Food production facility manager here. I work at a cookie factory.

At our facility, we use high pressure steam to clean all food contact surfaces daily, like big mixers that handle about a metric ton of dough and hoppers that transport the dough. When it comes to cleaning food equipment, steam is your friend. It sanitizes everything it touches and the high heat dissolves most lipids along with other food ingredients. Oh, and doesn't leave dangerous chemical residue to get into your next batch, which is always a bonus. Regularly, however, we do a shut down and use food grade detergents to foam our product conveyors and rinse/steam afterwards.

All food production facilities in the US operate under very strict FDA safety guidelines which regulate everything we do from ingredient tracking and handling to the chemicals we use for cleaning. All chemicals used in a food production facility have to be approved by the FDA. For example, we can't buy regular windex to clean the windows or mirrors in the bathrooms, it has to be a special, “approved” window cleaning solution rated for non-food contact surfaces with a specific “cleaning strength” for the application. Window cleaner has a cleaning strength of 4 and a standard disinfectant we use has a cleaning strength of 3. In contrast, we have a strong degreaser that we use when we wash down the floors with a cleaning strength of 7. I’d have to double check, but I don’t think anything above a 3 can be regularly used on food contact surfaces. All these chemicals have to be very carefully monitored and are locked in a chemical storage area with restricted access. Employees who have access and permission to use them, like our cleaning crew, have to be specially trained so they know how to properly dilute a chemical, clean with it, and rinse a surface in preparation for food contact, when applicable.

As rydalmere mentioned, even the lubricants our machines require to operate have to be food grade. Contrary to what you might think when you hear “food grade machine oil” it is dangerous if consumed in any significant quantity. Food grade simply means that it can go into a machine that handles food but not on a surface that is in direct contact with food, i.e. lube a drive chain of a motor, not the links on a conveyor belt. Food grade lubricants are formulated so that if a little food grade lube somehow ends up in a batch it won’t make you sick or cause cancer.

In addition to chemical regulation we also have special in-house uniforms that people have to wear while working in the facility. Anybody directly handling food has to wear a special smock which is classified as a food contact surface. Because it has to stay very clean, it cannot leave the food area during a shift, i.e. if somebody has to use the bathroom they have to hang up the smock and don it when they return. Other employees that do not directly handle product are required to wear an apron. All smocks and employee uniforms are cleaned and maintained by a certified 3rd party uniform company.

TL;DR High pressure steam is our MO for daily cleaning of food contact surfaces. Approved chemicals are used on a regular schedule for deep cleaning.