An oxygen absorber is a small packet of material used to prolong the shelf life of food. They are used in food packaging to prevent food colour change, to stop oils in foods from becoming rancid, and also prevent the growth of oxygen-using aerobic microorganisms such as fungi.
Oxygen supports the growth of microorganisms and causes changes in color and rancid odors in packaged foods. Plastic packaging is less able to exclude oxygen from packaged foods than are the older glass and metal containers. Oxygen absorbers absorb oxygen and effectively reduce the aerobic environment to 0% oxygen. Therefore aerobic bacteria and fungi are unable to grow in this environment. This will extend the shelf life of a food product from 1 week to several months. The advantages of oxygen-absorbing sachets versus vacuum packaging are that the food products are not crushed or squeezed, as some products are of high value and are fragile, and its simplicity of use.
The packaging itself and the food bag /container seal are crucial for the effectiveness of the oxygen absorber. A minor packaging fault or leak can render the oxygen absorber useless and the contents inside the package will perish. Thus, high barrier packaging (with a low oxygen transmission rate) and efficient seal techniques need to be employed.
Oxygen absorbers are made in different formulations to match the water activity of the foods they are protecting. Some are designed to be used in dry foods such as nuts and dried grains, others with moister foods such as bread and processed meats. In most formulations the active ingredient is powdered iron or iron salts, as well as a material to absorb moisture necessary for the reaction from the atmosphere, such as sodium chloride (table salt) or activated charcoal. The oxygen reacts with the iron to produce iron oxides.
- Cichello, Dr. Simon. "A Guide to Oxygen Absorbers". Wholesale Group International Pty Ltd. Retrieved March 2010.
- Yam, K. L., "Encyclopedia of Packaging Technology", John Wiley & Sons, 2009, ISBN 978-0-470-08704-6
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