Oct 16, 2026 - Foods
Clostridium botulinum – Invisible threat in pumpkin products
Why the safe preservation of pumpkin and winter squash requires special attention
Pumpkin products such as pumpkin butter, pureed pumpkin or pumpkin juice are very popular. However, their production and preservation carry a microbiological risk: Clostridium botulinum is a spore-forming, anaerobic bacterium that can produce the highly potent botulinum toxin under suitable conditions. This toxin causes botulism, a rare but potentially life‑threatening illness.
Pumpkin and winter squash are considered low‑acid foods with a pH above 4.6. Under low‑oxygen storage conditions, surviving spores can germinate and produce toxin. The Federal Institute for Risk Assessment (BfR) warns that conventional heat treatments at 100 °C do not reliably inactivate the heat‑resistant spores. Industrial processes therefore require validated sterilization conditions, for example treatment at 121 °C under pressure with a defined holding time.
The production of pureed or canned pumpkin products is particularly critical. Texture, acidity and water activity can vary. Therefore no universally safe canning time can be established for pumpkin butter or pumpkin purée. The addition of sugar, vinegar or lemon juice does not guarantee sufficient safety without a validated process.
A recall of pumpkin juice by the U.S. manufacturer Walker's Wine Juice illustrates the practical relevance: during an official inspection a too‑high pH was detected, so hot‑filling did not provide adequate microbiological safety.
At the BAV Institute and our Tentamus laboratories we test for Clostridium botulinum as well as the botulinum neurotoxin groups A, B, E and F. We provide you with reliable results and are happy to advise you on all questions related to product safety. If you have any questions, our customer advisors are available to assist you.
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