S. Yousefi Siahkalroodi - Department of Biology, Faculty of Biological Sciences, Varamin-Pishva Branch, Islamic Azad University, Pishva, Iran. Email: siamakyousefi@iauvaramin.ac.ir
P. mohebi derakhsh - Iranian Fisheries Science Research Institute, Agriculture Research Education and Organization (AREEO), Tehran, Iran
M. Yousefi Siahkalroodi - Faculty of Veterinary Medicine, Science and Research Branch, Islamic Azad University, Tehran, Iran

Using beetroot, safflower, and scarlet firethorn with ten treatments, three replications, and ۶۰۰ fish weighing roughly ۲۳۰±۱۰ gr that were established in a CRD experimental design for ۴۵ days, this study evaluated the pigmentation of the fillet and skin of rainbow trout. Three groups underwent treatments in which dietary sources of plant pigment were given, while a control group did not receive any plant-based pigmentation additive. Five fish from each replication were randomly chosen and euthanized on day ۴۵ of the experiment to evaluate the skin and fillet colors. Three criteria -L* (Brightness), a* (Redness), and b* (Yellowing) were used to evaluate the colorimetric indices after cutting a piece of fillet with skin on the lateral of the body and cooling it for ۲۴ h. According to the findings, there was no significant difference between the experimental beetroot groups and skin color groups for fillets (p>۰.۰۵). However, the beetroot group of ۱۰% had the highest percentage of the fillet and skin redness index, while the group without beets had the highest percentage of the yellowing and brightness index. The findings demonstrated that the addition of safflower improved skin discoloration compared to the control group (p<۰.۰۵). Scarlet firethorn was not significantly different in the experimental groups from the control (p>۰.۰۵). In conclusion, the supplementation of the rainbow trout diet with ۱۰% safflower resulted in better fillet coloration.

Pigmentation, Oncorhynchus mykiss, Carthamus tinctorius, Beta vulgaris, Pyracantha coccinea