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DryCardTM — A Low-Cost Dryness Indicator for Dried Products

1 Department of Biological & Agricultural Engineering, University of California, Davis, One Shields Ave, Davis, CA 95616, USA.
2 Department of Plant Sciences, University of California, Davis, One Shields Ave, Davis, CA 95616, USA.
3 Prime Minister’s Office, Marketing Infrastructure, Value Addition and Rural Finance Support Programme, P.O. Box 14416, Arusha, Tanzania
4 Department of Plant Science and Crop Protection, University of Nairobi, University Way, Nairobi, Kenya.

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 DryCardTM 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.
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1. de Beuchat LR (1981) Microbial stability as affected by water activity. Cereal Foods World 26: 345-361.

2. Grace D (2015) Food Safety in Low and Middle Income Countries. Int J Environ Res Public Health 12: 10490-10507.    

3. Bradford KJ, P Dahal, P Bello (2016) Using Relative Humidity Indicator Paper to Measure Seed and Commodity Moisture Contents. A&EL 1: 160018.

4. Tubbs T, C Woloshuk, K E Ileleji (2017) A simple low-cost method of determining whether it is safe to store maize. AIMS Agric Food 1: 43-55.

5. Solomon ME (1945) The use of cobalt salts as indicators of humidity and moisture. Ann Appl Biol 32: 75-85.

6. Miyauchi A, F Yokota, M Endo (2001) Quantitative Tristimulus Colorimetry for the Determination of Humidity. Anal Sci: i1651-i1653.

7. Greenspan L (1976) Humidity fixed points of binary saturated aqueous solutions. J Res Nat Bur Stand 81A: 89-96.

8. Carr DS, B L Harris (1949) Solutions for maintaining constant relative humidity. Ind Eng Chem 41: 2104-2015.

9. European Chemicals Agency, 2017. Available from: https://echa.europa.eu/substance-information/-/substanceinfo/100.028.718.

Copyright Info: © 2017, James F. Thompson, et al., licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons Attribution Licese (http://creativecommons.org/licenses/by/4.0)

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