The quality of a lab result starts with sampling

A laboratory can work with great precision, but if the sample it receives is not representative of the whole batch of raw material, the result may say little about the actual product quality. This risk is particularly relevant for powders and granules, where contaminants are not always evenly distributed through a batch.

For food and feed manufacturers, reliable sampling is therefore an essential part of quality assurance. Not only the analytical method, but above all the way a sample is taken, determines whether a test result is usable.

Why different raw materials should not simply be combined

In practice, combining different raw materials into a single composite sample is sometimes considered. It looks efficient: fewer lab analyses, lower costs and a simpler testing process.

Yet this approach can create significant risks. When five different ingredients are combined into one sample, two problems arise:

• Loss of traceability: if a test comes back positive, it is not immediately clear which raw material or which batch is responsible.
• Dilution of contamination: a contaminant in one ingredient can fall below the detection limit of the analytical method once it is mixed with other materials.

With microbiological risks such as Salmonella, this can have major consequences. A contaminated quantity in one specific raw material is diluted by mixing with several other ingredients. In addition, the final composition may fall outside the validation conditions of the analytical method used.

Combining different raw materials is therefore something other than taking a representative composite sample within a single raw-material batch.

Composite samples within one batch: a better approach

Combining several increments within the same raw material and the same batch can be a valuable method. Instead of taking one random sample from one bag, several increments are collected from different positions and depths. These are then combined into one representative sample.

With powders this is especially important. Contaminants are not always homogeneously distributed. They can be concentrated in specific locations, for example:

• In one individual bag within a larger lot.
• At the bottom or the top of a package.
• In lumps or local accumulations.
• Around seams, connections or damage to packaging.

A sample taken only from the top layer of a bag therefore does not necessarily give a reliable picture of the entire contents.

Closed sampling avoids additional risks

Besides representativeness, the way sampling is carried out also matters. Opening bags in a warehouse brings additional risks, such as dust formation, cross-contamination and operator exposure to raw materials.

A better approach is to use suitable sampling equipment that can reach several depths. Even more interesting is an integrated sampling point during unloading or transfer of raw materials. Samples can then be taken at a controlled moment in the process, without unnecessary manual handling.

A well-designed sampling point can contribute to:

• More representative samples.
• Less exposure to dust.
• Reduced cross-contamination.
• Better reproducibility of sampling.
• A more controllable quality process.

Saving costs without compromising quality assurance

When the cost of lab analyses plays an important role, there are alternatives to combining different raw materials. One example is a risk-based skip-lot programme.

New suppliers and high-risk raw materials are tested intensively. Once sufficient historical quality data is available, you can switch to a combination of supplier certificates (CoA), periodic verification and additional risk-based analyses. This can reduce the number of lab analyses without sacrificing the traceability of raw materials.

The role of powder handling in reliable quality control

At Hecht Technology we look at powder handling from the perspective of process control, product quality and safety. The design of discharge stations, transfer points and closed conveying systems affects more than productivity. The ability to take representative samples, limit dust and prevent contamination also deserves attention when an installation is designed.

For food and feed manufacturers, this is an important part of a reliable production process.

Conclusion

A good lab result does not start in the laboratory but at the sampling point. Combining different raw materials can mask contamination and makes it harder to trace the origin of a deviation. By taking several increments within one batch and integrating closed sampling points where possible, you get a more reliable picture of the actual product quality.