APPLICATION NOTE
Food & beverage
Direct measurement of fat and protein in drinking milk
•Non-contact optical measurement directly in the process line
•Continuous measurement of fat and protein in standardised milk
•Consistent product quality with reduced cream consumption
1. Background
To produce drinking milk with various minimum fat contents, the raw milk delivered is then separated in
the dairy into skim milk (approx. 0.05% fat content) and cream. In the milk standardising unit, as much
fat (cream) is added to the skim milk as is required to obtain the desired fat content in the drinking milk.
Mass flowmeters have typically been used to determine the amount of fat in the cream by measuring the
density. Taking into account the current flow rates of skim milk and cream, it is possible to calculate how
much cream must be added to achieve the desired fat content in the standardised milk. This calculated
fat content is checked in intervals by taking samples. In the case of any deviation from the target value,
the process control is set manually so as to add more or less cream accordingly.
This procedure presents a number of disadvantages: the result of calculating the fat content by
measuring the amount of fat in the cream flow can vary considerably from the actual fat content in
the standardised milk as deviations of the fat content in the skim milk can't be detected whatsoever.
Measuring by taking samples is not continuous and results are delayed because the sample must first
be analysed in the laboratory. Any necessary intervention in the process is then correspondingly late.
2. Measurement requirements
A large German dairy was looking for a solution to improve process control and eliminate delays by
measuring the fat content in the flow continuously and more accurately.
Application 304 EN 3.indd 1
29.10.13 10:09
APPLICATION NOTE
3. KROHNE solution
The dairy installed an OPTIQUAD-M 4050 W, a spectroscopic analysis system for the continuous, noncontact inline measurement of fat and protein in milk products. The OPTIQUAD-M was installed using
a standard VARINLINE process connection without bypass, directly in the production line. The entire
measuring section complies with hygienic requirements and is FDA-compliant. The optical measuring
system contains no moving parts and is cleaned by way of CIP. The Operating Unit was installed
separately.
The OPTIQUAD-M was calibrated on site based on reference values from the in-house laboratory. To this
end, the device features a sampling valve and an integrated automatic calibration function.
4. Customer benefits
Fat (%)
With KROHNE's solution, the dairy can measure fat and protein content directly and continuously in the
standardised milk. The accuracy of the OPTIQUAD-M approaches that of the reference measurements
taken by sampling both in-house and at independent laboratories. The fat content is thus available as
a control variable for the process control and for the addition of cream. The protein content is currently
only used for monitoring purposes. After a few weeks of test operation, the dairy established that by
using the OPTIQUAD-M, it was possible to significantly reduce the use of cream for the drinking milk
without having a negative affect on quality. The same quantity of raw milk thus yielded
4,5
more surplus cream which was then available
4,0
for use with other production lines. The
3,5
operator was impressed with the compact
3,0
2,5
design of the system and the lack of need
2,0
to check the fat measurement on a daily
1,5
1,0
basis using a reference milk, as is typical of
0,5
laboratory devices. Lastly, the extremely good
0,0
Samples
1
249
price-performance ratio convinced him to
Laboratory
OPTIQUAD
initiate other applications with the OPTIQUAD.
5. Product used
Measurements of the OPTIQUAD-M (red) compared to laboratory
values (blue)
© KROHNE 10/2013 -304- Subject to change without notice.
OPTIQUAD-M 4050 W
• Spectroscopic analysis system for the continuous inline measurement of protein, fat, lactose and total solids in milk products
• Non-contact analysis
• High precision and long-term stability
• For use in dynamic control loops
• Eliminates the need for sampling, sample transport and preparation
• No costs for chemicals, reagents and cleaning agents
• Wall mounting of Operating Unit in stainless steel housing (ingress protection class IP 65)
Contact
KROHNE
GmbH
KROHNEMesstechnik
Optosens GmbH
Ludwig-Krohne-Str.
5
Kantstraße 22
47058
41464Duisburg
Neuss
Germany
Germany
Tel.:
301
0 787 0
Tel.: +49
+49 203
2131
739
Fax:
+49
203
301
103 89
[email protected]
[email protected]
Please visit our website for a current list of all KROHNE contacts and addresses.
Application 304 EN 3.indd 2
29.10.13 10:09