Bananas are often sold in large quantities, often sold by pound or each banana, but Costco's 3-pound bundles have led to an issue of household management. The bulk format of these bananas has led to confusion about their ripening and timing. Some users complain that they can't eat large quantities before they go bad, which is a main issue for many shoppers. The ripening process can also be exacerbated by temperature fluctuating throughout the journey, which can cause unripeable bananas to turn yellow as starch converts to sugar. While bananas are typically picked green, the bulk of those eaten in the US come from Latin American countries far away from most North American grocery stores, which are often too soft and bruise-prone to survive fully ripe. Costco bananas may have been harvested too early, exposed to ethylene, or handled incorrectly. The article also includes a list of nine foods you should never buy at Costco.