Abstract
The quality of fish and fishery products constitute a major concern in fish industry all over the world. The current study was carried out to inspect the quality of some frozen marine fish species depending on some chemical indices. A total of 75 random samples of marine water fish represented by Barboni, Morgan and Mackerel (25 of each) were collected from local markets. Samples were subjected to chemical examinations to determine some proteolytic and lipolytic indices as well as their histamine content. The obtained results revealed that mean values of pH were 6.29 ± 0.06, 6.20 ± 0.04 and 6.39 ± 0.03 for Barboni, Morgan and Mackerel, respectively. Also, it was found that the mean of Total volatile Nitrogen (TVN) values was 16.5 ± 2.1, 17.4 ± 1.3 and 14.2 ± 1.6 mg % for examined samples, respectively. In addition, Trimethylamine (TMA) was estimated and it was recorded that the mean of TMA values was 7.35 ± 0.38, 5.59 ± 0.22 and 4.86 ± 0.15 mg % for examined samples, respectively. Moreover, thiobarbituric acid (TBA) was estimated as lipolytic index of spoilage and it was recorded that the mean of TBA values was 2.18 ± 0.19, 1.82 ± 0.14 and 2.21 ± 0.13 mg % for examined samples, respectively. Also, it was found that the mean value of free fatty acids was 0.31 ± 0.02, 0.23 ± 0.01 and 0.38 ± 0.01 mg % for examined samples, respectively. Finally, it was found that the mean values of histamine level for the examined fish samples was 16.62 ± 0.27, 15.76 ± 0.31 and 15.15 ± 0.29 mg % for Barboni, Morgan and Mackerel fish samples, respectively. Luckily, it was noticed that fish samples were accepted according to permissible limits stipulated by Egyptian Standards. This study highlighted the efficiency of application of certain chemical tests for evaluation of fish quality. Although, the recorded results were satisfying but Barboni and Mackerel should be consumed with caution due to rapid spoilage.

Key words: Spoilage, chemical indices, Frozen Marine, Fish