Air chocolate
Air chocolate or foam chocolate is a chocolate into which air or a gas is introduced during production and forms more or less fine cavities. Compared to normal chocolate, it usually has a softer bite and melt. Their density is lower, which means they have a larger volume for the same weight. Normal chocolate has a bulk density of about 1.3 g / cm³; In contrast, air chocolates can reach up to 0.1 g / cm³ depending on the type. It is not necessarily a reduced calorie product as the physiological calorific value of food is usually expressed in terms of mass, not volume.
variants
There are different forms of air chocolate that differ greatly in their properties.
- The best known type has a macroscopic foam structure with an average bubble diameter in the range 0.05-3 mm and a density of 0.4-0.8 g / cm³. For production, a shell-like half-shape made of conventional chocolate is first prepared in a casting or cold forming process. The foamed, still liquid chocolate is then injected into this and cooled until it is solid. Then a layer of conventional chocolate is poured on to complete the coating and create a smooth back. The surface of the finished product therefore consists of non-foamed chocolate and - apart from embossed lettering or the like - is correspondingly smooth. Air chocolate of this type was first launched in 1935 by the British chocolate manufacturer Rowntree under the name Aero . Aero is still available, but now comes from Nestlé (but not on the German market, here it is a Trumpf brand ).
- Another type has a microscopic foam structure with bubbles so small that they cannot be seen with the naked eye . A density down to 0.7 g / cm³ is possible, whereby the invisible ventilation is still perceptible through faster melting and a changed mouthfeel . The main area of application is cast chocolate biscuit products , which are lighter overall.
- Instead of a foam structure, air chocolate can also contain continuous, elongated cavities. Such products are made by extrusion of semi-solid or solid chocolate; an example is Spira from Cadbury .
- There are special gaseous cocoa products that differ from normal chocolate in that it is not the fat (i.e. the cocoa butter ) that holds the mass together, but other solids , namely the sugar . Such products are mostly whitish in color, have an irregular foam structure, can be produced with a very low density and low fat content and only melt at higher temperatures, but nevertheless dissolve quickly in the mouth. They are made by water evaporation (see below). Some of these products are not chocolate in the sense of food law .
Foaming process
In principle, chocolate can be foamed in three different ways: First, by expanding under vacuum; second, by impact under high pressure and subsequent pressure reduction; thirdly, by introducing and then evaporating water.
Vacuum process
Melted chocolate is placed in a vacuum and thereby foams. It is then cooled down, the foam structure solidifies and is retained even after it has been removed from the vacuum. The process can be supported by introducing gas - usually carbon dioxide - into the chocolate mass beforehand . The size of the bubbles formed is influenced by numerous process parameters, such as the viscosity of the chocolate, the negative pressure, the emulsifiers used and the cooling rate.
The operation and cleaning of vacuum systems are relatively expensive; Due to the high workload, the vacuum process is less common than high-pressure systems. The advantage, however, is that large-sized ingredients can be mixed in without any problems.
Letterpress process
Liquid already tempered chocolate mass is whipped with a high-speed tool under high pressure, wherein the gas from the environment and partly in solution is partly distributed in the form of bubbles in the mass. Care must be taken to ensure that the temperature does not increase so much that the temperature control is lost. The chocolate, which is still liquid, is then brought back to normal ambient pressure , which causes the gas to expand and the chocolate to foam. It is then immediately shed. It is very difficult to mix in coarse ingredients, which is the disadvantage of the high pressure method compared to the vacuum method.
The properties of the finished product depend to a large extent on which gas is used; there may be a connection with the different solubility of various gases in chocolate. Nitrogen and argon are less soluble and lead to small bubbles that cannot be seen with the naked eye. Carbon dioxide and nitrous oxide are more soluble and lead to a coarser, easily recognizable structure. Sensory studies show that chocolate that is foamed with the last two gases mentioned is perceived as being softer, airier and less creamy. In particular, nitrous oxide - which is comparatively expensive - is said to contribute to a more intense cocoa taste.
Evaporation process
To produce the special chocolate or cocoa products already mentioned, which are not held together by the fat content, various processes are used, which have in common that the water content of the chocolate is first increased and then more or less completely evaporated.
The first known process of this kind was patented by Cadbury in 1975 and worked by emulsifying cocoa mass and milk powder in sugar water and then reducing the water content to less than 2% in a two-stage vacuum drying process. The resulting product has a density of 0.1-0.3 g / cm³ and could be made so low in fat that it could not be sold as chocolate. It can be cut into pieces or crushed into grains and can be used in ice cream or cakes .
The second process has been patented by Nestlé and the Japanese chocolate manufacturer Meiji since around the turn of the millennium and is said to have been used to manufacture a product called poff on the Japanese market. In this process, liquid chocolate is emulsified with water, allowed to set and then the water is removed from it by freeze-drying , whereby the hollow spaces that are released are filled with air. This product can also be cut and shredded.
Web links
Individual evidence
- ↑ a b c Stephen T. Beckett: Non-Conventional Machines and Processes . In: Stephen T. Beckett (Ed.): Industrial Chocolate Manufacture and Use . 4th edition. Wiley-Blackwell, Oxford 2009, ISBN 978-1-4051-3949-6 , pp. 404 ff . ( limited preview in Google Book search).
- ↑ Josefin Haedelt, Stephen T. Beckett, Keshavan Niranjan: Bubble Included Chocolate. Relating Structure with Sensory Response . In: Journal of Food Science . Volume 72, No. 3 , 2007, ISSN 0022-1147 , p. E138 – E142 , doi : 10.1111 / j.1750-3841.2007.00313.x .