Quality assessment of commercially processed carbon monoxide-treated tilapia fillets.

Carbon monoxide (CO) has been used to stabilize the color of fish muscle during frozen storage and distribution. This study compared changes in the quality profiles of CO-treated and untreated (UT) tilapia fillets stored at 21 to 22 °C (room temperature), 4 to 5 °C (refrigerated), and 0 °C (iced). Samples (n = 3) were analyzed at different time intervals for chemical, lipid oxidation, microbiological, color, and expert sensory profiles. CO samples contained greater (P < 0.05) apparent ammonia and total volatile base nitrogen (TVB-N) at day 0, with greater (P < 0.05) TVB-N throughout refrigerated and iced storage. At time 0, peroxide values (POV) and thiobarbituric-acid-reactive substances were lower (P < 0.05) for CO samples and continued to have lower trends throughout all storage temperatures. Microbiological analysis at time 0 did not show any differences between UT and CO samples. Redness (a*) color values were greater (P < 0.05) in CO tilapia at time 0; however, treated product showed a more rapid decline in a* throughout all storage temperatures. While expert sensory evaluation showed no statistical differences between UT and CO tilapia at time 0, CO product failed sensory assessment sooner than UT product when stored refrigerated and in ice.

Impact of quality parameters on the recovery of putrescine and cadaverine in fish using methanol-hydrochloric acid solvent extraction.

Methanol (MeOH) extraction by AOAC Official Method 996.07 has resulted in low amine recoveries in fresh fish tissue. Addition of 25% 0.4 M HCl to the 75% methanol-water extraction solvent resulted in higher recoveries of putrescine and cadaverine. Average putrescine recovery increased from 55 to 92% in flounder, scup, bluefish, and salmon; from 92 to 98% in mackerel; and from 83 to 107% in processed mackerel. Average cadaverine recovery increased from 57 to 95% in flounder, scup, bluefish, and salmon; from 91 to 97% in mackerel; and from 92 to 108% in processed mackerel. Fish stored on ice for 12 days also showed differences between background concentrations determined with the two solvents. However, the values decreased with storage time, indicating that degradation of the protein matrix may cause more comparable measurements between the two solvents. However, consistently higher putrescine and cadaverine measurements were determined using MeOH-HCl. Although significant differences in the extraction of amines from the high-fat fish tissue were not seen between MeOH and MeOH-HCl, it would be ideal to have one solvent for biogenic amine extraction. This study confirms that MeOH-HCl is a better solvent for complete extraction and recovery of putrescine and cadaverine in fresh and processed fish tissues.

Quality assessment of filtered smoked yellowfin tuna (Thunnus albacares) steaks.

UNLABELLED: Filtered smoke (FS) has been used to preserve taste, texture, and/or color in tuna and other fish species. This treatment is particularly important in color preservation during frozen storage. The objective of this study was to compare changes in the quality profiles of FS-treated and untreated (UT) yellowfin tuna (Thunnus albacares) steaks stored in 3 ways: room temperature (21 to 22 °C), refrigerated (4 to 5 °C), and iced (0 °C). FS and UT steaks were processed from the same lot of fish and analyzed for chemical, microbiological, lipid oxidation, color, and sensory profiles. Similar trends were seen for microbial proliferation and accumulation of apparent ammonia and total volatile base nitrogen (TVB-N) during the storage temperatures evaluated. Notable exception in quality profile was found in lipid oxidation which was, as expected, lower for treated samples at all storage temperatures for TBARS (P < 0.05) and lower or significantly (P < 0.05) lower for POV values. FS increased the initial redness value significantly (P < 0.05). Unlike UT product, there was no loss of color value concomitant with quality changes for FS-treated tuna for all storage temperatures evaluated. PRACTICAL APPLICATION: The overall goal of this project was to evaluate filtered smoked tuna steaks as to the impact on the overall quality profile. As a color-stabilizing technology, it could mask deteriorating quality.

Effect of matrix on recovery of biogenic amines in fish.

Biogenic amines, such as putrescine, cadaverine, and histamine, in fish can be indicators of spoilage and/or safety. Methanol extraction used for AOAC Official Methods 996.07 and 977.13 has resulted in low amine recoveries in fish. Extraction methodology was evaluated to improve recovery from fish tissue. Samples were evaluated for recovery of known quantities of biogenic amines added to tissue prior to extraction. Addition of 25% 0.4 N HCI to the 75% methanol-water extraction solvent (according to AOAC Official Methods 996.07 and 977.13) resulted in higher recoveries (P < 0.05) of the biogenic amines. Putrescine recovery increased from 44 +/- 2 to 100 +/- 14% in flounder and scup, and from 53 +/- 21 to 119 +/- 27% in mackerel and butterfish; cadaverine recovery increased from 47 +/- 4 to 106 +/- 15% (flounder/scup) and 58 +/- 24 to 113 +/- 9% (mackerel/butterfish); histamine recovery increased from 54 +/- 13 to 89 +/- 28% (mackerel). MeOH extraction resulted in comparable recovery from canned tuna, indicating that protein denaturation from processing may eliminate possible matrix interference. Acidification of the solvent resulted in a more complete extraction of the added amines to fresh/frozen fish tissue. This finding could indicate that current extraction procedures may cause biogenic amines to be underestimated.