Hygrometer

Summary

The Food Processing and Post-Harvest Handling Innovation Lab (FPIL) at Purdue University has developed an affordable hygrometer-based moisture detection system for small-scale farmers and traders. Hygrometers are a simple device that measure relative humidity and temperature. When placed in a small hermetic bag with a handful of grain, the grain and air moisture provide an accurate measurement of maize moisture content (MC). The hygrometer retails for about $2.50-$3.00 in Kenya.

Challenge/Problem

Drying grain to low levels of 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.  First, 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 (touch, scent) to assess grain moisture levels that are neither precise nor accurate. For example, if maize is just above the 13.5%, the MC threshold where mold and fungi can grow, the dryness levels can be mistaken. Second, drying grain is relatively costly.  For example, the cost of drying can represent 5-10% of the value of maize, creating disincentives to completely dry the grain to safe levels if it is intended for sale. Third, there is a further disincentive to dry grains in many parts of SSA, because they are 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.

Solution

Below are potential strategies for commercializing hygrometers:

Some large-scale traders, millers, and government buyers are willing to pay a premium for grain with lower MC, as they sell to a segment of consumers who value food quality and safety. These large-scale actors could potentially sell or offer free hygrometers to the contract farmers and traders they buy grains from, enabling their suppliers to test and more accurately dry the grain in preparation for sale.

Another option for commercializing low-cost moisture detection devices is to have a third party, not associated with the grain transaction, charge a small fee for testing grain moisture prior to sale. The primary benefit of the third-party moisture detection service to the buyer is to not incur the full cost of purchasing a moisture detection device or worry about manipulation of the MC reading by their potential trading partner. 

Alternatively, low-cost moisture detection devices are potentially complementary products to other innovative post-harvest technologies like hermetic (airtight) grain storage bags.  When closed properly, the hermetic bags solve the problem of insects damaging grain in storage by choking off the air supply. Unlike moisture detection, the problem of insect damage is very visible and salient to most farmers. As a result, hermetic bags have been commercialized extensively in SSA over the past ten years.  As such, there is a potential for input suppliers to bundle and market the low-cost moisture detection devices to consumers as an additional product that is sold in tandem with the hermetic bag.

The hygrometer does not have any active licensing agreements or distribution exclusivity. It can be purchased online by a distributor or retailer who wants to sell it or a consumer who wants to use it.

Results

Low-cost moisture detection devices including the hygrometer can potentially help solve an important problem of assessing grain moisture before sales and storage occur, with relatively good accuracy at a much lower price than commercial-grade moisture meters. While these devices solve the problem of moisture assessment, most smallholder farmers and small-scale traders in rural markets of SSA are not incentivized to appreciate and pay for such assessments at the present time. Recent research indicates that relatively few farmers and traders in Kenya were willing to purchase low-cost moisture devices at or around their market price.  This suggests that creative strategies on the part of governments, donors, and  the private sector are needed to promote moisture assessment tools that can improve food quality and safety among rural populations in SSA. 

Lessons Learned/Potential for replication

- Public support: There is need for governments and donors to invest in accelerated training programs about the importance of grain moisture assessment tools and the advantages of low-cost moisture detection devices over traditional methods. Moisture assessment should be incorporated as part of all post-harvest extension training modules that includes drying, handling, and storage.

- Larger-scale actors: Larger-scale buyers who offer a price premium for grain that is dried to safe levels could support the sale of hygrometers to smaller-scale farmers and traders who sell the grain to them.

- Third-party testing: A third party operator could potentially purchase low-cost moisture detection devices and set-up moisture testing services at rural markets, grain aggregation centers, or within local villages.

- Bundling: Encourage input suppliers to bundle low-cost moisture detection devices with the sale of hermetic bags. The effectiveness of hermetic bags depends on the grain moisture levels prior to storage.

Next Steps

The four strategies listed in the previous section represent the best pathways forward for commercializing hygrometers.  We have piloted a third-party testing and bundling approach with youth in Eastern Kenya who offer moisture services to potential customers at the same time they sell hermetic bags. At the same time, there is increased need for more awareness building and support on training post-harvest technologies (similar to the hygrometer), and best practices for managing grain quality and quantity in order to minimize food loss and waste. We will continue to pursue these avenues and look for other opportunities to scale hygrometer uptake.