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Non-alcoholic beverages (NABs) can be divided into three main groups:

Juices and nectars

Soft drinks (e.g. spritzers, fruit juice drinks, lemonades, fizzy drinks, flavoured waters, sports and energy drinks, mixed drinks, etc.)

Waters (mineral water, table water, medicinal water, etc.)

Raw materials for non-alcoholic beverage production (fruit juice concentrates, base materials, flavourings, sugar syrups, etc.) are also listed.

Hot and cold drinks such as coffee, tea and milk are not included here.

With the exception of waters, this regulatory classification is based on their composition: mainly due to their juice content (0-100 %), flavouring (natural, natural-identical, artificial) and various ingredients such as caffeine, vitamins, minerals, etc.

Microbiological sensitivity of non-alcoholic beverages

The microbiological susceptibility of non-alcoholic beverages should be considered separately due to the diversity of the test matrix. It is characterised by the following key selective criteria:

Beverage ingredients:

The microbiological sensitivity of a beverage is expressed via the specific growth and inhibition substances. These include nutrient-rich substances such as carbohydrates, amino acids, minerals and vitamins etc., which provide the basis for microbiological growth. The presence of fruit acids, essential oils although also the lack of nitrogen sources, inhibit growth and thus provide additional inherent protection for non-alcoholic beverages.

pH value:

The pH value of a beverage plays a central role in beverage production and microbiological analysis. The acidification of the beverage is intended to prevent the growth of pathogenic microorganisms. However, there is no absolute limit value. In practice, a pH value of < 4.3 is considered sufficient protection, depending on the nature of the beverage and its ingredients. Vegetable juices, for example, are an exception.

Aerobiosis/anaerobiosis:

The carbonation of beverages creates an anaerobic environment to largely suppress the growth of aerobic microorganisms, for example. Depending on the type of packaging, sufficient CO₂ must be added to compensate for gas losses due to migration during the shelf life. For example, at least 3-4 g/l CO₂ is recommended when using lightweight PET bottles.

In general, the groups of acidophilic and acid-tolerant, aerobic and facultative anaerobic as well as anaerobic microorganisms are identified as potentially harmful to beverages in the NAB industry, provided that the pH value of the products is in the acidic range (pH value < 4.3). For NAB with more critical pH values (> 4.3), this increases the relevance of mesophilic and thermophilic microbes and potentially pathogenic microorganisms.

Osmophilic/osmotolerant microbes must also be taken into consideration. These can occur as spoilers, especially in highly concentrated raw materials for beverage production. These include, for example, fruit juice concentrates, fruit pulp, fruit preparations, base products, and also sugar syrups, etc.

The beverage-spoilage organisms in non-alcoholic still drinks are generally all yeasts, acetic acid bacteria, moulds and alicyclobacilli. Depending on the pH value, other germs such as Bacillus sp. become relevant.

In carbonated non-alcoholic beverages, fermentable and fermenting yeasts are particularly important, but also other microorganisms such as lactic acid bacteria. Depending on the pH value, other germs such as Bacillus sp. or potentially pathogenic germs such as Clostridium sp. can occur.

The listed groups of beverage spoilers can be categorised as primary contaminants from the corresponding raw ingredients or as secondary contaminants.

Due to the complexity and diversity in the NAB sector, the microbiological controls and analyses, both in the production process and in the end products, must be considered in a different way according to each product group. The requirements are always based on the specific selective criteria of the products in question.

Collection of representative samples

By law, compressed gases are considered food additives [1]. Therefore, the gas bottle should be checked for the following:

manufacturer name with address

lot/batch number

expiration date/best before date 

Wastewater samples are collected at regular intervals over a long period of time and combined to create composite samples.

Collecting samples correctly is a prerequisite for obtaining impeccable analytical results. The sample collection method must be tailored to fit the purpose of the analysis. As a rule, separate samples are taken for chemical and microbiological analyses, since different devices and vessels are required for collecting and handling the samples.