Like ice machines, frozen drink machines are very hard to keep clean and mold-free. Most places keep them running constantly and top off the drink mix without ever shutting them down for maintenance.
Sprouts are moist and uncooked – the perfect breeding ground for bacteria. In 2018, a multistate outbreak of salmonella at Jimmy John’s was linked to contaminated sprouts.
Fresh-squeezed juice may sound like a luxury but it can be a vector for bacteria because it is unpasteurized.
Refried beans are likely to be prepared in bulk and kept warm for serving. This can lead to bacterial growth that causes food poisoning if the beans aren’t heated to a high enough temperature to kill the bacteria.
Just like ice and frozen drink machines, soft-serve machines must be cleaned routinely or they will get moldy.