Fortified Flour Storage: A Packaging and Humidity Bound for School Feeding Programmes

SIMULATED, NOT MEASURED. A coupled moisture, nutrient-retention and rancidity bound for fortified flour (iron and B-vitamins, 20% whole-grain fraction) in 25 kg sacks for school feeding programmes. Across five climate profiles and four packaging classes (woven polypropylene unlined, multiwall paper, polypropylene with polyethylene liner, hermetic foil liner), maximum safe storage ranges from 195.0 days at 18 C in dry air (packaging-independent, rancidity-bound) to 6.5 days for an unlined sack in monsoon conditions; in a tropical humid store a liner extends the bound from 22.0 to 71.2 days, but no packaging class reaches a 90-day cycle in warm, tropical or monsoon climates. Where the 90-day cycle is feasible, packaging costs US$0.3456 per child per school year at 80 g per school day over 180 days. Failure cases for monsoon storage, sacks on bare floors and opened sacks are stated in full. Nothing was built and no food was used by children.