Patent ID: 7885521

Claim:
A system for frying food comprising: a fryer having at least one vat for containing cooking oil, the vat having an oil outlet and an oil return inlet; heating means for heating the cooking oil to elevated temperatures; an oil filter; a valve for permitting the flow of oil from the oil outlet to the filter; a pump for returning filtered oil from the filter to the oil return inlet; means for monitoring the elapsed time during which the cooking oil has been heated to the elevated temperatures since the last filtration of the cooking oil; means for monitoring the amount of food cooked in the oil since the last filtration of the oil while the means for monitoring elapsed time simultaneously monitors the elapsed time; and means for controlling the valve and pump to filter the oil when a predetermined threshold value is reached, wherein the determination of whether the predetermined threshold value has been reached is based on a combination of both the simultaneously monitored elapsed time during which the cooking oil has been heated to the elevated temperatures since the last filtration and the amount of food cooked since the last filtration.