BRi has one of the most sophisticated pilot plants for malting, roasting and brewing in the world. This plant offers a high degree of flexibility and accurate process control for new variety trials, new product development, process optimisation, and safety evaluation. A range of standard and specialist analysis together with tasting and malting consultancy is available to complement pilot trials.
Recent research activities have included an investigation into the role of lipid binding proteins and the flavour of beer, model-based control of the formation of colour and flavour during malt roasting, and a method of determining malt friability from the sound made during the milling process.
Today, its research activities are focusing on four main areas: developing a cheap instrument for quantitative measurement of water distribution in barley during steeping; an assessment of whether lipid binding proteins influence wort fermentability; a new method for assessing the fermentation performance of malt; and PDX, a supersonic mashing system that combines effective milling and mashing in
And it is this supersonic mashing system that has got the scientists excited. Research undertaken by BRi technical director Richard Sharpe and scientist Gary Freeman has shown that the innovative PDX fluid processing system from Pursuit Dynamics has the potential to make major improvements to the process efficiency of mashing and wort boiling during brewing.
In addition to delivering substantial savings in energy costs, the technology is also found to reduce processing times, simplify cleaning and maintenance, and reduce the risk of product contamination.
BRi is developing a new, improved brewhouse process sequence that involves changing the way it mixes, homogenises and heats mash, boils wort, heats cleaning in place (CIP) water and pasteurises beer. Much of the work with the PDX system took place on BRi's pilot plant, with other trials undertaken in a UK brewery production installation.
One of the advantages the BRi team found with the PDX system is that it is truly scalable. Also, unlike conventional pumps and mixers, the PDX unit has no moving parts to wear or clog, no bearings to cause problems and no grease to contaminate plant and product.
Instead, the technology makes use of steam and momentum transfer to cause the process fluid to flow. Thorough mixing and homogenisation is ensured by the creation of a controllable shock wave and phase change region within the process fluid that cause sudden changes in speed and pressure.
Furthermore, depending on the rate of addition of steam and the back-pressure applied, the temperature rise in the process fluid can also be controlled. As a result, the PDX system can be used as a pump, mixer, homogeniser, heater, or a combination of two or more of these.
All of this takes place in a compact device that is easy to install within process pipework and is virtually self-cleaning.
One of the first applications investigated by BRi was in a trial rig for mashing-in. The rig used a PDX25 with a 25mm bore just downstream from where the cold liquor and grist are added together to homogenise the mash and pump it to the mash conversion vessel (MCV).
With a steam flow of 180kg/h at 5.5bar and 162°C, a bulk flow rate of 150hl/h was achieved and the temperature was raised to 65°C.
In a scaled-up process, a PDX47 could flow 600hl/h and the PDX160 7000hl/h.
At the same time, a second PDX25 was installed to heat the mash in the MCV. Using a working flow rate of 150hl/h, 600hl of mash took 240minutes to mash-in.
BRi performed a detailed analysis of the mash and deduced that the PDX process did not cause enzyme damage.
Further side-by-side analysis of a standard lager wort and a PDX lager wort showed no significant differences between the two samples.
Having established that the PDX system is fully capable of mashing-in, the researchers looked at the energy savings achieved in comparison with conventional technologies.
Whereas indirect steam heating is normally around 60percent efficient, the PDX direct steam energy transfer is approximately 95percent efficient.
So for a 3mhl/y brewery, the annual energy savings could amount to around E75000.
Although actual savings might be lower if wort cooling and wort vapour energies are recycled, there are also potential savings through reduced maintenance and cleaning costs.
In addition, utilising PDX technology negates the need for a hot liquor tank, which typically costs around E75000. Plus there are no electric pumps and mixers required. Substantial capital cost savings are therefore possible.
Another PDX application studied by BRi was wort boiling. In this case a PDX13 was installed within a kettle in BRi’s pilot plant to heat 95litres of wort.
Again, detailed analysis showed no significant difference between a BRi standard lager wort sample and a PDX wort sample. However, the potential benefits are exciting: heat transfer is more efficient, boiling point can be reached more quickly, and the PDX unit does not lose efficiency through fouling – unlike conventional steam heaters.
A typical conventional CIP system has a 10000-litre hot caustic tank from which a 3kW pump draws cleaning fluid and passes it through a plate heat exchanger with regulated steam at 1.5bar and a flow rate of 1000kg/h to raise its temperature to around 70°C.
Trials have been performed in a UK brewery using a PDX47 operating at 5.0bar steam pressure and a flow rate of 600kg/h. This has successfully raised the temperature of the CIP fluid to 70°C and maintained it at between 60 and 70°C.
Over two shifts, the conventional system uses around 2168kg of steam, whereas the PDX47 used only 1440kg. This represents a reduction of approximately 33percent, with additional cost savings available from not having to own, operate or maintain a 3kW electric pump or plate heat exchanger.
BRi has also investigated pasteurisation. In tunnel pasteurisation the PDX unit supplies heat and
some pressure for the water sprays, with the advantage that heat is only applied when needed and there is
no need to maintain water tanks at an elevated temperature. For flash pasteurisation, the PDX was found to be successful with non-brewery bacteria, and preliminary evidence indicated higher kill rates than can be achieved by temperature alone.
Large-scale wort boiling
With the trials being unquestionably successful, BRi is now planning to undertake further work. Areas to be investigated include large-scale wort boiling, commercial-scale mash-in, conversion heating, cereal cooking and pasteurisation.
Indeed, BRi is enthusiastic about any brewery-based applications, and is actively seeking brewers with which it can work to trial the PDX technology.
Professor Richard Sharpe concluded: “We are looking here at nothing short of a potential revolution in cost savings terms for the brewing industry and one which could impact very favourably on the bottom line.”