The nutritional importance to local communities of fish caught off the coast of Qatar

This article focuses on the consumption of fish in Qatar and its health benefits for those living in the region. The nutritional value of fish from traditional fishing areas such as the UK has been much discussed but this article addresses the value of fish from warmer regions. Samples of popular fish were purchased from the local market in Qatar and were then analysed for levels of major nutrients and fatty acids. The likely nutritional impact of fish on the local diet was then evaluated. Problems of preservation of fresh fish, hygiene and mercury levels are also pointed out. Vigilance on behalf of the Public Health Authorities is urged to ensure the good reputation of fish in this region remains. 288 Nutrition & Food Science Number 6 . November/December 1999 . pp. 288±294 # MCB University Press . ISSN 0034-6659 (20:6 n-3) (DHA). It is claimed that the consumption of fish oils may help in the prevention and treatment of high blood pressure, asthma, arthritis, psoriasis and some cancers (Ward, 1995). However, while the nutritional value of fish has been the subject of much discussion in traditional fishing areas like the British Isles, little has been published about fish from warmer regions. Consequently, the aim of this project was to: . purchase samples of popular fish from the local market in Doha; and . analyse them for levels of major nutrients and fatty acids, in order to evaluate the likely nutritional impact of fish on the local diet. Materials and methods According to the Department of Fisheries, around 12 species of fish are widely consumed in Qatar, and these are listed in Table II. On three separate occasions, specimens of each species that weighed at least 1kg were purchased from the local market as soon as possible after landing, and transported to the laboratory in a chill box part-filled with ice. On arrival at the laboratory, each specimen was gutted and filleted in the manner practised in most homes, and the bone-free fillets were stored at 48C for a maximum of two hours before analysis. Analysis of the fillets One fillet, consisting of muscle tissue and a covering of skin on one side, was selected for each species and macerated in a high-speed blender. Duplicate sub-samples were extracted for determinations of moisture, crude protein, fat and ash; an indication of pH was obtained by direct insertion of a combined electrode into the macerate prior to removing the sub-samples. The pH meter was an Orion 720A. The moisture content of each sub-sample was determined according to ADAS (1986), as was the ash content. The fat content was measured by extraction with petroleum spirit in a Soxhlet extractor (Kirk and Sawyer, 1991), and total nitrogen content of the sample was found by the Dumas method using a Leco Nitrogen Determinator (Leco Instruments Ltd, Stockport, UK); the protein content was calculated as total nitrogen multiplied by 6.25 (Kirk and Sawyer, 1991). Analysis of fatty acids For analysis of the fatty acids in the fat extracted from the sub-samples, methyl esters were prepared by saponification followed by acidification and finally methylation with diazomethane (Punstinen et al., 1985). The methyl esters were analysed by GC on a Shimidzu GC15A with C-R6A chromatopac integrator. A 3mm 6 3M stainless steel 10 per cent Silar 10C column packed with 100-120 mesh Gas ChromQ was used. The injector and detector temperatures were maintained at 2508C. The column temperature was held at 1008C for 4 min, and then heated at a rate of 58C per min to a final temperature of 2108C and kept for 15 min. The total time of analysis Table I Local catches and imports of fresh fish into Qatar during 1987-1991; all figures in metric tonnes Year Local Imports Total 1987 2677.9 464.5 3142.2 1988 3086.2 231.6 3317.8 1989 4374.0 309.9 4683.9 1990 5702.2 830.5 6532.7 1991 8136.2 717.8 8854.