The present invention relates to a closed processing system for treating elongated food products comprising a housing bounding a process space, a transport path for displacing the elongated food products through the process space, at least one airflow generator for generating an airflow in the process space, at least one airflow conditioner for conditioning the generated airflow, and at least one detector for detecting process conditions in the process space, wherein the detected process conditions include at least the relative humidity and wherein the system is arranged to control the process conditions by adjusting the at least one airflow generator and/or at least one airflow conditioner based on the detected relative humidity. The present invention further relates to a method for treating elongated food products.