# Use of glycerol triheptanoate as a marker for processed animal by-products - results from 2010–2024

## TL;DR

This paper reports on the use of glycerol triheptanoate (GTH) as a marker in animal by-products to prevent unsafe materials from entering the feed chain, based on testing results from 2010 to 2024.

## Contribution

The study validates gas chromatography methods for GTH detection and evaluates compliance with GTH marking regulations in animal by-products.

## Key findings

- Approximately 10.5% of tested samples did not meet GTH content requirements under applicable law.
- Processed animal proteins had the highest non-compliance rate at 20.7%.
- Nearly 90% of samples were correctly marked with GTH or free of it, suggesting progress in marking technology.

## Abstract

Whole dead animals, parts of dead animals, products of animal origin or other products derived from animals that are not intended for human consumption are animal by-products, and legislation imposes restrictions on the use of those which may pose a risk to the food and feed chain. High-risk products should only be used outside the feed chain. Unsafe by-products are distinguished from safe ones, parcel by parcel, and those with the highest harm potential are permanently marked during processing with glycerol triheptanoate (GTH) to prevent their entry into the feed chain. The legislated minimum content of this marker must be 250 mg/kg of fat. This research is on the development and validation of methods using gas chromatography with flame ionisation or with mass spectrometry for GTH detection, and also comprises a report of compliance with the GTH content threshold among samples of animal by-products.

Between 2010 and 2024, 2,303 samples of meat and bone meal, rendering fat, processed animal protein, soil improvers, antioxidants, feed materials and mixtures, dog chews, feathers, bird balls and unknown material of animal origin were tested. Gas chromatography was used with either flame ionisation detection or mass spectrometry.

Samples that did not meet the requirements under applicable law accounted for approximately 10.5% (240 samples). The highest percentage of non-compliant samples was recorded in the processed animal proteins group (20.7%). Incorrectly marked meat and bone meal and rendered fat accounted for 8% and 12% of their groups, respectively.

Nearly 90% of the samples tested were correctly marked with GTH as required or free of it, which may indicate progress in developing effective marking technology at processing plants.