So you mean a plastic bag under the ring and band parts? Doesn't this prevent the jar from actually sealing properly?
sorry i wasn't more clear. i think a canning jar with a good lid will give you as tight a seal as ur going to get. you could put a poly bag over the canning jar lid and screw the ring down for insurance but the poly bag itself isn't going to stop the odor.
i'm in the filippines and i use poly bags for recycled jars, canisters, lidded cups, etc. that don't have lids with good seals/gaskets. for instance, i have a salt jar with a plain lid (no seal) and i lay the side of a thin poly bag over the opening before i put the lid on so there are actually two thicknesses of bag. it keeps the salt from caking. also works for herbs/seasonings.
i have a 1liter poly jar with a plain lid that i use to get young coconut juice (buko juice) from a street vender. i put a poly bag under the lid and it keeps the juice from leaking out as long as i keep the container upright (on a motorcycle). sometimes, i'll float a tomato or something similar in the jar; it helps to keep the juice from sloshing up the sides of the container. i learned that trick by transporting water in open top barrels with a piece of wood floating on the water but now i'm getting off topic...