Monitoring & metering Better data for better beer
Brewers will often attribute their success to passion, determination and innovation, but once a beer has been developed and branded, it is all about consistency. Process monitoring therefore has a key role to play. In the following article Keijo Pyörälä from Vaisala explains how in-line refractometers, located strategically at every stage of the brewing process, enable process optimisation, save energy, reduce waste, lower costs and help deliver top quality beer.
SamPlIng VS ContInuouS monItorIng Some breweries rely on manual sampling and laboratory analysis, but there are a number of significant disadvantages with this approach, so there is an inevitable trend toward in-line monitoring and increased automation. Laboratory analysis is obviously an essential
component of research and development; providing an insight into the effects of different raw materials or processes on characteristics such as flavour and aroma. Laboratory analysis also plays an important role in investigatory work; helping to understand the chemistry. However, from a production perspective, sampling and analysis can be of limited value because of the cost and the delay incurred - by the time a lab result uncovers a problem; a significant volume of product may have already passed through the brewery. Similarly, samples represent a ‘snapshot’ of the process at one moment in time, and are therefore unable to support feedback control or provide timely alarms, and are less able to uncover trends.
monItorIng teChnology Vaisala’s K-PATENTS sanitary refractometers can be calibrated in Plato, Brix, Balling, gravity, or density, depending on the preference of the
brewery. They are available with 3-A Sanitary and EHEDG certifications and are designed to withstand CIP/SIP cleaning and rinsing procedures. A number of different technologies have been
employed to monitor various aspects of the brewing process, but some methods such as turbidity and density can experience measurement errors from fouling and interference by the larger suspended particles (especially in mashing and the lauter tun) and by the bubbles and foam that are present in most stages. Refractive Index monitoring is therefore preferred, and the key advantage of the Vaisala refractometers is that they provide accurate measurements at every stage of the brewing process without suffering from these interferences. A further advantage of refractometers is
their speed of response, which is a particular advantage in the packing/filling line and CIP process – this will be discussed later. Refractive Index (RI) measurements are based
on the angle of refraction of light in the process medium, using an LED light source. A sensor continually detects the critical angle at which the total reflection of light commences, and the concentration of dissolved solids is calculated taking pre-defined process conditions into account. Vaisala’s sanitary refractometers are therefore supplied factory calibrated to meet the requirements of the specific brewery and are deployed at most stages of the brewing process, some of which are described below.
mashing Typically, mashing takes place in a tun, which is an insulated brewing vessel with a false bottom. Malt is steeped in hot water which activates enzymes that cause starch in the malt to break down and release simple sugars, producing wort. Mashing is a crucial step because it determines
the final structure of the beer, so it is important to maintain a consistent wort output. The refractometer is used to measure the concentration of the mash in water at the outlet pipe. The process by which the grains are
separated from the wort is known as lautering, which is often conducted in a separate chamber known as a lauter tun.
44 November 2021 Instrumentation Monthly
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