Interesting that you brought it up....from personal experience:
I use nitrogen saturation followed by high vacuum to seal cleaned parts at work (medical repair at a hospital). Normally these parts tarnish by the end of the day...I have parts that are ten years old that look like they are chromed.

Supposedly grain (wheat, popcorn, etc) sealed with this technique will last as long as the packaging. Removing the oxygen prior to vacuum sealing takes away anything the food might react to (oxidize/"rust"). Only caveat would be the amount of vacuum your pump could reach--ideal would be thirty inches of mecury (think the vacuum of space); I use an expensive two stage pump that gets past twenty nine inches. Most home machines, I fear (with no evidence to back this up) would probably only get 15 or so inches.

Then there's this:
http://www.viworld.net/pumpnseal/index.htm

Billy Guttery:

I am a certified HVAC-R technician and although I have not been active for years because of my knees, I still have all my equipment which includes a 2-stage vacumn pump and a refrigerant recovery unit.

These items by themselves should remove sufficient air and water vapor so that inert gas is not even necessary. I mention the inert gas specifically for people with home type vacumn units.

Carbon dioxide in dry ice form is recommended on a web site dealing with long term storage of powder and grain foods in sealed containers.

That site recommends putting dry ice at the bottom of cans or plastic containers and hand agitating the contents occaisionally so that the air is expelled as the dry ice goes directly to a gaseous state. Since carbon dioxide is heavier than air, the air will tend to be displaced and flow over the top of the container. They recommend that when you see the dry ice practically gone, you lay a sealing type cover on it loosely so that air movement does not allow the air to work its way back into the container. When you feel the dry ice has evaporated, screw down the lid.

I have heard of wheat and corn in Pharoahs tombs being made into edible bread and the corn sprouting when planted which leads me to suspect that it is moisture in the air that does the most damage and not the air itself.

Bountyhunter

Found a site, "Colorado State University Cooperative Extension" that indicates a 12 month storage time for canned milk, and a 24 month storage time for powdered milk at "room" temperature.

While I doubt the powdered milk, properly packaged would come to harm at most freeze-thaw temperature cycles, canned milk would have to be protected from freeze-thaw temperature differences.

Bountyhunter