All Food & Agriculture

About the quality control of cocoa mix and other instant beverages

This article describes the quality check of instant cocoa powder mix by FT-IR imaging. Multiple components are found including lecithin and theobromine.

Powdered beverages have seen a significant increase in demand in all age groups over the past decades. Just think of a hot cup of cocoa, or the Greek Frappé, which almost evokes a Mediterranean feeling and whose main ingredient is instant coffee.

But there is a lot of science and analytics behind this „instant“ path to delight. This includes a complex product development as well as quality control of the final product to ensure high production standards and customer satisfaction.

The chemistry behind instant cocoa mix

Instant cocoa mix is one of the most popular powdered beverages. Besides sugar and cocoa powder other ingredients are commonly added to the mix.

This includes maltodextrin, which serves as filler and anti-caking agent and lecithin, which improves the solubility of the mix. The quality of the cocoa mix can be strongly affected by a lack of homogeneity of these ingredients.

Analysis of cocoa mix can be challenging

To achieve good solubility, the particulates contained in powdered beverages are most often engineered to be very fine. Thus, visual examination or a conventional macroscopic analysis usually cannot or only partially provide the
necessary information about the product.

Advanced analytical methods are required to accurately analyze the composition of powdered beverages. FT-IR imaging enables identification of foreign contaminants as well as the individual major ingredients in a mixture by creating a chemical map to visualize the overall distribution.

The game-changer: FT-IR imaging

However, it is usually quite difficult to obtain an IR chemical image of such loose particles. However, it becomes a lot easier if a special germanium ATR hemisphere with a Ø 1000 μm crystal tip size is used. The large ATR crystal also helps to fix the powder in order to create a clear chemical image.

What the FT-IR Analysis of Cocoa mix tells you

Chemical image of the instant cocoa mix superimposed on its visual image.
Display of the content distribution as a false color image: maltodextrin (red), glucose (blue), cocoa powder (brown), lecithin (yellow) and theobromine (green).

A false color representation makes the result of the FT-IR analysis crystal clear. (Fig. 2). By using an algorithm called WTA (winner takes it all), each individual pixel is assigned with a color representing the dominating component. Which component predominates, results from the integration of the specific spectral signals.

The result: A true composition check

By comparing the IR spectra with those of a reference library (Fig. 3 ) the actual ingredients can be assigned to the spectral signals: maltodextrin (red), followed by cocoa powder (brown) and glucose (blue).

The yellow marked area is identified as lecithin. Even the smallest green particles in the sample have been resolved and are identified as theobromine, which is a bitter alkaloid of the cacao plant!

Summary and co(coa)nclusion

μ-FT-IR imaging plays an important role in the routine analysis of powdered beverage mixes for QA/QC purposes. It reveals foreign contaminants and yields a comprehensive composition and homogeneity analysis
of various beverage mixes:

  • Instant coffee
  • Iced tea mixes
  • Meal replacements
  • Nutritional supplements

You want to know more? Visit our website to learn about FT-IR imaging or contact one of our FT-IR experts to arrange a demo. You can also take a look at some of our other food applications here on the blog !