A client of mine has been challenged by the regulatory body to explain why are they using specific relative humidity values during the drying process of dry, fermented product (sausages). They maintain the relative humidity between 50% and 90%, and the only explanation on why they use these specific values was "we know it by experience". RH lower than 50% will speed up the process and give product of a lower quality, whereas 90% will create enough moisture for microbial development. Of course, this is not good enough for the government and I need ideas how to validate the relative humidity values during drying of fermented sausages. Any help or ideas are welcome.