The Freezer: It Keeps Your Carrots Awake at Night! *
AbstractBrrrr, freezing cold! It's the worst nightmare of any fresh fruit or vegetable! If the produce in your kitchen had legs, they would run in a panic every time the freezer door opens. Why? Well, freezing temperatures are not kind to fresh produce. Freezing kills the plant tissues and alters them on both a chemical and physical level. Chemically, the enzymes in the produce become more concentrated and do not work normally, so that discoloration, off-flavors, vitamin breakdown, and toughness may develop. Physically, the water inside the cells of the fruits and vegetables crystallizes and expands as it freezes. The cell walls become cut and damaged by the sharp crystals, so that when the produce thaws, the water leaks out, and the produce becomes floppy and limp.
Manufacturers of frozen produce try to get around these problems in two ways:
- They utilize a technique called blanching to inactivate the enzymes that cause problems.
- They freeze the produce very quickly and to very low temperatures (-40°F). This minimizes the size of the ice crystals; thus, less damage is done to the cell walls.
In this cooking and food science fair project, you will investigate the power of blanching to improve the quality of frozen vegetables. You will peel and chop a vegetable into equally sized pieces, and then divide it into two groups. One group will undergo blanching, where it will be immersed for 1-2 min in rapidly boiling water, and then immediately scooped up and plunged into an ice water bath to stop the cooking. After the blanching, the vegetable will be drained and frozen in a single layer as rapidly as possible. The other group will not undergo the blanching process, but will simply be frozen in a single layer. Compare the color, texture, and toughness of the two groups after they are frozen solid for a week and a half and then thawed. A testing method for toughness is given in the Science Buddies science fair project, Tough Beans: Which Cooking Liquids Slow Softening the Most?. You can also select a sample piece of vegetable from each group, cut a cross-sectional slice, and examine it using a magnifying glass. Note any structural differences that you see.
Cite This PageGeneral citation information is provided here. Be sure to check the formatting, including capitalization, for the method you are using and update your citation, as needed.
Last edit date: 2017-07-28
- McGee, Harold. On Food and Cooking: The Science and Lore of the Kitchen. New York: Scribner, 2004. pp. 18-19, 24, 146-147, 206, 277-278, 495-496.
This source describes the process of blanching:
- W Contributors. (2008, May 22). Cookbook: Blanching. Wikibooks. Retrieved October 9, 2008, from http://en.wikibooks.org/w/index.php?title=Cookbook:Blanching&oldid=1191292
This source describes how to prepare different types of vegetables for freezing:
- Heller, K., Bond, J.M. (1996, July). Freezing Vegetables. North Dakota State University Agriculture and University Extension. Retrieved October 9, 2008, from http://www.ag.ndsu.edu/pubs/yf/foods/he187w.htm
News Feed on This Topic
- If you have a freezer capable of "deep-freeze" temperatures, evaluate the physical properties and ice crystal sizes that are produced when blanched produce is quickly frozen at the lowest freezer temperature possible, against the physical properties and ice crystal sizes that are produced when blanched produce is frozen at 0°C (the freezing point of water).
Ask an ExpertThe Ask an Expert Forum is intended to be a place where students can go to find answers to science questions that they have been unable to find using other resources. If you have specific questions about your science fair project or science fair, our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.
Ask an Expert
If you like this project, you might enjoy exploring these related careers:
Plant ScientistWith a growing world population, making sure that there is enough food for everyone is critical. Plant scientists work to ensure that agricultural practices result in an abundance of nutritious food in a sustainable and environmentally friendly manner. Read more
Food Scientist or TechnologistThere is a fraction of the world's population that doesn't have enough to eat or doesn't have access to food that is nutritionally rich. Food scientists or technologists work to find new sources of food that have the right nutrition levels and that are safe for human consumption. In fact, our nation's food supply depends on food scientists and technologists that test and develop foods that meet and exceed government food safety standards. If you are interested in combining biology, chemistry, and the knowledge that you are helping people, then a career as a food scientist or technologist could be a great choice for you! Read more
BiochemistGrowing, aging, digesting—all of these are examples of chemical processes performed by living organisms. Biochemists study how these types of chemical actions happen in cells and tissues, and monitor what effects new substances, like food additives and medicines, have on living organisms. Read more
Food Science TechnicianGood taste, texture, quality, and safety are all very important in the food industry. Food science technicians test and catalog the physical and chemical properties of food to help ensure these aspects. Read more
News Feed on This Topic
Looking for more science fun?
Try one of our science activities for quick, anytime science explorations. The perfect thing to liven up a rainy day, school vacation, or moment of boredom.Find an Activity