News & Events

Importance of Metal Packaging

Author: Rachel Tan Choon Hui (Lecturer, UCSI University)

Packaging is one of the essential parts of all food processing operations and is a means of ensuring safe delivery of products in sound condition to the consumers at a minimum cost. We can find various types of packaging in the market ranging from cup, tube, laminated carton, bag, box, bottle and can. The development of food packaging started more than 200 years ago and there were many major breakthroughs ever since.

Nicholas Appert from France, who also known as "father of canning", was the one who invented canning process in 1809. The first canning factory in the world, which had been set up in Bermondsey, London, by John Hall and Bryan Donkin, sold perishable foods to the public packed in tinplate containers, for the first time, in 1812. During the 1960s, two-piece drawn and wall-ironed can was developed in the United States for carbonated drinks and beers (Coles and Kirwan, 2011). In 1976, US engineer Daniel Cudzik created a ring-pull on top of a can that stay-on after open.


A two-piece can. Precoated tinplate is cut to a disc and is drawn and ironed into a cup. Adapted from: http://www.chinacomputerparts.com/images/d-p1121790730354980625-aluminum_two_piece_rectangular.html


A three-piece can. Tinplate is rolled into cylinders and edges are welded. The rims (can ends) are curled and sealing compound are injected. Adapted from http://stravaganzastravaganza.blogspot.com/2012/02/modern-tinplate-cans.html#!/2012/02/modern-tinplate-cans.html


A ring-pull tab on an aluminium drinking can. Adapted from https://commons.wikimedia.org/wiki/File:Drinking_can_ring-pull_tab.jpg

One of the functions of packaging is the containment of food products before they can be moved from one location to another. The containment function of packaging has to be done properly to avoid product loss or alteration. It is also crucial that the type of packaging material is chosen carefully, which depends on the product’s physical form and nature. For instance, a viscous and acidic tomato concentrate should be packed in a sealed container and the packaging material should not react with the concentrate chemically. In this case, glass can be used as the packaging material because it is inert which means it is not readily reactive with other elements.

Packaging is also used for the protection of food products from degradation agents such as water, gases, odors, microorganisms, dust, and mechanical damage due to shocks, vibrations as well as compressive forces. Improper protection of food products caused by faulty packaging can be disastrous because a large scale food poisoning could occur in the society. Furthermore, it could also result in a major pollution of the environment. In March 2013, the U.S. Food and Drug Administration (FDA) announced a voluntary product recall by Bumble Bee Foods of its 5-ounce Chunk White Albacore and Chunk Light Tuna due to loose seals or seams. If a can integrity is breached, there will be a potential risk of product contamination by spoilage organisms or pathogens that may lead to illness if consumed. Therefore, food manufacturers always make every effort to implement and follow a stringent quality system during food production in order to ensure that their products have the highest margin of safety and quality.

Besides, packaging is essential for the sake of convenience not only for the pack handlers but also the consumers. In today’s society, the number of women in the workforce has increased tremendously. People are always on-the-run especially those who live in the city. How much time do people spend in the kitchen to prepare food nowadays? Some people spend less than eight hours a week in the kitchen preparing meals or having a cup of coffee. Having said that, there is a greater demand of convenient food especially food that is pre-cooked and can be reheated in a very short time. Ready-to-eat foods like ice-cream, canned seafood, pre-cut fruits, candy, nuts, hotdogs or soft cheese are loved by consumers of any age especially those that does not require removing them from their primary package. Thus, packaging plays an important role in meeting the demands of consumers for convenience.


Examples of ready-to-eat food: pineapple slices, chunks and crushed pineapple. Adapted from http://www.lee-pineapple.com/products.html

As far as the food industry is concerned, packaging is vital for brand communication. Imagine if all products in the supermarket are all packed in black color containers without any labelling, brand, graphics and whatnot. It would be a real pain in the neck in attempting to make purchasing decisions because you have to guess what is the content in each and every package. Through proper labelling, we can know the specific name of a product, the manufacturer’s address, weight of the content, ingredients used and expiration date. In some countries, the nutritional information is mandatory including Malaysia. This information is crucial as it helps consumers to choose a product that meets their requirement. For example, there are many brands of cheddar cheese and you may wonder which brand to choose. As a smart consumer, you may compare the price and weight of the product first. If both the price and weight are the same, this is when the nutritional information will help you decide whether you want the one that has a higher protein content or lower fat content.

There are various types of packaging materials including glass, metal, paper, plastics or a combination of materials. Metal is one of the most common packaging materials that is suitable for the canning process. Materials like aluminium, steel, tin and chromium are used for the manufacture of metal containers. Tin and steel or chromium and steel can be used as composite materials in the form of tinplate and electrolytically chromium-coated steel (ECCS). Tinplate has been used for preserving food for well over a hundred years that gives a long, safe, ambient shelf life with no, or minimal, use of preservatives.

One of the reasons why metal is chosen as packaging material is that metal is impermeable to dust, gases, water and microorganisms. Impurities like dust and dirt are undesirable in terms of hygiene. The presence of foreign water that migrates from environment to food will cause the deterioration of food. We also know that microorganisms will not only spoil our food but can also make us sick. Another feature of metal is that it has total protection of food products from light, which might cause deterioration of vitamin A and C. Therefore, due to its excellent properties in the protection of food against various degradation agents, metal is one of the best materials used in canning.


Double seam made of five layers compressed and ironed tightly to form a hermetic seal that prevents leakage. Adapted from http://packaging-technology.org/43-can-seamers.html

Metal cans are specifically designed to withstand handling and processing conditions that may involve high temperature and pressure. The melting points of aluminium, stainless steel, tin and chromium are 660oC, 1510oC, 232oC and 1860oC, respectively. In other words, metal packaging has the thermal stability and capacity for being moulded to various shapes or thicknesses. Other than being thermal stable, metal has higher heat conductivity compared to other packaging materials. For the sterilization process during canning, the temperature does not usually exceed 150oC. This is because the targeted bacteria during canning of low acidic food – Clostridium botulinum, cannot survive above 120oC. Clostridium botulinum contains a powerful neurotoxin that may cause double vision, slurred speech or paralysis. Even though Clostridium botulinum is heat resistant, they can be destroyed during sterilization including its spores.

Many consumers always wonder whether or not metal cans are suitable to be used as food packaging. They think that metal cans are easily oxidized or corroded and chemical reactions will occur because of the interactions between the metal packaging and the food product in the package. As a matter of fact, internal lacquers are available that reduce this effect by providing a barrier between the food and the metal can wall. The presence of lacquer also effectively prevents dissolution of tin into the product. In addition, tinplate has corrosion resistance to the acids found in foods. However, tinplate sometimes is lacquered where particularly aggressive products are packed like tomato purée, or where there is a danger of pitting corrosion or surface staining. Certainly, chemical reaction within a properly packaged metal can may occur if the can is handled improperly, suffer a severe mechanical impact or stored at high temperatures. Also, when sufficient concentrations of nitrates are present, which possibly originates from fertilisers in the ingredients of the food, detinning may occur at a rapid rate.

There is no doubt that the ever-increasing demand for canned food products for its convenience has generated tremendous amount of profit to many companies. The total world market for metal containers is estimated at 410 billion units per annum. Drink cans alone, including beers, soft drinks and juices account for some 320 billion units. Nonetheless, commercial canners are always in search of better packaging design and innovations to create and sustain the canning industry worldwide in order to meet consumers’ requirement.

 

References:

Blunden, S. and Wallace, T. 2003. Tin in canned food: A Review and Understanding of Occurrence and Effect. Food and Chemical Toxicology. 41: 1651-1662.

Coles, R. and Kirwan, M. 2011. Food and Beverage Packaging Technology. UK: Blackwell Publishing Ltd.

Food and Drug Administration (FDA). 2013. Recall, Market Withdrawals and Safety Alerts. http://www.fda.gov/Safety/Recalls/ucm342592.htm

Robertson, G. L. 2006. Food Packaging Principles and Practice. USA: CRC Press.

Smith, J. S. and Hui, Y. H. 2004. Food Processing Principles and Applications. USA: Blackwell Publishing Ltd.