Modified Atmosphere Packaging For Food
Food packaging now plays a pivotal role in ensuring that products retain their freshness, taste, and nutritional value, acting as a shield against external contaminants and minimizing waste caused by spoilage. Modified Atmosphere Packaging (MAP) modifies the internal packaging atmosphere to enhance the shelf life and maintain the quality of food products.
Adjusting the concentration of gases inside the package creates an environment tailored to the specific food type, slowing down the deterioration process. This approach is not just about prolonging the life of food; it’s about ensuring that when a consumer finally opens that package, the food inside is as close to its original state as possible.
Understanding Modified Atmosphere Packaging
The 1930s saw the first instances of using controlled atmospheres for storing apples. However, it wasn’t until the 1970s that MAP began gaining traction for commercial use, initially in the U.S. and Europe, especially for meat and poultry products. As technology progressed and the benefits of MAP became more evident, its applications expanded to other food categories like baked goods, dairy products, fresh produce, and ready-to-eat meals.
Modified Atmosphere Packaging (MAP) is a food preservation technique that involves altering the natural composition of air within a package to prolong the shelf life and maintain the quality of the food product. This alteration usually involves the regulation of gases like oxygen, carbon dioxide, and nitrogen, among others, depending on the specific requirements of the food being packaged.
Extension of Shelf Life: By adjusting the atmosphere inside the packaging, the growth of spoilage organisms and the rate of certain chemical reactions can be slowed down, allowing products to stay fresh for longer. This extended shelf life offers retailers and consumers more flexibility, reducing the urgency for immediate sales or consumption.
Food Quality and Freshness: By curbing the oxidation process and inhibiting the growth of harmful bacteria, the nutritional value, texture, aroma, and taste of the product are maintained. As a result, consumers experience food closer to its freshly harvested or produced state, even after days or weeks of packaging.
Reduction in Food Spoilage and Waste: With the extended shelf life provided by MAP, the chances of food going unsold or uneaten before it spoils are significantly reduced. This means less waste in retail and household settings, which translates to cost savings for businesses and consumers and contributes to environmental sustainability.
Product Appearance and Marketability: Aesthetic appeal is a significant factor in consumer purchasing decisions. MAP ensures that products, especially perishables like meats and produce, maintain their vibrant, fresh appearance. Oxygen reduction, for instance, can prevent the browning of fruits and discolouration of meats. This visual appeal enhances marketability, as products look as fresh and appealing as they taste.
How Does MAP Work?
Modified Atmosphere Packaging operates by altering the internal atmospheric composition of a food package to create conditions less conducive to spoilage and degradation. By controlling the proportions of various gases, MAP can slow down the growth of spoilage organisms, reduce enzymatic reactions in the food, and deter oxidation processes that degrade food quality.
Oxygen (O2): Oxygen is essential for the survival of aerobic bacteria and fungi, and it’s also involved in oxidation reactions that can lead to rancidity in foods, especially fats. In many MAP applications, the concentration of oxygen is reduced to curb microbial growth and prevent oxidation. However, in some cases, oxygen is retained or introduced to maintain the red colour of fresh meat or to support respiration in fresh produce.
Carbon Dioxide (CO2): Carbon dioxide has antimicrobial properties, especially against mould and bacteria. By increasing CO2 levels in the package, the growth of spoilage organisms can be inhibited. This is particularly useful for products like meat, poultry, and some dairy items. However, too much CO2 can cause package collapse or damage to delicate products, so its levels must be optimized based on the specific food product.
Nitrogen (N2): Nitrogen is an inert gas, meaning it doesn’t typically react with food components or with many microorganisms. It is often used as a filler gas to replace oxygen and maintain package volume. Since it doesn’t encourage microbial growth or partake in detrimental chemical reactions with food, it helps maintain freshness by simply displacing oxygen and preventing package collapse.
Applications in Different Foods
The application of MAP varies significantly based on the nature of the food product, its perishability, and its susceptibility to different spoilage mechanisms. When utilized appropriately, MAP offers food producers and retailers a potent tool to deliver fresher, longer-lasting products to consumers.
Meats and Poultry: To maintain the freshness, colour, and shelf life of both red and white types of meat, specific gas mixtures are employed. A higher oxygen concentration is typically used for red meats to retain their appealing red colour. Poultry might see a higher proportion of carbon dioxide to prevent bacterial growth. The benefits include extended shelf life, discolouration prevention, and reduced microbial spoilage.
Fresh Produce (Fruits and Vegetables): Fresh produce continues to respire after harvesting. The aim is to slow down this respiration and enzymatic processes to retain freshness. Balancing oxygen and carbon dioxide levels is critical. Too little oxygen can induce anaerobic respiration, leading to off-flavours. The benefits include texture, colour, and flavour preservation and reduced wilting and spoilage.
Dairy Products: Dairy products, including cheese and yoghurts, benefit from MAP to prevent mould growth and rancidity. High levels of carbon dioxide combined with low oxygen levels are commonly used. The benefits include shelf life extension, creamy texture maintenance, and preventing moulds and off-flavours.
Bakery Products: For bakery items, MAP can prevent staleness, mould growth, and rancidity of fats. Typically, oxygen is minimized to reduce oxidation, and carbon dioxide levels are increased to prevent microbial growth. The benefits include fresher tasting products, mould prevention, and extended shelf life.
Ready-to-Eat Meals: Ready meals require the preservation of multiple components, from meats to vegetables. MAP helps in preserving these diverse ingredients in a single package. A balanced combination of gases, often tailored to the specific meal and its ingredients. The benefits include longer shelf life, retention of flavours, and prevention of microbial contamination.
Seafood: Seafood is highly perishable. MAP aims to retain the fresh taste of the sea and inhibit bacterial growth. Carbon dioxide plays a crucial role in inhibiting bacterial and fungal growth. Nitrogen can be used as a filler to prevent package collapse. The benefits include an extension of the freshness period, preservation of texture and taste, and reduced spoilage.
Snacks and Nuts: MAP prevents the oxidation of fats in nuts and helps keep snacks crispy. High nitrogen content is typically used due to its inert nature, displacing oxygen and preventing oxidation. The benefits include crunchier snacks, prevention of rancidity in nuts, and overall freshness retention.
Packaging Materials and Technologies
Different types of food require varied packaging materials to maximize the benefits of MAP. Some of the commonly used materials include:
- Polyethylene (PE): A versatile plastic with good sealing properties, often used for its moisture resistance.
- Polyvinyl Chloride (PVC): Commonly used for its clarity, making it ideal for products where visual appeal is important.
- Polypropylene (PP): Offers good barrier properties against moisture and is often used for products requiring higher temperatures, like ready-to-eat meals.
- Ethylene-Vinyl Alcohol (EVOH): An excellent barrier against gases, often integrated as a layer in multi-layered packaging.
- Polyethylene Terephthalate (PET): Known for its clarity and mechanical strength, it is often used for beverage and ready-to-eat meal trays.
Barrier Properties and Selection Criteria: The choice of packaging material is crucial. The right material ensures that the modified atmosphere remains stable over time. Key considerations include:
- Gas Permeability: The rate at which gases can pass through the material. Materials with low permeability are essential to maintain the modified atmosphere inside the package.
- Moisture Resistance: Essential for foods sensitive to moisture changes, like dry snacks or certain baked goods.
- Mechanical Strength: The packaging must withstand transportation and handling without compromising its integrity.
- Transparency: The packaging material should offer clarity for products where visual appeal is important.
- Compatibility with Sealing Technology: Some materials are more amenable to certain sealing technologies, ensuring airtight packages.
Seal Integrity and Packaging Machinery: Ensuring the package is sealed correctly is crucial to maintaining the modified atmosphere.
- Seal Integrity: A compromised seal can allow the modified atmosphere to escape and external gases to enter, reducing the effectiveness of MAP. Regular checks and quality control are essential.
- Vacuum Packaging: This technology removes air from the package before sealing, creating a vacuum. It’s often combined with MAP, especially for meats, to enhance shelf life.
- Gas Flushing: A method where the packaging is filled with the desired gas or gas mixture before sealing, displacing the ambient air.
- Packaging Machinery: Modern MAP machinery allows precise control over gas mixtures, ensuring consistency. These machines often have sensors and feedback systems to monitor and maintain the desired atmosphere.
Modified atmosphere packaging (MAP) is a solution in the modern food industry with its ability to extend shelf life, maintain product quality, and reduce waste. As food supply chains become more complex and consumer expectations change, ensuring food safety and freshness is essential. Humi Pak provides an array of food packaging solutions designed to safeguard product quality and extend shelf life. Reach out to our packaging engineers to discover more.