Effect of natural carotenoids obtained from Haematococcus pluvialis, Paracoccus carotinifaciens, and Phaffia rhodozyma on flesh pigmentation and related biochemical mechanisms in Atlantic salmon (Salmo salar L.)

The present study highlights the efficiency of natural carotenoid sources ( Haematococcus pluvialis , Phaffia rhodozyma , and Paracoccus carotinifaciens ) in terms of Atlantic salmon pigmentation, lipid profile, oxidation status (glutathione (GSH)/glutathione disulfide (GSSG)) ratio, and genomic stress markers ( nrf2.1, keap1b1, hsp70 , and h2q8 genes) during an 88-day feeding trial. As controls, fish fed synthetic astaxanthin was used. Four experimental diets with equal nutritional composition, except for the pigment source, were tested in an experimental design of 12 tanks and 372 fish ( n = 3 × 31 per feed, start weight of 149 ± 27.5 g). Astaxanthin from H. pluvialis , P. rhodozyma , and P. carotinifaciens were found to be as efficient as synthetic astaxanthin in terms of visual perception, oxidation status and lipid peroxidation as there were no significant differences ( p > 0.05) in a* value, GSH/GSSG ratio, or lipid profile between the different groups. Additionally, there were no significant differences in the gene expression of nrf2.1 , keap1b1 , or hsp70 in the NQC or the PC. Fish fed P. rhodozyma showed the most favorable results as it had the numerically highest a* and C* values and the lowest L* value. Moreover, no significant difference in total muscle astaxanthin concentration was observed between the fish fed P. rhodozyma and those fed synthetic astaxanthin. However, the fish fed synthetic astaxanthin had a significantly higher concentration of total flesh astaxanthin than those fed H. pluvialis and P. carotinifaciens . The results conclude that naturally produced astaxanthin has a significant potential in Atlantic salmon pigmentation. However, further research on slaughter-ready salmon is essential to prove the concept. • The effect of natural astaxanthin sources on biochemical mechanisms was studied. • Pigments from P. rhodozyma gave comparable results to synthetic astaxanthin (ax). • Pigment source did not affect the fillet redness. • Salmon fed P. rhodozyma and H. pluvialis were darker than those fed synthetic ax. • The pigment source did not affect oxidative markers neither in the flesh nor liver.