Oxygen is one of the important factors that cause food spoilage. There are many components in food that are closely related to the presence of oxygen. From a biochemical perspective, fats will oxidize and decay when exposed to oxygen, vitamins and various amino acids will lose their nutritional value, and oxygen can also cause unstable pigments to discolor or fade; From a microbial perspective, most microorganisms grow well in an aerobic environment. Even if the oxygen content is as low as 2-3% in the packaging environment, most aerobic and facultative anaerobic bacteria can still grow and biochemical reactions will still occur. Therefore, removing oxygen from packaging has very important practical significance. Through chemical reactions, oxygen is removed from sealed containers in a short period of time, leaving the food in an anaerobic state (O2 concentration below 0.01%), effectively controlling the growth of microorganisms such as bacteria and mold, preventing oil oxidation, effectively maintaining the color, aroma, and taste of the food, preventing the oxidation and destruction of nutrients such as vitamins, and extending the shelf life of the food.
Deoxidizers can be divided into two types based on their composition: (1) Deoxidizers based on inorganic matrices, such as reduced iron powder. The principle is that iron powder is oxidized into iron hydroxide in the presence of oxygen and water vapor. Another example is the sulfite based deoxidizer, which uses hydrosulfite as the main agent and Ca (OH) 2 and activated carbon as side agents to react in an environment with water. (2) It is based on organic substrates, such as enzymes, ascorbic acid, oleic acid, etc. Ascorbic acid (AA) itself is a reducing agent. In the presence of oxygen, copper ions can be used as a catalyst to oxidize or dehydrogenate ascorbic acid (DHAA), thereby removing oxygen from the environment. This method is commonly used to remove oxygen from liquid foods. Ascorbic acid deoxidizers are one of the more safe deoxidizers used, while enzyme based deoxidizers commonly use glucose oxide, It uses oxygen consumption during the oxidation of glucose to gluconic acid to achieve deoxygenation.
The commonly used reaction principles of deoxidizers include iron powder oxidation (iron system), enzyme oxidation (enzyme system), ascorbic acid oxidation, photosensitive dye oxidation, etc. Most of the deoxidizers used are based on iron powder oxidation reactions. This iron based deoxidizer can be made into bags and placed in packaging to reduce the oxygen concentration to 0.01%. The general requirement is that 1g of iron powder can react with 300mL of oxygen. When using, an appropriate amount can be selected based on the amount of oxygen remaining after packaging and the oxygen permeability of the packaging film. The applied products include candies, dried seafood snacks, cooked meat products, rice cakes, pasta, cheese, and dried vegetables. In addition to bagged deoxidizers, plastic labels or various cards containing active iron powder are also inserted into the packaging.
In addition to iron based deoxidizers, enzyme based deoxidizers are also widely used. Enzymatic deoxidizers are sensitive to changes in pH, Aw, salt content, temperature, and other factors, and require water to participate in the reaction. Therefore, their application in low moisture content foods is not effective. However, in bottled beer or Baijiu drinks, the deoxidizer can be directly made into small bags and put into the bottle cap. In addition, enzyme systems can also be immobilized on polypropylene or polyethylene membranes. Another type of deoxidizer is photosensitive dye deoxidizer. This deoxidization technology involves sealing a small sheet of ethyl cellulose film on the top of a transparent packaging bag (with photosensitive dye and monomer dissolved inside)