As the German purity law does not clarify everything: the analysis of beer along the supply chain

Did you know that the idea of a purity law has existed for over 500 years?

Duke Wilhelm IV issued such a decree as early as April 1516, naming barley, hops and water as the sole ingredients to prevent counterfeit beer of inferior quality. He thus improved consumer protection and product quality and at the same time regulated the use of different types of grain.

The modern purity law

However, Duke Wilhelm’s decree only endured for about 35 years so that later various spices were also legitimized. In fact, over the years there have been numerous laws regulating the brewing of beer in Germany.

Today, the purity law defines hops, malt, yeast and water as the only four ingredients in beer production.

To be more precise, the purity law allows only barley malt for bottom-fermented beers, while other types of grain may also be used for top-fermented beers, as well as some types of sugar and the colorants produced from them.

The basic analysis of beer: original gravity & alcohol

First of all, the analysis of beer is concerned with the determination of some core factors that divide beer into different categories under food law.

Types of beer based on the original gravity

The basis of the subdivision of beer into categories is the original gravity. This is the content of soluble substances in the unfermented original wort from which the beer is produced. Among other things, it also influences the taste, alcohol content, nutritional value, carbon dioxide content and even the beer tax.

The original wort content is calculated from the residual extract and alcohol content of the beer. The types of beer are divided as follows:

Light beers have an original gravity of less than 7g per 100g
Draught beers have a gravity of 7 to 11g per 100g
“Full” beers have an original wort content of 11 to 16g per 100g
Strong beers have an original wort content of over 16g per 100g

Alcohol content tolerances

The original wort is also the greatest influence on the later alcohol content of the finished beer. There are also limits and tolerances for deviations. A beer with a declared alcohol content of up to 5.5% vol. may only differ by 0.5% vol. A tolerance of 1.0% vol. is permitted for a declared alcohol content of over 5.5% vol.

Product typical challenges

Thankfully, beer is fundamentally a very safe food. The four ingredients for the production of beer according to the German purity law even have positive properties: the ingredients of the hops, the slightly acidic pH value, the alcohol and the carbon dioxide in the beer inhibit the growth of pathogens.

Nevertheless, the purity law does not guarantee absolute food safety. During cultivation, production, storage and delivery, the beverage may come into contact with substances that pose various risks. A comprehensive analysis of beer and its supply chain must therefore also take these risks into account.

Challenge in cultivation: beer analysis for pesticides

Beer consists of raw materials that are cultivated and, as is usual in the cultivation of many foods, pesticides are also used. Of course, none of these are intended to enter the finished product, but some pesticides survive the brewing process at least partially, so that glyphosate was discovered in 2016 during an analysis of beers. Since then the breweries have made significant improvements, but even in organic beers, glyphosate has been detected - probably through its use in neighbouring fields.

Challenge in production: beer analysis for N-nitrosodimethylamine

During the production of beer, N-nitrosodimethylamine, one of the most dangerous carcinogenic substances, is produced in the process of drying and roasting the germinated barley. When the German Cancer Research Center detected larger amounts of this NDMA in beer in 1978, concrete guidelines were introduced. A maximum value of 0.5μg per kg applies. In order to reduce the formation of nitrosamine, breweries have, for example, introduced indirect drying of barley and additional internal control systems which have led to a noticeable reduction in contaminated samples.

Challenge in storage: beer analysis for ochratoxins

Ochratoxins are mycotoxins and are widely used in many storage products. They are formed by typical storage fungi and can damage the kidneys. Indeed, Europe-wide studies have shown that ochratoxin A can be detected in almost the entire population. Besides cereals and coffee, beer is one of the products that contribute most to the contamination.

Challenge in delivery: lye bottles

Beer is sold in returnable bottles which must first be cleaned by the bottling plants. The bottle washing machines in this process work with lye. It can be the case that lye residues remain in the empties and are not detected before filling. In the worst case this can lead to burns at the end consumer. In order to ensure greater safety in this special case, technical inspection equipment is implemented that automatically detects any lye residues in empties.

Challenge at the bar: dispensing systems

The operators of a dispensing system are responsible for ensuring that the beer is in perfect condition by regular and thorough cleaning. If a company does not adequately fulfil this responsibility, the tapped beers can be microbiologically abnormal. Here too, it is therefore necessary to monitor in order to keep the risk as low as possible.

The food safety of beer is therefore not only guaranteed by the purity law. On the journey from the field, through production and storage, and finally to the end consumer, various risks arise that must be analysed and evaluated.