It's damning if you are convinced she is guilty.
It's explanatory if your mind is still open to possibilities.
eg did she imagine that if she didn't get rid of it that something would be planted on it?
Was she afraid of her former husband?
Was she so upset at the attack on her that she simply deteriorated mentally?
There are multitudes of reasons for why women take certain actions because of the words or actions of a man, perceived or real.
We simply do not know enough.
That's my opinion anyways.
Come what may, I won't ever be sorry for remaining unprejudiced and objective, no matter what the case is.
Regardless of their mental state, I think there are very few people who would try to destroy evidence that was exculpatory. If someone accused me of stealing something--no matter how upset I was--I couldn't imagine that I would run home and get rid of the receipt that proved I'd purchased it.
And of course it's not just the dehydrator. There's so much in her story that's implausible. Such as she only used store-bought mushrooms and has no idea where the poison came from. Or that she can't remember where the dried mushrooms were purchased. Or that she somehow avoided the illness even though the way Beef Wellington is prepared means everyone should have received a hefty dose of the toxin.
When you look at the totality of the facts in evidence, it becomes really hard for me to swallow her story. If that makes me unobjective and prejudiced, so be it.