In the realm of food packaging, gas - barrier functional films play a pivotal role in preserving the quality and extending the shelf - life of various food products. As a supplier of functional films, I am well - acquainted with the diverse requirements that these films must meet to ensure optimal performance in food packaging applications.
1. Oxygen Barrier
Oxygen is one of the primary factors that can cause food spoilage. It can lead to oxidation of fats, which results in rancidity, and can also promote the growth of aerobic microorganisms. Therefore, an effective gas - barrier functional film should have a low oxygen transmission rate (OTR).
The OTR is measured in units such as cc/(m²·day·atm). For high - value food products like fresh meat, seafood, and certain types of cheese, a very low OTR is required. For example, fresh red meat needs a film with an OTR of less than 10 cc/(m²·day·atm) to prevent discoloration and the development of off - flavors caused by oxidation.
Materials such as ethylene vinyl alcohol (EVOH) and polyvinylidene chloride (PVDC) are commonly used in gas - barrier films due to their excellent oxygen - barrier properties. EVOH has a particularly low OTR, especially in a dry environment. However, its performance can be affected by humidity, so it is often used in combination with other polymers in a multilayer film structure.
2. Moisture Barrier
Moisture can also have a significant impact on the quality of food. Excessive moisture can lead to mold growth, softening of dry products, and loss of crispness in snacks. On the other hand, some foods may need to retain a certain level of moisture, and a proper moisture - barrier film can prevent dehydration.
The moisture vapor transmission rate (MVTR) is used to measure the ability of a film to prevent moisture transfer. For dry foods like crackers and cereals, a low MVTR is essential. A film with an MVTR of less than 1 g/(m²·day) is often required to keep these products fresh and crispy.
Polyethylene (PE) and polypropylene (PP) are commonly used for their moisture - barrier properties. High - density polyethylene (HDPE) has a relatively low MVTR compared to other types of PE. In addition, metallized films, which are made by depositing a thin layer of metal (usually aluminum) on a polymer substrate, can also provide excellent moisture - barrier performance.
3. Carbon Dioxide Barrier
For carbonated beverages and some modified atmosphere - packaged (MAP) foods, a good carbon dioxide barrier is necessary. Carbon dioxide is an important component in maintaining the carbonation in beverages and can also be used in MAP to inhibit the growth of aerobic bacteria.
Similar to OTR and MVTR, the carbon dioxide transmission rate (CO₂TR) is used to evaluate the carbon dioxide - barrier performance of a film. Films with a low CO₂TR can help retain the carbon dioxide in the package for a longer time. EVOH and PVDC also have relatively good carbon dioxide - barrier properties, and they are often incorporated into multilayer films to meet the specific requirements of carbon - containing food products.
4. Aroma and Flavor Barrier
Foods have their unique aromas and flavors, and the gas - barrier film should prevent the loss of these volatile compounds and also protect the food from absorbing external odors. For example, coffee and tea are highly aromatic products, and a film with good aroma - barrier properties is needed to preserve their characteristic scents.
Some polymers have inherent aroma - and flavor - barrier properties. For instance, nylon has been shown to be effective in preventing the migration of flavors and aromas. Additionally, the surface properties of the film can also affect its ability to retain or prevent the transfer of volatile compounds. A smooth and non - porous surface can reduce the adsorption and desorption of aromas and flavors.
5. Chemical Resistance
The film should be resistant to various chemicals that may be present in the food or the packaging environment. This includes acids, bases, and oils. For example, fatty foods can contain lipids that may interact with the film material. A film that is not chemically resistant may dissolve or swell in contact with these substances, which can compromise its gas - barrier properties and also pose a safety risk if components of the film migrate into the food.
Polymers like polyesters are known for their good chemical resistance. They can withstand contact with a wide range of food ingredients without significant degradation. In addition, proper surface treatments can enhance the chemical resistance of the film.
6. Mechanical Properties
The gas - barrier film must have adequate mechanical properties to withstand the stresses during the packaging process and storage. It should have sufficient tensile strength to be handled during film production, printing, and filling operations. A film with low tensile strength may tear easily, leading to the loss of its gas - barrier function.
Elongation at break is another important mechanical property. It indicates the ability of the film to stretch without breaking. For flexible packaging applications, a film with a high elongation at break is preferred, as it can conform to the shape of the food product and withstand some degree of deformation without damage.
Puncture resistance is also crucial, especially for packaging products with sharp edges or irregular shapes. A puncture - resistant film can prevent the formation of holes that would allow gas exchange and compromise the food's shelf - life.
7. Thermal Stability
During the packaging process, the film may be subjected to heat, such as in heat - sealing operations. The gas - barrier film should have good thermal stability to maintain its gas - barrier properties under these conditions. If the film degrades or loses its integrity when exposed to heat, it can no longer provide an effective barrier.
Some polymers have better thermal stability than others. For example, polyimides have high thermal resistance and can withstand high - temperature processing without significant degradation. In multilayer films, the choice of polymers and the overall structure need to be carefully designed to ensure thermal stability during the packaging process.
8. Regulatory Compliance
Food packaging materials are subject to strict regulations to ensure food safety. The gas - barrier film must comply with relevant national and international standards, such as the Food and Drug Administration (FDA) regulations in the United States and the European Union's food contact material regulations.
These regulations cover aspects such as the use of approved polymers, the migration limits of additives and monomers from the film into the food, and the labeling requirements. As a functional film supplier, we are committed to ensuring that our products meet all the necessary regulatory requirements to provide our customers with safe and compliant packaging solutions.
9. Transparency and Printability
In many cases, transparency is an important requirement for food packaging. Consumers often want to see the product inside the package, especially for fresh produce and some high - end food items. A clear and transparent gas - barrier film can enhance the visual appeal of the product.
At the same time, the film should also be printable. High - quality printing on the film can provide important information about the product, such as ingredients, usage instructions, and branding. Polymers like polyethylene terephthalate (PET) are popular for their good transparency and printability.
10. Cost - effectiveness
Finally, cost - effectiveness is a key consideration for food manufacturers. The gas - barrier functional film should provide the required performance at a reasonable cost. This may involve optimizing the film structure, choosing cost - effective raw materials, and improving the production process to reduce waste and increase efficiency.
As a supplier, we work closely with our customers to develop customized solutions that meet their specific requirements while also being cost - effective. We offer a range of gas - barrier films with different performance levels and price points to suit various food packaging applications.
In conclusion, the requirements for gas - barrier functional films in food packaging are multifaceted. Meeting these requirements is essential for ensuring the quality and safety of food products. As a functional film supplier, we are dedicated to providing high - quality films that can meet all these diverse needs. If you are in the food packaging industry and are looking for reliable gas - barrier functional films, we would be more than happy to engage in a procurement discussion with you. Our team of experts can help you select the most suitable film for your specific application.
If you are also interested in other types of functional films, you can visit the following links: Flame Retardant Coating, Mucous Membrane, Release Film.
References
- Robertson, G. L. (2012). Food Packaging: Principles and Practice. CRC Press.
- Han, J. H. (Ed.). (2014). Innovations in Food Packaging. Academic Press.
- Kerry, J. P., O'Grady, M. N., & Hogan, S. A. (2006). Past, current and potential utilization of active and intelligent packaging systems for meat and muscle - based products: A review. Meat Science, 74(1), 113 - 130.