Question

"Here's a Food Wrapper You Can Eat"
by Randy Rieland

Consider the cheese stick. It is not a beautiful food. It also isn't particularly healthy. Cheese sticks are about as commonplace as snack food gets.

Yet in the packaged version that ends up in so many kids' lunch boxes, each cylinder of mozzarella or cheddar is individually wrapped, like a high-end truffle. And, every day, thousands of those little pieces of plastic wrap are thrown in the trash.

But that may not be the case for long.

Two researchers at the U.S. Department of Agriculture (USDA) have developed a film made from a milk protein. The film can be eaten with the cheese. Which means that it may not be too long before we have a wrapper we can eat. It also could be healthy. Edible plastic exists, but it's largely made of starch, not protein.

"The benefit," says Peggy Tomasula, one of the lead researchers, "is that it can be consumed with the food so it gets rid of one layer of packaging, like with individually wrapped cheese sticks. It also gives you the opportunity to add vitamins or minerals or ways to block light damage to the food. And, you can add flavors. If you wanted to add a strawberry flavor to something, you can embed that in the film."

The key component in the innovative packaging is casein, a group of milk proteins with high nutritional value. Tomasula has been researching casein since 2000, and actually created a new version of the protein using carbon dioxide. She noticed that it wasn't very soluble in water, and that made her believe it might be used to make a film coating that could extend the shelf life of dairy foods.

Tomasula kept exploring the potential of this research and when another scientist, Laetitia Bonnaillie, joined the USDA team, Tomasula asked her to see if dry milk could be used to produce the film. That would also allow them to make use of surplus milk powder during times when dairy farms are producing too much milk. Bonnaillie also focused on refining the product by making it less sensitive to moisture and improving the process by which the film was made so it could be more uniform and commercial.

At the annual meeting of the American Chemical Society, they announced the results of their efforts. It is edible, biodegradable packaging. The casein film could either come in sheets, not unlike plastic wrap, or be sprayed on as a coating. And, it's been found to be significantly more effective at blocking oxygen than ordinary plastic wrap, so it can protect food from spoiling for a much longer period of time.

Use the passage to answer the question.

In 3-5 sentences, explain the author's purpose and analyze how the author used rhetorical devices to achieve this purpose. Include evidence from the text to support your answer.

Answer 1

The author's purpose is to inform readers about a new edible, biodegradable milk-protein film and to persuade them that it is a practical, environmentally friendly improvement over conventional packaging. To engage readers and highlight the problem, the piece opens with a concrete image and mild shock value—cheese sticks are “individually wrapped, like a high-end truffle,” and “thousands of those little pieces of plastic wrap are thrown in the trash”—which appeals to pathos and frames the need for change. The article builds credibility (ethos) and logical support (logos) by quoting a lead researcher—“The benefit...is that it can be consumed with the food”—and by giving technical details about casein and that the film is “significantly more effective at blocking oxygen,” which argues for its practical advantages. Finally, the brief narrative of the researchers’ work and use of surplus milk shows real-world feasibility, strengthening the persuasive, informative aim.