Plastic buckets are air permeable, and resent studies have shown seals in both regular and gamma lids are unreliable. Lining buckets with Mylar bags, which can be sealed, protects food from oxygen.
You can buy food packaged in buckets lined with Mylar bags, called Superpails. Or you can purchase the bags, buckets, and oxypaks (oxygen absorbers) and package foods yourself. Look for bags with ziplock closures, which close easily after opening, protecting your food from moisture. Ziplock closures make bags easy to seal after adding your own food and oxypaks. Some people prefer to buy Mylar bags that must be heat sealed to ensure bags are sealed well.
This method of packaging is especially beneficial for rice, oats and other foods that have a greater risk of going rancid. (Rancid foods are dangerous to eat.)