Practical Advice - PIKA Weihenstephan GmbH

Practical Advice Around Common Industry Problems

Testing for spoilage organisms is one thing, but how do you know what to look for, and how do you know how to respond when you have the results? Through our work with many breweries, wineries and fruit juice manufacturers we have first-hand experience and knowledge which can help you tackle these issues head on, saving you time, effort and money.

We’ve outlined some of the most significant question areas below and prepared an Application Note around each which is available for you to download. We also have a selection of further frequently asked questions related to testing and our product range pulled into one easy to view document below.

Lactobacillus acetotolerans

A new beer spoiler?

Lactobacillus acetotolerans was not regarded as a beer spoiler until the first recall actions due to contaminated beers occurred. At PIKA Weihenstephan, we had the first issues with a L. acetotolerans contamination in late summer of 2004 in a Bavarian brewery. Symptoms of the contamination were extreme low pH value plus turbidity in some bottles – the first customer complaints came only after the beer was on the market for some months. All routine process controls had been negative, and not the whole lot was affected. In the last years, the same problem became relevant for some breweries in the USA, and the solution is still as difficult as it was more than nearly 20 years ago.

Turbid Beer

Avoid such risk by continuous and targeted routine control

(Naturally) Turbid beer is produced by many breweries in different types as a speciality product. But turbid beer also may be a source of complaint – in the case when beer spoiling bacteria or yeasts proliferate in the finished container. The good news: With regular and targeted process control, turbid beer can be avoided. If a contamination with a beer spoiler is known, it is essential to localize the source of contamination instantly to prevent spoilage of the following batches.

Detection of Anaerobic Beer Spoilers

Why is the detection of anaerobic beer spoilers so hard?

Anaerobic beer spoilers only became an issue since the technology of beer production was improved in concern of avoiding entry of oxygen into the production process.

The first anaerobic beer spoiling Pectinatus strains were isolated in 1978, Megasphaera was the first time detected in beer and described as a new species in 1986. Both are responsible for bad smell and extreme off-flavor in beer. They are usually detected in finished products or other liquid samples, most often in low or non-alcohol beers.

Samples contaminated with anaerobic bacteria are often described with terms such as “animal waste”, “sewage” or “baby’s vomit”. But odor analysis alone is not sufficient to identify these anaerobic bacteria – we have also detected Pectinatus in spoilt non-alcohol beer showing no unusual odor at all.

In some cases we have identified Clostridium species as sources of bad smell, so Clostridium butyricum and Clostridium beijerinckii (formerly Clostridium acetobutylicum) from beer, and Clostridium pasteurianum from banana juice. Clostridia are spore formers and therefore resistant to high temperatures which makes them causing severe and long lasting problems.

During routine process control, anaerobic bacteria mostly stay undiscovered, therefore back-tracking to their contamination source is difficult to impossible.

Lactic Acid Bacteria

Sometimes desired, but often spoilers

Lactic acid bacteria are often causing a considerable pH reduction when they grow. Therefore, such cultures are traditionally used in the production of foods with a prolonged shelf life as yoghurt, sauerkraut, pickles, kombucha or salami. In the beverage production, mainly in the production of beer and wine, the identical microorganisms are regarded as the most common spoiling microorganisms, as they are able to grow well in sour environments such as beer and fruit juice.

Microbial Growth Surviving Heat Treatment

Routine control must be adjusted to include heat resistant microorganisms

By heat treatment – flash or tunnel pasteurisation – microorganisms in the product are destroyed and the shelf-life of the product is extended. Commonly used procedures are optimized for the typically occurring microorganisms. In breweries, the settings for time and temperature are aiming on the inactivation of yeasts and bacteria. Nevertheless live microorganisms reach the product – why does this happen?

Positive Results in Enrichment

Warning of problems in quality control

Growth of bacteria, yeasts or molds in routine control are advance notice of product quality problems. But what is the damage potential? This is the essential question. Some bacteria or yeasts are proliferating in enrichment media while they are not able to grow in the beverage itself. So everything is only false alarm? Not at all – and nothing which you should ignore.

Pressure Formation - Burst Risk

Originated by gas producing microorganisms

Pressure formation in a container is usually caused by proliferation of gas producing yeasts, rarely by bacteria. Depending on the nutrient availability, some microorganisms degrade carbohydrates under anaerobic conditions thus producing carbon dioxide. The gas production may proceed until containers swell and even can burst. In case of a yeast contamination, the burst risk especially for glass containers is very high. Prevent damage and avoid recall campaigns which are everything else but good advertising.