What is the TIXOTHERM™ process and why use it?
Whey and permeate from ultra filtration of whey and milk is considered as low-price by-products, if processed into a powder or expensive if disposed off into sewage plants. With the increasing cheese production there will be more and more whey and/or permeate available. This is whey GEA Niro has developed a new process – the TIXOTHERM™ process – which will convert this by-product into a first-class non-caking powder product using less energy. A reduced building volume means lower total investment.

How does it work?
Precrystallized whey and permeate concentrates are very thixotropic, i.e. if the concentrate is not agitated continuously in the crystallization tank in the traditional process, it will solidify, and the higher total solids in the concentrate, the more solid becomes the concentrate. This phenomenon is used advantageously in the TIXOTHERM™ process.

The TIXOTHERM™ process is a four-step process, where the whey or permeate is evaporated in a falling film evaporator to 60 % TS. From the evaporator the concentrate is pumped to a vertical agitated film high concentrator. Here the solids are increased up to 85 % TS. The high shear rate in the agitated film, however, keeps the viscosity relatively low. The combination of high solids and low temperature as a result of the evaporation initiates the lactose crystallization, and many nuclei are formed.

In the subsequent process – the mixing crystallizer –  a phase-conversion of the product takes place enhanced by addition of fines particles/recycled cold product from the subsequent fluid bed drying/cooling. This encourages a rich lactose crystallization.

At the discharge of the mixing crystallizer, the product is now like a semi-solid mass with a friable texture ideal for the following fluid bed drying and cooling. In this last step of the process the remaining moisture is evaporated in an agitated back-mix fluid bed followed by final drying and cooling in a plug flow VIBRO-FLUIDIZER®. The drying air for the bag mix and plug flow fluid bed is exhausted through a SANICIP™ bag filter, from where the collected fines particles are returned back to the mixing crystallizer.

The result of the TIXOTHERM™ process
The final powder has almost 100 % of the lactose crystallized, i.e. the total moisture content is 5 % or more. The powder is non-hygroscopic and non-caking. Energy consumption is reduced by more than 30 %, and building requirements are reduced by more than 50 %. No crystallization tanks are needed, and no spray drying plant is involved to produce whey or permeate powder.

The capacity of a given TIXOTHERM™ plant is a function of the content of protein, galactose and lactic acid in the product. That is why a TIXOTHERM™ plant for whey/permeate from mozzarella cheese has a lower capacity than for instance whey/permeate from Swiss cheese.

 The TIXOTHERM™ process is available in four industrial-scale configurations:
Nomical capacities:

  • 1,000 kg/hr final powder – 400,000 litres of whey permeate/day
  • 2,500 kg/hr final powder – 1,000,000 litres of whey permeate/day
  • 5,000 kg/hr final powder – 2,000,000 litres of whey permeate/day
  • 7,500 kg/hr final powder – 3,000,000 litres of whey permeate/day