Although some of the pre-processing of the tuna is done on board of the fishing vessels or in specialized companies that only produce precooked loins, in general all processing activities take place under the roof of the cannery.
The tuna is supplied to the canneries both in chilled and in frozen form. If the fish is supplied, frozen tuna has to be thawed before processing, preferable by running water around 10-15 degrees Celsius. Larger sized tuna often have longitudinal cuts and entrails removed on board the vessel prior to freezing. Skipjack is frozen as wholefish. Once defrosted, tuna is washed and inspected for spoilage and cleaned if this has not been done properly.
The fish is then pre-cooked as it will be easier to loin and remove the oily parts of the fish. Pre-cooking is done by places the fish in baskets on racks and rolled into cookers. Within the cookers steam is added through steam spreaders on the floor. Air vents and drainage valves ensure the removal of excess air and condensation. Actual temperature and cooking time depend on the size of the fish. For example, individual batches of small tuna may be around 1,5 hours, while large tuna need 8 to 10 hours to be properly cooked. Some canneries also use new technologies such as brine cooking.
After the tuna is cooled, the fish is loined individually by hand. The head and skin is removed and the fish is split in halve before removing the tail and backbone. Loins are made by splitting the halves of the fish along median line. Blood, red and dark meat is removed. The loins, edible flakes and waste products are separated for further processing. Loins are cutted into chunks and filled into cans. Also flakes and grated tuna from broken loins and chunks are filled into cans. Additives such as vegetables, salt or other spices, and oil or water are added before cans are (vacuum) sealed. The cans are than washed and sterilized before labelling.
Quality control checks can differ between canning companies and occur at the different stages of tuna processing. Before actual processing, equipment and eventual water that will be used, is checked for bacteria; Employees are checked for meeting hygiene standards. During processing, histamine and metal content is checked, as well as quality of added products like oil, vegetables, salt.
The product portfolio of the processing companies in the canned tuna supply chain mostly includes frozen loins (mostly yellowfin tuna), chunks and flakes, as well as canned products. Although some of the processors focus on tuna alone, most of the companies also export other canned species. Other canneries focus on other canned products especially for the domestic market. Compared to skipjack tuna, canned yellowfin tuna hold higher prices as quality is better. Skipjack tuna and yellowfin tuna are usually labelled as light meat, except in Japan where skipjack cannot be legally labelled as tuna. Canned albacore is market as white meat tuna and is more expensive. The canning company PT Juifa International Foods almost entirely produces white meat for the United States’ market.
After a period of recess in the 2000’s, the cannery sector has started to revitalize, by opening new or re-opening of old canneries. Tuna canneries are concentrated in Medan (Sumatra), Surabaya and Banuwangi (East-Java), Cilacap (Central Java), Bitung (North Sulawesi), Sorong (Irian Jaya) and Biak (Papua) (World Fishing and Aquaculture 2007; FFA 2011). Especially the processing companies in East Java rely heavily on domestic transport of raw material and imports, which tend to be unreliable and expensive. Bitung is one of the major tuna canning centres, residing large companies such as Sinar Purefoods International, International Alliance Food and Deho. Some of the canneries are struggling to keep their operations running as they are confronted with a lack of raw material supplies. According to Indonesian Investment Coordinating Board, around 38 fish canneries are operating in the area from Bali to Sumatra, but says nothing about other locations. Older sources talk about at least 13 canneries being in operation (2010).
In 2015 Greenpeace issued a tuna cannery ranking for both Philippian and Indonesian canneries on sustainability and equitable fishery guidelines. Criteria against which the canneries were evaluated included traceability, sustainability, legality, equity, sourcing policy, transparency and driving change. Of the 14 Indonesian tuna canneries involved, all scored low on these criteria either based on survey results (3) or no response (11).
Sardines are processed by smaller canneries mostly operating in East Java, like CV. Pacific Harvest. Production figures were estimated to be 300 million cans a year for sardines and mackerel, with a 90:10 ratio respectively (World Fishing and Aquaculture 2007). In terms of tonnes, the FFA estimated a figure of 120,000 tonnes in (FFA, 2011).