Pre-centrifuge Fish Processing Steps
The incoming fish leftovers and water are heated in a cooker. This process sometimes uses steam to break down the raw fish and release the oil.
The cooked fish biomass passes through a screening process to separate the bulk of solids from liquids. The solids separated at this phase are proteins. This solid phase is dried and is known as a fish meal. Fish meal is a valuable product for many commercial uses in aquaculture and agriculture.
The liquid phase from the abovementioned process consists of oil, water, and fine solids. There are two ways to separate this fluid's three phases (oil, water, solids).
Using a Tricanter for Fish Oil Production
The first method uses a tricanter or a three-phase decanter centrifuge to separate the oil, water, and solids simultaneously. A tricanter is a three-phase horizontal centrifuge that separates bulk solids from water and oil. So, a tricanter processing this strained fluid separates the remaining fish meal from the stick water and fish oil.
However, there is an inherent limitation with using a tricanter due to the lower centrifugal force generated. A lower g-force may not be sufficient to efficiently separate the oil and water phases in the feed.
Using a Decanter and Disc-Stack Centrifuge for Fish Meal
The other method is a two-step process using a 2-phase decanter centrifuge as the first step to de-sludge the process fluid. The decanter separates the fish meal solids from the oil and water. The oil and water fluid passes through a three-phase disc-stack centrifuge in the following step.
Surimi Processing
Surimi is a seafood substitute often found in imitation lobster, crab meat, or fish balls. Minced, refined white fish meat is
separated from unusable fish parts to make pure fish protein paste known as Surimi. Whitefish such as pollock and whiting are the primary feedstock for surimi production.
The meat from these fish goes through a sophisticated process to produce a surimi gel. It is a cheaper and sustainable replacement for seafood, especially since it is also made from farm-raised fish.
Surimi Processing Centrifuge
A surimi centrifuge processes minced, refined white fish meat into a thick fish paste, the base product for commercially sold surimi.The centrifuge separates the gutted fish and fillets from water to produce high-grade surimi.
Traditional Surimi Processing Methods
Traditionally, surimi production involves repeated washing of the white fish meat, also known as leaching. One or more dewatering steps follow this washing process.
A refining step separates unwanted fish parts such as skin, bones, and fins. A screw press squeezes the refined fish meat into primary-grade surimi.
The discarded fish parts from the step above go through another leaching step, followed by a screw press to produce
secondary-grade surimi.
The total yield from this traditional process rarely exceeds 50% of the original fish meat processed.