Table of Contents
Antibacterial packaging refers to packaging that can kill or inhibit spoilage and pathogenic bacteria that contaminate food. It can have new antibacterial functions by adding antibacterial agents and using antibacterial polymers that meet traditional packaging requirements in the system.
The main reason for the spoilage of fresh food is the growth and reproduction of microorganisms. In order to inhibit the growth of spoilage bacteria in food, antibacterial substances can be made into small bags and sealed together with the food into packaging bags, or several antibacterial substances can be polymerized into packaging bags, or coated inside the packaging film to create a film that can release antibacterial agents.
During the storage process of food, antibacterial substances in membranes or small packages are slowly released. When the antibacterial agent comes into contact with bacterial pathogens, it can penetrate the cell wall, thereby disrupting its function and preventing food spoilage.
Antibacterial agents should have the following characteristics:
- Antibacterial ability and broad-spectrum antibacterial activity;
- Special effects: washability, wear resistance, and long service life;
- Weathering resistance: Heat resistant, sun resistant, not suitable for decomposition and failure;
- Good compatibility or processability with the substrate, easy to add to the substrate:
- Good safety, harmless to health, and does not cause pollution to the environment.
Safe food grade packaging manufacturers, [email protected]
Types of antibacterial agents
The antibacterial function of packaging materials is currently mainly achieved through the following two methods:
- Direct antibacterial, where the antibacterial agents in packaging materials come into direct contact with food to achieve antibacterial purposes;
- Indirect antibacterial: add substances that can change the microenvironment in the packaging materials, or use special properties such as selective permeability of carriers to inhibit the propagation of microorganisms.
Antibacterial agents are the core substances of antibacterial materials, which can inhibit the growth and reproduction of specific microorganisms present in food.
The antibacterial agents added to food packaging should have good compatibility with the packaging substrate, and antibacterial agents with toxic, side effects, high irritation, strong odor, and significant impact on food quality should not be used.
There are many types of antibacterial agents, and common antibacterial agents can be divided into the following three types.
A) Inorganic antibacterial agents
Inorganic antibacterial agents are antibacterial agents made by utilizing the antibacterial properties of metals, metal ions, or metal oxides such as copper, silver, and iron. They can usually be divided into two categories: photocatalytic and dissolution.
Compared with other types of antibacterial agents, inorganic antibacterial agents have the advantages of good heat resistance, broad-spectrum antibacterial activity, high antibacterial persistence and safety, low toxicity, and no drug resistance.
The disadvantages are difficult manufacturing, complex process, and different metals have limitations in application. For example, copper based antibacterial agents have darker colors, silver based antibacterial agents are prone to oxidation, discoloration, and expensive prices, while zinc and other metals have relatively poor antibacterial effects.
B) Organic antibacterial agents
Organic antibacterial agents have a longer history of application than inorganic antibacterial agents. At present, there are over 500 organic antibacterial agents synthesized, but only a few dozen of them are commonly used.
Organic antibacterial agents can gradually bind with anions on the surface of microbial cell membranes and enter the interior of cells, causing protein denaturation and hindering the normal metabolic reproduction of microorganisms in the synthesis of cell membranes.
The advantages of organic antibacterial agents are relatively prominent, such as a wide range of sources, fast sterilization rate, convenient processing, and good color stability.
At the same time, the production cost of organic antibacterial agents is relatively low, and they have good operability and specificity in the production and addition process.
The disadvantage is poor heat resistance, easy to precipitate in solvent environments, and prone to volatilization and decomposition to generate toxic products. Moreover, it is also prone to develop drug resistance after long-term use.
Based on this, antibacterial materials produced through the combination of organic and inorganic antibacterial agents have gradually entered people’s vision, with the high efficiency and sustained characteristics of organic antibacterial agents, as well as the safety and heat resistance of inorganic antibacterial agents, while avoiding their respective shortcomings.
C) Natural antibacterial agents
In history, natural antibacterial agents were the earliest used antibacterial agents, although most of them are organic compounds, they have significant differences from organic antibacterial agents.
Natural antibacterial agents are mainly extracted from plants or synthesized through microorganisms, with outstanding advantages: wide antibacterial range and high safety, non-toxic, harmless, environmentally friendly, good biocompatibility, and abundant resources.
The disadvantage is poor heat resistance, short efficacy period, and limited production conditions and equipment.
Natural antibacterial agents mainly include chitosan, bacteriocins, lysozyme, plant essential oils and their extracts, etc.
Types of antibacterial packaging
A) Volatile antibacterial packaging
Volatile antibacterial packaging involves adding small bags containing volatile antibacterial substances, such as sachets, liners, etc. to the packaging. There are three common types: moisture absorbents, oxygen absorbents, and ethanol gas release agents.
Moisture absorbents and oxygen absorbents were initially used in the packaging of instant noodles, baked products and meat to reduce oxidation and moisture accumulation. Moisture absorbents can reduce the water activity in the environment, thereby inhibiting the normal metabolism of microorganisms.
Although oxygen absorbents themselves do not have antibacterial properties, they can inhibit the growth of aerobic bacteria, especially mold, by reducing the amount of oxygen in the packaging environment.
Ethanol releasing agents typically exist in the form of capsules in carriers or packaging bags, which inhibit bacterial growth by releasing ethanol.
B) Packaging materials with direct addition of antibacterial agents
At present, research on the direct addition of antibacterial agents and the synergistic effect of multiple antibacterial agents in food packaging materials is gradually increasing.
This type of packaging material is added with antibacterial agents through melting or melting to achieve the purpose of inhibiting microbial growth and reproduction. During production, it is mainly achieved through the following two methods:
- Direct mixing method
First, add antibacterial agents to the plastic substrate, mix well, and then directly process to form an antibacterial plastic product. This method is simple to operate, and the dosage of antibacterial agents can be accurately adjusted according to different actual application conditions.
However, antibacterial agents are concentrated and distributed in the substrate, with poor dispersion, resulting in relatively poor antibacterial performance.
- Antibacterial masterbatch method
This method involves using a twin screw extrusion mechanism to form a concentrated masterbatch of base resin or/and a resin with good compatibility with the base resin and antibacterial agent, which is then added to the packaging material for molding.
This method effectively solves the uniformity problem of macroscopic and microscopic dispersion, and is one of the main production methods for antibacterial products.
C) Wrapped or adsorbed antibacterial packaging
Antibacterial agents with low high temperature resistance can be added and produced using this method.
First, make the packaging substrate into the required form, such as film, and then perform surface treatment to improve its adsorption capacity. Finally, the antibacterial agent is coated or adsorbed on the surface of the substrate to give it antibacterial properties.
D) Packaging materials with inherent antibacterial properties
There are some edible natural antibacterial materials in nature, which are not only safe and non-toxic, but also have excellent antibacterial effects and can be directly used for food antibacterial packaging, such as chitosan.
At present, the mixed modification of chitosan with other substances (such as vinyl alcohol, starch, etc.) has become a research direction for packaging materials.
Application of Antibacterial Packaging Technology in Food Preservation
A) Antibacterial packaging film
The working mechanism of packaging film relies on the gradual precipitation of antibacterial agents from packaging materials and their release to the surface of food to exert antibacterial effects.
A European company uses cinnamon essential oil as an antibacterial agent and fixes it at a thickness of 30 μ On the microporous polypropylene film of m, the shelf life of baked food has been extended by 3-10 days.
In terms of inhibiting fungal applications, Korean scientists have developed LDPE membranes composed of potassium sorbate (1.0% mass fraction), which significantly reduces the growth rate of yeast and prolongs the delay period of fungal growth.
Showa Corporation in Japan has developed a polystyrene film with strong bactericidal effect using silver loaded phosphate as an antibacterial agent and has been widely used in food packaging.
In addition, chitosan and its derivatives have been widely used as antibacterial agents in the production of antibacterial films due to their own characteristics.
B) Antibacterial paper
Antibacterial paper refers to functional paper that has the ability to inhibit and kill microorganisms, and can extend the shelf life of packaged food.
At present, various antibacterial agents are mostly added to paper through three methods: wet end addition, surface processing, and fiber manufacturing, in terms of natural antibacterial agents.
A company has tested the antibacterial activity of fruit and vegetable packaging antibacterial paper with antibacterial agents such as cinnamon, clove, and oregano natural essential oil, and found that cinnamon essential oil rich in cinnamaldehyde has the best antibacterial and durability, which prolongs the shelf life of packaged food.
The Korean Chemical Industry Experimental Research Association extracted antibacterial substances from five natural aromatic plants and determined their safety. The antibacterial food packaging paper made from them has a strong inhibitory effect on the growth of mold and other microorganisms.
Safe food grade packaging manufacturers, [email protected]