Distinguer le bœuf nourri à l'herbe du bœuf nourri aux céréales grâce à la spectroscopie proche infrarouge
This article examines the use of Near-IR spectroscopy to separate grass-fed beef from grain-fed beef. Some cattle graze on pastures, which are lands covered with grass. Other cattle are fed maize, which is essentially corn or other grains. Grass-fed beef has superior nutritional quality compared to grain-fed beef. It is also exceptional in terms of safety and environmental friendliness compared to grain-fed beef¹. Figure 1 depicts the different feeding scenarios for the cattle.
Figure 1 : Méthodes d'alimentation à l'herbe et aux céréales2
La figure 2 montre la différence entre les deux types de viande.
Figure 2 : Différence entre le bœuf nourri à l'herbe et le bœuf nourri au maïs3
As shown in the figure, grass-fed beef on the right has less pronounced marbling than corn-fed beef. It also has a distinguishable yellow fat due to the presence of vitamin A in the grass. There is also more variety in taste and texture between breeds and origins. The corn-fed beef, on the other hand, is produced by feeding corn or other types of grain to the cattle, antibiotics, and hormones to fatten them. The fat also appears whiter due to a lack of vitamin A. There is also less variety between breeds and origins.
Distinguishing between the two types of meat, especially if done quickly and non-intrusively, is quite helpful for two reasons. First of all, consumers can be aware of the higher quality of meat they are purchasing. Secondly, it stops the fraudulent activities that sell grain-fed beef at a higher price in place of grass-fed beef.
Near-IR spectroscopy is a suitable technique for this kind of investigation, and a number of researchers have already examined the different spectra obtained from grain-fed and grass-fed beef1,5,6. Near-infrared spectroscopy of intact beef (Beef that has not been minced) predicts various quality features, such as fatty acid profiles and pH. Handheld near-IR spectrophotometers are readily available in the market that connect via Bluetooth and save spectra on the smartphone (Android or iOS)1,6.
La figure 3 montre la différence de spectre entre les échantillons de bœuf intact nourris aux céréales et ceux nourris à l’herbe5.
Figure 3 : Différence de spectres entre l'alimentation au pâturage et l'alimentation à l'ensilage de maïs5
There are some distinct differences between the two spectra. First of all, the spectra of animals on maize silage showed four absorption bands at 1732 nm and 1754 nm, related to the CH2 stretch first overtone (different lipid content). At 2310 nm and 2350 nm, respectively, are associated with CH combinationsAt 2310 nm and 2350 nm, respectively, are related to CH combinations. First of all, the spectra of animals on maize silage showed four absorption bands at 1732 nm and 1754 nm, related to the CH2 stretch first overtone (different lipid content), and at 2310 nm and 2350 nm, associated with CH combinations, respectively. First of all, the spectra of animals on maize silage showed four absorption bands at 1732 nm and 1754 nm, related to the CH2 stretch first overtone (different lipid content), and at 2310 nm and 2350 nm, associated with CH combinations, respectively. Secondly, differences at 1638 nm and between 2200 nm and 2300 nm, associated with C-H and C=C groups, suggest that differences in polyunsaturated fatty acids could further contribute to muscle classification (as seeat 1638 nm and between 2200 nm and 2300 nm, related to C-H and C=C groups, suggest that differences in polyunsaturated fatty acids could further contribute to muscle classification (as seen in the absorption spectra). Using NIR spectra, correct classification rates of 80-83% for pasture-fed beef and 79-80% for maize-fed beef were achieved.
Le spectrophotomètre Nirvascan proposé par ASP Laser Inc. a été utilisé dans l'une de ces études1 et a permis de classer avec succès le bœuf nourri au grain et le bœuf nourri à l'herbe avec un taux de réussite supérieur à 85 %. La classification a été effectuée à l'aide des méthodes d'analyse discriminante linéaire (LDA) et d'analyse discriminante des moindres carrés partiels (PLS-DA).
La figure 4 montre un spectrophotomètre Nirvascan à fibre optique, connecté à une source externe de 5 watts qui comprend également une lentille collectrice (DRP1) pour mesurer à partir de bœuf intact contenant de la graisse.
Figure 4 : Nirvascan à fibre optique utilisé avec une source lumineuse halogène externe pour mesurer le spectre d'absorption du bœuf intact
Plusieurs pics d'absorption, notamment pour la liaison CH (graisse, pic à 1200 nm) et la liaison OH (humidité, protéines, pic à 1450 nm), sont observés dans le spectre d'absorption mesuré.
Pour plus d'informations sur le spectrophotomètre Nirvascan et ses différents modèles, reportez-vous au lien suivant.
https://www.alliedscientificpro.com/nirvascan
Références :
- Les méthodes spectroscopiques vibrationnelles portables peuvent faire la distinction entre le bœuf nourri à l'herbe et le bœuf nourri aux céréales, C.Coobs et.al, JINRS, 2021
- https://www.foodfirefriends.com/grass-fed-vs-grain-fed-beef/
- https://onpasture.com/2017/03/13/whats-the-difference-between-grain-fed-and-grass-fed/
- https://paleorobbie.com/post?id=52
- Spectroscopie de réflectance visible/proche infrarouge pour la prédiction de la composition et le traçage du système de production du muscle de bœuf, D.Cozzolino et.al, Animal science, 2002
- Un spectromètre infrarouge proche portatif permet de prédire en ligne les caractéristiques de qualité du bœuf, A Goi et.al, Meat science, 184, 2022