast level. The correct way to roast and the proper roast level is that process which provides nibs in an efficient and cost-effective manner with the flavor system and produces the products meeting the consumers' needs in a specified market.

Winnowing

Winnowing, cracking, fanning and hulling are some of the terms and phrases which describe separation of shell (hull) and meat of the bean (nib). It is a process where obtaining a clean separation of the two components is driven by economics, product integrity and, in many countries, government regulation. A winnower is shown in Fig. 3.3.

Food regulations usually specify a maximum level of shell in nib. For example, in

Chocolate Winnower
Fig. 3.3 Winnower. Source: Carlo and Montanari.

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the USA this level is a maximum of 1.75%. The level of nib in shell is of no concern to anyone other than the manufacturers and their concern is one of economics.

Having excessive levels of nib in shell is one way for a manufacturer to lose large amounts of money quickly, because nib is typically worth in excess of $2000/tonne, but as part of the shell stream it essentially becomes worthless.

The amount of shell in nib can also impact on the life of the processing equipment. Cocoa shell is very abrasive and can accelerate equipment wear resulting in increased maintenance costs.

Finally, the level of shell in nib can affect the quality level of the resulting chocolate liquor. Excessive levels of shell can alter the flavor of the finished product by contributing off-flavors. Examples of off-flavors are fiber-like notes and, occasionally, moldy notes. Of major concern is production of chocolate liquor that contains pathogenic organisms, unacceptably high microbiological counts or high levels of extraneous materials. As stated earlier, the nib is clean. Bacteria are found on the shell and other foreign material and it is the incomplete separation of the shell and nib as well as inadequate roasting that can lead to chocolate liquor with the previously mentioned defects.

Nib grinding has seen many advances in the last half of the 20th century. Before liquor mills, one method of grinding nibs was mixing nibs with granulated sugar and placing the mixture in a mélangeur. This process yielded a material with a consistency ranging from a paste to a fluid.

It should be stated that a modern nib grinding system consists of a pre-grinder (e.g. Fig. 3.4) and a finish grinder. Pre-grinding of nibs results in a fluid material with a particle size normally exceeding 100 |im. Finish grinding reduces the particle size of the chocolate liquor to a value dependent on the planned use of the material. The particle size and particle size distribution values are critical if chocolate liquor is to be used in operations such as cocoa pressing and chocolate making.

The early mill of choice appears to have been the stone mill. This is one type of three basic mills which will be reviewed. Two others are the ball mill and roller refiner. Many other pre-grinding and finish grinding devices are available and are described in the literature. When selecting a grinding device, numerous factors need to be considered. Examples are the initial cost, operating costs, floor space required, control capability of particle size and particle size distribution and flavor impact on finished product (2).

The ball mill (as shown in Fig. 3.5) is a grinding system which has gained wide use in recent years. Both continuous and batch types are available. The ball mill requires an upstream nib-grinding device, which will allow the liquor to be pumped into the grinding chamber for exposure to the grinding action of moving balls. The grinding chamber is filled with steel or ceramic balls with diameters

Nib Grinding

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