Bürkert Fluid Control Systems - a leading manufacturer of control and measuring systems for fluids and gases - has recently trialled its air dosing system for use in the automated oxygenation of brewers' wort. The trial was conducted by Campden BRI, an independent food and drink technology company.
Ensuring precise control of the oxygenation process of brewers' wort is an essential part of manufacturing high-quality with consistent flavour and strength, and the characteristics of individual beers are defined by the yeast strain and the rate of oxygenation of the wort. Once the boiled wort has been cooled, oxygen is used to begin the process of fermentation, but the wort's ability to absorb oxygen decreases as its specific gravity increases. This means, for example, that breweries that want to produce higher strength beers may need to use pure oxygen rather than air to achieve the required levels of oxygen saturation.
Bürkert's air dosing system comprises several elements:
Combined, these instruments are used to control the oxygenation of the wort as it travels between the wort receiver vessel and the fermenter vessel.
During the test the wort was brewed conventionally from malt extract that included hop extracts and brewing quality water. After the wort was boiled it was passed through a plate heat exchanger to cool it before the oxygen was added. The wort was analysed using standard brewing parameters, such as present gravity, pH, fermentability and bitterness, to ensure that it was a true representation of a commercial product.
The oxygen levels and temperature were measured at two points, a sample point in the transfer line and in the fermenter vessel. The measurement probes were calibrated and the Bürkert control module was commissioned before the tests were carried out.
The dissolved oxygen concentration was controlled by adjusting the set point value on the control unit. The aim of the test was to see if a linear adjustment to the setpoint resulted in a representative increase in dissolved oxygen levels.
The results from three tests showed that both DO probes indicated a linear response to an increase of the setpoint, which would indicate the suitability of this control system for a commercial enterprise.
The trial at Campden BRI has proved the feasibility and accuracy of the Bürkert Air Dosing System. As a package it can be developed to suit any commercial business, from a modest craft brewery to a large-scale enterprise.