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BASIC FISH MEAL AND OIL PROCESS

 

In principal, the manufacturing process of fish meal and oil simply implying best possible separation of the natural 3 main constituents of the raw material:


-Oil fraction

-Solid fraction
-Water fraction


The typical composition of industrial fish specie like lean sardine, being 6% oil, 18% solids and 76% water. Expected average production yields from this raw material by conventional processing 21,9% meal and 4% oil. Thus, for each tons of raw material, 219 kg of fish meal and 40 kg of fish oil being extracted by a combination of mechanical and thermal de-oiling and de-watering technologies. Important to emphasise that best possible yields, besides important for the overall feasibility, are very important for preventing pollution by fat and solid contents in effluents. With this perspective, raw material of high quality playing an essential role. This of outmost importance in the planning the raw material supply, handling and storage facilities.

 

The enclosed mass balance showing a conventional fish meal and oil processing system, based on the complete recovery concept. From external storage, the raw material is fed into the cooker for indirect heating and coagulation of proteins. Although regarded as a non advanced processing step, this is by far the most critical point in the whole de-watering pathway.


Next step, after intermediate pre-straining of coagulated material, the main mechanical de-watering, generally executed by slow rotating twin screw presses. The solid fraction from this twin screw press is transported directly to the final thermal stage, the dryer(s). Liquid fraction together with liquid from pre-strainer, to be further separated in various steps of centrifuges.

The pre-strainer and press liquid containing, besides oil, both suspended and dissolved solid materials. The suspended solids are removed from this liquid by a decanter centrifuge and mixed together with solid fraction from screw press prior to drying stage.


Next step is the de-oiling of the decanter liquid. This is executed by high speed centrifuge separators in one, two or three steps depending on raw material and processing conditions. The oil fraction(s) finally cooled down to storage temperature below 40 °C.
The water fraction from main separator still containing approx. 10% dissolved solid material. This liquid fraction, stickwater, is concentrated in a multi-effect evaporator up to approx. 35% solid content, before mixed together with press cake and decanter sludge prior to drying.

 

The drying process often being considered the most difficult part of the process. The technological solutions at this stage are really what divide the high quality from low quality manufacturers. Today, the old generation direct flame dryers is rapidly fading out. The dominant types now being indirect steam dryers and/ or indirect hot air or Airless (superheated steam) dryers. In large capacity systems, steam dryers are frequently being used as pre-dryers in combination with hot air/ Airless dryers as final stage. This combination enabling a reduced energy consumption and high quality of final meal product.

Typical energy consumption from a process with such serial dryer configuration approx. 35 kg of fuel oil per ton of raw material. As typical electrical consumption, approximately 30-40 kWh per ton raw material can be regarded as average.

QUALITY ASSURANCE


Our tuna meal and crude tuna oil undergo strick Q.C inspections along with lot by lot laboratory analysis throughout the production process. Final product is sampled regularly for physical and sensory testing. Plant hygiene is strictly controlled along with a full line cleaning each day.