Fish is a source of high quality protein which is easily digestible. Fish also provides a good balance of lipids, vitamins and minerals Edirisinghe (2000) as cited by (Karunarathna & Attygale 2009). And tuna is a good source of high quality proteins. According to Gopakumar (1997) as cited by (James, and Kumar, 2013), white and pink to dark red flesh are seen in a tuna. Greater quantities of myoglobin in its muscle influence the color of the flesh. Tuna is generally considered as a food rich in omega-3 fatty acid. This food is low in saturated fat and sodium. It is also a good source of magnesium, phosphorus and potassium, thiamin, niacin, Vitamin B6 and selenium.
Raw fish and seafood are highly delicate compared to other fresh meat supplies
But, the fish first undergoes sensory evaluation to assess its freshness or spoilage. Delay must be prevented when moving the fish to the chilled storage facility. The facility must have a calibrated indicating thermometer. Moreover, the fish must be stored in shallow layers and must have sufficient finely divided ice or a mixture of water and ice before being processed and with such, damage due to over stacking or overfilling of boxes must be prevented. Frozen fish undergoes thawing before being graded while chilled fish can be graded directly. Frozen fish must be glazed and/or wrapped to prevent dehydration in addition to that; the product with defects that cannot be eliminated to an acceptable level should be rejected. Proliferation of microorganisms and development of histamine, distinct odors and off-flavors indicating decomposition or rancidity should be controlled and prevented by observing thawing time and temperature. Products should not be exposed to excessively high temperatures upon thawing. When water is used as a thawing medium, there should be sufficient circulation to produce even thawing. Water used must be potable and if recycled water is used, care should be observed to avoid the buildup of microorganisms. Efficient draining of the thawed fish must also be observed and the product should be processed or refrigerated immediately at the adequate temperature. After grading, the