A method for assessing a product (C), especially a smoking article or a filter element therefor, to determine product quality and/or product integrity, the method comprising the steps of: passing a gas sample (G) through the product (C); directing the gas sample (G) to a sensor assembly (S) downstream of the product (C) for detecting at least one flavour compound (X); and analysing the gas sample (G) with the sensor assembly (S) to detect the at least one flavour compound (X) in the gas sample (G); characterised in that - holding the product (C) or smoking article in a testing zone between a gas inlet (I) and a gas outlet (O) and generating a flow or stream of the gas sample (G) through the testing zone from the gas inlet (I) to the gas outlet (O), wherein the testing zone is located in a transport path which is provided to convey the product from a manufacturing equipment to a packaging equipment; and - the step of passing the gas sample (G) through the product (C) comprises streaming the gas sample (G) through the product (C) at a flow rate in the range of about 0.1 l/min to about 20 l/min, and wherein the sensor assembly (S) comprises a plurality of sensors (S1, S2, S3) arranged in parallel, and wherein the step of directing the gas sample (G) to the sensor assembly (S) comprises switching a flow path of the gas flow (G) from one sensor (S1, S2, S3) to another sensor (S1, S2, S3) after detecting the flavour compound (X) in the gas sample (G). passing a gas sample (G) through the product (C); directing the gas sample (G) to a sensor assembly (S) downstream of the product (C) for detecting at least one flavour compound (X); and analysing the gas sample (G) with the sensor assembly (S) to detect the at least one flavour compound (X) in the gas sample (G); characterised in that - holding the product (C) or smoking article in a testing zone between a gas inlet (I) and a gas outlet (O) and generating a flow or stream of the gas sample (G) through the testing zone from the gas inlet (I) to the gas outlet (O), wherein the testing zone is located in a transport path which is provided to convey the product from a manufacturing equipment to a packaging equipment; and - the step of passing the gas sample (G) through the product (C) comprises streaming the gas sample (G) through the product (C) at a flow rate in the range of about 0.1 l/min to about 20 l/min, and wherein the sensor assembly (S) comprises a plurality of sensors (S1, S2, S3) arranged in parallel, and wherein the step of directing the gas sample (G) to the sensor assembly (S) comprises switching a flow path of the gas flow (G) from one sensor (S1, S2, S3) to another sensor (S1, S2, S3) after detecting the flavour compound (X) in the gas sample (G). - holding the product (C) or smoking article in a testing zone between a gas inlet (I) and a gas outlet (O) and generating a flow or stream of the gas sample (G) through the testing zone from the gas inlet (I) to the gas outlet (O), wherein the testing zone is located in a transport path which is provided to convey the product from a manufacturing equipment to a packaging equipment; and - the step of passing the gas sample (G) through the product (C) comprises streaming the gas sample (G) through the product (C) at a flow rate in the range of about 0.1 l/min to about 20 l/min, and wherein the sensor assembly (S) comprises a plurality of sensors (S1, S2, S3) arranged in parallel, and wherein the step of directing the gas sample (G) to the sensor assembly (S) comprises switching a flow path of the gas flow (G) from one sensor (S1, S2, S3) to another sensor (S1, S2, S3) after detecting the flavour compound (X) in the gas sample (G). <EOS>