The Feed the Future Innovation Lab for Food Processing and Post-Harvest Handling at Purdue University has published a new brief describing the business case for two low-cost moisture detection devices: the hygrometer and the DryCard. The brief summarizes what is known about the market potential for commercializing and scaling these devices for smallholder farmers and small-scale traders in sub-Saharan Africa. 

Background

Drying grain to low levels of moisture content (MC) before storing is essential for preserving safe, nutritious food throughout the year. Unfortunately, proper post-harvest drying of grain is difficult for smallholder farmers and small-scale traders in rural areas of sub-Saharan Africa (SSA) because of three significant challenges: 

1. MC is difficult to accurately measure in places where commercial grade moisture meters (costing more than $200 per device) are unaffordable and unavailable. Without this technology, most people rely on traditional methods to assess grain moisture. These include biting, use of sounds and touching kernels, which can indicate general levels of MC, but are not accurate. For example, if maize is just above the 13.5% MC threshold where mold and fungi can grow, the dryness levels can be mistaken.
2. Drying grain is relatively costly. For example, the cost of drying can represent 5%-10% of the value of maize, creating a  disincentive to dry fully to safe levels if it is intended for sale. 
3. There is a further disincentive to dry grains in many parts of SSA, because grain is often sold by either volume or weight. Dry grains weigh less and occupy a lower volume compared to wet grains; therefore, sellers earn more money when grain is sold wet.

The lack of accurate and affordable moisture detection devices in rural areas creates a limited incentive to dry crops to levels needed for safe storage and consumption.

In response to these challenges, two low-cost moisture detection devices have recently been developed with funding by USAID:

• First, the hygrometer is a simple device that measures relative humidity and temperature in the air. When placed in a small hermetic bag with a handful of grain, the grain and air moisture provide an accurate measurement of maize MC.
• Second, the DryCard is a laminated strip of cobalt chloride paper which changes color depending on the humidity levels in the atmosphere. The color change has been calibrated for specific humidity levels. Like the hygrometer, the DryCard is placed in a sealed container with grain to be tested for MC. A blue-colored strip indicates that the maize is sufficiently dry and ready for storage, and a pink-colored strip indicates that the maize is too wet for storage.

Both devices take about 10-20 minutes to produce an accurate reading, which is a disadvantage over commercial-grade moisture meters that give instant readings. However, when comparing prices with commercial meters, the low-cost meters create a possible opportunity in the market for small-scale producers and traders to adopt the technologies and use them. In Kenya, the hygrometer retails for about $2.50-$3.00 and gives a more accurate numerical reading of temperature and relative humidity that can be converted to MC. The DryCard has a lower price point, retailing for about $1.00 in Kenya, but gives a less accurate reading of MC.

Read the full brief for more information on low-cost moisture meters, a list of potential commercialization strategies and recommendations for facilitating scaling of these devices.