Effect of Different Cooking Methods on Selenium Content of Fish Commonly Consumed in Thailand.

Although fish are good sources of selenium (Se), an essential trace element for the human body, very limited data exist on Se content in commonly consumed fish in Thailand. Consequently, this study investigated selenium content and the effect of cooking among 10 fish species (5 freshwater and 5 marine) most-commonly consumed by the Thai people. The fish were purchased from three representative wholesale markets within or nearby to Bangkok. All fish species were prepared to determine their edible portions (EP) and moisture contents. Total Se in fresh, boiled, and fried fish were analysed using Inductively Coupled Plasma-Triple Quadrupole-Mass Spectrometry (ICP-QQQ-MS). In general, higher levels of Se were found in marine fish (37.1−198.5 µg/100 g EP in fresh fish, 48.0−154.4 µg/100 g EP in boiled fish, and 52.9−262.4 µg/100 g EP in fried fish) compared to freshwater fish (6.9−29.4 µg/100 g EP in fresh fish, 10.1−26.5 µg/100 g EP in boiled fish, and 13.7−43.8 µg/100 g EP in fried fish). While Longtail tuna showed significantly higher Se content than other fish (p < 0.05), boiled Longtail tuna had significantly lower true retention of Se than the other fish (p < 0.05). Most fish species retained a high level of selenium (ranged 64.1−100.0% true retention in boiling and frying). Longtail tuna, Short-bodied mackerel, Indo-pacific Spanish mackerel, Nile tilapia, and red Nile tilapia−cooked by boiling and frying−are recommended for consumption as excellent sources of selenium.