A sealed bag is not a preserved bag. Standard single-layer film delivers zero meaningful grain shelf life extension — oxygen permeates back within days, triggering fat rancidity and mold growth that destroys product before it reaches the retailer. This engineering breakdown covers grain respiration biology, the aflatoxin oxygen threshold that causes full-lot EU customs rejections, and the exact barrier film for grains specification a vacuum packaging machine for grains must run to deliver verified 12-month shelf life. Grain vacuum packaging done correctly is an atmospheric engineering outcome — not a label claim.