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Manufacture of fresh plant tinctures


The quality of a herbal medicine is firstly determined by the quality of the raw material and secondly by the production method. Systematic, fully controlled checking of all process steps and control procedures is known as validation and is in each case meticulously recorded in a manufacturing document.

It is only possible to manufacture to the desired quality in a reliable and reproducible way, batch after batch, if you have help from validated production processes. By ensuring quality, validation is also an important element in guaranteeing the safety of medicines.

Time limit for processing the fresh plants

Speed is of the essence once the plants have been delivered direct from the field. Consequently, fresh plants must generally be processed within 24 hours. A period of 48 hours can only be allowed in exceptional cases – if, for example, the harvest has to be transported a long distance from contract farmers. In such cases, however, additional controls are required before any processing is carried out. 

Analyses during all production processes

After checking the identity of the plant and for the presence of any foreign contaminants such as weeds, samples of the batch are removed for analysis by the laboratories in Roggwil/TG. These are equipped with modern equipment and use state-of-the-art testing methods such as gas chromatography (GC), high-performance liquid chromatography (HPLC) as well as the proven thin-layer chromatography (TLC).

GC is, for example, used for the quantitative analysis of organic substances or mixtures of substances and also for their qualitative analysis. The latter involves identifying substances and conducting purity tests for the most important applications. 

However, natural products with complex molecular structures and thermal instability require more gentle processes, such as HPLC, to separate their constituent substances. This allows us to identify components using corresponding standards and determine their concentrations.

This level of laboratory equipment and trained personnel is essential when processing medicinal plants because of the extraordinarily large complex of active substances, constituents and lead substances, and because there are hundreds of different combinations in a plant.

One of the simplest processes involves determining the water content of plants. It is a basic prerequisite for all further steps because this provides the only basis for calculating the formula that determines the ratio between plant mass, water and alcohol for manufacturing a tincture. 

To calculate loss on drying, the plant is exposed to a specified temperature for a certain period of time. The resultant figure for dry matter is then included in the calculation of the alcohol and water content. Depending on the method of manufacture, the water content already existing in the plant is then deducted again.

Ethanol – extracting agent and preservative

Alcohol is the most natural preservative for plant-based active substances. Alcoholic extracts are effective, can be kept for long periods, are practical to use and are not harmful to health if used in the prescribed dose.

Alcohol serves several purposes at the same time. The water-soluble and fat-soluble substances from the cell interior of the plants are absorbed by it and any bacteria present are killed off. The alcohol used is ethanol (i.e. potable alcohol), which is obtained by natural fermentation. This also complies with the company's principles and quality requirements, which state that the minimum possible number of chemicals should be used. 

Once the amounts of ethanol and water have been calculated, processing of plants can begin. This comprises several steps. 

Creating the macerate

The fresh plants are first crushed by machine. They are then moved by conveyor to fill a 1000 litre container or an even bigger maceration tank. The prescribed quantities of alcohol and water are added to the plant components and all the ‘ingredients’ are thoroughly mixed. 

This is the macerate. The amount of time that the plant material then has to infuse in the liquid (maceration) is precisely specified, as is the frequency and duration with which the mass is further agitated.

When developing new products, the R&D department conducts a series of lengthy tests in order to determine the ideal maceration time and alcohol content. Numerous analyses are conducted for this and each of the newly developed processes is validated (checked). 

The experts remove samples at specified times (after hours or days) to allow them to precisely determine how the extraction process is developing. Various steps are performed with three different plant deliveries/batches before maceration times for the individual plant species can be determined. 

Some medicinal plants only need to infuse in the water/alcohol mixture for a single day, whereas others need five, ten or even twenty days. 

Repeated control checks on the tinctures

After the end of the prescribed time, the macerate is pressed and the tincture is separated from the solid residue. This is known as ‘the marc’ and recycled. A specific process is used to compost it with mushroom or horse manure so that it can be used as a fertiliser or soil improver. Anything that remains from the marc is then sent to a biogas facility.

After further laboratory tests, the filtered tincture is returned to huge storage tanks with capacities ranging from ten to forty thousand litres. At this stage, too, samples are regularly taken for quality control purposes and the laboratory uses fluorescent labels to inform employees about the respective testing status. For example, orange stickers indicate: "Do not touch: tincture is in quarantine". 

The tank in question is only moved to the filling department when a green label is applied, signifying that the contents have been "released by the laboratory". It then undergoes a further identity check in the filling department. 

Filling and packaging

Some of the tinctures are used to fill bottles sealed with dropper caps, while others undergo further processing. Additional control checks are carried out in the Filling and Packaging department. This includes checking the fill levels in bottles, and using barcode readers to make sure that the correct labels, the package leaflets and the boxes are used.    

 • Angelika Eder/Ingrid Zehnder-Rawer 

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