Final answer:
The food worker should discard the potato salad that has exceeded the safe temperature threshold of 40°F, as it may have become a breeding ground for harmful bacteria.
Step-by-step explanation:
When a food worker records the temperature of potato salad in a refrigerated display case to be 51°F, this indicates a failure of temperature control. Perishable foods should not be left in the temperature danger zone of 40°F to 140°F for more than two hours, as this allows for rapid bacterial growth. The food worker who begins their shift at 12 pm and records this temperature should immediately discard the potato salad to prevent any potential foodborne illness.
It is important to monitor refrigeration temperatures with a thermometer to ensure food safety. Foods meant to be cold should be kept at or below 40°F. To be safe, food should reach temperatures high enough to kill bacteria, which means that the potato salad that has stayed above 40°F for several hours is unsafe to eat.