Research On Tuna

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Research of Food
Sample : Saltwater fish (Tuna)

INTRODUCTION
The availability of saltwater fish products in the market was depend on the coastal fishing vessels operation. One species that is widely consumed around the globe is Tuna (Thunnus sp.). Tuna is widely available both in Pasific and Atlantic ocean. The nutritional content of tuna, both bluefin tuna and yellowfin tuna according to the USDA National Nutrient Database can be seen in Table 1 (1). Fish nutritional composition is varied between species. It is likely the variety of nutritional composition were based on gender, age, season, water temperature, type, and abundance of available food (2). Recent fisheries study indicated that fishing method can impact the freshness of cod flesh (3). Those fishing methods including haul size, haul duration, and direct gutting before storage period. Olsen et al. (2013) also concluded that the fishing method will affect the muscle pH, blood pH, glucose and lactase concentration during rigor period (3). It is likely those factors also responsible for the number of microflora in saltwater fish flesh.

Table 1. Nutritional content of Tuna (raw)
Nutrient Bluefin Tuna Yellowfin Tuna
Value per 100 g
Water 68.09 74.03
Protein 23.33 24.4
Total Lipid 4.9 0.49
Carbohydrate by difference 0 0
Source:http://ndb.nal.usda.gov/ndb/foods/show/4580 & http://ndb.nal.usda.gov/ndb/foods/show/4587

Majority of saltwater fish are well known as healthy diet since they are considered good source of omega-3 and omega-6 fatty acid. One example of omega-6 fatty acid is linoleic acid, while omega-3 consist of linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) (19). Based on study, cod contain 300 mg/100 g concentrated of EPA and...

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...ological content of Tuna significantly since the limited amount of oxygen in fish flesh will disturb the live of aerobic microorganism. Recent publication by Pivarnik et al. (2011) asserted the important treatment of filtered smoke using 16% of CO on Tuna steak. Although, the statistical analysis showed that there is no evidence that the microbial, chemical and sensory quality of untreated tuna with filter-smoked tuna is significantly different. The filter smoke treatment can enhance the color of Tuna and it will impacts the consumer buying perception. MPN content indicated 4 MPN/g and the result from EMB agar confirmed that it does not contain fecal coliform but other enterobacteriacea. It is probably because tuna lives in pelagic habitat of the ocean which is far away from a shore. It is considered free from fecal coliform which can be microflora of river water.

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