Cold smoking can aid in prolonging the shelf life of a product but not for an extended period of time (3 days to a week). In the past decade there are a few fish companies that actually treat their product with a cold tastless smoke prior to flash freezing the product. They first create the cold smoke and then filter it thru water before the smoke reaches the product, removing the flavor from smoke but adding the slight shelf life extender (also helps it retain the color, not always a good thing, food could be tainted and not exhibit the usual tells, smell & taste (histamine build up yummy). The two biggest killers in any food product is moisture and temperature. If there is no moisture than their is little if any food for the bacteria to feed on. By smoking, curing, etc. food they are actually doing it to remove some of the moisture from the item. The flavor that it imparts is only an added benifit.