May 25, 2017

Hygroscopic Salts

Hygroscopic Salts


Phase 1 – Fall 2016

Produce is gathered in usually humid and moisture filled environments (i.e outside). Once the produce is gathered, companies take care to dry the produce and store it at a controlled temperature and dry environment. The methods today used by industrial countries are usually gas powered and heat based. For other third world or agrarian countries this might not be an option due to expense.

The focus of this experiment is to use hygroscopic salts to dry produce. These salts take moisture out of the air, cooling the area and creating a dry environment. Our lab has designed an experiment to use these salts in drying corn.

A video detailing our research can be seen here:

Our updates: 

We’re proud to report that Phase 1 of our Hygroscopic Salts and DryBead’s research has been completed. Let’s take you through what happened:

Take a look at the abstract to get a good overview on what problem we were looking at, how we carried out our experiment, and what results we got.

Abstract Phase 1

Once you’re done checking out that abstract, check out the poster! It will give you a great visual on how Phase 1 proceeded!

Phase 1 Poster

Overall comments: 

Here at the DG Lab we obsess over the interaction of food and humans. Believe it or not, we think that Earth still has the capability of feeding our growing population – but only if we create innovative ways to harness that food. When we saw that close to one third of food produce was lost for a sizable 4.5 billion people due high moisture content and humidity effects (like aflatoxin growth) during harvest and storage, we immediately saw a need to develop something better. In countries like the United States, this problem does not exist! The issue of food insecurity for 4.5 billion people is frankly unacceptable – so we sprung into action.

We saw some immediate causes of this food insecurity – chiefly food producers lacking the infrastructure and resources to properly harvest and store their produce. We knew that food must be kept dry, clean, and free of harsh environments in order to be nutritious, appealing, and safe to eat. We also recognized that in these countries lacking infrastructure, the economic cost of keeping their produce safe on any scale was high. We knew that these two factors must shape our research and solution. We must develop a solution that is high quality and cost effective to those we are researching for.

In order to keep food produce safe during storage there is really one main factor that drives everything else – the food must stay dry. To solve this we saw the need for a desiccant, or an item that can pull moisture out of the environment and keep everything around it dry. Keeping cost in mind, we saw that farmers and land owners use an incredible tool in other aspects of their agriculture – fertilizers. Many of these fertilizers are the same hygroscopic salts we used for Phase 1, and are widely available and do not cost much. We were not however just limited to the salts. These natural resources are widely available, but ultimately are finite and set in their natural properties. With the power of engineering at UC Davis, it made sense to create a desiccant that can perform better than any natural salt because of the ability for it to be “upgraded”. This is where the DryBead desiccant came in. Now we had a custom solution we could test against the salts and keep on refining.

We figured out how to dry, and now we needed to figure out what to dry and where to dry it. Corn is a food produce that is used in almost every part of the world, and we thought it would be a good idea start with drying corn – something that can easily succumb to aflatoxin growth under high humidity conditions. Farmers in developing countries do not have the huge silos we see in the Midwest of the United States to store and dry their produce, so how would the local farmer use our solution? To start on the individual farmer scale, we saw value in the good old Home Depot buckets. These buckets coming in at 3 dollars provided a nice compact solution that could suite the individual farmer. Of course we drilled holes into the bucket and designed it in order for sensors to fit inside to take readings. We had a total of 8 buckets (6 salts, 1 DryBead, 1 Control) – here’s how one of them was structured:

Top of bucket: One layer of moisturized corn, 4 baggies of moisturized corn, one sensor

Middle of bucket: One layer of moisturized corn , one hygroscopic salt package (in the middle to adsorb moisture) , 4 baggies of moisturized corn, one sensor

Bottom of bucket : One layer of moisturized corn (to simulate corn in a field) , 4 baggies of moisturized corn (simulate the corn the farmer picks) , one sensor (sensing relative humidity and temperature)

We monitored this set up for 12 days, after which we took out the baggies of corn to analyze how moisture content and water loss had changed during the length of the experiments. Check out the poster to see the results!

At the DGLab we want to use the power of biology and the tools of engineering to offer solutions to the worlds challenges with food. Food insecurity is the worlds most daunting challenge in the coming years, and have no doubt that we as a lab will be at the forefront of providing solutions to that challenge.


Phase 2 – Summer 2017

With further funding granted for research, our research will continue with evaluation of hygroscopic salts for drying produce. In order to further reduce moisture obtained during storage in areas lacking infrastructure, we will be enhancing aeration of the produce inside of our storage unit. This will be achieved through cost effective solar and electric powered fans. These fans will project air into the produce container, and a custom built tube placed in the center of the unit will promote the flow of air + moisture out of the storage container.

Through our findings in Phase 1, we discovered that 3 hygroscopic salts (MgCl2, K2CO3, NaI) along with the proprietary DryBeads had the best water reduction in our moisturized corn samples. We will be using these 4 desiccants, along with a control to proceed in a second run (Phase 2) of the experiment (addressing moisture content, water reduction, and changes in temperature of storage unit and relative humidity) with the added solar/ electric powered aeration feature. Our goal is to mimic conditions farmers and food producers have in less developed countries, where infrastructure for storage, and electricity for aeration are severely limited.

Take a look at our initial design:


A non-SolidWorks design


The exterior of the bucket system with sensor probe wires.




The bottom bucket, housing only the desiccant



Inside of the empty top white bucket, containing the aluminum separating disk, base, PVC pipe for air flow, and fan.



Top bucket housing the sample corn (in black bags) to be placed on bottom, middle, and top levels inside the bucket.


Middle layer of top bucket, containing surrounding corn and corn in sample bags for analysis.


Top layer of corn in the top bucket, it can now be sealed and the fan turned on for progression.



View of multiple buckets and sensors