Monitoring Gases in Dried and Frozen Food Storage

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A variety of food preservation methodologies are available when looking to increase the lifespan of perishable items, including salting, pickling, jellying or canning. Each of these methods has a different impact on the properties of the preserved food, and thus different methods are best suited to different foods.

Freezing and dried food storage are two of the most commonly used preservation processes.

Freezing food can help to reduce nutrient loss and can also stop the development of bacteria and other microorganisms, thanks to the low temperatures involved.1

Alternatively, bacterial growth inhibition can also be achieved with a drying method, by eliminating moisture from the food, and thus slowing down enzyme activity.2

To ensure the highest quality produce, it is vital to consider atmospheric conditions, not only during the freezing or drying process, but also throughout storage of the preserved goods, paying close attention to the relative ratios of various atmospheric gases, as well as humidity levels.

Storing produce in ‘modified atmospheric conditions’ i.e., in deliberately chosen, controlled blends of gases, can triple the lifespan of dried products, such as flour or cereals, by preventing the chemical reactions that cause degradation and spoilage.3

Modified Atmospheres

Within the packaging, storage and transport of both fresh and frozen foods, it is now common to employ modified atmospheric conditions.4

Increased levels of carbon dioxide, alongside lower oxygen levels, can assist in eliminating unwanted insect species or microorganisms that could grow on and degrade the food during storage. Furthermore, increased concentrations of nitrogen can help to manage humidity for dried foods, ensuring produce maintains its good quality and extending its lifespan.5

Using blends of gases, as opposed to insecticides or added preservatives, such as nitrates to meats, makes modified atmospheric packages and controlled atmosphere storage an adaptable and effective method for the preservation of foods, without added chemicals or processing steps.7

Carbon dioxide, oxygen and nitrogen represent the three most significant gases in modified atmosphere storage. Despite their useful properties, controlling and sustaining the ratios of these gases can be tricky, particularly in dried food storage.

To achieve the most favorable conditions, immense precision is required, with gas concentration ranges needing to be controlled at ± 1% of a target value. A further challenge when dealing with foods such as cereals is that they generate and release carbon dioxide and carbon monoxide8 throughout their storage period, requiring continual adjustment of atmospheric conditions.

The ability to monitor gas levels is helpful both in sustaining an ideal storage atmosphere, and in the early detection of food spoilage, signified by increased carbon dioxide generation.9

Frozen and Dried

There are a number of challenges to be considered when conducting gas monitoring in relation to frozen and dried food.

Food is frequently frozen using carbon dioxide as a cryogen. The carbon dioxide is usually employed in its solid form, also known as ‘dry ice’, and has a temperature of -79 C. This low temperature allows produce to be cooled rapidly, minimizing the risk of contamination and maintaining high quality.

However, the National Institute for Occupational Health and Safety have stated that CO2 levels of 40,000 ppm (4%) represent an instant risk to life and wellbeing10. Ten hour workplace exposure limits are set at a much lower point.11

In order to minimize food wastage, cryogenic conditions like this may also be employed to maintain the quality during transportation and prior to use. As such, it is vital to health and safety that dependable gas monitoring is carried out throughout the freezing and storage processes.

Over time, dried foods, including even dried fruits, generate significant levels of carbon dioxide12. It is, therefore, necessary for both food preservation and employee wellbeing that carbon monoxide monitoring is in use for storage of large quantities of dried fruits, such as in grain barges.

Gas Detection

The ability to monitor and log gas levels in real-time can be a valuable tool in minimizing wastage in frozen and dried foods, as well as for maintaining ideal conditions for this produce. The successful application of this process relies on gas detectors, which can offer continuous online analysis with fast response times and high accuracy.

One of the leading developers and producers of non-dispersive infrared sensors (NDIR) is Edinburgh Sensors. Since a large number of hydrocarbon gases and molecules, such as carbon dioxide, absorb infrared light very efficiently, NDIR sensors deliver a highly sensitive method through which to identify even small concentrations of such molecules.

Gascard NG from Edinburgh Sensors

Gascard NG from Edinburgh Sensors

Edinburgh Sensors offers a number of NDIR sensors, including the Gascard13, the Guardian NG14, and the GasCheck.15 Each of these instruments boasts a long lifespan, with little need for recalibration. They can self-correct measurements across humidity conditions ranging from 0 – 95%, allowing for maximum accuracy and reliability.

Each device from Edinburgh Sensors can be interfaced with networking data logging systems. If users prefer to set up feedback systems to preserve manual control over modified atmospheric conditions, more complex control software can be set up.

With the Gascard, this can be achieved through on-board R323 connections, however, the Boxed Gascard16 version of this instrument also allows for quick connection through USB for instant use.

Edinburgh Sensors’ products can deliver carbon dioxide monitoring with accuracy within the ± 2% range, with a range of gas monitoring solutions suitable for even the most challenging environments. Comprehensive technical sales advice is also offered, both before and after purchases.

References

  1. Rickman, J. C. et al., Nutritional comparison of fresh, frozen and canned fruits and vegetables. (2007). Part 1. Vitamins C and B and phenolic compounds, J. Sci. Food Agric., 87, 930–944.
  2. Sagar, V. R. and Suresh Kumar, P., Recent advances in drying and dehydration of fruits and vegetables: A review, (2010). J. Food Sci. Technol., 47, 15–26.
  3. Dried Food Storage (2019), http://www.airproducts.com/microsite/ie/MAP_selector/results/DriedFoodProducts.htm
  4. Correct Gas Concentrations for Atmospheric Packaging, (2018), https://www.azosensors.com/article.aspx?ArticleID=1012
  5. Suleiman, R. et al. (2013). Effects of Deterioration Parameters on Storage of Maize, J. Nat. Sci. Res., 3, 147–165.
  6. Jayas, D. S. and Jeyamkondan S. (2002). Modified atmosphere storage of grains meats fruits and vegetables, Biosyst. Eng., 82, 235–251.
  7. Hussein, Z., et al,, (2015). Perforation-mediated modified atmosphere packaging of fresh and minimally processed produce-A review, Food Packag. Shelf Life, 6, 7–20.
  8. Reuss, R. and Pratt, S., (2001). Accumulation of carbon monoxide and carbon dioxide in stored canola, J. Stored Prod. Res., 37, 23–34.
  9. Maier, D. E. et al. (2006). Monitoring carbon dioxide levels for early detection of spoilage and pests in stored grain. Proceedings of the 9th International Working Conference on Stored Product Protection PS10-6160.
  10. NIOSH Guidelines, (2019), https://www.cdc.gov/niosh/docs/76-194/default.html
  11. HSE on CO2, (accessed 2019) http://www.hse.gov.uk/carboncapture/carbondioxide.htm
  12. Miranda, G. et al., (2019) Dried-Fruit Storage: An Analysis of Package Headspace Atmosphere Changes, Foods, 8, 56.
  13. Gascard NG, (2019), https://edinburghsensors.com/products/oem/gascard-ng/
  14. Guardian NG (2019) https://edinburghsensors.com/products/gas-monitors/guardian-ng/
  15. Gascheck (2019), https://edinburghsensors.com/products/oem/gascheck/
  16. Boxed GasCard (2019) https://edinburghsensors.com/products/oem/boxed-gascard/
  17. 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.
  18. Suleiman, R. et al. (2013). Effects of Deterioration Parameters on Storage of Maize, J. Nat. Sci. Res., 3, 147–165.
  19. Tuite, J., and Foster, G. H. (1979). Control of storage diseases of grain. Annual Review of Phytopathology, 17(1), 343-366.
  20. 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.
  21. Correct Gas Concentrations for Atmospheric Packaging, (2018), https://www.azosensors.com/article.aspx?ArticleID=1012
  22. Pekmez, H. (2017). Cereal Storage Techniques: A Review, J. Agric. Sci. Technol. B, 6, 1–6.
  23. Reuss, R. and Pratt, S., (2001). Accumulation of carbon monoxide and carbon dioxide in stored canola, J. Stored Prod. Res., 37, 23–34.
  24. Maier, D. E. et al. (2006). Monitoring carbon dioxide levels for early detection of spoilage and pests in stored grain. Proceedings of the 9th International Working Conference on Stored Product Protection PS10-6160.
  25. Gascard NG, (2019), https://edinburghsensors.com/products/oem/gascard-ng/
  26. Guardian NG (2019) https://edinburghsensors.com/products/gas-monitors/guardian-ng/
  27. Gascheck (2019), https://edinburghsensors.com/products/oem/gascheck/
  28. Boxed GasCard (2019) https://edinburghsensors.com/products/oem/boxed-gascard/

This information has been sourced, reviewed and adapted from materials provided by Edinburgh Sensors.

For more information on this source, please visit Edinburgh Sensors.

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