MF HAMBURG - Machines & Plants - Confectionery and Chocolate Industries

Process Technology

Technical explanation

Chocolate Production
Production of dark chocolate consists essentially of a finely ground mix of cocoa mass and sugar, with sufficient added cocoa butter to enable it to set in block form when moulded, or as a firm shell on confectionery centres when used for covering. The characteristic of chocolate in comparison to other confections is due largely to the physical nature of the cocoa butter which enables the product to be firm enough to handle, and yet have the attractive break or "snap" at normal temperatures, yet melt and dissolve in the mouth without any sensation of waxiness.

Incorporation of milk during manufacture produces the very popular milk chocolate, which is much milder and also softer in texture due to the lower melting point of milk fat. For milk chocolate production, it is essential to remove practically all the water from the milk before the refining stage.

After grinding, all chocolate, whether dark or milk, undergoes a treatment known as 'conching', where the mixture is pummelled for hours by the conching machines.

The temperature of the chocolate for conching is higher for dark than for milk chocolate. The time of conching may take 12 hours or less, particularly for milk chocolate, but it may take days for the highest quality chocolate. The viscosity of the chocolate is reduced during the early stages of conching.

The flavour development is subtle, and the changes which are responsible for it are complex. Extra cocoa butter is usually added towards the end of the conching to adjust the viscosity of the chocolate to the requirements of its particular use, such as moulding or for covering confectionery centres.

Before chocolate can be moulded or used for coating confectionery centres, it is necessary for it to be "conditioned" by the process called "tempering" or "graining". The transition from liquid to solid chocolate occurs during the cooling stage of the moulding and enrobing. This involves removal of heat if the chocolate is to set rapidly and uniformly, with good colour and keeping properties.

Usually the chocolate is cooled in a mixer provided with an efficiently scraped cold surface. The temperature is below the crystallisation point of the cocoa butter, so that the crystals are continually being formed, scraped off and mixed with the liquid, but supercooled, chocolate. The temperature of the chocolate is thus steadily lowered until the chocolate is ready for depositing into moulds. Due to the presence of milk fat, milk chocolate requires cooling to several degrees lower to achieve the same result.

For moulding solid blocks, tempered chocolate is machine deposited into polished moulds previously warmed and carried under the depositor by a moving belt. Fruit, nuts, and other ingredients are sometimes mixed with the tempered chocolate before depositing into the mould. The filled moulds are shaken to spread the chocolate evenly and to release air bubbles. Carefully controlled temperatures give reasonably rapid setting and a product of good appearance.

The solidification of the chocolate causes it to contract from the mould, so the block can be discharged without difficulty, leaving the mould clean and, after warming again, ready for use.

For chocolate assortments and chocolate covered bars, confectionery centres or bars are fed onto a wire net and conveyed through a shallow pool of chocolate to coat the bottoms. Then they pass through a falling curtain of tempered chocolate which flows continuously over the centres or bars. The excess chocolate passes through the wire net into the tank of the enrober (as the machine is called) for recirculation. The weight of chocolate in the centres is controlled by appropriate shaking and blowing while the product is still on the wire belt.

Finished blocks and bars are wrapped by automatic wrap machines and are test weighed to meet weight requirements. They are then packed into outers and placed on the conveyor system which takes them through to our warehouse for storage prior to distribution. Packaging Packaging is concerned with presenting the product in an attractive and appealing manner and in a way which will maintain it in top condition. The ideal package needs to give protection against absorption or loss of moisture, absorption of foreign odours and protection from any contaminants. It should exclude light which can accelerate oxidative changes and should have sufficient mechanical strength to withstand the action of modern high speed packaging methods and also the hazards of transport. The packaging material itself must be free from constituents which could adversely affect the product. Tempering Cocoa exists in a number of polymorphic forms and the nature of the crystalline form depends on the method of cooling the liquid cocoa butter. The process of tempering consists of cooling down the chocolate with continuous mixing to produce cocoa butter seed crystals and distributing these throughout the mass of liquid chocolate. The following temperatures are given as an example. Heat chocolate to 40-45ºC - Melts all crystal forms Cool to 26-29ºC - To produce seed crystals Heat to 29-32ºC - Melts unwanted crystals Tempering gives chocolate its shine, texture, and colour characteristics. Emulsifiers The main emulsifiers used in chocolate are Lecithins and polyglycerolpolyricinoleate (PGPR). Chocolate is a dispersion of very fine solid particles in a fat phase. The degree of flow of chocolate (viscosity) is greatly dependent upon the ease with which the solid particles are able to move over one another within the liquid phase. Emulsifiers coat the solid particles so that they move more easily in the fat phase of chocolate. Therefore there is a direct relationship between the viscosity of the chocolate and the amount of emulsifier added. Viscosity Reducing Cocoa butter can also be used to increase the flow properties of chocolate. By increasing the fat phase by adding cocoa butter, the ratio of solid particles to liquid fat is greater, therefore the solid particles flow more easily. Blooming This is often seen when chocolate becomes white in colour. This is when the chocolate has been heated and the fat crystaline forms are destroyed. The chocolate is then cooled again and the particles migrate to the surface.