The present disclosure relates to a control device for a food processing apparatus, and to a food processing apparatus, the apparatus comprising a food processing compartment (3) for a food substance, a heating unit (15) arranged to apply a heating procedure to the food substance, a weight sensor (44) arranged to monitor the weight of the processed food substance, and a control device (40) that is arranged to obtain weight information for the food substance, compute a derivative signal that is indicative of a weight loss rate of the food substance, compute a characteristic value of the derivative signal, and in an initial stage of the heating procedure, based on the characteristic value, determine an estimate for an initial fat content of the food substance, for the ongoing heating procedure, and/or an estimate for a resulting fat content change for the food substance. The present disclosure further relates to a method of operating a food processing apparatus.
