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A fish oil processing centrifuge is an industrial centrifuge that separates fish oil and fish meal from the process water, also known as stick water. Industrial fish processing involves cooking and grinding leftover fish parts that are separated into fish oil, stick water, and protein or fish meal.
Fish oil centrifuges operate by using a high centrifugal force to affect the separation of the three phases of processed fish residue. These centrifuges separate Fish Oil, Fish Meal, and stick water from inedible fish processing residue. The fish residue consists of non-saleable fish parts such as skin, guts, heads, bones, offal, and fins.
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, and solids).
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.
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.
The following diagram shows a fish oil and fish meal processing plant designed by Dolphin Centrifuge.
The disc-stack separator exerts a higher centrifugal force than the decanter, separating the fine solids and the oil from the stick water continuously. The separator discharges the fish oil and stick water through independent outlets while intermittently ejecting the fine fish meal solids.
If you have simple, routine questions: We have condensed our 40+ years of disc-stack centrifuge experience into 101 Frequently Asked Questions about Disc Stack Centrifuges!
Further evaporation concentrates the separated stick water into a thick syrup. Mixing this stick-water slurry with the strained fish meal produces the final fish meal product.
A fish oil polishing centrifuge separates the fine suspended fish meal particles and stick water to produce pure fish oil. The fish oil produced by the tricanter centrifuges contains residual water and fine suspended particles due to the lower centrifugal force exerted by a tricanter.
Fish oil polishing centrifuges are food-grade, disc-stack-type centrifuges. They could be 'manual-clean' or 'self-cleaning' type centrifuges depending on the level of contamination. The higher g-force generated by a disc-stack centrifuge, up to 7,000 g's, is adequate to separate particles down to 0.5µ level and all remaining free water.
The accompanying image shows a fish meal centrifuge type Alfa Laval NX418 Decanter Centrifuge. This model is ideal for processing up to 8 Tons per hour of minced fish and water mix.
| Fish Meal Centrifuge Models | Alfa Laval FPNX 309 | Alfa Laval UVNX 314 | Alfa Laval NX 418 |
| Centrifuge Type | Decanter | Tricanter | Tricanter |
| Capacity (GPM) | 10 | 40 | 80 |
| Gear Box | 1.0 kNM Cyclo | 2.5 kNM Planetary | 2.5 kNM Planetary |
| Bowl RPM | 5,600 | 4,000 | 4,000 |
| Motor Power (HP) | 5 | 10 | 20 |
| Frame Size (in) | 24″ x 40″ x 40″ (H) | 36″ x 48″ x 60″ (H) | 36″ x 48″ x 96″ (H) |
| Weight (Lbs) | 800 | 1,400 | 2,500 |
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.
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.
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.
An Alfa Laval decanter system replaces the screw press in the traditional system. It also makes several of the washing steps redundant. Elimination of these steps makes for much more compact process equipment.
In this replacement process, the fish fillets go through the mincer to separate the skin. The minced fish, with added water, goes through the refiner to separate the remaining unwanted parts, i.e., skid, bones, fins, etc.
The cleaned meat slurry goes through a decanter centrifuge, which separates the water from the fish meat. The separated fish meat is the surimi base. Average recovery rates of over 70% from feedstock are considerably higher than the traditional screw press process.
Enzymes break down fish processing byproducts into Fish Protein Hydrolysates or FPH. The process involves using specific enzymes to digest fish protein into a human consumable form.
There are precise process requirements considering the product is for human protein substitutes. In some forms, FPH is pre-digested and is directly used for medical supplement use.
The preceding image shows a Hydrolyzed Fish Protein processing facility centrifuges supplied by Dolphin Centrifuge.
FPH is available in liquid as well as solid forms. Longer shelf life and ease of transportation make solid FPH more desirable.
One of the main challenges in the production of solid FPH is the drying of semi-digested fish protein. Alfa Laval decanter centrifuges work well to dewater the reacted fish protein slurry at controlled temperatures.
A food-grade, three-phase disc centrifuge separates the fish oil before the enzyme reaction step. An Alfa Laval AFPX213 Purifier centrifuge is an ideal centrifugal separator for this process step because it continuously separates the oil from the water and protein solids.