Finding the best tools and approaches to your postharvest needs can be a daunting task, and with 26,000+ apple producers in the United States¹, it’s important to find the answers that can help you remain competitive. In our Ask the Agronomist series, we are turning to the scientific experts who know the ins and outs of the fruit we treat to better guide your search for the right postharvest answers.  

In our first installation of this series, we sat down with one of Hazel’s most experienced agronomists, Postharvest Scientist, Dr. Enrique Garcia, to discuss one of Hazel’s anchor crops – apples – and the industry-leading postharvest solution, 1-Methylcyclopropene, widely known as “1-MCP”.

Dr. Garcia holds a B.S. in Biotechnology Engineering, a M.S. in Biotechnology from the Tecnologico de Monterrey and earned a Ph. D. in Food Science from Washington State University. Before joining Hazel, Dr. Garcia worked as the R&D Lab Manager at Stemilt Growers where he conducted research on the postharvest quality of new cultivars of apples, pears, and cherries.

During our Q&A we talked about the different ways 1-MCP is applied to apples postharvest and what growers should consider when selecting a 1-MCP solution, or mix of solutions, for their operation.  

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Erica Powell, Content Marketing Specialist at Hazel: 1-MCP technology initiated a revolutionary shift in the apple industry and has been adopted by many U.S. growers since; can you give us some background on 1-MCP and how it’s been used over the years?

Dr. Enrique Garcia, PhD, Postharvest Scientist at Hazel: The ethylene action inhibitor 1-MCP, a gas, was discovered by Ed Sisler and Sylvia Blankenship in 1996². Since then, it has changed the way apples are handled and stored. 1-MCP is used commercially to maintain freshness and delay the natural ripening of apples. Traditionally, 1-MCP is released into a sealed room and the exposure period is roughly 24 hours. The target concentration of 1-MCP is one part per million (PPM).

EP: What are some important factors to consider when looking into a 1-MCP solution?

EG: It is important to know the fruit conditions at harvest, such as firmness, brix, titratable acidity and starch index, as these parameters will help determine the potential storability of the fruit. Also, knowing these parameters will help determine the timeframe for the application of 1-MCP. During the traditional, fumigation-based, 1-MCP treatment, it is important to have room verification to confirm that the room was treated efficiently or if the room needs re-treatment. The faster the verification process the better.

EP: The more recent invention of “slow-release” 1-MCP has been considered a breakthrough in postharvest solutions. Can you explain what “slow-release” 1-MCP is and the main differences between a slow-release treatment, like a Hazel 100, and a fast-release treatment, like traditional fumigation?

EG: To be used commercially in apple rooms, 1-MCP gas must have a “delivery system” (a way for the 1-MCP to enter or “release” into the treatment environment). This system can be divided into two categories, slow-release and fast-release.

The main difference between slow-release, like Hazel 100™, and fast-release, like fumigation, relies on the mechanism used to release the 1-MCP gas -- slow-release is passive and fast release is active. In the slow-release mechanism, 1-MCP is absorbed into a matrix (metal organic framework, MOF), which means that the matrix is temporarily holding onto the gas that later is released by exposure to a humid environment and distributed into a treatment room by its refrigeration fans.³

On the contrary, in the fast-release mechanism, the 1-MCP molecules are encapsulated in a material, typically cyclodextrin, which needs to be dissolved in water to release the trapped 1-MCP. Other methods of fast release use 1-MCP precursors to generate the 1-MCP in situ.⁴

EP: Are there any factors that should be taken into consideration when deciding between slow-release (Hazel 100) or fast-release (fumigation) applications?

EG: Fruit maturity at harvest would be the most important parameter to decide which application to use. Less mature fruit will have less ethylene production and accumulation in the room, so either application could be used. When the fruit is more mature, a fast-release application is recommended.

EP: When would you recommend a slow-release application of 1-MCP over a fast-release application?

EG: Slow-release, like Hazel 100 packets, may have additional benefits when treating a room, as the room does not need to be full or sealed while apples are treated with 1-MCP. Thus, it has the advantage of treating sensitive apple varieties as they are temperature conditioned. Also, it has the advantage of treating the fruit as it is being placed into the room, which suppresses ethylene in “early bins.”  

On the contrary, in the fast-release treatment, it is more convenient to do the treatment once the room is full of apple bins. This can be problematic not only because it's tedious and takes several days (3 to 10 days) to fill a room, but it can be damaging to quality, as many of the “early bins” are already emitting ethylene by the time the fast-release fumigation begins. Overall, you can start treating fruit with a slow-release 1-MCP product right after harvest. This is something you cannot do with a fast-release product.

Slow-release applications are easier to handle, seeing as most fast-release applications require devices like air bubblers to apply. The only exception to this that I can think of is Hazel CA™. Both methods of application will have the same results, delaying fruit ripening.

EP: Can you tell me more about varieties you may recommend a slow-release application for?  

EG: This is anecdotal, but I have heard directly from some customers that they like the Hazel 100 bin packet for Premier Honeycrisp and summer varieties. It can be because they don’t have a huge volume, so the harvest might go slowly. It can also be due to the fruit being a temperature sensitive variety, so they prefer to treat those bins with a slow-release of 1-MCP while temperature conditioning the fruit.

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As a grower, every decision you make leads to the end goal of providing the highest quality apples to retailers and consumers throughout the fresh produce market. At Hazel we understand how complicated these decisions can be and we’re here to help.  

With our suite of solutions, you have the flexibility and freedom to apply 1-MCP treatments on your own, without additional labor or infrastructure. Whether you’re looking for a fast-release fogging treatment, like Hazel CA, or you want an innovative slow-release treatment, like Hazel 100, we have the answer.

Reach out today to learn more about how our solutions can make your postharvest process simpler.  

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Sources:

¹ “Industry at A Glance.” US Apple Association. 30 May 2023. Link.

² Beaudry, Randy. “Options for sourcing 1-MCP for 2023”. Michigan State University Extension Department of Agriculture. 23 September 2021. Link.

³ Lee, Y. S., Beaudry, R., Kim, J. N., & Harte, B. R. (2006). Development of a 1‐methylcyclopropene (1‐MCP) sachet release system. Journal of Food Science, 71(1), C1-C6.

⁴ Silva, Aline & Engelgau, Philip & Sugimoto, Nobuko & Beaudry, Randolph. (2022). 1-MCP release from an α-cyclodextrin formulation is adversely affected by low water temperature. 30. 26-29.

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