Physiologic Responses to Stress and Changes in Atlantic Bluefin Tuna (T. thynnus) Meat Color During Trap Fisheries Capture and Processing in Sardinia (W. Mediterranean)

This study investigated plasma cortisol, lactate, and glucose as descriptors of hematological stressors; while the RGB color model using the percentage of monochromatic channels Red (Rp), Green (Gp), and Blue (Bp) was used for the analysis of muscular tissue of the Atlantic bluefin tuna, Thunnus thynnus. The experimental design provided a comparison of stressors and color channels Before and After the stress state and the analysis of variability of monochromatic channels for Fresh and Frozen specimens collected at three time intervals. Results showed a rapid accumulation of cortisol levels (from 73.3 ± 9.5 to 148.0 ± 21.2 ng/mL), lactate (from 5.7 ± 2.9 to 17.0 ± 2.2 μmol/mL), and glucose (from 83.5 ± 8.0 to 128.6 ± 19.3 mg/dL; p < 0.05). The colorimetric analysis highlighted that this accumulation did not in fact affect the color variability of muscle. Analysis of variance carried out to test the effects of color variability in Fresh samples showed significant differences for Rp, Gp, and Bp channels (p < 0.05), whereas no differences were found in Frozen samples. Highly significant differences (p < 0.001) were found comparing Fresh and Frozen for Rp and Bp, indicating a drop of these channels under diverse treatments.