Is there a way, and if so, what's the best practice for checking a mushroom to verify it is clear of worms?


2 Answers 2


The way to go is to cut the shroom into slices (including the stem) and to check if they have needle-size brown tunnels. Also good to know - there is no need to peel the shroom.

  • 1
    Citing a source for your answer would, as always, make it more valuable to those of us who don't know you well enough to simply take your word on it.
    – msh210
    May 6, 2015 at 12:44
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    "Shroom"??? Is dat dee common "shlang" term used for this type of fungi? Also, there are different types and shapes of mushrooms. Some, like the portabello, are pretty much flat and don't have much of a stem. Is a different method required? How about pre-sliced mushrooms? Do they need to be checked?
    – DanF
    May 6, 2015 at 14:33

According to the CRC
"Mushrooms – Fresh mushrooms must be rinsed and a cursory inspection is needed. Portabella mushrooms should have the brown under part removed. All dried and frozen without any added kosher sensitive ingredients are acceptable. Canned or jarred mushrooms must have a reliable hashgacha." Source: http://www.crcweb.org/fruit%20&%20veg%20guide.php

According to the Star-K
"H. Mushrooms (all types) 1) Wash well, especially the fan area under the crown. 2) No further checking necessary." Source: http://star-k.org/bugcheckingquickreference.pdf

According to the OU
Type of insect: Small white or red worms
Location of insect: Imbedded in underpart or inner sections of the mushroom
Method of Inspection:
Shitake and Button: Wash thoroughly.
Oyster: Break apart in several places, especially the base; examine inner sections. If insects are found, discard mushroom.
Portobello: Remove stem; examine detached cap. Remove entire brown fanlike underpart. Wash thoroughly." Source: https://www.ou.org/jewish_action/12/2006/kosherkopy_debugging_your_home/

  • Good work. Now I know what to do with the portabellos. If possible, see if you can locate anything regarding pre-sliced fresh mushrooms. They're quite common.
    – DanF
    May 6, 2015 at 15:00
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    @DanF In what ways do you think pre-sliced might differ from whole, with respect to checking for infestation? My reading of the quotes in the answer above is that there is no practical difference.
    – Yehuda W
    May 6, 2015 at 15:41
  • WHole mushrooms often have a lot of dirt on them, thus, worms may be hiding in the dirt. Pre-sliced tend to be washed, which may reduce the likelihood of worms and bugs being there. Also, esp. related to OK method, pre-sliced doesn't have a "fan", esp. the common button mushrooms.
    – DanF
    May 6, 2015 at 16:02

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