well something you should NOT wear when preparing and dealing with food, is fluffy jumpers, cardigans etc as they can easily shed fluff and bits into the food. I suppose this idea could be carried on to include items of clothing with beads and sequins in case they drop off unnoticed into the food. Obviously whatever clothing is worn should be clean and practical ie no long trailing sleeves. A hat could possibly be worn, it depends if you are talking about a domestic or commercial setup. If the person dealing with the food has long hair, it should be tied back if not covered.