Oxygen Scavengers For Food Preservation

Oxygen is responsible for the degradation of living things. A lot of food products are sensitive to oxygen. Food degradation majorly is caused by oxidation reactions in the food or because of the presence of spoilage aerobic microorganisms. When packing or in order to preserve food items it is important to remove oxygen. In this article, We describe about Oxygen Scavengers for Food Preservation.

Oxygen accumulates in the packaging and that is the main reason for food degradation. Other oxygen also reacts with other gases and creates residual gases. Food degradation also occurs due to inefficient vacuum. Vacuum packaging of food is the most common method of food packing to prevent oxygen seeping in from the environment. But oxygen is said to seep in even through the packing material and degrades the food.

Other alternative methods include oxygen absorbers packets and modified atmosphere packaging (MAP). These are used to reduce the O2 inside the food packaging. However, in the case of Modified atmosphere packaging (MAP) technologies, the residual oxygen levels are too high. These are not suitable to increase the shelf life of the food. The use of oxygen absorbers packets is much better than the Modified atmosphere technology (MAP) as the oxygen present inside the food or in the packaging can be reduced to lower levels. This drastically increases the shelf life.

To eliminate residual O2, many research and development have been conducted. Active packaging is a field that has incurred great research. Active packaging includes oxygen absorber packets or scavengers, ethylene scavengers, carbon dioxide scavengers, humidity controllers, flavour emitters or absorbers and antimicrobial agents.

In the case of oxygen absorbers packets, reactive compounds are contained in packets that have a semi-permeable membrane or are directly compounded with the packing material.

The first patent of the oxygen absorber packet was acquired in Finland in 1938. This was mainly developed to remove the residual oxygen in the area that apart from food in the metallic containers. However, after this hydrogen gas introduction method was commercialized in the 1960s. The introduced hydrogen used to react with oxygen gas in the presence of palladium present inside the packing. But this method never became popular because hydrogen was expensive and it was very unstable inside the packing material. Today oxygen scavengers or oxygen absorbers packets are becoming more popular among the food manufacturers.

The oxidation absorption technology is based on the oxidation of one of the following chemicals like iron in the form of iron powder, ascorbic acid, enzymes, several photosensitive polymers etc. These elements reduce the levels of oxygen as low as 0.01%. An oxygen scavenger is chosen depending upon the level of O2 in the headspace or the level of O2 present inside the food. It is also dependent on the nature of the food, water quantity and desired shelf life of the food.

The most important requirement the oxygen scavengers need to fulfil is interaction with the human body. They need to be harmless to the human body. They also need to absorb oxygen at the desired rate all the time without producing toxic substances, gases or pungent odours. They need to compact in size and easy to pack. The most important thing is that they need to absorb oxygen at a much higher rate than their own size.

To be suitable for the food industry they need to be in the form of sachets and are mostly found in the form of various iron-based powders. Non-metallic scavengers are also made popular as the metallic derived scavengers can leave metallic taints to the food products. They include ascorbic acid, ascorbate salts or catechol. Many enzyme-based scavengers are also popular for food products that use glucose oxidase or ethanol oxidase. They can take the form of a sachet label, packaging film, card, or container lining.

The oxygen absorbers packets are the most satisfactory but they come in with the precautions one needs to take to use them effectively. The most important precaution includes the packet rupture and thereby ingesting these.

For these packets to be effective the following conditions need to be fulfilled;

Packing containers or films with high oxygen barriers must be used. Not using them will make the packets saturated and will lose their ability to trap O2 molecules faster than they should.
Heat sealing should be used to avoid air leaks.
The right amount and volume of oxygen scavenger must be used

These systems are usually combined with Modified atmosphere packaging to increase effectiveness.

Types of Oxygen Scavenger system include;