Of novel microbes and exploding packaging

People are drinking fewer alcoholic beverages as part of a greater trend towards more healthful lifestyles. For those who miss the juice of the barley and the pleasing piquancy of the hop, non-alcoholic beer (NAB) fills a void. The popularity of NAB has caused brewers of all stripes to want to produce them. Simply put, some should refrain from doing so. Why?

Beer is a 13,000 year old beverage. It has lasted this long, in part, because it has served as a safe source of nutrition. Brewers are lucky. Beer and wort spoilers are not pathogens. They only make for an unpleasant drinking experience. Pathogenic microbes do not grow in beer for a variety of reasons – if it’s produced correctly! Let’s go into a little detail…

Supply of nutrients and O₂

No matter what, both of these must be low. The anaerobic environment through the evolution of CO₂ during fermentation keeps some microbes in check. Plus, fermentation reduces their supply of nutrients. Mixed microbial beers, like lambic or sour beers, contain even fewer nutrients than beer fermented solely with Saccharomyces species, because any starch fragments or other compounds are consumed by super-attenuating yeast and bacteria. In either case, a lack of anything to eat plus a dearth of oxygen act as a defense against pathogens.

Types of nutrients, boiling and hops

These parameters may vary somewhat. If one decreases, the others must compensate. The types of nutrients determine which microbes survive and thrive. Put milk and beer wort out in open containers on your back porch for ten days. Two very different sets of microbial colonies will be present in them. The substrate determines the bugs. Thus, brewing yeast will effortlessly dominate the wort, IF the maltster and brewer do their jobs during malting and mashing correctly. If they don’t, the “infection pressure” increases, which is dangerous. Let’s not even bring up adding fermentable sugars in the form of fruit or syrups! Furthermore, boiling the wort not only eliminates any harmful microbes floating in it, but the heat solubilizes the α-acids and other bacteriostatic agents derived from the hops.

Ethanol and acidity

These may also vary, but others must take their place if they’re inadequate. Invariably, however, regular beer must possess a pH of less than 4.5. There’s no wiggle room. Historic beers brewed without the benefit of hops generally had a pH nearer 3.5, for good reason. Pathogens hate acid. Lactic acid or Sauergut can be added at some point to lower the pH. Likewise, the ethanol content in beer (usually between 3.5 and 6.5 % ABV) makes pathogens shy away from it.

Food safety, beer and NAB

Together, these factors are quite potent in regular beer. Take away or diminish any of them, other measures MUST be taken for reasons of product safety. NAB’s much lower alcohol concentration, higher pH, lower hopping rates and high residual extract are all factors posing potential risks. Under the right conditions, pathogens have a potential for causing illness in NABs. Brewers must, therefore, take extra measures to ensure that this product is safe for consumption.

For this reason, non-alcoholic beer (NAB) should not even be classified as “beer”, since beer is an alcoholic beverage, produced through the degradation AND fermentation of cereal malt starch. Consumers assume that non-alcoholic beer is just regular beer with little to no alcohol.

However, most brewers know it’s not that simple. The production processes for NABs have to be approached from a different perspective for purposes of food safety because too many of the parameters outlined above are driven to near zero in NAB production.

One problem in the industry is that some brewers, usually at smaller facilities, simply have no understanding of these concepts. They’re merely attempting to make a quick buck on a popular trend. In doing so, these NAB producers are putting their customers at risk – even if they only walk near them on the shelf at their local retailer. Cans and bottles of NAB have been known to explode.

By the way, it bears repeating that when the yeast has “settled out”, there are still plenty of yeast in suspension – just so we’re all on the same page.

Monsieur Pasteur to the rescue

How does one mitigate these risks? The only way to be absolutely certain is to properly tunnel pasteurize the filled cans and bottles. Other methods, such as flash pasteurization or membrane filtration are effective; however, the potential for re-contamination is high. The addition of preservatives, such as Velcorin, Chiber or Nagardo, might work, but these are only applicable with some beverages, require special handling and have explicit pH requirements.

NAB production

A combination of these methods is normally used in NAB production:

Brewhouse

• Alternative mashing regimes (e.g., the “spring” method uses decoction to skip the β-amylase rest) reduce the nutrient supply for yeast – but increase the “infection pressure”. Combined with other methods.

Microbiological

• Halted/arrested/interrupted fermentation prevents some ethanol production. If conducted at low temperatures, this is known as the “cold contact” method.
• Alternative microbes generate fermentation by-products other than ethanol.
• Maltose-negative yeast is an alternative to traditional brewing yeast.

These methods require little to no additional energy input into the process.

Physical

• Distillation reduces alcohol to 0.0% in the beer; regular beer is added back to 0.5%. A falling film evaporator plus rectification or vacuum evaporation can be employed.
• Membrane separation, i.e., reverse osmosis or dialysis likewise remove alcohol.
• Two-step CO₂ extraction is particularly prevalent in the wine industry.

Avoiding pitfalls

It is best to plan ahead by reviewing the entire production process in order to mitigate risk. Identify all points in the process where pathogens might enter. More stringent testing of water and raw materials, including all gases used in production, is essential. This should also encompass processing aids, brewing equipment, the CIP system, packaging materials and brewery staff. SOPs and training should focus on avoiding contamination.

During production, avoid exposing the wort to any contaminants after the boil, e.g., the practice of dry hopping, a typical method for improving the bouquet of NAB. A low pH is critical to curb the growth of pathogens. Without exception, the pH of the finished NAB should be ≤ 4.2. As with any product, critical control points should be defined and serve as the basis for a safety monitoring program. And last, but not least – a recall plan is essential. Again, brewers would simply be best advised to pasteurize their packaged NABs, so they can sleep well at night.

Nevertheless, if they’re produced correctly, NABs are a much more healthful – and flavorful – alternative to soft drinks, diet or otherwise. So, pop open a cold one or two after running that half-marathon or biking over those mountain passes.