Juan Antonio Fernández Pierna, Ouissam Abbas, Pierre Dardenne, Vincent Baeten
Quality Department, Walloon Agricultural Research Centre (CRA-W)
24, Chaussée de Namur, 5030 Gembloux (Belgium)
Changes to the rules on forbidden and authorized raw and processed animal materials in feed formulations require the development of a strategy to assess the absence of illicit materials in the feed mills and producers, as well as at the rendering plants. Until now, the official controls have been based exclusively on the microscopic identification of illicit ingredients. Mainly on searching in the sediment fraction of the feed, bone particles in the presence of processed animal proteins (PAP) but also scale particles in the specific case of presence fish meal.
Several options have been studied in order to help the official control and industrial laboratories. These options can be also used to complement the strategy by allowing animal species-specific detection.
Developments based on a combination of techniques have enabled powerful methods to be elaborated for the analysis of feed ingredients and compound feeds. Methods as a near-infrared spectrometer coupled with a microscope (NIRM) have been successfully used to detect animal proteins in feed. The NIRM installed at the CRA-W has operated under accreditation since 2005, following International Standard ISO 17025. This method has provided good results for detecting a series of feed ingredients of animal or vegetal origin traditionally used in the formulation of feedstuffs. The advantage of NIRM is that it combines the optical microscopy benefits (detection based on the presence of animal particles not affected by the rendering process applied to the MBM) with the spectroscopic benefits (detection based on the specific chemical composition of animal tissues and no need for trained and skilled technician). The main limitation of NIRM is that it is slow because of the sequential collection of particle spectra.
An alternative to NIRM is the use of a more recent technology called near infrared hyperspectral imaging (NIRHI). The success of NIR hyperspectral imaging stems from a combination of factors: high-performance and uncooled NIR sensitive focal plane array detector including thousands of individual elements, appropriate and high resolution wavelengths selector and an adequate hardware and software components allowing to handle the huge amount of data generated. The decisive advantage of NIRHI for the detection and quantification of PAPs is the high number of particles that can be analysed by unit of time (up to hundreds or thousands particles by minute according to the technology used and the configuration selected).
BSE; PAP; NIRM-NIR Microscopy; MBM; NIRHI-NIR Hyperspectral Imaging