Role of %RH in product shelf life studies

If you are looking for a text on the subject you could try Food Packaging Principles and Practice- 3rd Ed. Taylor and Francis
There is a chapter on shelf life studies.

Percent Relative humidity had a significant effect in ASLT studies. Assuming similar temperature but at different humidity values: a product stored at 90%RH spoils faster (about 3 times as fast) if compared at an RH of 75%.
If for example a food product stored for 30 days at 90% RH the effect will be equivalent if stored at 90 days at 75% RH..

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