What Ethylene countermeasures are in place across the supply chain?

Current industry solutions involve invasive handling and inaccurate practices that are more data reactive than proactive when it comes to the conservation of produce across the cold chain lifecycle. One of the most effective ways for cold chain operators to counteract ethylene levels around fresh produce is for the introduction of 1-MCP
(1-methylenecyclopropene) into the atmosphere.

With a structural build of ions and molecules, 1-MCP treatments suppress Ethylene production in an effort to prevent the ripening of fruits. The mechanism of action for 1-MCP involves tightly binding to the ethylene receptors in fresh produce, acting as an inhibitor for ethylene’s stimulating qualities.

AVG (Aminoethoxyvinylglycine) and AOA (aminooxyacetic acid) are compounds that inhibit the synthesis of ethylene within the fruit. Pre-harvest applications of these chemicals enable fruit to reach greater maturity and colour development on the tree prior to harvest. They do this by inhibiting the ACC (1-aminocyclopropane-1-carboxylic acid) synthase enzyme. ACC synthase is thought to be the rate-limiting step in fruit for the production of internal ethylene - ACC being the precursor molecule to ethylene in the ethylene biosynthesis pathway.

Ozone generators, when used in coolrooms, are also alleged to react with and ‘scrub’ ethylene in the storage atmosphere. While ozone will destroy ethylene on contact, its use in coolrooms carries other risks to worker safety with 0.1 µL/L ozone being the limit of exposure.

Ethylene action has also been noted to slow at lower temperatures, in fact, at their minimum temperature levels, fruit is basically inactive and does not respond well to externally supplied ethylene.

While these methods have been proven to be an effective countermeasure for the effects of ethylene on fresh produce, the biggest challenge supply chains have faced when using 1-MCP is knowing when to deploy the chemical and at what quantity in order to get the best results, or for how long they should keep produce in heavily refrigerated conditions. An industry that is strongly dependent upon guesswork and loose monitoring methods is doomed to have large wastage numbers.

Conventional methods adopted by most warehouses and cold stores, of lowering temperature and humidity often require using gases like nitrogen and sulphur to increase the shelf life but have several disadvantages in regard to changing the natural properties of fruits and vegetables. Refrigeration and humidity control helps slow the decay of fresh produce but is not enough to halt the production of ethylene gas in cold stores and warehouses. This makes ethylene control absolutely necessary in the cold chain.

Thus, the most practical solution is ethylene control and removal in the cold chain. Ethylene removal is a natural process that does not affect the properties of the fruit or vegetables. This article discusses at length how ethylene control through adsorption and chemisorption can ensure that fruits and vegetables retain their “naturalness”. These can be ripened as per demand without bearing traces of toxic gases.

What are the current monitoring methods?

Monitoring and controlling the ripeness of fresh produce is becoming a very important issue in the fruit industry since the state of ripeness during harvest, storage, and market distribution determines the quality of the final product measured in terms of customer satisfaction. Many methods to monitor the ripeness of fruits and vegetables have already been proposed. The main disadvantage of the majority of these techniques is that they are not practical for cultivars or storage stations. Moreover, most of them require the destruction of the samples used for analysis. This is why, nowadays, optimal harvest dates and predictions of storage life are mainly based on practical experience and human sensory testing. Leaving these critical decisions to subjective interpretation implies that large quantities of fruit are harvested too soon or too late and reach consumer markets in poor condition.

Human sensory testing boils down to judging the quality of fresh produce based on the human sensors of touch, taste, smell, sight and sound. While this may work for end consumers selecting loose fruit at their local market, its a whole other story for deciding the fate of large quantities of fresh produce being shipped.

How PostHarvest helps optimise Ethylene levels across supply chains

PostHarvest has developed a form of amplification technology, which allows users to accurately measure and forecast optimal delivery times, maximise outgoings, and minimise food wastage. PostHarvest’s amplification technology allows for atmospheric reads in the form of parts per billion (PPB), this measurement is often used to describe concentrations of contaminants found within an atmosphere in its most precise and finite form (currently an unmatched industry standard).

PostHarvest’s Environmental Sensor is a wall-mounted device that sits within storage facilities as it continuously captures ethylene samples, along with other chemical compounds from within the controlled atmosphere of a cold chain operation, providing the most accurate ripeness readings in the industry. This data provides conditioning & health reports to help cool store operators forecast their processes, supplies, and optimal delivery times, maximising outgoings and minimising food wastage as a result.