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
final powder has a higher degree of crystallized lactose than achieved by the
traditional method, and the total moisture content is approximately 2%. 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