Scaling Oxygen Scavengers in Hermetic Bags for Improved Grain Storage

The phasing out of most chemicals has created a demand for alternative methods to preserve grain quality and market value. Hermetic storage offers a chemical-free solution for pest control by creating an airtight environment that naturally leads to insect death. Adding oxygen scavengers can further enhance hermetic storage by accelerating oxygen depletion. However, no study has examined scaling hand warmers in hermetic storage bags used by large grain handlers and farmers. We evaluated the effects of 1, 2, or 3 hand warmers in 25-kg PICS bags and 2, 4, or 6 hand warmers in 50-kg PICS bags on oxygen consumption and grain quality. We hypothesized that doubling the number of hand warmers used in 25-kg to 50-kg PICS bags would maintain the same rate of oxygen reduction. Oxygen levels decreased as the number of hand warmers increased. Additionally, oxygen concentrations in 25-kg PICS bags with 1, 2, or 3 hand warmers closely mirrored those of 2, 4, or 6 hand warmers in 50-kg PICS bags, respectively. Using 2 or 3 hand warmers in 25-kg PICS bags and 4 or 6 hand warmers in 50-kg PICS bags reduced oxygen concentrations below the 5% threshold for pest suppression within 12 h and maintained it for at least 8 days. While a slight rise in relative humidity was observed with more hand warmers, this did not negatively affect seed moisture content or germination rates. Doubling hand warmers along with the bag size from 25 to 50 kg produced similar oxygen depletion rates. These findings are helpful for large grain handlers and farmers who use 50-kg hermetic bags to store seeds or specialty crops to maintain quality. Hermetic bags combined with hand warmers promote sustainability by reducing chemical usage and minimizing food and nutrient losses.