Brookfield Engineering

Fish Meal Slurry/Concentrate

Process Viscometer Application Data Sheet


Brookfield's TT-100® in-line viscometers are ideal solutions for monitoring and controlling fish meal processing operations around the world. These operations are common in the U.S., most notably Alaska and the Gulf Coast, in South American countries like Peru, Ecuador and Chile, and in Scandinavian nations like Norway, Denmark and Iceland. This type of process is also used for meat and bone meal processing with approximately 300 meat and bone meal plants in the U.S. alone and many others worldwide.

The processing of fish meal concentrate efficiently utilizes as much of the raw fish catch remains, known as the by-catch, as possible for resale as animal feed, fertilizer, peat moss additives and other products, as well as use in aqua culture. The raw fish material left after fish products are packaged for human consumption is conveyed to a fish cooker and heated to approximately 198°F. This procedure breaks down some of the protein in the fish waste. A steam heating process then dewaters the waste, with part of the oil, water and solids being extracted out of this slurry. This liquid paste of water, oil and solids is then squeezed through a press. The product, now a dry paste, contains about 50% moisture with solids. This is then again sent to a steam dryer where the 50% moisture is reduced to 8% moisture. The result is the finished fish meal product.

Problem Description

Today's modern fish meal processing plants, both land and sea based, require reliable and dependable viscosity measurement and control, especially in 24-hour per day operations.

The initial press-liquid phase, which in years past was discharged as a polluted stream of oil and solids back into the land or ocean, is recovered and recycled back into the process. By using a high speed industrial centrifuge, some of the oil is extracted from the stream and resold for animal feed, soap, perfumes, pharmaceuticals and other medicines. The remaining solution typically contains 92% water and 8% solids, and is introduced to a multi-stage evaporator through as many as four stages. By reboiling the mixture at progressively lower pressures, more water is evaporated, without additional energy input, out of the stream.

Brookfield's TT-100® viscometers control the water evaporation process to that point where the slurry contains about 60% water and 40% solids. It's necessary to maintain viscosity below a specific value, or the tubes in the evaporator will coat and foul. Conversely, if the solids concentration is maintained at a low but “safe” level, the process equipment won't run at its highest thermal efficiency.


Brookfield TT-100® viscometers, leading instruments in all slurry applications, are ideal solutions for fish meal processing operations because they operate under defined shear conditions and have proven their ruggedness over many years of uninterrupted use in a wide variety of applications. The use of Brookfield's TT-100® inline process viscometers provides instantaneous and repeatable measurement under constant use.

In the processing of fish meal slurry, viscosity measurement and control improves the maintenance of the proper water content of the concentrate. At the stage in the process where the concentrate is approximately 60% moisture and 40% solids, the Brookfield TT-100® viscometers ensure that uniform viscosity is maintained, thus preventing heat transfer surfaces from fouling. This saves downtime due to repeated cleaning of the evaporators and lengthens the time between “stop and cleans.”

The TT-100® viscometer operates under the exact shear rate (velocity gradient) conditions occurring at the evaporator tubes. This reliable, constant automated monitoring and control of viscosity assures operators that the processing equipment will run at peak efficiency 24 hours a day. Other methods of viscosity measurement are not applicable because:

  • They cannot duplicate shear conditions and provide proper measurement for this shear-sensitive mixture
  • They separate the mixture phases in their shear field, thus measuring one phase only
  • They are fouled by solids

Qualifying Your Application

Ask the following questions:

  • Are you a fish processing operation, either land-based or shipboard?
  • Do you use multiple-effect evaporators for increasing yields of fish meal, bone meal or meat products?
  • Are you experiencing fouled evaporators that cause lots of down time?
  • Is your operation a 24-hour/day continuous process?


  • Helps with the recycling of solid wastes, thus saving costs and meeting environmental standards
  • Helps prevent evaporators from fouling from thickened concentrate, reducing down time
  • Unlike some vibrating viscometer devices, handles multiple-phase fish meal slurry without separating mixture, thus insuring that the concentrate is measured, not just its water component
  • Proper viscosity of concentrate assures efficient equipment operation which increases the production rate
  • Mounts easily in evaporator piping system
  • Gives an extremely quick payback, particularly when installed in large continuous operating systems


Available upon request

Return on Investment

The use of Brookfield's TT-100® viscometer typically provides a payback of instrument cost and installation in six months to a year.