TV Shows
Image default
Business and Services

The different mechanisms and importance of quality control in powder mixing

Particle coating, also known as the process of encapsulation, has been used in the food, pharmaceutical, feed, metal and other industries for more than 60 years. It is a process in which liquid and solid ingredients are used as an effective barrier to environmental or chemical interactions until release is desired. In the food industry, the coating process is widely used in the production of dry flavourings because raw flavourings easily become sticky or deteriorate under ambient conditions of temperature and humidity. Therefore, it is necessary to lock the flavour components in the form of a dry, free-flowing coating layer. This can be achieved through encapsulation technology. In the production of dairy products, this coating process is always used for milk powder to protect the core material from oxidation and unwanted odours. In addition to the benefit of protecting the core ingredients, other typical benefits of using coating and encapsulation processes include: (1) control of the release of the coated ingredients (e.g. slow release fertiliser, release of citric acid during sausage production), (2) improvement of stability under temperature, humidity, oxidation and light (e.g. oxidation barrier for cocoa powder, oxidation barrier for beta-carotene, protection during freezing and thawing cycles and extension of shelf life), (3) concealment of undesirable flavour (e.g. hiding the odour of protein for baby milk powder, taste masking of potassium chloride for dietary supplements), (4) improving particle morphology properties by preventing clumping, improving flow, reducing dust formation and modifying particle density.

In our test area, we can apply coating to small particles, grains and related solid materials on different types of instruments. We have pancoaters and drum coaters available for different coating processes where we can apply different coating conditions ranging from low to higher temperature and with aqueous and non-aqueous coating materials.

In our laboratory, we can test the strength of the coating after encapsulation under dynamic conditions such as pneumatic transport or the rotating drum method, or via static conditions such as the strength tester. Known from the pharmaceutical industry, but also for example in crop protection, is the phenomenon of controlled release or slow release to obtain dosage over a longer period of time. In certain cases, coatings are also used to improve powder flow by, for example, creating a smoother or more inert surface. After the coating/ encapsulation process, various analytical measurements can be used to determine the quality of the coating layer. For example, SEM-EDX coupled to a microtome can help determine the coating thickness. All these aspects can be investigated in our laboratory.

Coating and encapsulation of particles are used in many different industries, such as the food and feed, pharmaceutical and medical device industries. We have worked for a wide range of customers and can help you with your question.

What are the different mechanics used in powder mixing?

Several mechanisms are used in powder mixing, namely convection mixing, diffusion mixing and shear mixing. In convection mixing, masses or groups of particles move from one location to another. In diffusion mixing, individual particles are distributed over a surface located within the mixture. In shear mixing, groups of particles are mixed by forming sliding surfaces within the mixture.

Quality control is very important in the mixing process because it helps to detect and understand any unwanted segregation of powder mixtures. When mixing solids or powders, particles with different densities may tend to sink to the bottom of the mixture. Also, the fine particles may segregate from the larger particles when put into motion. By performing quality control, it is possible to assess whether the mixing process results in a homogeneous mixture and whether there is unwanted segregation. This can be done, for example, by taking representative samples of the mixture and analysing the particle size and segregation.

In short, understanding the different mixing mechanisms and performing quality control are essential for a successful mixing process.