Fecha de publicación: 12/01/2023 Fuente: Wipo Milk or dairy products The present invention relates to food processing line comprising a fryer (1) for frying food products comprising a frying vessel (11) for accommodating a frying oil (10) at least one storage tank (28.I, 28.Ill, 28.V) arranged in fluid communication with the frying vessel (11), a guided wave radar sensor (21) and an analysis unit (24) for determining a permittivity of the frying oil (10) accommodated in the frying vessel (10) based on measurement data of the guided wave radar sensor (21) and/or an optical sensor (18) for determining the colour of the frying oil (10) in the frying vessel (11) or in the at least one storage tank (28.I, 28.Ill, 28.V), the food processing line further comprising a control unit (25) that is configured to control an inflow of replacement frying oil into the frying vessel (11), preferably from the at least one storage tank (28.I, 28.Ill, 28.V) that is arranged in fluid communication with the frying vessel (11); and/or an outflow of used frying oil from the frying vessel (11), preferably to the at least one storage tank (28.I, 28.Ill, 28.V) that is arranged in fluid communication with the frying vessel (11) based on the measurements of the guided wave radar sensor (21) and/or the optical sensor (18).