Ahmed Rashed Al-Najada
Abstract: Changes in the shelf life indices of iced species from the Arabian Gulf Shaeri (Lethrinusminiatus) and Hamour (Epinephelus chlorostigma) were evaluated. Perishable food products can be determined through an assessment of the bacterial tests or by chemical tests such as the determination of Trimethylamine (TMA) which is produced by the reduction of trimethylamine oxide (TMAO), Trimethylamine contents and Physical assessments evaluations were performed at 0, 3, 5, 7, 10 and 13 days postmortem. Initially, trimethylamine (TMA) values were higher (P <.05) in marine species and TMA values increased with storage period, yet none of the species under investigation reached the rejection (30 mg TMA-N/100g) level. Sensoryly the keeping time of the different fish species were found to be around 6.33 and 10.9 days for Hamour and Shaeri respectively. Hamour had way less (P <.05) sensory scores than Shaeri. In general, torry meter scores for marine fish species decreased to varying degrees with storage period. Shaeri had higher values than Hamour. In the first three days of storage changes in torry meter values of Shaeri and Hamour were very minimal during this period. Initially, marine fish species under investigation had pH value higher than 6.8. Throughout the storage period marine fish species had Changes in the Hunter color values L*, a* and b* were followed for up to 7 days of storage. Generally, throughout the storage period tested marine fishes had hunter color values higher than (P <.05) L*. Marine species. Upon storage became darker i. e. their a* values increased with storage time to reach their peaks 8.69 and 10.67 for Hamour and Shaeri respectively. None of the two marine fish species had aw below 0.9. However, throughout the storage period studied, no significant differences (P >.05) in moisture content were noticed in marine fishes, the initial protein content of Shaeri was slightly (P >.05) higher than the protein content of Hamour. Storage period had no effect (P >.05) on the protein content of either Shaeri or Hamour. The iron content of marine fish species (Hamour and Shaeri) had initially similar (P >.05) iron content. Upon storage (day 5) and showed substantial increases (P <.05) of 44 % and 48 % for Hamour and Shaeri respectively. The effect of storage on the copper content was similar to that of iron i. e. a decrease in content with storage except for Shaeri where a 45 % increase.
Keywords: Marine fish, Shelflife, postmortem changes, TMA, , Sensory evaluation and Hunter color values