Ashwini,
Ideally what metadata extractor does is it get the properties from the files which we are uploading and attach it to the newly created content in the alfresco as metadata.
Ex.
When any word doc or pdf document lying in your c or d drive it has some set of properties like author,name,title etc… right?
When you upload that in to alfresco
metadataextractor comes in to picture and extract those property and attach it to the newly created file in alfresco as metadata of the file according to the model in alfresco.
As per your requirement what you need to do is either extend the handler class of metadata extractor to achieve what you are looking for
or
create a script which read those property and create txt file (simpler approch)