Botulism - Ask Extension
Is there a general category of foods, or characteristic properties of that foods that preclude it from being vacuum sealed? As for instance : garlic...
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Botulism #715080
Asked August 19, 2020, 12:50 AM EDT
Is there a general category of foods, or characteristic properties of that foods that preclude it from being vacuum sealed? As for instance : garlic and mushrooms. What is it about these foods that can potentially produce botulism poisoning?
Thank you
Thank you
Washington County Oregon
Expert Response
Hi there,
This is a great and important question.
Botulism is a type of food poisoning that occurs when someone consumes botulinum toxin. This toxin is produced by a specific bacteria - Clostridium botulinum - when it transitions from a spore (dormant) form to a rapidly growing (germinated) form. Clostridium botulinum is commonly found in soil. Botulism toxin is a potent neurotoxin that attacks multiple parts of the body causing paralysis, and potentially death (paralyzes diaphragm so you can't breathe). Very scary and tragic.
Fortunately, Clostridium botulinum only grows under certain conditions - no (or very little) oxygen, moderate acidity (pH >4.6), moderate temperature (above refrigeration, typically), and high water activity (available water). So, we can use the opposite of these characteristics to prevent growth - plenty of oxygen, low pH (pH <4.6), refrigeration, and/or reduced water activity.
Vacuum packaging or canning creates a no-oxygen environment and these items are typically stored at room temperature, so we have to be very, very careful to make sure that there is another control point (either low pH and/or reduced water activity). Otherwise, we have the perfect conditions for growth and toxin production.
Garlic and mushrooms are low in acid (moderate pH ~ 6.0) and high in available water. Both are also grown in contact with the soil so the likelihood of Clostridium botulinum being on the garlic and mushrooms is high. So, if you remove the oxygen by vacuum sealing and store at room temperature, you have created a nearly perfect set of conditions for Clostridium botulinum to grow and produce toxin.
Other foods, like nuts, grains, or properly prepared jerky, can be stored safely by vacuum sealing. These have moderate pH, but they have very low available water (low water activity). Dried fruits are also safe to store in vacuum-sealed containers because they have a low pH and low available water.
I hope this helps to clarify things. Please let me know if you have additional questions.
This is a great and important question.
Botulism is a type of food poisoning that occurs when someone consumes botulinum toxin. This toxin is produced by a specific bacteria - Clostridium botulinum - when it transitions from a spore (dormant) form to a rapidly growing (germinated) form. Clostridium botulinum is commonly found in soil. Botulism toxin is a potent neurotoxin that attacks multiple parts of the body causing paralysis, and potentially death (paralyzes diaphragm so you can't breathe). Very scary and tragic.
Fortunately, Clostridium botulinum only grows under certain conditions - no (or very little) oxygen, moderate acidity (pH >4.6), moderate temperature (above refrigeration, typically), and high water activity (available water). So, we can use the opposite of these characteristics to prevent growth - plenty of oxygen, low pH (pH <4.6), refrigeration, and/or reduced water activity.
Vacuum packaging or canning creates a no-oxygen environment and these items are typically stored at room temperature, so we have to be very, very careful to make sure that there is another control point (either low pH and/or reduced water activity). Otherwise, we have the perfect conditions for growth and toxin production.
Garlic and mushrooms are low in acid (moderate pH ~ 6.0) and high in available water. Both are also grown in contact with the soil so the likelihood of Clostridium botulinum being on the garlic and mushrooms is high. So, if you remove the oxygen by vacuum sealing and store at room temperature, you have created a nearly perfect set of conditions for Clostridium botulinum to grow and produce toxin.
Other foods, like nuts, grains, or properly prepared jerky, can be stored safely by vacuum sealing. These have moderate pH, but they have very low available water (low water activity). Dried fruits are also safe to store in vacuum-sealed containers because they have a low pH and low available water.
I hope this helps to clarify things. Please let me know if you have additional questions.
Dr. Waite-Cusic,
Thank you for your great response. Must we consider onions in the same light as garlic? High acidity, high moisture. Are there general categories of foods that should be avoided when vacuum packing? If garlic, for instance, is vacuum packed, but then frozen, can the toxin be totally avoided? Once the conditions for the toxin formation are met, vacuum, moisture, room-temperature, how long does it take for the formation of the toxin? Thank you for taking your time to satisfy a curiosity.
Thank you for your great response. Must we consider onions in the same light as garlic? High acidity, high moisture. Are there general categories of foods that should be avoided when vacuum packing? If garlic, for instance, is vacuum packed, but then frozen, can the toxin be totally avoided? Once the conditions for the toxin formation are met, vacuum, moisture, room-temperature, how long does it take for the formation of the toxin? Thank you for taking your time to satisfy a curiosity.
Hello again,
Yes, onions are also high acidity and high moisture, so they are also a risk. All vegetables fit in this risk group.
It is a great idea to vacuum package AND freeze. This will retain a high level of nutrients and quality. When you thaw these, you should cut or open the bag to allow oxygen into the package.
The time question is a harder one to answer. The general recommendations that we give on the amount of time that cooked foods (leftovers) may be in the temperature danger zone (40-140F, 2 hours) is based on a number of different potential food safety risks - these are based on the fastest growing problems (Staphylococcus aureus and Clostridium perfringens). Clostridium botulinum is a slower grower and it depends on how well it can grow on that food, but we don't want to toy with it. Therefore, I would recommend that after you vacuum package something, you would want to get it into the fridge or freezer within two hours.
Hope this helps!
Joy
Yes, onions are also high acidity and high moisture, so they are also a risk. All vegetables fit in this risk group.
It is a great idea to vacuum package AND freeze. This will retain a high level of nutrients and quality. When you thaw these, you should cut or open the bag to allow oxygen into the package.
The time question is a harder one to answer. The general recommendations that we give on the amount of time that cooked foods (leftovers) may be in the temperature danger zone (40-140F, 2 hours) is based on a number of different potential food safety risks - these are based on the fastest growing problems (Staphylococcus aureus and Clostridium perfringens). Clostridium botulinum is a slower grower and it depends on how well it can grow on that food, but we don't want to toy with it. Therefore, I would recommend that after you vacuum package something, you would want to get it into the fridge or freezer within two hours.
Hope this helps!
Joy
Thank you, Joy.
Stay safe, but enjoy the remainder of this great summer. And please vote.
Warmly,
Jim Stecher
Stay safe, but enjoy the remainder of this great summer. And please vote.
Warmly,
Jim Stecher
Thank you for the kind words. I will happily take all of that advice.
