Coloring of Arctic charr / Coloring of charr hold
An experiment was carried out with the aim of evaluating the activity of an organic pigment, Ecotone ™, and an inorganic pigment, Lucantin® Pink, on the coloration of char meat. The effect of 25% and 30% fat in feed on the activity of the pigments was also studied. All experimental items were tested in triplicate. The mean weight of the experimental fish was 564 g at the beginning of the experiment and 1381 g at the end of the experiment after 131 days. The temperature during the experimental period averaged 8 C̊ and the salinity of the broth was 20 ‰. The digestibility of astaxanthin in Lucantin® Pink was much higher than in Ecotone ™. The difference in body color measured by different methods turned out to be much smaller, which indicates a better utilization of the color in Lucantin® Pink. Little effect on body coloration was found by different amounts of fat in the feed and this was true for both pigments. The organic dye is more expensive to buy than the inorganic one and it results in approx. 5.5 % is more expensive to dye char with Ecotone ™ compared to Lucantin® Pink. During the analysis of the color of the feed at the beginning and at the end of the experiment 16 weeks later, it was found that there was a significant loss of color from the feed and that loss appeared to be independent of the type of color.
A feeding trial was conducted to compare the pigmenting efficiency of the biological colorant Ecotone ™ containg astaxanthin and prepared from the red yeast Phaffia rhodozyma, and the synthetic colorant Lucantin® Pink in Arctic charr. Both colorants were incorporated into diets containing either 25 or 30% lipid. All treatments were run in triplicate. The initial average weight of the fish was 564 g and the final weight 1381 g after a trial period of 131 days at 8 C̊ and 20 ‰ salinity. The digestibility of astaxanthin seems to be very much dependent upon the astaxanthin source. Differences in flesh color indicate a better utilization of astaxanthin from the synthetic source (Lucantin® Pink) as compared to the biological source (Ecotone ™). There was only a minor effect of lipid content on utilization of the astaxanthin. The biological astaxanthin source is more expensive than the synthetic source, resulting in about 5,5% higher production cost of fish produced with the “organic” colorant Ecotone ™ as compared to fish produced with the synthetic source of astaxanthin (Lucantin® Pink). The astaxanthin content in all diets proved to be very unstable when the feed was stored under conditions that are common in production of Arctic charr (10 - 20 ̊C indoors). The loss of astaxanthin ranged from 21-40% and tended to be higher in diets containing Ecotone ™. Thus, it is very important to avoid high temperatures, light and oxygen during storage of the feed.