We talk a lot about replacing gases, flushing them out, keeping them low and keeping them out. But there are also gases that we deliberately add to Modified Atmospheres. Carbon dioxide is one of them. Why do we do that and what effect does carbon dioxide have on your products? Time to dive in.
The battle against microorganisms
Carbon dioxide works as an antimicrobial agent in packages. It is often used in combination with nitrogen. Together they form an anaerobic environment and prevent aerobic microorganisms to grow and flourish. It’s important to note that the antimicrobial activity of carbon dioxide is higher at lower temperatures.
What levels of carbon dioxide are used depend heavily on the product. It can vary from 25% to 40% and go up to 100% for products like cheese. According to some studies, high concentrations of carbon dioxide can increase the mould-free shelf life up to months. This is promising, but for instance, baked goods can still go stale in other ways and to that, even carbon dioxide is rendered powerless.
The solubility of Carbon Dioxide
An important thing to consider when determining the desired carbon dioxide levels is its solubility. In products rich in moisture and fats, this could be a challenge, since it’s highly soluble. It could produce carbonic acid which can lead to changes in the acidity of the product.
Due to its solubility, high levels of carbon dioxide can cause your product packaging to collapse. That’s why we often use nitrogen to fill up the packaging further.
Moreover, the solubility changes with changes in temperature. Its solubility increases as the temperature decreases, an important factor to consider during transport and storage. Other factors to keep in mind are pH levels and water activity, but also the gas-to-product ratio.
Rather than only looking at the composition of the gas, one should also consider the volume of gas that is used in Modified Atmosphere Packaging. The product absorbs part of the gases, so it is crucial to know how much to add for it to actually have an effect inside the packaging.