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In order to ensure sustainable and robust food supply, the storage of cereal crops and other foodstuffs is crucial. Usually, cereal crops are harvested between mid-July to mid-September but can be kept for periods longer than a year with careful storage.1
The successful storage of cereals involves the balance of a number of environmental conditions to ensure the original properties of the grain and the maintenance of quality, including appearance and weight. Ideally, in terms of appeal and nutrition, stored grain should be able to match freshly harvested grains.
Poor quality storage not only threatens global food security, which is a growing concern in a world with expanding energy demands and populations, but also comes with a high financial cost. Maize crops which are lost due to poor storage conditions account for between $500 million and $1 billion of lost revenue for the developing world alone.2
These are huge motivations to look for reliable techniques for the monitoring and optimizing of environmental conditions for grain storage. Some common reasons for spoilage of stored cereals include invasion by insects or microorganisms, humidity and water damage, or even decomposition.3
Common methods to kill invasive species were to fumigate storage silos with toxic chemicals4 but this only combats the issue of damage by organisms, and due to concerns about the safety of using such chemicals on foodstuffs, has generally become less popular with time.
Yet, it has been discovered that not only can humidity and temperature damage be minimized, but the decomposition rate slowed and even the growth rates of microorganisms minimized, by utilizing modified atmospheric conditions.5
Modified atmospheric conditions mean an environment which deliberately has its gas composition controlled, often achieved by the complete replacement of the local atmosphere with a combination of deliberately chosen gases.6
In all aspects of food preservation, from the packaging on supermarket shelves for vegetables and meat to their utilization in storage silos for cereals, these are extremely common.
One of the benefits of utilizing modified atmospheric conditions for cereal storage over traditional physio-chemical techniques is that there are a lot fewer safety concerns associated with the employment of chemical products and a number of contributors to cereal spoilage can be tackled using the same process.
For instance, the uptake of water by the cereal is one of the most common causes of food spoilage in humid areas, which often results in mold growth and decomposition.
Decreasing the humidity in the environment does not just have to be performed using a physical dehumidifying process, like using a refrigerant to condense water out of the air, but it can be achieved by increasing the nitrogen concentration. Higher oxygen and nitrogen concentrate can also be utilized to kill microbes and insects.7
Carbon dioxide is one gas that is often controlled carefully in modified atmospheric conditions. Carbon dioxide is often utilized in high concentrations to inhibit insect life in the cereal8 for preservation, but the detection of carbon dioxide levels can be extremely useful as an indicator of spoilage of crops.8
A combination of carbon dioxide and highly toxic carbon monoxide is generated as decomposition of the cereal starts to happen. This can be used as a diagnostic for the quality of the storage.9
If decomposition happens as a result of the presence of microorganisms, one of the challenges is that if the problem is not rectified quickly, the microorganisms will continue to grow and more of the cereal will be wasted.
Therefore, sensitive gas monitors can help not just to ensure modified atmospheric conditions are optimal but to survey for signs of spoilage or the formation of toxic gases.
Grain silos can become anaerobic environments and spoilage can generate high volumes of carbon dioxide, which could lead to the asphyxiation of workers. Gas monitoring is needed as part of health and safety legislation as a result of this.10
Many cereal storage facilities are retroactively fitted with modified atmosphere equipment and so are simple to install. Robust independent gas monitors are the perfect complement.
Edinburgh Sensors supplies a wide scope of OEM gas sensors based on nondispersive infrared (NDIR) technology. This is an accurate and highly sensitive method for the detection of many gaseous species like carbon monoxide and carbon dioxide.11
Edinburgh Sensor’s GasCard NG is the perfect way to ensure optimal storage conditions for crops in cereal storage facilities.12
No reference gas is required as the device is calibrated in the factory, (the detector is suitable for use with a number of different gases but one device can detect one gas at a time), and installation and utilization are designed to be as straightforward as possible.
The alteration in carbon dioxide levels may be very small, as, in the instance of spoilage, the accuracy of ±2% in measuring carbon dioxide concentrations between 0 – 100% is ideal.
The GasCard NG can be connected easily to external data logging devices by utilizing an RS232 interface or TCP/IP protocol. As the sensor is supplied with logging software, it only requires a connecting cable to be purchased to be ready for real-time data logging.
With a response time of fewer than 90 seconds and a short warm-up time of a minute, the GasCard NG is also suitable for high throughput measurements on a quickly changing and complex environment of a storage silo, ensuring problems can be detected and solved before they evolve any further to significantly reduce food spoilage.
References and Further Reading
- Fleurat-Lessard, F. (2003). Physico-Chemical Treatment. In Encyclopedia of Grain Science (pp. 254–263).
- Shiferaw, B. et al. (2019). Crops that feed the world 10. Past successes and future challenges to the role played by wheat in global food security. Food Secur., 2013, 5, 291–317.
- Suleiman, R. et al. (2013). Effects of Deterioration Parameters on Storage of Maize, J. Nat. Sci. Res., 3, 147–165.
- Navarro, S., and Navarro, H. (2016). Emerging Global Technological Challenges in the Reduction of Postharvest Grain Losses. Proceedings of the 15th International Cereal and Bread Congress, 39.
- Calderon, M. and Barkai-Golan, R (1990) Food Preservation by Modified Atmospheres
- Correct Gas Concentrations for Atmospheric Packaging, (2018), https://www.azosensors.com/article.aspx?ArticleID=1012 accessed 28/02/2020
- Jayas, D. S. and Jeyamkondan S. (2002). Modified atmosphere storage of grains meats fruits and vegetables, Biosyst. Eng., 82, 235–251.
- Pekmez, H. (2017). Cereal Storage Techniques: A Review, J. Agric. Sci. Technol. B, 6, 1–6.
- Whittle, C. P., Waterford, C. J., Annis, P. C., & Banks, H. J. (1994). The production and accumulation of carbon monoxide in stored dry grain. Journal of Stored Products Research, 30(1), 23–26. http://www.hse.gov.uk/carboncapture/carbondioxide.htm, accessed 28/02/2020
- OEM Sensors (2020), https://edinburghsensors.com/products/oem-co2-sensor/, accessed 28/02/2020
- Gascard NG (2020), https://edinburghsensors.com/products/oem-co2-sensor/gascard-ng/, accessed 28/02/2020
This information has been sourced, reviewed and adapted from materials provided by Edinburgh Sensors.
For more information on this source, please visit Edinburgh Sensors.