Bilirubin vs. Carotenoids
The meat inspectors wanted to determine wether the cause of yellowing was physiological due to accumulation of carotenoid pigments or if it was a case of jaundice (pathological accumulation of bilirubin).
We performed histopathological examination of the liver and lymph nodes to rule out the presence of lesions which would explain a pathology. The ether-alcohol test was performed with adipose tissue: it consists in depositing adipose tissue fragments of the affected carcass in two containers, one with ether and another with alcohol, then the mixture is stirred and the result read in 1-2 hours. Carotenoids are soluble in ether and will stain the liquid yellow, on the other hand bile pigments are soluble in alcohol and will stain the other vial yellow (see figure 2) (Higiene e Inspección de carnes, B. Moreno Garcia, 2003, Ed. Diaz de Santos).
The lack of liver lesions and the positive reaction to ether suggested that this was a case of yellow coloration due to accumulation of carotenoid pigments.
Yellowing physiological changes can also be observed in aged animals and are more common in some breeds of cattle (Jersey and Guernsey). Carotenoid pigments, upon oxidation, may diminish its colour or even disappear during the airing of the carcass.
Evident yellow discoloration of the adipose tissue.
When depositing adipose tissue fragments in alcohol and ether, ether turned yellow while this was not the case with alcohol, indicating that the tissue contained carotenoid pigments.
2 comment(s)
Thanks for your posting.
Can you give me the detailed protocol for ether-alcohol test if available ?
The protocol is available at the book: “Higiene e inspección de carnes” by Benito Moreno García Ed. Diaz de Santos. 2003