The two main ingredients (cocoa nibs and sugar) prior to mixing or simultaneously with it must be crushed in the machine, combining grinding and mixing processes. Methods for generating cocoa from cocoa nibs we have described in previous chapters.
The process of converting granular sugar into a state of fine powder is considered insecure because of its explosiveness, and the equipment operates, as a rule, very noisy. So now experts are developing equipment that does not use the principle of refining sugar. Cocoa butter and other fats liquefy, avoiding overheating and long-term storage in liquid form (especially milk fat).
Milk should not be stored in an open container. It should be used as much as possible immediately after delivery. Moisture content should not exceed 3%, since the content of the above 4% leads to deterioration of the product. Sometimes milk powder and cocoa powder is further dried prior to mixing, but it refers more to the production of mixed glaze
The majority of installations for the development of the chocolate should be automatically dispersed (Distribute) the ingredients in the correct proportions according to the recipe using a computer.
Sometimes the ingredients are dosed and mixed in a continuous mode, and sometimes they enter the batch mixer. On the advantages and disadvantages of methods for continuous and batch mixing ingredients are still being lively discussions and debates.
Undoubtedly, continuous processing, which is increasingly used in many areas of the food industry, has certain advantages, but this method requires constant accurate dosing of the ingredients over a long period of time. Minor errors in dosing the main ingredients (sugar, cocoa mass or milk powder) are unlikely to significantly affect the quality of the final product, however, incorrect dosing of emulsifiers, flavors and fats can have quite serious consequences. The amount of lecithin, often added at the stage of preliminary mixing, is known to vary, which leads to a change in the viscosity of the mass entering the grinders. This factor causes problems associated with product yield and particle size. Batch mixing is considered more reliable, and the batch volume processed in one cycle can be from 700 to 3000 kg. Errors in the supply of raw materials to the mixer (mixer) in this case have less effect on the quality of the whole lot, which remains unchanged. In any batch mixing process, to ensure a consistent consistency, it is important to establish the exact mixing time (usually 12-15 min).
Is it possible to make the system of continuous batch mixing? mixers work can be divided in such a way that as long as one of these products are unloaded, the other is mixing another batch. It may also be used grinders and mixers between the intermediate storage system.
In one of the systems for each chopper uses an automatic hopper. Combined bunkers can take the whole party coming from the mixer. Each tank is equipped with a discharge mechanism which continuously feeds the feed roller.
continuous mixing method is used by many manufacturers of chocolate. Kneading Machine Bus-Ko combines vibration and mixing movement with the release of the treated mass onto a steel conveyor belt coming into the shredder hopper. Other types of mixing equipment manufactured by Werner Pfleiderer, and Baker Perkins. An example of a combination of both methods can serve as a stirrer Bauermeister Beetz.
The diagram of the automatic feeding and batch mixing system is shown in the figure. Other mixing systems will be discussed below when describing alternative methods of making chocolate.
Before grinding in the process of mixing is usually obtained a slightly rough texture plastic chocolate mass. If it is too thin, it will act on the rolls correctly, and if it is too thick, its passage between the rolls is obstructed or uneven. In any recipe consistency of the mass is first selected empirically, and then set the standard mixing mode.
Grinding the chocolate mass is an important process step and is used in order to form a uniform texture, which is required in modern production of chocolate products.
The influence of various factors on the uniformity of the texture of chocolate is controversial, but it is obvious that if the maximum hold grinding, whereby the chocolate is obtained with a particle size of not more than 25 microns, it becomes a viscous texture (especially for milk chocolate).
The results of studies on the influence of the particle size distribution suggests that the best texture of the chocolate milk is formed in the presence of a small amount of up to 65 micron particles, whereas for dark chocolate production quality needed maximum particle size 35 microns. These figures are largely random and depend on the type of products and flavorings (such as the famous cream tiles, which are successfully sold on the market for many years, the size of chocolate particles is about 75 microns).
Another factor that relates the particle size, particle aggregation is associated with sugar, cocoa powder or crumb breast - depending on the degree of aggregation are different felt in the mouth. Large sugar crystals are perceived as individual grains, cocoa powder particles provide a stable feeling
roughness, and baby milk softens and disperses quickly in the mouth is an effect that is said to eliminate the sensation of viscosity.
When the question of the degree of grinding a particular type of chocolate solved, the problem of maintaining the desired consistency. Industrial and laboratory methods of its maintenance will be discussed below.
chocolate particles by their size distribution is also important because as the "mouthfeel" associated with larger particles, the presence of large numbers of very small particles require more expensive consumption of cocoa butter.
Modern roller mills - is exactly adjustable installation consisting of five fixed vertical rollers feed below. These rolls are made of cast stainless steel, and they have a very hard surface and slightly convex shape that promotes the maintenance of the entire roll surface layer of chocolate of the same thickness.
roll rotation speed increases from the bottom to the top is called the differential. Thus, a layer of the chocolate mass flows from one roll to the next, and the degree of the pressing roller causes a corresponding shift.
Modern mills of the pressure between the rolls is controlled hydraulically and each roller is equipped with an internal water cooling (water temperature is thermostatically controlled). Correct cooling is important, as in the mill at a friction, a large amount of heat, and it leads to uneven dispersion of the deviations of the rolls, causing a gradual deterioration and occurrence of roughness on the surface.
old-style mills without thermostatic control of water temperature caused the problem set the correct operating parameters. Upper rollers sometimes overheated, and their supercooling was difficult to track, particularly when using a conventional water pipe, leading to accumulation of condensation on the surface of the rolls and the negative effect on the quality of the chocolate mass layers.
Fig. 5.2. stirring system and double refining
1 - BMS mixer for mixing ingredients and obtaining the initial chocolate mass; 2 - 5Ya.-900 - five roll mill for preliminary grinding of chocolate mass; 3 - BvG-conveyor with steel box for directing pre-chopped chocolate to the mill; 4 - BP-1800 - five-roll hopper for final grinding of chocolate mass; 5 - control panel with programmable controllers for the correct supply of ingredients to the mixer and automation of the entire installation; 6 - loading hoppers Buhleg company, Uzwil, Switzerland
The roll cooling should be checked regularly, and despite possible deviations (due to different formulations and particle sizes in the final product), the following parameters are standard: top roll - 26-35 ° C; fourth roll - 38-49 ° C; third roll - 29-40 ° C; second roll - 26-35 ° C; feed roller - 26-35 ° C.
You should also monitor the temperature of the roll surface, comparing them with the water temperature. The degree of grinding may be assessed by taking samples of the chocolate mass of the upper roll and the measurement of particle size.
Samples should be taken from the middle and the drum edges. If the pressure and cooling settings are correct, the numbers must match.
The regular care needs and a scraper that removes a layer of chocolate from the top of the roll. To completely remove the layer it should be set at the correct angle and pressure. If the chocolate mass passes the scraper, it will; It interferes with the chocolate mass on the lower roller. Driving a modern mill shown in Fig. 5.3.
Machines of the above type in comparison to the same operation with adequate mills are characterized by three times greater productivity. Depending on the degree of grinding their productivity is up from the 800 1000 kg / hour. Moreover, the performance of some new machines are even higher.
The main purpose of the roller mill is fed trituration chocolate mass, but it also performs the function of the dispersant, the particles and agglomerates was triturated ensures complete wetting of ingredient containing cocoa butter (fat) in the liquid phase.
In recent years there has been a tendency to return to the method of double-grinding, in which granulated sugar is used and thus excludes the use of explosive sugar mills (see. Fig. 5.2). Such a system was used many years ago, but less than perfect equipment.