Guide to Using Oxygen Absorbers at Home

We often see little white sachets packed together inside the food packaging bought from supermarkets and grocery stores. The small packets are oxygen absorbers that contain fine iron powder and salt. They are used in packaging and storage, designed specifically to remove the residual oxygen inside sealed environments.

Their primary function is to extend the shelf life of perishable goods by preventing the growth of harmful bacteria and mould. Additionally, they help in preventing oxidation in various products. This article provides a concise overview of their benefits and usage in domestic settings.

Understanding Oxygen Absorbers

In a sealed environment, such as a jar or bag, iron absorbs 99% of the oxygen. These sachets are made of a semi-permeable layer which prevents the iron powder from seeping into food products while allowing oxygen and moisture to enter. Oxygen absorbers are natural food preservatives that help extend foods’ shelf life by preserving their natural colour, flavour, and taste.

As some foods are susceptible to oxygen damage, oxygen absorbers remove oxygen from a sealed atmosphere, resulting in a nitrogen-rich condition suitable for long-term food preservation. They help preserve the quality of dry goods by protecting them from insect and fungi growth. Oxygen absorbers function based on a simple yet effective chemical principle. At their core, these packets contain iron powder. When exposed to oxygen, a chemical reaction known as oxidation occurs. Here’s a breakdown:

• Oxidation Reaction: The iron inside the packet reacts with the oxygen in the atmosphere, forming iron oxide or rust. This reaction is exothermic, meaning it releases heat.
• Oxygen Removal: As the iron oxidizes, it effectively “absorbs” or removes the oxygen from the surrounding environment. In a sealed container, this means the amount of available oxygen decreases, which prevents the growth of aerobic bacteria and fungi.
• Moisture Role: Some oxygen absorbers also contain small amounts of salt or activated carbon, which help in the absorption process. Additionally, a minimal amount of moisture inside the container accelerates the oxidation process, making the oxygen absorber more effective.
• Result: Within a sealed environment, the oxygen level drops typically to below 0.01%, making it inhospitable for most bacteria and fungi, which require oxygen to thrive.

Benefits of Using Oxygen Absorbers

Oxygen absorbers play a role in safeguarding the quality and safety of a wide range of products, making them suitable for both food storage and the preservation of valuable items.

Inexpensive: They are not only safe but also an inexpensive solution for long-term food storage. Alternatively, vacuum seal foods can be used to remove oxygen from the sealed bags.

Food-Safe: They can be safely placed on top of the food and will not harm the food they come into contact with because they are sealed. Food is preserved using oxygen absorbers that do not contain artificial additives or chemicals. Hence, they are safe and long-lasting.

Prevents the growth of microorganisms: Microorganisms such as fungi and mould can grow in an aerobic environment when oxygen is present. The growth of these microorganisms significantly weakens the integrity of the food package. Food products can discolour and become rancid, leading to food poisoning. A nitrogen-rich environment is inhospitable to many unwanted organisms and moulds.

Extending Shelf Life of Food Items: One of the primary advantages is their ability to prolong the freshness and shelf life of various food items. By removing oxygen from a sealed environment, foods like dried fruits, grains, and nuts can be preserved for longer durations, retaining their nutritional value and taste.

Reducing the Risk of Oxidation: Oxidation is a natural process that can cause foods to become rancid, change colour, or lose their nutritional value. For instance, fats and oils can turn rancid when exposed to oxygen for prolonged periods. Beyond foods, other products like pharmaceuticals can also degrade due to oxidation. Oxygen absorbers mitigate this risk, helping maintain the quality and efficacy of these products.

Guide to Using Oxygen Absorbers

Before using an oxygen absorber, it’s essential to inspect the items intended for storage. Especially with foods, they should be fresh and devoid of any signs of spoilage or mould. If storing dry foods like grains or legumes, they must be entirely free from moisture. The presence of excess moisture not only hampers the efficiency of the absorber but can also promote the growth of mould.

Also, consider packaging choices. Materials that are impermeable to gases, such as moisture barrier bags, glass jars with airtight seals, or vacuum-seal bags, are the most effective for long-term storage. HDPE plastic bags can also be used, as it has a low oxygen transmission rate. If bags are vacuum-sealed or airtight, they can prevent oxygen from entering for around five years

Placing the Absorber Inside the Package

Upon opening the pack of oxygen absorbers, it’s important to start using them immediately. These absorbers are active as soon as they are exposed to the ambient air. If it is not intended to use all the absorbers at once, promptly seal the remainder in an airtight bag.

When positioning the absorber inside the storage container, it’s typically best to place it on top of the stored items, ensuring it’s exposed to the maximum amount of residual air. However, its exact placement isn’t overly critical. Once the container is sealed, the oxygen throughout will be absorbed, regardless of the absorber’s position.

Sealing the Container Effectively

A crucial step in the process is sealing the chosen storage container. If using vacuum-seal bags, endeavour to remove as much air as possible before the final sealing. The lesser the initial volume of air inside, the faster the absorber can complete its task.

Following this, ensure that the chosen storage medium, whether it’s a bag or container, is sealed without any gaps. Even minute air leaks can compromise the effectiveness of the absorber, allowing fresh oxygen to permeate. For future reference and organization, it’s a sound practice to label the container with both the date of sealing and the size of the oxygen absorber used.

Checking the Vacuum Effect After Some Time

Post-sealing, it’s beneficial to monitor the stored items. In flexible packaging like Mylar or vacuum-seal bags, the bag should visibly draw inwards after a while, indicating the oxygen absorber is working and creating a vacuum effect. For more rigid containers, like jars, a noticeable vacuum effect might be absent.

However, the effectiveness can be gauged by the lid’s tightness, which might become harder to open due to the internal pressure change. Periodic monitoring, especially in the initial stages, can also help spot issues like a ballooning package, signalling either a seal failure or a saturated absorber.

How to Choose the Right Oxygen Absorber

Each oxygen absorber is rated to absorb a certain amount of oxygen. They are rated in CC (Cubic Centimetres). Humi Pak’s Osorb is available in sizes ranging from 10 CCs to 3000 CCs.

Here is a guide on the recommended amount to use when storing foods:

Match Absorber Size to Container Volume:

• Understanding Capacity: Absorbers are rated by their capacity to remove oxygen, typically measured in cubic centimetres (cc). This rating indicates how much oxygen a specific absorber can handle.
• Calculating Volume: Determine your container’s volume first. For example, a quart-sized jar is about 946 cubic centimetres. The contents will occupy some space and won’t contain as much oxygen as the void. Typically, select an absorber that aligns with the volume of the space, but opting for a slightly higher rating can offer better protection.
• Density of Packed Goods: Tightly packed containers may need a smaller absorber. Conversely, for loosely packed or porous items, consider a larger size.

Determine the Type Based on the product:

• Food Varieties: Different foods require distinct preservation needs. Foods rich in fats or oils may be more prone to rancidity from oxidation and might need a more potent absorber. In contrast, dry items, like grains, have separate requirements.
• Non-food Goods: For items like metal tools or documents, look for absorbers that also control humidity. Some variants combine desiccant properties, making them ideal for such applications.

Conclusion