I have a 30 Oz plastic jar of Roasted, Unsalted Archer Farms Cashew Nuts. I've noticed that after having it 'open' for a week or two (i.e. the lid is tightly screwed onto the jar, but the initial paper seal has been broken), the nuts begin to develop a fish-like smell. They are still hard and there is no sign of mold --- the nuts are perfectly good, but they don't taste quite like typical cashews.
First, what's going on here? I read somewhere that this is due to oxidation, perhaps a too-high moisture level in the air when I open the jar. Second, how can I correct this? Would it be better if I were to keep the cashews in the freezer? Should I buy salted cashews instead? Intuition tells me that salted cashews should not be affected by this issue, as the salt would absorb the moisture.