This lesson focuses on how food packages are designed and made. Students will learn three of the main functions of a food package. They will learn what is necessary of the design and materials of a package to keep food clean, protect or aid in the physical and chemical changes that can take place in a food, and identify a food appealingly. Then, in the associated activity, the students will have the opportunity to become packaging engineers by designing and building their own food package for a particular type of food.

There is a whole industry devoted to packaging engineering and this industry is expanding as more and more products are created. Packaging engineers have to focus on all the components that the students will focus on in this exercise which include research, design, production, marketing, and analysis. chemical changes design food marketing packaging phase change physical changes physical properties Physical properties of matter: mass, volume, melting point, boiling point, and texture. Chemical properties of matter: combustibility, solubility, flammability. Physical changes: phase change, shape change. Chemical changes: oxidization, evolution of gas. Identify four functions of a food package. Explain how each food package design works. Identify the chemical and physical changes different types of materials prevent or facilitate. Explain what a food packaging engineer does. There is a whole field of engineering that concentrates on designing packages for different food products. Today, we are going to look at some packages food engineers have already designed and see why they made them the way they are. How many of you have ever drank out of a bottle? (Hold up a soda bottle) Have you ever realized why a bottle is designed the way it is? Tell me some of the qualities of this bottle and the reasons why the bottle has those characteristics. (Write them on the board). Now, lets look at this bag of flour. (Hold up a bag of flour) What is different about the characteristics of this bag than those of the soda bottle? (Main differences: material and structure) Why do you think that the bag is so different from the bottle? Now look at these two other packages (Hold up a package that holds soup or noodles that can be heated and a food in a plastic bag). Please write down the qualities of these packages and why you think they have those characteristics. Looking at the reasons for each of the packages, can we brainstorm three important functions of a food package besides just to carry the food? To keep the food clean. To protect the food product from unwanted physical and chemical changes (such as oxidation and destruction from insects) and to facilitate in desired physical changes (such as heating or cooling). To identify the product and provide sales appeal. Now please write beside each characteristic you wrote down, what function is being fulfilled. As you can see, the materials that a package is made out of plays a huge role in the function of that package. If you wanted to be able to put your food and package in the microwave, would you make the package out of metal? Why not? If you wanted to make sure your food would not be crushed by something heavy, would you put your food in a plastic bag? Would you put a liquid in a package made of paper? Besides a package's materials, its actual structural design is very important for its functions. What type of food package structures can you think of? Cartons (milk carton) Boxes (cereal box) Bags (bag of chips/bag of vegetables) Cans (can of soup) Bottles (bottle of soda) Wrappers (candy) What are the advantages and disadvantages of these package structures? Let's look at these two different packages for the same food. (Bring out a food packaged aesthetically and the same food packaged less appealingly). Which one would you rather buy? What qualities does that package have that the other does not? (A symmetrically shaped package, a pretty label, a nicely colored package, etc). Food packages have four main functions besides just providing something to carry a food around in. To keep the food clean. To protect the food product from unwanted physical and chemical changes (such as oxidation and destruction from insects) and to facilitate in desired physical changes (such as heating or cooling). To identify the product and provide sales appeal. To be inexpensive, both in its materials and its transportation. In this lesson, a focus on the first three functions of a food package will provide a great introduction to how package materials are chosen. The first function is pretty simple to fulfill. Cohesive materials should be used in packaging to prevent dirt from getting into the food. However, fresh produce is an exception to this rule as a fruit or vegetable's skin protects the inside from contamination and consumers are always expected to clean the product before eating. Fruit and vegetables are basically "self-packaged." The second function of food packages is probably one of the hardest to understand. There are a number of physical changes that can be looked at for this function. The main physical change that can occur is physical damage. Food can be crushed and bruised without the proper protection from its package. Another physical change that children can relate to is soda going flat. The scientific word for this happening is effervescence, which is the escape of air bubbles from a liquid. This physical change occurs when a carbonated beverage is opened. The carbonation quickly escapes through the opening. Students should consider this physical change in the packaging of beverages. Bottles can be resealed to prevent the further escape of air bubbles but cans cannot. Also many children are familiar with mixing. Mixing here means to disperse one substance throughout another usually by swirling. A food example would be dissolving a lemonade powder in water. This process is not a chemical change because the water and powder do not form new chemical. The powder is solely dispersed evenly throughout the water to make a mixture of individual water and lemonade molecules. A major physical change that should be talked about is phase change. Phase changes occur if a food changes state between solid, liquid, or gas. An example of a food whose package must consider phase change is ice cream. An ice cream carton is meant to hold an almost solid ice cream. However, the design must also anticipate liquid in case of melting. The design must also be capable of being put in the freezer and also taken out by the consumer. Therefore, a good point to make is that a food package designer would not make an ice cream package out of metal because it would be too cold to touch and remove from the freezer. Also, designs for packages for foods that are meant to be warmed up in a microwave should take into account the melting point (the temperature at which a material changes from solid to liquid) of the package materials. If the package is to be microwaved, a material with a low melting point would not be considered, as the package would melt into the food! A major chemical change involved in the creation of food packages organic growth in a food. This organic growth occurs by way of microorganisms, which feed on a food. As these microorganisms feed, the food rots and the microorganisms multiply. It is not eating the rotten food that makes a person sick but it is eating the vast number of microorganisms on that food. Microorganism growth can include the growth of bacteria, molds, and yeast. Microorganisms grow and affect different foods at different rates. The package in which a food is held affects a food's rate of organic change. Such organic change affects how long a food can be stored before and after its opening. Plastics and cans do not allow moisture to seep into the food product that they hold. Thus, they keep microorganisms from outside away from the food. Vacuum sealing removes all of the oxygen from a food. Without oxygen, microorganisms cannot grow and so the food does not rot. If a food's dangerous microorganisms have been removed through processing, these packages will prevent most organism growth in the food and will allow its shelf life to be considerably long. These non-perishable foods and can last for two years or longer. After the opening of a food package, however, microorganisms in the air can quickly get in to the package to start an organic degradation of the food. This event is why food packages say, "refrigerate after opening". Microorganisms can only grow in certain temperatures so refrigeration will slow rotting and freezing will usually stop degradation all together. In spite of this, naturally non-perishable foods whose majority is not fruit, vegetable, nut oil, or dairy will be okay if not refrigerated for a reasonable amount of time since their rate of organic change is very slow. Many different processes exist to make a food non-perishable as discussed earlier. A major process is thermal processing, where foods are treated with heat to destroy all of their microorganisms. Thermal processing takes a lot less energy for plastic packaged foods than metal packaged foods. Thus, taste is preserved more in plastic packaged food than canned food. This is a major advantage to use plastic in packaging rather than metal. Paper packages allow the entrance of oxygen and moisture. Thus, such packages usually hold foods whose rate of organic change is very slow or foods whose consumption is assumed to happen within days of production. Despite the physical and chemical changes that some materials may prevent or encourage, all materials have their advantages and disadvantages which are listed in the Food Packaging Materials Worksheet. The temperature at which a substance changes from liquid to gas. The temperature at which a substance changes from solid to liquid. A transition between liquid and gas or liquid and solid. The ability for a substance, the solute, to dissolve in a solvent. Package Those Foods! Ask the students to analyze the physical properties of a food and identify the chemical and physical changes that they need to pay attention to in the creation of their food package. Have them describe how they would address each of the functions of a food package. American Management Association. Packaging Division. Packaging for Retail Impact, with Specific Applications to the Dairy, Meat, Candy, and Baking Industries. New York: American Management Association, 1965. Food Packaging Materials Worksheet (pdf) Food Packaging Materials Worksheet (doc)