When we go to the grocery store and buy products such canned soups, cookies, juice and other foods and beverages, we interact with different forms of food packaging. For example, milk is usually packaged in plastic or glass, but shelf-stable versions of the product may also be found in packaging such as cans. Food packaging is durable, strong, and protective, and it also plays a role in safety, convenience, efficiency, and consumer information. It additionally acts to block light and protect nutrients and colors in food products—keeping a food’s quality consistent throughout a product’s shelf life.
The packaging options offered by food and beverage producers have changed over time to meet the demands of consumers and enhance manufacturing productivity. Milk is a great example of how food and beverage packaging has changed over time. In the early 1950s, milk was delivered to people’s homes in glass bottles. Today, having a visit from a milk man is not the norm and the glass packaging has since transitioned to High Density Poly Ethylene (HDPE) plastic. Milk may also be packaged in a plastic-paper combination (paper carton with a plastic liner) that allows for an even longer shelf life. To understand how different forms of packaging allow for quality and reliability, let’s break down some of the main forms of packaging material.
Paper may be the oldest form of food packaging, dating back to the first or second century BCE, when it was used by the Chinese to wrap their food. Over the next 1,500 years, materials from bark and flax fibers to linen rags and wood pulp were used. During this time, the first commercial cardboard was invented to replace wooden crates used for trade. The paperboard carton was invented in the 1870s and became popular in making cereal cartons. Paper is a versatile packaging material, with uses ranging from parchment papers to carton board for products such as frozen and fast food to corrugated boxes such as pizza boxes. Paper is permeable and has great strength-to-weight properties and low costs, meaning you get bang for your buck. Paper is usually treated with materials such as waxes, resins and lacquers to provide protective and functional properties. For example, glassine is greaseproof paper used as a liner in baked and fast foods. Paper is also made from renewable resources, meaning it can be regrown and will never run out. When it comes to recycling paper food packaging, most of the paper is recycled into non-food product packaging due to mineral oils and other substances that could potentially migrate into other food.
Glass packaging material dates back to 7000 BC, when it was invented by the ancient Egyptians. Nicholas Appert began using glass as a food preservation method in the early 1800s when he used glass bottles with corks secured with wire as a way to contain and heat foods in order to preserve them. Glass provides a barrier against gasses and microorganisms, can be sterilized, and is easy to reuse. Glass is 100% recyclable without loss of quality or purity compared with some of its other packaging counterparts—but it also requires a good amount of energy for recycling. Why isn’t glass used more often? Primarily because it’s extremely fragile and can be very heavy, leading to high transportation costs. That said, glass cans once provided a great start to food preservation before being succeeded by metal cans due to metal’s ability to be processed more readily and to have a longer shelf-life.
Metal packaging also dates back to ancient times, when boxes and cups were made from silver and gold, (although these materials were not commonly used due to their value). Other metals and stronger alloys were developed over time, during which iron, tin and steel came into use. Metal canisters were invented around the 1760s but were unpopular due to the toxicity of the metals used. It wasn’t until the 1800s that these containers became popular. They were first used by Appert as a way to preserve foods in the form of tin containers. Like glass, metals have good barrier properties, are heat-resistant, and can be heat-treated and sealed for sterility. Aluminum is used for foil and soft drinks, while tin plate is used for processed foods and aerosol cans (like whipped cream). The majority of aluminum-, steel- and tin- generated food packaging is recycled. Metal materials are recyclable, but they may require extra processing, such as pinhole formation for aluminum foil or sorting and separating for laminated and metallized films.
Metal food and beverage cans are coated with an organic layer that protects the integrity of the cans from the effects of food and prevents chemical reactions that may occur between the metal and the food. These liners play a huge role in making cans stronger by reinforcing their structure and making them safer from pathogens and other contaminants, including Clostridium botulinum.
In comparison with other packaging materials, plastic is the youngest in terms of when it was discovered—but not lacking in terms of its use and safety. In fact, it is the most versatile and commonly used material due to its lightness, inexpensiveness and heat resilience. In the 19th century, plastic was mainly used for military and wartime purposes. Vinyl chloride was discovered in the 1830s and later developed into molded bottles that today are used in some water and vegetable oil containers. It wasn’t until the 1950s, though, when plastics became popularized in the food industry in the form of styrene, which functioned in boxes, cups and trays. The plastic bottles we see today are mainly made of PET (polyethylene terephthalate) and entered the food industry over the past 50 years. Plastic materials also are used because they can provide barriers to moisture, gasses and chemicals. Some plastics, such as polyvinylidene chloride, are also heat-sealable and allow for high temperatures during a process called hot filling. Foods such as sauces, salsas and jams, and beverages such as juices and isotonics (sports drinks) are hot-filled.
Plastics have great functionality like their other material counterparts, but how do they match up in terms of recycling? Most plastics can be recycled but require high amounts of energy. There also may be concerns about contamination of plastics during the recycling process. However, the FDA has guidance and protocols to monitor the situation.
Now that you know a little bit about how food packaging plays a role in the quality of your food, the next time you’re at the store, you can pick up that jug of milk or that canned soup and know that the packaging it’s in is there to provide you with the best-quality and safest product. And when you’re done with it, don’t forget to properly dispose of or recycle it!
This article was written by Minh Duong, MS, IFIC’s 2020 Sylvia Rowe Fellow