Metallic taste for any period of time is not uncommon, but only due to one medical reason. The etiologies for this can be simplified and separated into only 2 groups: allergy or chemical toxin (this includes medicines). Most people who have allergies to peanuts or other nuts already know it, so IMO that leaves only one possibility if they are coming from China.
On a similar side note, were you aware that the is an area of China that has no honeybees or other pollinators of fruit trees related to mass insecticides used there decades ago. The government will do nothing about it and the farmers learned to manually pollinate the flowers by hand, every one of them, using chicken feathers and a method of collecting and drying the pollen. You can do a search with the phrase "hand pollinating pears trees in china" if you want more, but I saw it on a discovery channel type of documentary I rented. Yes I like documentaries so much I rent them too. That and I was too lazy to search for cliff notes on it.