In recent decades, packaging and containers have become an essential element in food purchases. The food is packaged and packed with the aim of being transported and stored. That is, not only is it a container, but "the container must protect what it sells and sell what it protects" (Briston-Neill, 1972).
From the business perspective, the appearance of packaging is particularly important because it identifies the product in the distribution chain and differentiates it when it reaches the consumer.
Next, the most used materials in the food industry are detailed: plastics, glass, metals and wood and its derivatives.
Plastics are organic polymeric materials that can be molded into the desired shape. The lightness and versatility of these have been confirmed over decades in the processing and packaging of food. Plastic containers and packaging protect against the contamination of food and offer adequate mechanical strength.
Due to a lower cost and lower energy consumption during manufacturing, plastics have replaced traditional packaging materials. In addition, they are able to preserve and protect the food for longer, minimizing the use of preservatives.
In relation to the consumer, they are easy to handle and open, and offer an effective surface for printing labels or brands. However, although plastics are recyclable materials, they are pollutants.
In the plastic manufacturing process, there are many varieties of plastic resins, with the most used being:
- Polyvinyl chloride (PVC): very resistant to humidity, fats and gases
- Polyethylene and its varieties (PET, HDPE, LDPE). The development of the PET range has revolutionized the packaging industry, allowing plastic to compete directly with glass bottles.
- Polystyrene (PS) is the plastic of choice for thermoforming due to its strength, malleability and low cost.
Cellulose is a biodegradable substance obtained from the cell wall of many vegetables and fungi. It was the first transparent film that was used in packaging and is currently used for confectionery and pastry products, in situations where vapors need to "breathe" to avoid deforming the product
Polyamides are a type of polymer that can be found in nature such as wool, or synthetically, like nylon. They are used for boiled products in bags, frozen foods, fish, meat, vegetables and processed meat and cheese.
Metals (steel, tin, aluminum)
The main use of these metals is the preservation of canned foods and beverages. The most commonly used are tin-coated steel and aluminum cans. It is an opaque material that provides an advantage for food that is sensitive to light.
Tin cans are made of steel sheet coated with tin as a measure of protection against corrosion of steel, especially when they contain products with low pH.
Aluminum is increasingly used for canning due to its lightness, low cost and capacity to be recycled. It can be found in packaging, bottle closures and wraps and laminates. It has the same barrier properties as steel but with the advantage of being resistant to corrosion.
Aluminum foil is formed by layers of laminated aluminum. It is a highly flexible product that allows to preserve or protect food in the domestic environment. However, it is difficult to use in modern fast packaging equipment due to wrinkles, rips and marks.
Thin-walled aluminum cans are suitable for carbonated beverages, while wide-walled cans are suitable for steam sterilization. Optionally, internal lacquers can be used to avoid interaction with the product and externally to protect the ink from the labeling.
Glass is an inert material that is impermeable to gases and vapors. It is an excellent and completely neutral oxygen barrier when in contact with food. However, it is a fragile, heavy material that requires a lot of energy to be manufactured.
Glass uses one of the most abundant raw materials on the planet, silica, but it is not renewable. Despite this, it is a recyclable product, since it can be used as a container repeatedly.
More than 75 billion glass containers are used per year in the food industry, being its main use for wines, juices, baby food and soft drinks
Glass containers can be bottles (the most used), jars, glasses, ampoules, jars, etc. However, this material is not used for frozen products due to the risk of breakage.
Wood, cardboard and papers
Products derived from wood are widely used in the packaging of food in the form of paper and cardboard. Paper is a very cheap, lightweight product with excellent printing capacity. Although it is very sensitive to moisture, it can be corrected with a combination of paper and other materials such as plastic or paraffin.
Cardboard is a material made up of several superimposed layers of paper, making it thicker, harder and more resistant than paper. Its main use is for packaging and containers in the form of boxes.
In recent years, paper and cardboard manufacturers are paying special attention to issues related to health and the environment by working with recycled products that increase the useful life of these raw materials.
Advances in packaging techniques
The evolution of packaging techniques, together with those of food preservation, transform the processes of manufacturing, distribution, purchase and preparation of food, for both businesses and consumers.
Technological advances, such as the incorporation of antioxidants in food packaging, increase the shelf life of food. This system is based on the addition of particles to the packaging materials to prevent the oxidation of nutrients. In this case, the antioxidants can be incorporated during the manufacturing process or impregnate the walls of the container before coming into direct contact with the food.
In short, it is important to choose the appropriate packing and container material for each food to be conserved, taking into account the transport circumstances and storage conditions to which it is going to be subjected.