We always see Fresh fish rapidly deteriorates unless some way can be found to preserve it. Drying is a method of food preservation that works by removing water from the food, which inhibits the growth of microorganisms. Open air drying using sun and wind has been practiced since ancient times to preserve food. Water is usually removed by evaporation (air drying, sun drying, smoking or wind drying) but, in the case of freeze-drying, food is first frozen and then the water is removed by sublimation. Bacteria, yeasts and molds need the water in the food to grow, and drying effectively prevents them from surviving in the food. Fish are preserved through such traditional methods as drying, smoking and salting. The oldest traditional way of preserving fish was to let the wind and sun dry it. Drying food is the world’s oldest known preservation method, and dried fish has a storage life of several years.
Some important spots are: Dublar Char of SUNDARBANS, ST MARTIN’S ISLAND, Rangabali, Sonadia Island, Moheshkhali, Cox’s Bazar, lbrahimpur of Sunamganj, and Joshomantapur of Jamalganj. Estuarine and marine set bag nets (Behundi) are the main gears for supplying fishes for drying; harvested fishes are carried to the drying yards and then segregated species-wise by hired labourer.
The important marine and freshwater species that are dried are Loitya (Harpodon neherius), Chhuri (Lepturacanthus savala), Punti (Puntius sarana, P. stigma), CHAPILA (Gadusia chapra), Lakhua (Polynemus indicus), Rupchanda (Pampus chinensis), and shrimps (Metapenaeus species and Penaeus species).
Two to eight days are required for drying depending on the size and species of the fishes. The segregated fishes are placed on mats, or hung from raised racks/poles. The dry fishes are often infested by blow fly (Chrysomya species) and their larvae (maggot) during the drying phase, especially in the cloudy and rainy days; and by beetle (Necrobia species) and mites in the store causing considerable amount of weight loss of the finished product every year. To protect the products from the infestation of insects, the merchants often use various harmful insecticides and fungicides. But the availability of sterilization of dried fishes by radiation can ensure pollution-free environment. Institute of Food and Radiation Biology of Bangladesh Atomic Energy Commission is currently engaged in research on storage technology of dried fishes using nuclear radiation.
Fish species used for dried fish processing
Product type is considerably wide depending on the season, availability of fish, infrastructure and technical know-how of the processors. These are mainly processed from marine fishes that are caught by the artisanal fishermen and marketed throughout the country by multistep marketing channel up to reaching to the consumer. Due to the importance of the product in terms of market volume as well as its major role in the socio-economic condition of millions of people of the country, the sector needs proper attention by appropriate authorities to ensure quality and safety of the product produced and marketed. In this paper, different methods of sun drying practiced traditionally in the coastal region of Bangladesh and associated marketing systems are reviewed. It is expected that training of processors on Sanitation Standard Operating Procedures and monitoring by appropriate government body would be necessary to improve quality and simultaneously ensure safety of sun-dried fish produced in the coastal region of Bangladesh.
