White sediment at the bottom of a can or jar of green beans can look like spoilage, but in most cases it’s caused by the water used during canning, not the beans themselves. According to Penn State Extension’s home food preservation guidance, a white deposit can form when hard water’s calcium content reacts with pectic acids in the beans, producing an insoluble precipitate. A related Penn State Extension resource on canning ingredients notes this is especially common in low-acid foods such as green beans.
Hard water, not the beans, is usually to blame
