Brewers who wish to reach their sustainability goals - and produce more stable, fresher beer - should consider embracing a technology which is changing the face of the brewing industry. New research promotes sterile filtration as the optimum technique for brewers to control microbial hazards. Sterile filtration has been around for some time and there are many systems in operation in breweries around the world. However, the filtration industry still feels that the benefits of this technology are at times, poorly understood within the brewing community.
The trends shaping the industry… and triggering change
Beer sales are in decline – putting pressure on large breweries.
Beer production costs are increasing – for example energy prices are increasing at a rate of around six percent, with hop and labour costs also rising across Europe.
Craft beer is a growing market, with high demand for quality and a longer shelf-life.
In a nutshell, the industry is under pressure: people are drinking less beer and it is more expensive to produce. Therefore, producers are looking for ways to protect bottom line profits. And, although the craft beer market is set to rise 11 percent in Europe by 2021, this brings its own production challenges to ensure a quality taste and long shelf-life, especially to support export sales.
Why microbial control is needed to extend shelf-life
Although beer is acidic, alcoholic, anaerobic and contains hop compounds that act as preservatives, there are some microorganisms that can survive through this and thrive on beer’s nutritionally rich properties.
These microorganisms can cause spoilage of beer in the form of a haze or sedimentation, a sour or rancid taste and over-carbonation. The main spoilage culprits are:
Lactic acid bacteria (Pediococcus and Lactobacillus)
Wild yeast (Brettanomyces)
Brewing yeast (Saccharomyces)
If beer is to last more than a few days once packaged, then care must be taken to either completely eliminate or control these spoilage organisms using microbial control.
What is more important when running a microbial stabilization process?
During a recent webinar, Extending Beer Shelf-Life While Reducing Processing Costs, Parker discussed the subject of microbial control and asked:
"When running a microbial stabilisation process to achieve spoilage-free beer, what is more important to you?"
A) Control of contamination (31.3%)
B) Impact on beer taste (31.3%)
C) Impact on shelf-life (25%)
D) Running cost (12.5%)
As the results show, control of contamination and impact on beer taste are coming out on top, followed by the all-important shelf-life. What may come as a surprise – despite the challenges in the industry – is that running cost is less of a factor. Perhaps that is because the technology is perceived as expensive and brewers feel that corners can’t be cut.
For now, let’s look at the technology available and how it impacts the top three priorities.
1) Pasteurisation is a function of heating the beer for a certain period of time in order to thermally kill any contaminating organisms. It is referred to in pasteurisation units (PU) where 1PU = 60º for 60 seconds.
2) There are typical PU units from fruit juices through to low-alcohol beer and lager which determine when the product will be pasteurised. Though for beer, any overheating can be detrimental to the taste and as the above poll suggests, taste and control of contamination are most important to brewers and consumers.
3) Pasteurisation does not remove contaminants from the produce – they are still present but in a deactivated state. This could, however, still lead to produce spoilage over time.
There are two types of pasteurisation – the first process, which was once commonplace is tunnel pasteurisation. The process, rather than focussing on the beer as a whole, treats the entire product (bottle included), meaning that the margin of error for overheating is high as the treatment must first penetrate through the container to reach the beer inside – and heat that at the appropriate PU – all of which is a long-winded process that wastes energy.
This is why many breweries invested in flash pasteurisation which aims to increase efficiency and shelf-life. In this process, beer enters the plate exchange heater, which exposes it to the correct PU level and any remaining organisms are inactivated during the heating process.
However, this process can be negatively impacted if there is any deviation to the PU level, such as from a batch change. If this is the case, beer may not be properly pasteurised, so to ensure there are no contaminants left active the whole batch must be dumped and water flushed through the system – which is costly and uses a lot of energy.
Introducing an optimum approach: Sterile filtration
The sterile filtration process takes place in a hygienic and sealed environment, which uses a polyethersulphone (PES) membrane replaceable filter cartridges to remove spoilage organisms without affecting flavour and characteristics of beer. The process is typically easier to run and not time dependent like pasteurisation.
The CSM range of sterile filtration systems also offers a number of added benefits such as full automation, integrated clean-in-place (CIP) and one or two beer lines for batch or continuous processing.
One of the key areas for concern when using a type of pasteurisation is ensuring the heat is set in the right proportion to deactivate the cells. With the process of sterile filtration, the membrane used in the filter prevents the cells passing through. In a bacterial retention study, the filter was challenged with 10 million viable cells per square centimetre of membrane without a single cell passing through. This validated the performance of the filter cartridge.
Addressing each of the industry concerns in turn and comparing the results
The first set of results are shared by a customer, who did some independent research when investigating if sterile filtration was a worthwhile benefit to them – over that of flash pasteurisation. The deciding factors pointed to a technology that would make the beer taste better and have a longer shelf-life.
Results show sterile filtration beer is found to have a more bitter and crisper taste vs. a sweeter, softer and sulphur tasting beer when pasteurised – these are negative characteristics for the beer being tested.
Results show after 12 months over 90 percent of the flash pasteurised bottle beer has a very strong or moderate oxidised taste. This was in stark contrast to beer that had been treated through sterile filtration, where over 95 percent of the bottles had a total absence of very low level of staling or oxidised flavour.
This demonstrates that sterile filtration protects the shelf-life and taste of beer more effectively than flash pasteurisation. So if either of these, or contamination of product is an important factor, and you’re not already looking at sterile filtration, then you may want to know more.
What about running costs?
Our global automation partner, Agidens, has applied its experience in brewing and design to be able to present information to compare flash pasteurisation in like-for-like running costs against sterile filtration – let’s have a look at the comparative results.
With sterile filtration, there is a requirement to replace blocked filters when they reach the end of their usable life. However, Parker Bioscience is working with end-users to reduce the change-out frequency through understanding their beer and optimising cleaning regimes. Watch our short video on how Parker engineers have created a high performing, long-lifetime filter membrane for beer stabilisation.
Final question: What does all this mean?
Answer: Sterile filtration is 44 percent more efficient than pasteurisation.
Yes, this is a bold statement but is based on sound engineering principles and compared to like-for-like process conditions.
The differences are realised through:
Reduced beer losses
Reduced water consumption
Reduced electrical energy consumption
This demonstrates that sterile filtration represents a process evolution which can ensure the sustainability of brewing in the challenging years ahead.
These findings were taken from our webinar, Extending Beer Shelf-Life While Reducing Processing Costs.
Visit our landing page to request a free full cost analysis based on your specific process.