Chocolate Pigging

Innovative pigging technique for pipe cleaning in the chocolate industry

Workgroup: Confectionary machines

Research Partner and Scientific Guidance:

  1. Fraunhofer Institut für Verfahrenstechnik und Verpackung IVV Freising, Isabell Rothkopf
  2. Fraunhofer Institut für Verfahrenstechnik und Verpackung IVV Dresden, André Boye

Financing: IVLV e. V.
Duration: 2019

Starting situation:
In order to be able to offer attractive products in the dynamic chocolate market, producers are required to launch new flavor variants, seasonally changing products and special products in small series. The cleaning of the systems is only pos-sible with a lot of rinsing mass and high cleaning effort. During the cleaning process, cocoa butter or the mass for the next production is added for intermediate cleaning and an optical assessment is made of when the next production can be started. The mass used for rinsing is in the best case used for the production of other masses or fillings. Otherwise it will be discarded. This causes enormous costs and a considerable waste of food. Therefore more and more pigging systems are used for cleaning. A plastic plug, the so-called pig, is inserted into a pipeline and then pushes out the product. In order to be able to use this technology efficiently, high demands are placed on the pipelines. In order to avoid this, a new pigging process – ice pigging – has recently been launched on the market for cleaning food processing equipment. This process uses a non-form stable plug made of water and ice. The use for products with fat as a continuous phase, as they occur in oil production and in pipelines, was also demonstrated. Here, however, the oil usually contains particles that are inert to water, such as sand, rock or waxy deposits.

The aim of the project is to test the transferability of the basic idea of the non-form stable ice pig for the cleaning of pipelines in the chocolate industry where a water-based pig cannot be used.

The resulting sub objectives are as follows:

  • Development and adaptation of a chocolate and cocoa butter based slurry for the cleaning of chocolate plants
  • Stability of the developed slurry at typical residence times and temperatures
  • Experimental set-up on a pilot scale for practical tests of an ice pig
  • Cleaning tests with verification of resource savings compared to conventional standard cleaning methods

For the implementation of the project, the findings from the application of ice pigs in other areas will first be used. These include the rheological characteristics, stability and length of the pig compared to the length of the track to be cleaned. The known properties are translated into dimensionless parameters and form the basis of the pig to be developed. For the exact description of the pig, physical measuring methods have to be adapted or developed, especially with regard to the flow properties. Initially, the pigging systems will be developed on a laboratory scale. The first step will be to work with recipe components of chocolate: Sugar in cocoa butter, cocoa butter slurry (supercooled, partially solidified cocoa butter), high-melting cocoa butter fractions in liquid cocoa butter, larger fragments of the product dispersed in new product or in cocoa butter. First, the effect is investigated in a small piece of pipe with an uniform diameter (disposable syringe without closure). With suitable systems, the stability of the dispersed particles is then tested at typical temperatures and residence times (40 °C for 10 min). For the transfer into industrial practice and further investigations of the cleaning effect, a test bench on a pilot scale is required, which is provided by the project partners. To prove the feasibility and the positive economic effects, a comparison of conventional cleaning methods and the use of the ice pig on the pilot plant test rig will be carried out at the end of the project. The system is filled with one chocolate each (e.g. milk chocolate) and rinsed with a second chocolate (e.g. white chocolate). In a further experiment, an intermediate rinse with cocoa butter is carried out and finally the developed ice pig is used for cleaning the pipes.