To prevent the spoilage of drugs, the following should be observed during storage: The moisture content of the drugs must not exceed 12%. The relative humidity in the storage rooms should not exceed 60%, and the room temperature should not exceed 25°C; ideally, storage should occur at +5°C in air-conditioned rooms, and under no circumstances (!) should storage occur on a so-called herb floor under the roof. The storage temperature should remain as constant as possible, as warm air acting on cold drug material leads to the formation of condensation. Exposure to light should be avoided, as light contributes to the formation of radicals and thus promotes oxidative changes. Drugs should be stored as unground as possible. The destruction of tissues, particularly the tearing of secretory containers, and the enlargement of the surface area promote the loss of volatile substances and the effects of oxygen. Drugs should not be stored together with volatile chemicals or other strongly smelling drugs, as they will absorb the smell of these materials. Storing dried herbs in sacks is not advisable, as crushing occurs when stacked. Rigid containers are better suited for storage. Drugs should be stored in tightly sealed, airtight containers, for example, in porcelain, glass, or tinplate vessels for smaller quantities. These vessels prevent the evaporation of volatile components as well as the ingress of water vapor, oxygen, and insects. Bags made of polyethylene or polypropylene are unsuitable, as the lipophilic material retains water vapor but is permeable to volatile lipophilic substances, such as essential oils. Drugs susceptible to insect infestation must be freed from live insects and their eggs before storage, i.e., subjected to disinfestation. This can be done by fumigation with methyl bromide or by pressure disinfestation with CO2, the so-called Maba-Pex process. Liquid or semi-solid drugs, such as essential and fatty oils, should be stored in completely (!) filled, airtight containers to exclude oxygen as much as possible. Drug containers should always be completely emptied and cleaned before the next batch is filled. Residues contaminated with microorganisms or insects, and radicals formed in fatty and essential oils, accelerate spoilage.

Hi Ghasem

Reducing the micro load of herbs and spices has bene typically done by heat exposure : dry heat and/or steaming. Nevertheless, this will necessarily induce some side effects liek in change in flavor profile or loss of volatile compounds ( especially for the steam treatment).

Some country will allow the ionisation procedure ( typically gamma rays ) . This is very effective to clean up for micro-organisms but will be of no effect on toxins. As far as I'm aware, the HMO allows a 10 Gray dose onto food items.

Last but not least, ethylene oxyde has been popular for the desinfection of seeds ( typically sesame).Once again, not allowed everywhere and rules for residual content are quiet strict and well monitored by autorities.

Final word on my side, time is your friend. Any food powder will a low water activity will show a slow but steady decline in the overall mesophilic population along storage as the bugs will switched from revivable to non-revivable.

Hope this helps. Cheers

On an industrial scale, the most commonly used sterilization method to reduce the microbial load in herbs and spices before extraction is gamma irradiation.

Gamma irradiation is a highly effective method for the sterilization of herbs, spices, and other food ingredients. It involves exposing the materials to high-energy gamma radiation, typically from a cobalt-60 or cesium-137 source.

The key advantages of using gamma irradiation for industrial-scale sterilization of herbs and spices include:

1. Efficacy: Gamma radiation is highly effective in reducing the microbial load, including bacteria, yeasts, molds, and spores, without significantly altering the chemical composition or sensory properties of the herbs and spices.

2. Penetration: Gamma rays can penetrate deeply into the packaged products, ensuring uniform sterilization throughout the product volume.

3. Minimal heat exposure: Gamma irradiation is a cold sterilization process, which means the herbs and spices are not exposed to high temperatures, thus preserving their natural properties and quality.

4. Regulatory approval: Gamma irradiation for the treatment of herbs, spices, and other food ingredients is approved and widely accepted by regulatory bodies, such as the FDA (United States) and EFSA (European Union), as a safe and effective method for microbial load reduction.

Other sterilization methods, such as ethylene oxide (EtO) treatment or steam sterilization, may also be used on an industrial scale, but gamma irradiation is generally considered the most commonly employed technique due to its effectiveness, efficiency, and regulatory acceptance.

It's important to note that the specific sterilization method used may vary depending on the type of herbs and spices, the desired level of microbial reduction, and the specific regulatory requirements in the country or region where the processing is taking place.

well before you use methods that you have to justify as gamma irradiation you have GACP guidelines preventing this in most cases... That means a key strategy to ensure the microbial purity of herbal drugs is the implementation of Good Agricultural and Collection Practice (GACP) guidelines, which aim to minimize microbial contamination from the outset. These guidelines encompass a series of measures applied throughout the entire process of obtaining herbal drugs, from cultivation and harvest to processing and storage. For instance, controlling cultivation conditions by selecting appropriate sites, using clean water sources, and monitoring soil quality significantly reduces the risk of microbial contamination during the growth phase. Additionally, the controlled use of chemical fertilizers and pesticides ensures that the soil and plant microbiome remain unaffected by harmful practices. During harvest and processing, strict hygiene practices, including staff training, the cleaning of tools and equipment, and the prevention of cross-contamination, are essential to minimizing microbial load. After harvest, herbal drugs must be stored under controlled conditions to prevent microbial growth, which involves managing temperature and humidity levels and protecting the materials from pests. Transportation in suitable packaging is also necessary to avoid contamination and preserve quality.

Despite strict adherence to GACP guidelines, additional microbial decontamination measures may sometimes be required when the microbial limits set by pharmacopeial standards are not met. One such method is the use of ionizing radiation, particularly gamma irradiation. Gamma irradiation is a recognized method for microbial decontamination, effective in killing a wide range of microorganisms without significantly altering the physical appearance of herbal materials. The European Pharmacopeia (Ph. Eur.) acknowledges gamma irradiation as a permissible method, provided certain conditions are met. It emphasizes that irradiation should only be employed when other methods are insufficient to achieve the required microbial limits, ensuring that the treatment does not adversely affect the efficacy and safety of the herbal drug. The use of gamma irradiation is also addressed in the German Pharmacopeia (DAB), which follows the same stringent criteria as the Ph. Eur. It requires that the application of irradiation be well justified, carefully documented, and that the radiation dose be precisely controlled. Compliance with these regulations ensures that no residues are left that could compromise the safety of the final pharmaceutical product.

Ensuring the microbial purity of herbal drugs is essential for maintaining the quality and safety of herbal medicinal products. The GACP guidelines provide a comprehensive framework to minimize microbial contamination from the outset, and strict adherence to these guidelines can, in many cases, prevent the need for additional microbial decontamination, such as gamma irradiation. However, when necessary, gamma irradiation can be an effective method, provided it is conducted under strict control and in accordance with the requirements of both the European and German Pharmacopeias. This approach complements the preventive measures established by GACP and helps maintain the high-quality standards expected of herbal medicinal products.

Phil Käding Is fumigation with methyl bromide prohibited? As you mentioned, we can store herbs under suitable conditions, but most microbial contamination originates from farming and processing, particularly during the drying of herbs. I've heard that stem sterilization is employed on an industrial scale in herbal pharmaceutical companies. Are you familiar with this method?

David Sturm Thanks David. MY research on sterilization methods highlights several techniques, including radiation (Gamma, UV, Microwave), fumigation (methyl bromide, ozone), and cold plasma, each with its advantages and disadvantages. For instance, Gamma radiation effectively reduces microbial loads but may negatively impact secondary metabolites. Methyl bromide, while effective, leaves residues on herbs and is now prohibited.

Recently, I came across the stem sterilization method used by some German companies. If this method can effectively reduce microbial contamination, it would be a significant advancement, especially since it is completely eco-friendly.

Mehrab Dashtdar Thank Dear Mehrab.

Gamma radiation can indeed have negative effects on the structure of secondary metabolites. Due to its high energy, gamma radiation can cause ionization and excitation of atoms and molecules, leading to various forms of damage, including:

In summary, while gamma radiation is useful for various applications, its high energy can indeed destroy or alter biomolecules, including secondary metabolites, potentially leading to undesirable effects in biological systems.

The use of methyl bromide for fumigation has been largely prohibited in many parts of the world due to the adverse environmental and health impacts associated with its application. Methyl bromide is a potent ozone-depleting substance, and its use has been significantly restricted under the Montreal Protocol, an international treaty signed in 1987 with the objective of phasing out substances that deplete the ozone layer. As of 2005, the use of methyl bromide has been prohibited in most developed countries, although certain critical applications remain exempt (United Nations Environment Programme [UNEP], 2006). In the European Union, for example, the use of methyl bromide for fumigation in agriculture and storage has been prohibited since 2010, with certain exemptions permitted only in cases where no feasible alternatives exist (European Commission, 2009). Consequently, it is unlikely that methyl bromide is still used extensively in the herbal pharmaceutical industry.

With regard to the storage and preservation of herbs, it is accurate to conclude that microbial contamination frequently originates from farming and processing, particularly during the drying phase. To mitigate this risk, a range of sterilization techniques are employed to ensure that herbal products meet the requisite pharmaceutical standards for microbial quality. One such technique that is commonly utilized in the herbal pharmaceutical industry is steam sterilization.

Steam sterilization, also referred to as moist heat sterilization, is a process that employs saturated steam under pressure to achieve microbial inactivation. This method is widely employed due to its efficacy in eradicating a diverse range of microorganisms, including bacteria, fungi, and spores. The process entails the denaturation of proteins and nucleic acids within microbial cells, ultimately leading to their demise. Steam sterilization is regarded as a highly efficient technique due to its ability to penetrate dense materials and complex structures, such as herbs with multiple layers or dense stems (Pankaj et al., 2017).

In the context of herbal pharmaceuticals, steam sterilization offers a number of advantages. Firstly, steam sterilization is a non-toxic method, which is crucial for preserving the safety of medicinal herbs. Unlike chemical fumigants, such as methyl bromide, steam sterilization does not leave any harmful residues, ensuring the final product is safe for human consumption. Secondly, steam sterilization is relatively inexpensive and can be scaled up for industrial applications, making it suitable for large-scale production (Beuchat, 1998).

However, the process of steam sterilization also presents certain challenges in the context of herbal products. The high temperatures involved can lead to the degradation of thermolabile compounds, such as essential oils or certain phytochemicals, which contribute to the therapeutic properties of the herb. Therefore, steam sterilization must be carefully controlled in order to achieve an appropriate balance between microbial reduction and the preservation of the active ingredients (Frohling et al., 2011).

To offset these disadvantages, numerous herbal pharmaceutical companies utilize steam sterilization in conjunction with alternative techniques, such as vacuum drying, to minimize the duration of high-temperature exposure for herbs. Alternatively, other methods, such as gamma irradiation or microwave-assisted sterilization, may be employed as adjuncts to steam sterilization to achieve a more balanced outcome in terms of microbial control and preservation of active constituents (Schaarschmidt et al., 2019).

In conclusion, while fumigation with methyl bromide is generally prohibited due to its environmental and health risks, steam sterilization is widely used in the herbal pharmaceutical industry as a method to control microbial contamination. Steam sterilization offers several advantages, including effectiveness and non-toxicity, but must be carefully controlled to preserve the integrity of heat-sensitive compounds in herbal products. Therefore, this method represents a balance between ensuring microbial safety and maintaining the therapeutic efficacy of the herbs.

For further information, please refer to the following sources:

Beuchat, L. R. (1998). A review of the literature on the surface decontamination of fruits and vegetables intended for consumption without prior cooking. Food Safety Unit, World Health Organization.

European Commission. (2009). Regulation (EC) No 1005/2009 of the European Parliament and of the Council of 16 September 2009 on substances that deplete the ozone layer. Retrieved from https://eur-lex.europa.eu

Frohling, A., Schlüter, O., & Knorr, D. (2011). The impact of high hydrostatic pressure, ultrasound, and steam sterilization on microorganisms in food. Journal of Food Science, 76(8), 121–128.

Pankaj, S. K., Shi, H., & Keener, K. M. (2017). A review of novel physical and chemical decontamination technologies for aflatoxin in food. Trends in Food Science & Technology, 71, 73-83.

Schaarschmidt, S., Fauhl-Hassek, C., & Wörner, B. (2019). The impact of gamma irradiation on microbial contamination and phytochemical properties of medicinal herbs. Radiation Physics and Chemistry, 165, 108398.

United Nations Environment Programme (UNEP). (2006). Handbook for the Montreal Protocol on Substances that Deplete the Ozone Layer. Retrieved from https://ozone.unep.org

Phil Käding Thanks a lot. "Your explanation was very clear. Could you recommend a company that manufactures stream sterilization equipment?"

Thank you for your feedback! For companies that manufacture steam sterilization equipment, here are a few reputable options:

1. Getinge Group: A Swedish company that provides a wide range of sterilization equipment, including steam sterilizers for healthcare and life sciences industries.

2. Steris Corporation: Based in the United States, Steris offers a variety of steam sterilization solutions for medical, pharmaceutical, and laboratory use.

3. Belimed AG: A Swiss company known for producing high-quality steam sterilizers and other decontamination equipment for the medical and pharmaceutical industries.

4. Tuttnauer: An Israeli company specializing in autoclaves and steam sterilization equipment for hospitals, laboratories, and clinics.

5. Astell Scientific: A UK-based company that manufactures autoclaves and steam sterilizers for medical, laboratory, and research settings.

These companies are well-regarded in the industry and offer a variety of sterilization solutions. It would be best to contact them directly, Getinge is really good.

If you need more specific information or alternatives, feel free to ask!