For the last several months I have been taking you through the general processing steps for tuna starting from thawing to cooling. I have always emphasized the importance of having a system of accurate control and temperature monitoring. This will result in excellent quality, and maximum recoveries/yields. For filling, delay times are very important as this will have a direct affect on quality and recovery. This article will take you through filling and can sealing(seaming).

Once the cooked tuna have been properly cleaned and segregated as to premium or standard, the loins and flake should be staged for filling right away. Normal delay time for staged loins and flakes should not exceed 30 minutes but ideally it should be around 15  minutes. You will experience oxidation, moisture loss, and quality loss if the staging time is prolonged. An efficient operation will not allow this to occur.

There are several types of filling machines used by tuna canneries. The most common are Luthi, Hermasa, and Carruthers. All are acceptable, some much better than the other, but it would depend on individual preference and requirements. Appearance, quality, squeeze loss are all directly correlated to the type filling machine. Squeeze loss will impact on your fish recovery.

Normally loins are placed on the feed conveyor of the filling machine. It is very important that the loins are placed in a manner which they are interlocked and parallel to each other. They should also be firmly placed so that they are not tight or loose. Depending on the buyer requirements, the flake percentage should be sprinkled between the loins during this step. There are several methods for evenly distributing the flake on the loins so that it will result in a finished product that is within the specifications.

After exiting the filler, normally an inspector should remove any cans that are improperly filled or with an uneven cut. After the medium is added utilizing a manual or automated dispenser, the cans will then be ready for sealing through the seamer. The medium can be water, brine, vegetable oil,  and or broth. There are several seamers that work quite well. The speed and rotation within the seamer are important factors that will determine how much tuna meat and liquid you loose during the seaming process. Normal speeds are around 200 cans per minute while high speed seamers are 400-500 cans per minute. The faster the speed, the more spillage you will incur. The most reliable and most efficient seamers are manufactured in the USA. They are Angelus, Canco, and Continental. A straight line feed conveyor directly into the seamer is ideal compared to one that has several curves. This will reduce your spillage prior to seaming.

Please mail your questions to: askdon@atuna.com

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