DryCard™ — A low-cost dryness indicator for dried products


This article about the DryCard was written by James Thompson, Michael Reid, Lucia Felix, Irwin Donis-Gonzalez, Bertha Mjawa, and Jane Ambuko and published October 2017 in the Journal AIMS Agriculture and Food.

Article abstract

Mycotoxin contamination of food and feed is a significant health hazard in humid areas of the world. Fungal development can be halted if the water activity of dried products is kept below 0.65. This preliminary study evaluates the color response and response time of a low-cost humidity indicator that estimates water activity. The DryCard™ has a consistent color response to relative humidity and its response time is fast enough to be used in practical situations for estimating water activity. The card comes with use instructions and it can be reused many times. It is a crucial tool to assist smallholder farmers and traders in ensuring their crops have been adequately dried.


Thompson, J.F., M.S. Reid, L. Felix, I. Donis-Gonzalez, B. Mjawa, and J. Ambuko. 2017. DryCard™ — A low-cost dryness indicator for dried products. AIMS Agriculture and Food. 2(4):339-344. doi:10.3934/agrfood.2017.4.

If you encounter problems accessing the full text of this journal article, you may contact one of the authors. The corresponding authors can be contacted at jamfthompson@gmail.com.

Value Chain

Postharvest practices


DryCard Dry chain