Pressurized CO2 used to bacteria-proof dried almonds

By Ben Coxworth

While you might think that dried almonds are one of the “safer” foods, they’re actually prone to contamination by harmful bacteria. A simple new process could help keep that from happening, while also boosting their shelf life.

It is already a known fact that exposure to pressurized carbon dioxide kills pathogenic bacteria in drinks such as orange juice. Led by researcher Karen Fuchs, scientists from Germany’s Fraunhofer Institute for Environment, Safety, and Energy Technology set out to see if the same thing might work for dried nuts like almonds.

Working with colleagues from Canada’s University of Alberta, they devised an experimental technique in which dried almonds and antimicrobial oils were placed in a high-pressure autoclave, then treated with pressurized carbon dioxide. Doing so not only killed any bacteria that were present, but it also caused the nuts to become coated with the oils, providing a shield that kept new bacteria (such as Staphylococcus carnosus) from getting in.

According to Fraunhofer, the process is not energy-intensive or harmful to the environment, and leaves no carbon dioxide residue within the almonds.

What’s more, the flavor, consistency and other qualities of the nuts are reportedly unaffected by the treatment. Because the oils also have antioxidant qualities, however, it is believed that they should allow the almonds to last longer before spoiling. Additionally, certain flavorful oils could be used to add seasoning to the nuts.


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