Effect of safflower (Carthamus tinctorius), beetroot (Beta vulgaris), and scarlet firethorn (Pyracantha coccinea) fruit on fillet and skin pigmentation of rainbow trout (Oncorhynchus mykiss)

Using beetroot, safflower, and scarlet firethorn with ten treatments, three replications, and 600 fish weighing roughly 230±10 gr that were established in a CRD experimental design for 45 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 45 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 24 h. According to the findings, there was no significant difference between the experimental beetroot groups and skin color groups for fillets (p>0.05). However, the beetroot group of 10% 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<0.05). Scarlet firethorn was not significantly different in the experimental groups from the control (p>0.05). In conclusion, the supplementation of the rainbow trout diet with 10% safflower resulted in better fillet coloration.