September 20, 2016

Biological and Agricultural Engineering

Started Spring of 2016 – Current research – Fruits, vegetables, rice, nuts, and all types of produce are essential to the human existence. Since the advent of technology, humans have sought ways to ensure efficient and safe methods of postharvest handling, traceability, processing, safety, and quality. Here at UC Davis, I will be using the tools of molecular biology, and engineering to develop new methods to efficiently handle and process postharvest produce with the goal of reducing energy consumption while ensuring high food quality and safety.



Research location : Bainer Hall – Department of Biological and Agricultural Engineering – UC Davis College of Engineering – Davis CA

Research leads : Shira B.  (PhD candidate Biosystems Engineering) – Lucia F. (Masters candidate Biosystems Engineering) –  Umayr S. (Biochemistry and Molecular Biology emphasis) – Carlos O. (Electrical and Mechanical Engineering emphasis)

Research Faculty : Dr. Irwin Donis-Gonzalez

Associated Research :

Cherry cracking and storage

The California cherry is one of most sought after fruits in the world. The California cherry industry has asked our lab to investigate the problem of “cherry cracking” , where cherries picked and stored from the field are coming to customers with visible skin cracks, either cosmetic or even splitting the cherry at certain points. This problem could be associated with the method produce companies process and store the cherries, or the method in which they pick or even grow them.

Our lab created an experiment to simulate the storage of cherries on an individual scale. This experiment included storing the cherries in different temperatures of water (consisting of mixtures of calcium or sucrose), and completely dry. Both were stored in fridges simulating 0, 10, 15 Celsius. Instruments to measure quality, colour, firmness, size, BRIX sugar content, weight, and dry matter were used to evaluate how these cherries were behaving with different storage methods. The cracks that occurred were also counted, and quantified based on length in mm.

A sample excel file, contain such info is produced below:

Cherry Data example

Example Cherry Data taken from a trial.


In addition to testing storage methods, a concept of injecting calcium into the cherry skin using a vacuum was also tested. This vacuum method was tested to see if the additional calcium injection could reinforce the cherry skin, preventing cracking. These injected calcium cherries would also be stored using the same methods as above, and evaluated in the same way.


Summary conclusion :  Analysis of the results is on going. A full report to the California cherry industry will be presented by Dr. Irwin-Donis Gonzalez on behalf of UC Davis.


Hygroscopic Salts

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.

Check out the page for this project – detailing more

A video detailing our research can be seen here:



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 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 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.


Computer Vision – Walnuts

Researchers at the UC Davis Postharvest Lab have long been studying the colour and shape of walnuts. This historically important and lucrative crop is individually examined to determine its colour and relative size.

Seeing a need to aid researchers, Dr. Irwin developed a unique way to asses these fine detailed qualities using a precise camera and in-house algorithm, all under a secure dome system. Researchers can now enter multiple walnuts (by the tray) and through a simple program, evaluate the colour and other details of walnuts to high accuracy.

A picture of the movable system is found below :



*Note that 4 black panels that help block out light are not installed on this picture.


Walnut drying system

*Currently on-going

The Donis-Gonzalez lab plans to reduce energy consumption and develop more friendly methods of drying Walnuts, for research and possibly industrial use.


A video of the BETA completed dryer – custom built by the Donis-Gonzalez lab :