In brief
Kratom powder, when stored correctly in dry, cool and dark conditions, is typically stable for 12-24 months. The main degradation processes are the oxidation of alkaloids (especially the conversion of mitragynine to 7-hydroxymitragynine), the growth of microorganisms at increased humidity, and the formation of mycotoxins.
Optimal conditions
For maximum alkaloid stability and microbiological safety, the following storage parameters are recommended in practice:
- Temperature: 5-20 °C (a cool environment slows oxidative reactions),
- Relative humidity: < 60 % (above this value the risk of mould growth increases),
- Light: darkness or indirect lighting (the UV component accelerates the breakdown of alkaloids),
- Oxygen: minimise access to air (vacuum packaging, low-permeability bags),
- Contamination: separate storage from strong odours (onion, roasted coffee) - the powder absorbs aromas.
The commercial warehouses of distributors with a PML licence have temperature and humidity control as part of the licensing requirements.
Breakdown of alkaloids
The main degradation reaction of kratom is the oxidation of mitragynine by oxygen to 7-hydroxymitragynine and other oxidation products. Factors that accelerate the process:
- access to air (open packaging),
- UV radiation (direct sunlight),
- increased temperature (above 25 °C),
- the presence of trace metals (iron, copper from dust or from the packaging).
From an analytical standpoint, the shift in the alkaloid profile manifests as a decrease in the relative content of mitragynine and an increase in 7-OH-MG. In long-stored material, the total alkaloid content may also decrease (oxidation to further degradation products).
Typical shelf life (12-24 months)
When optimal conditions are maintained, kratom powder is microbiologically and chemically stable:
- in sealed metallised film with a protective atmosphere (N2): typically 18-24 months,
- in a standard PE doypack with a ZIP closure: typically 12-18 months,
- in a paper bag (warehouse raw material): typically 6-12 months.
The shelf life in the EU is marked as "best before" (minimum durability) - after it is exceeded, the material is not automatically unusable, but the manufacturer no longer guarantees the declared profile. The COA always states the date of analysis, which is an input for determining the shelf life.
Packaging
PE doypack with a ZIP closure
Standard consumer packaging. The advantage is user accessibility; the disadvantage is partial permeability to oxygen and moisture. For longer storage it is combined with an inner bag with an aluminium layer.
Aluminium bag (Mylar / aluminised film)
A barrier packaging with minimal permeability to oxygen, moisture and light. Suitable for long-term storage. Often combined with filling in a protective nitrogen atmosphere.
Dark glass container
Suitable for small quantities. Glass is an inert material, and dark glass limits photodegradation. The disadvantage is weight and fragility during handling.
Frequently asked questions
Can kratom be frozen?
From the standpoint of alkaloid stability, yes - a low temperature slows oxidation. From a practical standpoint, it is important to let the powder warm up to room temperature inside the packaging before opening, so that atmospheric moisture does not condense on it on contact with warm air.
What does "best before" mean?
Minimum durability - the date up to which the manufacturer guarantees the declared parameters. After it is exceeded, the material need not be unusable, but conformity with the original specification is not guaranteed.
Does the colour change with ageing?
Yes. Freshly ground powder has a rich green hue (for the "green" type); with ageing and oxidation it shifts to brown-green or light brown. The colour change is a visual indicator of oxidation but does not allow the remaining alkaloid content to be quantified - for that, HPLC analysis is required.
How can material that has been stored improperly be recognised?
Visual signs: stickiness, visible mould, a pungent or musty smell, a pronounced colour change. In such a case the material does not meet the microbiological limits and cannot be considered safe - see the article Microbiological safety of kratom.
References
- Sengnon N. et al. (2021). Phytochemical comparison among different colour-vein cultivars of Mitragyna speciosa. Molecules, 26(17), 5141.
- Brown P. N. et al. (2017). A botanical, phytochemical and ethnomedicinal review of the genus Mitragyna. Journal of Ethnopharmacology, 202, 302-325.
- ICH Q1A(R2). Stability Testing of New Drug Substances and Products. International Council for Harmonisation.
