Development of metal-organic framework for gaseous plant hormone encapsulation to manage ripening of climacteric produce

Authors: ZHANG, BOCE - Orise Fellow; Luo, Yaguang - Sunny; KANYUCK, KELSEY - University Of Maryland; Bauchan, Gary; Mowery, Joseph; ZAVALIJ, PETER - University Of Maryland

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/2/2016
Publication Date: 6/27/2016
Citation: Zhang, B., Luo, Y., Kanyuck, K., Bauchan, G.R., Mowery, J.D., Zavalij, P. 2016. Development of metal-organic framework for gaseous plant hormone encapsulation to manage ripening of climacteric produce. Journal of Agricultural and Food Chemistry. 64(25):5164-5170.

Interpretive Summary: Food waste costs associated with overripe produce amount to about 2 trillion U.S. dollars per year, globally, and roughly 25 percent of the food supply in the United States. Currently, producers usually harvest and ship unripe climacteric fruits to distribution centers for storage over weeks and months. Before shipping to the retailers, the distributors treat the fruits with ethylene gas which stimulates the fruits to ripen quickly, but also leads to quality deterioration. Because of the difficulty in controlling the ripening stage and timing, the fruits sold in the markets are often too unripe to eat, or too ripe to store. In order to address this problem, we have developed a novel porous metal-organic framework (MOF) which is used to store and release ethylene at concentrations between the threshold for ripening and the safety limits. Given the user-friendliness of this MOF-Ethylene kit, this invention may become the enabling technology for the supermarkets and consumers to ripen the fruits wherever and whenever they want ("ripen by design/desire"). This technology will not only provide perfectly ripe fruits with great quality to the consumers, but also significantly reduce post-harvest losses of fruits in the supply chain.

Technical Abstract: Spoilage of fruits and vegetables accounts for 50% of the 2.6 trillion U.S. dollars lost annually to global food wastage. Seventy-eight percent of this wastage is associated with overripe produce. Fresh fruits and vegetables are composed of biological tissues and their life processes continue after harvest. Shelf life can be extended by controlling environmental conditions such as temperature and humidity to reduce respiration rate and by limiting exposure to ethylene. Climacteric fruits can be harvested while still green, stored for extended periods of time, and then treated with ethylene to stimulate ripening before shipping to retail markets. However, once the fruits are exposed to ethylene, they ripen quickly and then senesce rapidly, often resulting in waste if produce is not consumed quickly enough after treatment. A potential solution is to improve the predictability of ripening by minimizing the storage time between ethylene treatment, autocatalytic ripening and consumption. However, this point of consumption (POC) approach is restricted because of the risks associated with handling highly flammable ethylene gas. Therefore, a major challenge and technological gap is the development of a material for gaseous hormone storage that releases and maintains hormone level between the ripening threshold and safety limit. In this study, a novel porous metal-organic framework (MOF) has been developed to store and release ethylene to promote controllable metabolic changes during ripening of climacteric produce. Specifically, copper terephthalate (CuTPA) MOF with a total pore volume of 0.39 cm3/g were synthesized via a solvothermal method. A 50 mg portion of CuTPA MOF could allow POC ripening of climacteric produce, and reduce ripening time by 50%. This technology provides a feasible solution to safe and predictable ripening at the point of consumption, which could address the food waste challenge by reducing spoilage of overripe produce.