English Walnuts - Ask Extension
We moved to a new house this spring and were excited to find we had three English Walnut trees. We've harvested them all and have been cracking them...
Knowledgebase
English Walnuts #434056
Asked November 08, 2017, 1:22 PM EST
We moved to a new house this spring and were excited to find we had three English Walnut trees. We've harvested them all and have been cracking them, but I've noticed some of them have a slight fuzz on the outside of the nut meat, inside the shell. I assume this is mold and I should throw these out. My question is what if I miss some? Is there something I can do to assure I get rid of any that may be on them? Should I be soaking and dehydrating them? What's the best way to store them? Thank you!
Lenawee County Michigan
Expert Response
Picking up walnuts off the ground frequently can help reduce one type of mold. Other molds can be the result of insect damage, poorly developed kernels, and handling and drying processes. The University of Nebraska suggests not to allow them to sit on the ground for very long and to hull walnuts quickly and make sure they are allowed to dry. https://lancaster.unl.edu/hort/factsheets/064.shtml
The University of Minnesota offers some practical tips on harvesting, hulling and storage of the nuts at: https://www.extension.umn.edu/garden/yard-garden/trees-shrubs/harvesting-black-walnuts/
The University of Minnesota offers some practical tips on harvesting, hulling and storage of the nuts at: https://www.extension.umn.edu/garden/yard-garden/trees-shrubs/harvesting-black-walnuts/
Can I blanch them to kill any mold that may be on them already?
The ones with the mold should be thrown out and with the drying process described in the University of Nebraska and University of Minnesota bulletins it should reduce the chance of mold development in storage. It is a matter of moisture. The University of Missouri has a fact sheet that states to discard all nuts with mold and do not try to use them. It also states not to not soak walnuts. I cannot find anything that states blanching would help.
Do you know why it says not to soak them? I've read that soaking/sprouting then dehydrating them can reduce the amount of Aflatoxin on them. I'm just concerned that there may be some mold on them that I didn't see. Is it mostly a concern if it a visible mold? Just don't want anyone getting sick....
The walnut processors focus on harvest procedures to eliminate molds such as the one you mention. They point to the harvest of walnuts immediately. Do not leave nuts on the ground with some saying to use tarps and that picking them up immediately, removal of their husks and proper drying prevents the molds. None of the research based sites recommend blanching walnuts to remove molds. This is a practice for almonds. Other nuts like pistachios can be dried in an oven but the literature says this will ruin a walnut. The only mention of water is to wash walnuts after removal of husk to limit staining but soaking is not suggested and the walnuts that are washed need to be dried immediately.
Ok, thank you for your help. We did harvest every day, but layed them out in the basement to dry for a couple weeks so maybe it was too damp. I hate to lose any, but not worth getting sick. Just not sure how careful I need to be. That Aflatoxin is scary stuff!
You may be right about the basement being too damp. I know mine would be. I believe the one reference talks about curing in a well ventilated, cool and dry area for two weeks.
