The Cranberry: Natural History and Home Made Cranberry Sauce Recipe
What's the story of cranberries?
Cranberries are a common side for holiday dishes in North America, especially around Thanksgiving and Christmas. The red berries are tart and appropriately colored for the season with a bright red color. For many the only thing they may think of when they prepare cranberries is that sucking sound that the solid mass of cranberry makes as it slides out of the can. But, If you're like me, you might like to make home made cranberry sauce, or know a bit more about where those berries came from. I firmly believe in knowing about what you eat, how it grows, and how it is produced. So, in this light, much like the Turkey Snood post, we'll start this one with a short natural history of the cranberry and follow up with a homemade cranberry sauce recipe that has been in our family for a long time. At the end of the post I'll also provide you with some neat resources for teaching about cranberries in the classroom or on an interpretive hike.
Cranberry Natural History
Cranberries are a type of evergreen shrub, which is perhaps why they have come to represent the holidays, with their red berries and evergreen trimmings. They are in the genus Vaccinium and sub-genus Oxycoccus. The North American species is Vaccinium macrocarpon. They are found in Eastern North America, in acidic bogs and wetlands. Often you will find them near stands of pine and possibly oak trees. They require sandy and peaty soil to survive, along with a growing season from April-November. Cranberries grow along the ground as a creeping shrub that can get up to 6-7 ft long. They also usually don't get over 8 in tall. Their stems are somewhat woody (think of pine tree branches) and have small evergreen leaves. A cold season is required to chill the buds of the fruit into ripe berries before harvesting. This is why they do well in the North Eastern US.
Cranberries get their name from their flowers, which are dark pink, and look like the bill of a crane. Originally craberries were called "craneberries." Cranberries are also called mossberries and fenberries in England. Native Americans cultivated cranberries and incorporated it into their pemmican (a mixture of meat, berries, animal fat and sometimes seeds dried into portable food, think of today's power bars). It's thought that Algonquian Native Americans introduced them to European settlers. There are records of early ships using the berries to prevent scurvy. The vines are long-lived and some are thought to be over 150 years old, which makes them ideal for cultivation because they do not need replanting. However, it takes about 6 years before the young vines produce fruit.
Cranberries are grown in flooded bogs, with new growth of vines emerging in the Spring. The plants require a great deal of water to cultivate, and the bogs in which they grow must be kept continually wet and moist. Cranberries can be dry harvested, with machines that comb the berries off the vines and into burlap bags. However, the most iconic images of cranberry growing comes from the wet harvesting (which is about 95% of cranberries harvested). Wet harvesting is when cranberry bogs are flooded with water. Cranberries have pockets of air inside them, which is why they float. Large machines that look like paddle wheels as are run through flooded cranberry bogs, and used to dislodge the berries from the vines. Plastic booms are then used to round up the berries, where they are sucked into trucks and taken to a cleaning station. Fresh cranberries bounce when dropped. John Webb (from New Jersey) figured this out. So, when growers process the berries at a plant they use a bounce-board which is a separator. The firmest fruits bounce on to be packaged for our dinner table (or juice), while the bruised or rotten berries don't bounce.
In the winter, January-February, some growers protect their vines from the cold (and drying out) by ice sanding the cranberries. This happens when the flooded bogs are frozen, with 3-4" of ice on them. The farmers use a technique developed by Captain Henry Hall, who discovered that by leaving sand on the ice when the ice melts and the sand falls into the vines it stimulates the development of new roots and covers the base of the plants, protecting the root system. This may also be beneficial for controlling pests, fungal spores, and insects, as well as helping to bury new seeds. Blowing sand, which causes growth and stimulation, may partly be why cranberry bogs are often found in sandy soils.
Here's a great video on how cranberries are harvested. You'll never look at them the same way again.
The Benefits and Potential Harms of Cranberries
Have you ever tried to eat a cranberry that hasn't been sweetened? It's quite sour. The berries are high in vitamin C and also have a high salicylic acid content, this is why you have to add sugar to cranberry compote or sauce (on a side note, salicylic acid is what is used in facial cleaner pads for its astringent properties). An old wives tale is that that you should drink cranberry juice to cure a urinary tract infection (UTI) or kidney problem. There is no good correlation between cranberries and treating UTIs. Check out this paper by the European Food Safety Authority (EFSA) or from the Cochrane Collaboration of not-for-profit researchers that also concluded that there is no evidence of this theory. The National Institute of Health suggests that cranberry juice helps prevent UTIs though. It is thought that that acidity of cranberries, and the chemicals in them, prevent bacteria from sticking to the lining of the urinary tract. The salicyclic acid in cranberries is also an ingredient found in aspirin, which is is used to reduce swelling and prevent blood clots. The trouble comes from the fact that cranberries have high levels of a chemical called oxalate. Drinking cranberry juice can increase the amount of oxalate in urine by as much as 43%, which is a lot! Kidney stones are mostly made from oxalate combined with calcium, so if you drink too much cranberry juice you may be putting yourself at risk of kidney stones. So, all things in moderation.. Nutrition Facts about cranberries can be found by clicking here.
Recipe for Homemade Cranberry Sauce
Despite the benefits and potential harms of cranberries, they are a delightful food that you shouldn't shy away from. Most cranberries are made into juice, jelly/compote, or sauce. This is especially true around the holidays (though some do go into cosmos too). Cranberry sauce is a long running tradition in my family (and I usually end up calling Mom the day before because I can't remember the recipe). So, from our family to yours:
Mom's Homemade Cranberry Sauce
Resources for Teaching About Cranberries
- Cranberries: Fruit of the Bogs, Burns and Bellville (Children's book ages 7+)
- The Legend of the Cranberry, a Paleo-Indian Tale, Greene (Children all ages) A Delaware Native American story about how the first peoples were given cranberries from the death of a mastodon.
- Cranberries, Jaspersohn (adult)
- A unit from Penn State (originally for 4H) about cranberry pigment or anthocyanin (an acid).
- Learn About Cranberries free curriculum from the Wisconsin Cranberry growers.
For younger students you can do cranberry math with the actual berries. For older students you can try cooking a recipe using cranberries and incorporate measurement skills and chemistry into the mix.