An odor detection device (1) includes an odor sensor (10), environmental information measurement means (11, 12), odor information collection means (20), difference information acquisition means (21), and correction means (22). The odor sensor (10) detects information on an odor emitted from an odor source (2). The environmental information measurement means (11, 12) measures information on an environment, correlated with the amount of water vapor contained in surrounding gas. The difference information acquisition means (21) acquires the difference amount of water vapor, indicating a difference between information on an environment surrounding the odor sensor (10) and information on an environment surrounding the odor source (2). The correction means (22) corrects information on an odor, collected by the odor information collection means (20), on the basis of difference information acquired by the difference information acquisition means (21).

The invention relates to a method for determining properties of hygroscopic material in real-time during modification wherein, in the method, pieces of hygroscopic material to be modified are stacked and a batch of the hygroscopic material (15) being thereby formed is placed in a modification chamber (11) of a modification apparatus (10) wherein the pieces of the hygroscopic material to be modified are modified. In the method according to the invention at least weight, volume, amount of water in the batch of the hygroscopic material as well as average moisture content of the batch of the hygroscopic material (15) are determined before modification and/or at least once during and/or after modification of the batch of the hygroscopic material (15). The invention relates also to an apparatus for determining properties of hygroscopic material in real-time during modification of the batch of the hygroscopic material (15).