Quality Index Method developed for Frigate tuna (Auxis thazard)

Abstract

An investigation was carried out to develop and evaluate a Quality Index Method (QIM) scheme for Frigate tuna (Auxis thazard) for the prediction of past and remaining storage time in ice. The quality index method (QIM) provides weighted evaluation of the key parameters in deterioration of individual species, assigning demerit points according to the importance of each parameter. For the development and evaluation of QIM scheme, Frigate tuna were stored in ice and assessed raw and cooked. The QIM developed for raw Frigate tuna comprised of 11 parameters (appearance of skin and stiffness: cornea, form and colour of eyes; colour, smell and mucus of gills; condition of viscera; colour of blood and fillets) covering attributes, which gave a total of 25 demerit points. Sensory analysis of cooked Frigate tuna using Torry scheme were carried out in parallel to determine the shelf life. In order to obtain more information about the quality of Frigate tuna, Total viable counts (TVC), hydrogen sulphide (H2S) producing bacteria, trimethylamine (TMA), total volatile basic nitrogen (TVN) content and pH value were determined. The sensory evaluation was carried out by a panel of 6-7 judges and the rejection level was found to be 22 days. The QIM scheme developed for Frigate tuna showed a linear relationship between QIM scores and storage time in ice, (r2 = 0.9378) with slope of 0.755. The TVC varied from 102 cfu g-1 to 106 cfu g-1 within 7 to 22 days and H2S producing bacteria at 102 cfu g-1 within 22 days of storage in ice. The TMA and TVN amounts increased with time and the amounts ranged from 1.2 mg/100g to 2.5 mg/100g and 17.2 mg/100g to 34.9 mg/100g respectively. The variation of pH ranged from 5.4 to 5.9 within the storage. The QIM calibration curve obtained for Frigate tuna indicates it’s applicability to determine the storage life of fish in ice. Further, it will facilitate the requirements of buyers and sellers while fulfilling the demands of inspection authorities and the consumers.

Combined impacts of oregano extract and vacuum packaging on the quality changes of frigate tuna muscles stored at 3±1°C

“…The quality index method (QIM) was employed for frigate tuna fillets with slight modifications for sensory assessment [ 8 ]. The QIM procedure contained five quality parameters including surface and skin appearance, odor, texture and color of fillet, and plant extract odor.…”

“…Sensory evaluations of cooked frigate tuna fillets were assessed in line with the same method of Ariyawansa et al . [ 8 ] without any modification. Frigate tuna fillets were microwaved in for 3 min.…”

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“…Sri Lanka is one of the oldest and one of the most famous tuna producing islands in the Indian Ocean. Yellowfin tuna, Skipjack tuna, Marlin, Sailfish, Swordfish, rays, and sharks are some commercially valuable fish species live around Sri Lanka (Ariyawansa, Wijendra, and Senadheera 2003;; Indian ocean tuna commission 2019). Among these species Skipjack tuna (Katsuwonus pelamis) is an important migratory fish that significantly contributes to the economy and the global fishery industry.…”