Measurement of protein and total solids in WPC

1. Background

A German dairy company produces different whey derivatives at one of its sites. Everyday, the whey (a by-product of cheese production) is refined into different products and sold to cheese processing plants and companies in the food, beverage and animal feed industry.

One of these whey products is whey protein concentrate (WPC). This is whey protein, which is produced through the concentration of whey. The standard method used is ultrafiltration (UF). The aim is to increase the total protein to total solids ratio by removing water, lactose, and other non-protein compounds. In doing so, the whey is separated in a lactose-containing permeate and a protein-containing retentate.

2. Measurement requirements

The customer uses a two-stage UF plant for the concentration process. The first plant produces WPC 60 directly, or initially WPC 35 only, which can then be concentrated as WPC 80 in the second plant. To ensure optimum operation of the UF plant, the ratio of protein to total solids (TS) in the retentate must be known.

In the past, the customer had the protein and total solids content determined through laboratory testing. This not only required manual sampling, which is very time consuming, but also meant that there was always a time delay between the measured values and the production process. A continuous adjustment of the operating parameters was therefore not possible. To automatically regulate the UF plant, the whey processing company decided to use an inline analysis system. This was designed to continuously control the final concentration in the retentate and without much time and personnel effort, in order to set the operating parameters in such a way that the greatest WPC yield is achieved.

APPLICATION NOTE Food & Beverage

• Continuous inline measurement in the production of WPC, e.g. 35, 60 and 80• Spectroscopic analysis to verify the protein/TS ratio in the retentate• Automated control of ultrafiltration using second-by-second measured values

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APPLICATION NOTE

Contact

KROHNE S.A.S.2, Allée des OrsBP 9826103 ROMANS SUR ISERE CEDEXFranceTel. : +33 (0) 475 056 703Fax : +33 (0) 475 050 048level@krohne.com

Please visit our website for a current list of all KROHNE contacts and addresses.

3. KROHNE solution

For the continuous measurement of protein and total solids, the whey processing company now uses the OPTIQUAD 4050. The spectroscopic inline analyser was coupled to the process via an optical window in the standard VARINLINE® housing behind the ultrafiltration of WPC 35/60 and 80. Unlike conventional bypass-devices, measurement takes place directly in the pipeline – and without the measuring sensor coming into direct contact with the medium. The OPTIQUAD uses several light sources for measurement. Up to four optical methods and up to 12 wavelengths are used. At the request of the customer, a measured value is provided every 3 seconds and transmitted to a controller.

4. Customer benefits

Using the OPTIQUAD-M, the customer can now determine the ratio of protein to total solids continuously. With connection to a PLC system, the dairy plant can operate an automated control loop. This allows the customer to readjust the operating parameters dynamically as soon as the actual WPC value deviates from the setpoint. In this way, the company can better drive the process up to a desired minimum threshold, without ever falling short. This also enables the production of more WPC using the same raw materials.

Today, the customer can forgo time-consuming and labour-intensive sampling and their laboratory testing as much as possible. This also reduces the known sources of errors associated with manual sampling. The procurement cost of the OPTIQUAD-M is attractively priced as other comparable devices (such as the FT NIR spectrometer) and is financed by the dairy plant through flexible leasing.

In the future the customer could optimise its process even further. If the dairy plant were also to use the OPTIQUAD-M in front of the UF units for the whey standardisation, an even more precise protein and total solids content could be set in advance and the WPC production further maximised.

5. Product used

OPTIQUAD-M 4050 W• Spectroscopic analysis system for the continuous inline measurement

of protein, fat, lactose and total solids in milk products• For use in dynamic control loops• No time loss through sampling, sample transport and preparation• No costs for chemicals, reagents and cleaning agents

   

Process diagram for WPC60/80 production using the OPTIQUAD-M

Measurement of protein (in %)blue = OPTIQUAD-M, red: lab

Measurement of total solids (in %)blue = OPTIQUAD-M, red: lab

WPC 60 or WPC 80

10 °C

OPTIQUAD

Ultra FiltrationWPC 80

Permeate

WPC 35 WPC 80

WPC 60

WPC 60/80 Production

Ultra FiltrationWPC 35/60

Permeate

Whey