Science Fair Project Effects of Packaging on Foods

“Best if used by… Three weeks ago?” What now? Ah, but of course: “Mom, can I still eat these crackers?”

“Sure honey, knock yourself out.”

Rustle, rustle, munch, munch… “Eww, gross! They’re soft and taste like sawdust.”

With any luck, you haven’t experienced this scenario too frequently, but odds are that you’ve come face to face with stale or expired food at some point. Expiration dates on foods aren’t always exact, but they aren’t simply a random number either. The manufacturer or packager has spent a good amount of time studying the shelf life of their product. They have to choose packaging material that lets their product survive long enough to be useful, while keep costs low enough that the consumer can afford to buy it.

Harkening back to the crackers, they were probably stored in a plastic bag inside a cardboard box. This is a fairly common packaging arrangement for dry goods. Why not simply a cardboard box? That would surely serve to hold the crackers in. But then, what happens if the box is set on a puddle? Cardboard doesn’t keep moisture out, and that same moisture can help make crackers stale and soggy. (Worse, they might get moldy.) The plastic bag creates a moisture barrier.

Spills aren’t the only source of moisture. On any summer day there are likely thousands of people complaining about the humidity at any given moment. Humidity is simply water vapor, and if there is moisture in the air, it can be transmitted to anything it touches – particularly dry, absorbent items like crackers. Any barrier that can keep water vapor out can help preserve freshness.

Air isn’t just water vapor, of course. A good 20% of it is oxygen, which is great news for those of us who want to breathe – including aerobic bacteria that would love to grow on your food. Packaging that keeps air out also helps stop them from proliferating. If the food itself can react with oxygen (as when raw meats or apple slices turn brown), preventing exposure to oxygen is also desirable.

Temperature controls are used to slow both bacterial growth and oxidative processes. Chemicals can be added for the same purpose. In short, there are many ways to help protect food freshness, but most people never give it a thought other than to peel off the wrapper and throw it away.

Your mission, should you choose to explore this topic, will be to examine how different packaging configurations affect food preservation and expiration, and to identify best storage practices. You will have the opportunity to test existing methods and those of your own creation. Taking it to the next level, you will also compare the costs associated with good versus better packaging options.

Step 1: Choose Your Weapons

Select two or three different food items that you will study. Try to choose foods with different characteristics. For instance, if you choose crackers as one (dry, salty, and made of grain), your second choice should not be cereal. Instead, bologna (moist and almost made from meat), milk (liquid cow juice), apple sauce (moist and fruity) would provide the necessary variety.

Step 2: Know Thy Enemy

It would be silly to start from scratch when companies have been packaging foods for generations. Get out and research how your target foods are typically packaged. Is there an industry standard that is followed, or are there several common packaging options? Check the posted expiration dates on a number of packages to see about how long the food lasts in each type of packaging. (Hint – most stores put their newest goods at the back of the shelf, following the “first in, first out” rule. See if you can guess why they do this.)

Step 3: Battle Plans

Choose several different packaging configurations to investigate for each food you’ll be testing. You can try to simulate the commercial packaging for one. You’ll likely have to be creative. Most people won’t have the necessary equipment to heat seal various plastics. A cracker box with plastic liner could be simulated with a shoe box and a sealable food storage bag, for example. On top of mimicking the commercial storage solution, try a few of your own. If you have access to canning supplies or mason jars, you might give either a try. You can look at plastic containers, plastic wrap, wax paper, newspaper, sealed bank vaults, and any combination that you may choose to put together. As a control study, remember to also have a No Packaging sample, so that you can observe whether the other packaging arrangements have had any effect. Besides the container, also consider the environment. Will the item be stored at room temperature? In the refrigerator? Outside (where temperature fluctuates)? In the light or in the dark? In a humid place or a dry place? While you don’t need to try all options, it is important that you record those that you do. Try to choose those conditions that best reflect how the food is likely to be stored, to keep the study relevant.

Once you have chosen the conditions, consider your time frame. How long do you need the study to last? (You can use your research to help with this. Assume that you may want to be able to keep the study going at least as long as the manufacturer does. That decided, you’ll also have to decide how often you will examine your samples. This is important because you have to prepare a separate package for each time point that you plan to examine them. You can only open a package once before the storage conditions have changed, and you’ve exposed it to air/moisture/light/germs. (It is usually best to test frequently at the start and less often later on. You might start with every day, then every two days, every week, etc.) Lastly, you’ll have to decide what test you will use to determine the freshness/expiration of your food when you sample it. Will you use smell, taste, appearance, texture or some other criteria as your measure of the food’s fitness. (If you’re doing raw meat, please don’t use taste.)

Step 4: Have at Thee

With your plans made, buy up all the food and packaging material you’ll need for the duration of the study. In one day, prepare all the packages of your food and place them in the designated storage places. (Remember, you’ll have seven, or twelve, or fifty of each package in each place, depending on how often you plan to test your samples and for how long.) This is your Day Zero, when you know everything was fresh. Take care in packaging that you use clean materials (and hands) so that you don’t cause spoilage sooner than expected.

On your designated days, sample one of each packaging type, and record freshness or not-so-freshness in your notebook, chart, or other data log. You’ll have to decide on a rating system depending on the food. (Crackers are: hard and tasty, hard and tasteless, somewhat soft but tasty, very soft and tasteless, somewhat soft and covered in green fuzz…) In the end, you’re going to identify when (if ever) the food in a certain package type expired. Once that happens, you don’t have to continue testing that packaging type. (Food doesn’t un-spoil, after all.)

Step Five: Mopping Up

Now it’s time to evaluate your data and write your report.

Give the basic facts: Define each packaging type, and Report how long it kept food from expiring.

Evaluate: Compare the relative effectiveness of the different packaging types, based on how long they kept the food good. Compare this against the amount of time given by the manufacturer. Draw conclusions about which types of packaging materials are most effective at preserving which types of foods. (Conclusions must be supported by your research – no speculating.)

Apply the knowledge: Look at the cost of each type of packaging, and estimate what it would cost to use on a large scale. Dividing the packaging cost by the number of packages gives an idea of how much must be added to the price of the food. Is there a best option for packaging versus expense?

Speculate: Let the creative juices flow – describe how you could take the experiment further to build upon what you’ve already learned. If any questions were raised by your experiments, describe how you can go about answering them. Best of all, if you got into this project, this is your chance to start planning to continue it for next year.

One last note – if you find a better, cheaper way to package food – apply for a patent. (Don’t delay!) Then you can slap the label “Patent Pending” on your project before anyone can steal your idea, and you get to sell it to the food companies.