Progress 07/01/18 to 08/31/19

Outputs
Target Audience:During this Phase I program, we discussed our technology and its impact to the shelf life of fresh fruits and vegetables (FFVs) with FFV distributors and providers, food service providers, and trade organizations who specialize in postharvest chain manangement. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Impact. Food loss is an enormous problem: 46% of fruits and vegetables worldwide are lost postharvest, which amounts to 575 million metric tons of valuable food products. One approach to reducing food loss is to extend the postharvest shelf life of fresh fruits and vegetables by removing ethylene from the storage environment. Ethylene is a plant hormone that promotes ripening, but it can also lead to a deterioration of produce quality for susceptible produce exposed to high ethylene levels. An effective, widespread solution for ethylene control will extend the shelf life of fresh fruits and vegetables and help combat global food waste, which also addresses the management of valuable land and water resources. Effective ethylene control will also allow cold storage areas to be maintained at warmer temperatures without impacting produce quality or shelf life, thereby saving energy in the postharvest cycle. Sonata Scientific has developed a catalyst that can be activated with energy-efficient light-emitting diodes to oxidize ethylene in fruit and vegetable storage and distribution areas to nonhazardous products already present in these areas, e.g., water and CO2. These photocatalysts have been optimized to have improved performance in the high relative humidity (>80%) environments typical of produce storage. The effectiveness with which these novel light-stimulated materials remove ethylene and their unique properties enable their use in compact, energy-efficient systems for extending shelf-life at a significantly reduced cost. This non-toxic, noncontact solution can be applied broadly across distribution, transportation, and storage facilities to a variety of produce, including organic fruits and vegetables where there are limitations in the ethylene control measures that can be implemented. Extending the postharvest lifetime of produce translates to less food loss and greater food availability. Reducing cost and waste throughout the postharvest cycle will allow produce prices to be dropped, particularly in those areas where high prices cannot be sustained. Cost-effective, general ethylene control measures should encourage changes in the handling of produce throughout the postharvest cycle, including the generalized strategy of applying cold storage to all produce. Outcome. The goal of the Phase I project was to develop a reliable, cost-effective, facile approach to ethylene control that could be widely adopted across many parts of the postharvest cycle to prolong the storage life of fruits and vegetables. The objectives that were developed as a strategy toward achieving this goal are listed here along with key outcomes and accomplishments. Develop and optimize a catalyst for the photooxidation of ethylene under a high humidity environment with properties that translate to a reduction in energy costs for system operation. Major activities completed. A series of catalysts was prepared with different properties and evaluated under different humidity environments in a screening system to quickly identify the catalysts that were most effective under these tested conditions. Based on the results and trends, structure-property relationships were revealed that were used to optimize the catalysts to maximize performance at relative humidity greater than 80%. Data collected. Photocatalyst properties were characterized. Ethylene mineralization rates were calculated for the different photocatalysts under the different environmental conditions probed. Discussion of results. The properties of the photocatalysts play a large role in their ability to oxidize ethylene under different environmental conditions. This work has led us to identify the critical properties for optimizing ethylene removal rates at different relative humidity levels, which will be important when designing systems for storage and distribution areas. Key outcomes. A key outcome from work on this objective is the fundamental structure-property relationships identified for optimizing performance of the photocatalysts in the relevant fresh fruit and vegetable environmental conditions, specifically the high relative humidity which traditionally causes a significant decrease in ethylene oxidation rates. This knowledge will be exploited to optimize the efficiency of the overall photocatalytic system. Develop catalyst form factors suitable for rational system designs that optimize the performance of the catalyst with respect to ethylene reduction. Major activities completed. A strategy for depositing the photocatalyst onto a solid support was developed such that the active material is chemically bonded to the support. This innovative methodology can be applied to a variety of form factors to enable various system designs that will be exploited to enhance performance. Data collected. Ethylene mineralization rates were determined for the different photocatalysts in different system configurations. Attrition rates were determined for photocatalysts on supports. Discussion of results. The low attrition of the resulting supported photocatalysts allows them to be utilized in various system configurations depending on the requirements of the application. This attribute enables the development of photocatalyst-system designs to elucidate the critical parameters for maximizing ethylene oxidation rates. Key outcomes. A key outcome from work on this objective is the novel approach for preparing low-attrition supported photocatalysts. This methodology can be applied to a variety of form factors. Coupled with the key learnings from the first objective, these outcomes support a scalable system design for delivering an energy-efficient ethylene mitigation solution to fresh fruit and vegetable distribution centers and storage areas. Characterize the performance of the catalyst for ethylene reduction efficiency under typical storage conditions. Major activities completed. A small recirculation chamber was constructed to serve as the storage space for simulation experiments. A photocatalytic subsystem comprising a novel form factor was also developed for testing the rate at which a known quantity of ethylene is removed from a container. Data collected. The recirculation chamber was charged with ethylene at different relative humidity levels, and the photocatalytic removal of ethylene was monitored with time. Apparent rate constants were measured as a function of photocatalyst properties at the different relative humidity levels. Discussion of results. Rate constants are a function of the photocatalyst properties, consistent with mineralization rates measured in earlier photocatalyst screening experiments. Models were developed from the rate data to predict ethylene removal rates of the photocatalytic subsystem in fresh fruits and vegetables storage containers. Key outcomes. A key outcome from work on this objective is the predictive model that will be used to guide photocatalytic system development in Phase II. The results from the tests in the recirculation chamber confirm that this technology can be scaled to the desired application requirements.

Publications