Ethylene measurement to control quality and shelf-life

Ethylene is a phytohormone that is naturally produced by agricultural and horticultural plants at nearly all stages of their lifecycle. Managing plant response to ethylene has grown into a crucial commercial industry, as the hormone can have both negative and positive impacts on the production of agricultural and horticultural crops. Not surprisingly, there are precision tools that have been developed to detect even trace amounts of this gaseous hormone.  Postharvest monitoring of qualityThere are many uses and applications of ethylene measurement other than monitoring ripening, given that this phytohormone is involved in many crucial physiological processes in a plant. It is also used in quality control and disease detection. Ripen Fresh Produce Climacteric fruits, such as apples, mangoes, and bananas, are harvested when they are physiologically mature, but unripe. They can ripen postharvest with the help of artificial ethylene so that the carbohydrates stored as starch are converted to sugars during ripening. Suppliers use artificially produced ethylene, in combination with specified temperature, oxygen, and carbon dioxide levels, to provide ideal conditions for ripening climacteric fruits. The amount of ethylene introduced has to be precisely monitored during the entire process to maintain levels of around 100 ppm, requiring sophisticated devices. Whether the ripening is carried out in simple storage or sophisticated ripening rooms, the monitoring of ethylene remains a vital aspect of the process. Control quality to increase shelf-life Non-climacteric fruits, on the other hand, do not use ethylene for ripening, and carbohydrates are accumulated not as starch, but as sugars. Hence, they are harvested when mature and ripe, as ripening postharvest is not possible, as is the case with strawberries, peas, eggplants, etc. However, the non-climacteric fruits are still sensitive to the ethylene effects of senescence and rotting. Ethylene also increases the respiration rate of produce, leading to weight loss and associated profits. This is also true for climacteric fruits. So, when non-climacteric produce is stored, ethylene levels are monitored to keep them between 0.03-0.38 ppm. Even climacteric fruits storage time can be extended by 10-30% by storing them below 0.005 ppm until they need to be ripened. Extra ethylene gas is removed by ventilation or scrubbing to keep the produce fresh and increase shelf life. Ethylene is also monitored when tubers, like potatoes, are stored. Ethylene production due to the use of machines, or the presence of other ethylene producing climacteric fruits, can result in the sprouting of tubers, which reduces their weight or makes them unsuitable for consumption. Detect Fungal Diseases We lose 40-50% of fresh produce due to rotting in the post-harvest stage and about 22.5% of the rotting is caused by fungi. Vegetables and fruits with thin skin are more prone to damage during transport, handling, and storage. The damaged produce provides ideal conditions for the growth of fungal pathogens. Mycotoxins produced by some fungi can result in human health risk. Ethylene production, which occurs during infestation stress, can be estimated by non-destructive measurement taken precisely, easily, and rapidly by portable devices like the F-900 Portable Ethylene Analyzer. These measurements can be used anywhere in the supply chain, to cull and sort infested commodities. This will limit the spread of produce disease and profit loss. Since ethylene is regarded as a stress hormone, non-destructive measurement of the gas can be used to check for all pest and disease attacks in the post-harvest stage, as in the following examples:      - It is possible to detect diseases even before physical external symptoms occur in tomatoes and grapes.     - Ethylene produced by an infestation of the fungus Aspergillus flavus in grains like maize can be used to detect the pathogen.  Picture1. Ethylene production during climacteric fresh produce development and ripening. (Original diagram courtesy of I. B. Ferguson).