food & drink processing 39
sauce during manufacture. The aim was to be able to quality control in the production of milk powder2. The
assess the benefits of online measurement compared Hydramotion viscometer was the only one in its class to
with the industry standard offline standards1. achieve such a high rating.
Sauce viscosity has traditionally been measured using Advantages highlighted by the researchers include
rotational viscometers or consistometers, but the ‘high immunity to plant vibration, ease of cleaning and
researchers found that these offline techniques were low maintenance requirements’.
time-consuming and could be subject to a degree of Milk powder is produced by the process of
operator influence. Online viscosity measurement ‘spray-drying’, where concentrated milk is forced at high
offered a number of advantages, including pressure through very fine nozzles into a
continuous real-time analysis, improved process chamber of warm air. This process is widely
control and less chance of operator error. used in the food and chemicals industries
Moreover the consequent labour saving for making products as diverse as baby
helped to reduce costs. foods, coffee, soup mixes and dyestuffs.
The XL7 online viscometer was installed The efficiency of drying is largely
in the pipeline between the sauce determined by the degree of
production ‘kettle’ and the storage vats. atomisation, which is directly
Sauce samples were also taken from proportional to the viscosity of the
the vats for offline consistometer feed solution. Thus, the viscosity of
measurements, and the results of the milk at the atomisation step has a
the various methods were crucial effect on the characteristics of the
compared for repeatability, variability resulting milk powder.
and stability. With the Hydramotion viscometer in place,
In their report, the researchers concluded that viscosity could be measured continuously in
the Hydramotion viscometer gave ‘very stable real time, ensuring that changes are
readings and the lowest standard deviation of all immediately detected. Importantly,
the instruments used. The Hydramotion measurements are unaffected by changes in
readings gave relatively tight output ranges and flow rate or the presence of suspended solids
had the least inherent variability’. or gases. Installed at the pre-atomiser point,
The XL7 was also ‘easily capable of measuring all the viscometer offered significantly better control
sauces encountered’ and ‘was capable of handling the of the atomisation process, leading to reductions in
particulates suspended within the pizza sauces. Two wastage, lower energy consumption and better
sauces were out of specification, and the Hydramotion control of product texture, bulk density and
viscometer was capable of picking out these out-of- moisture content.
spec sauces when this occurred.’
“Once installed, the Hydramotion viscometer
Chocolate
required little or no operator input, unlike viscosity Chocolate is a dispersion of finely-divided sugar,
readings obtained from the rotational viscometer,” the milk protein and cocoa in a continuous fat phase,
report added. “Subjectivity and errors due to operator generally cocoa butter or cocoa butter equivalent.
variability were removed. The Hydramotion online During production, molten chocolate must be
instrument can easily be integrated into the current cooled in a controlled way in order to promote
process monitoring system.” the formation of small, stable fat crystals, a
The dedicated readout unit, which can be process known as ‘tempering’. Stable cocoa butter
located up to 1000 metres from the transducer, crystals provide the right qualities of texture,
provides a 4–20mA analogue signal and serial data surface gloss and melting behaviour in the
output for continuous viscosity monitoring and finished product. If the crystals are small enough
control, either on a stand-alone basis or integrated the chocolate will taste smooth and melt just
into a plant-wide control or SCADA system. where it should, in the mouth (at a temperature
“Unlike the single offline measurement of of about 35°C) but not in the hand (at about
‘kettle’ viscosity, online XL7 viscometer provides 20°C).
100–200 real-time measurements per batch that The viscosity of melted chocolate depends
can be recorded electronically and
Fig. 2. The Hydramotion XL7 online
directly on its fat content and the
independently as part of the batch
viscometer.
degree of tempering, so monitoring
record.” viscosity gives an immediate window
into the production process. With this in mind, a leading
Milk powder
UK manufacturer of chocolate products recently
In another application, the Dairy Products Research installed XL7 online viscometers on pipelines leading to
Center in Co Cork, Ireland, gave a four-star rating to the its mixing tanks as part of a global automation project.
Hydramotion online viscometer for its contribution to By continuously monitoring the viscosity of the liquid
☞
www.scientistlive.com
Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52