If you're talking about alkalines, I don't believe they off-gas at all. No reason why you can't shrink wrap them.

Though that depends on what you mean by long term storage. I have cheapo alkaline AAs that have been sitting in their well sealed packets for 3+ years. No evidence of trouble. Do a visual check now and again just in case.

IME, it's the name brand alkalines that spew caustic goop without provocation. Especially when the voltage drops below 1.2V. Go figure. YMMV.