Cranberries are a group of evergreen dwarf shrubs or trailing vines in the genus Vaccinium subgenus Oxycoccos, or in some treatments, in the distinct genus Oxycoccos. They are found in acidic bogs throughout the cooler parts of the Northern Hemisphere.
Cranberries are low, creeping shrubs or vines up to 2 m long and 5 to 20 cm in height;[1] they have slender, wiry stems that are not thickly woody and have small evergreen leaves. The flowers are dark pink, with very distinct reflexed petals, leaving the style and stamens fully exposed and pointing forward. They are pollinated by domestic honey bees. The fruit is an epigynous berry that is larger than the leaves of the plant; it is initially white, but turns a deep red when fully ripe. It is edible, with an acidic taste that can overwhelm its sweetness.
Cranberries are a major commercial crop in certain American states and Canadian provinces (see "Cultivation and Uses" below). Most cranberries are processed into products such as juice, sauce, and sweetened dried cranberries, with the remainder sold fresh to consumers. Cranberry sauce is regarded an indispensable part of traditional American and Canadian Thanksgiving menus and European winter festivals.
Since the early 21st century within the global functional food industry, there has been a rapidly growing recognition of cranberries for their consumer product popularity, nutrient content and antioxidant qualities, giving them commercial status as a novel "superfruit".[2][3]
Species and description
There are three to four species of cranberry, classified in two sections:
- Subgenus Oxycoccos, sect. Oxycoccos
- Vaccinium oxycoccos or Oxycoccos palustris (Common Cranberry or Northern Cranberry) is widespread throughout the cool temperate Northern Hemisphere, including northern Europe, northern Asia and northern North America. It has small 5-10 mm leaves. The flowers are dark pink, with a purple central spike, produced on finely hairy stems. The fruit is a small pale pink berry, with a refreshing sharp acidic flavour.
- Vaccinium microcarpum or Oxycoccos microcarpus (Small Cranberry) occurs in northern Europe and northern Asia, and differs from V. oxycoccus in the leaves being more triangular, and the flower stems hairless. Some botanists include it within V. oxycoccos.
- Vaccinium macrocarpon or Oxycoccos macrocarpus (Large cranberry, American Cranberry, Bearberry) native to northeastern North America (eastern Canada, and eastern United States, south to North Carolina at high altitudes). It differs from V. oxycoccus in the leaves being larger, 10-20 mm long, and in its slightly apple-like taste.
- Subgenus Oxycoccos, sect. Oxycoccoides
- Vaccinium erythrocarpum or Oxycoccos erythrocarpus (Southern Mountain Cranberry) native to southeastern North America at high altitudes in the southern Appalachian Mountains, and also in eastern Asia.
Cranberries are related to bilberries, blueberries, and huckleberries, all in Vaccinium subgenus Vaccinium. These differ in having stouter, woodier stems forming taller shrubs, and in the bell-shaped flowers, the petals not being reflexed.
Some plants of the completely unrelated genus Viburnum are sometimes inaccurately called "highbush cranberries" (Viburnum trilobum).
Cranberries are susceptible to false blossom, a harmful but controllable phytoplasma disease common in the eastern production areas of Massachusetts and New Jersey.
Etymology and history
The name cranberry derives from "craneberry", first named by early European settlers in America who felt the expanding flower, stem, calyx, and petals resembled the neck, head, and bill of a crane (bird). Another name used in northeastern Canada is mossberry. The traditional English name for Vaccinium oxycoccos, fenberry, originated from plants found growing in fen (marsh) lands.
In North America, Native Americans were the first to use cranberries as food. Native Americans used cranberries in a variety of foods, especially for pemmican, wound medicine and dye. Calling the red berries Sassamanash, natives may have introduced cranberries to starving English settlers in Massachusetts who incorporated the berries into traditional Thanksgiving feasts. American Revolutionary War veteran Henry Hall is credited as first to farm cranberries in the Cape Cod town of Dennis around 1816. In the 1820's cranberries were shipped to Europe. [4] Cranberries became popular for wild harvesting in the Nordic countries and Russia[citation needed]. In Scotland, the berries were originally wild-harvested but with the loss of suitable habitat, the plants have become so scarce that this is no longer done.
Cultivation and uses
Cranberries are a major commercial crop in the U.S. states of Maine, Massachusetts, Michigan, Minnesota, New Jersey, Oregon, Washington, and Wisconsin, as well as in the Canadian provinces of British Columbia, New Brunswick, Ontario, Nova Scotia, Newfoundland and Quebec. According to the Economic Research Service of the United States Department of Agriculture, Wisconsin is the leading producer of cranberries, with over half of U.S. production. Massachusetts is the second largest U.S. producer, with 28% of total domestic production. A very small production is found in southern Chile, in the Baltic States, and in Eastern Europe.
Historically, cranberry beds were constructed in wetlands. Currently cranberry beds are constructed in upland areas that have a shallow water table. The topsoil is scraped off to form dikes around the bed perimeter. Clean sand is hauled in to a depth of four to eight inches. The surface is laser leveled with a slight crown in the center to facilitate drainage. Beds are frequently drained with socked tile in addition to the perimeter ditch. In addition to making it possible to hold water, the dikes allow equipment to service the beds without driving on the vines. Irrigation equipment is installed in the bed to provide irrigation for vine growth and for spring and autumn frost protection.
Cultivation
Cranberry vines are propagated by moving vines from an established bed. The vines are spread on the surface of the sand of the new bed and pushed into the sand with a blunt disk. The vines are watered frequently during the first few weeks until roots form and new shoots grow. Beds are given frequent light application of nitrogen fertilizer during the first year. The cost of establishment for new cranberry beds is estimated to be about US$70,000 per hectare.
A common misconception about cranberry production is that the beds remain flooded throughout the year. During the growing season cranberry beds are not flooded, but are irrigated regularly to maintain soil moisture. Beds are flooded in the autumn to facilitate harvest and again during the winter to protect against low temperatures. In cold climates like Wisconsin, Massachusetts, and eastern Canada the winter flood typically freezes into ice, while in warmer climates the water remains liquid. When ice forms on the beds, trucks can be driven onto the ice to spread a thin layer of sand that helps to control pests and rejuvenate the vines. Sanding is done every three to five years.
Harvesting and food uses
Cranberries are harvested in the fall when the fruit takes on its distinctive deep red color. This is usually in late September or early October. To harvest cranberries, the beds are flooded with six to eight inches of water above the vines. A harvester is driven through the beds to remove the fruit from the vines. For the past 50 years, water reel type harvesters have been used. Harvested cranberries float in the water and can be corralled into a corner of the bed and conveyed or pumped from the bed. From the farm, cranberries are taken to receiving stations where they are cleaned, sorted, and stored prior to packaging or processing.
Although most cranberries are wet-picked as described above, 5-10% of the US crop is still dry-picked. This entails higher labor costs and lower yield, but dry-picked berries are less bruised and can be sold as fresh fruit instead of having to be immediately frozen or processed. Originally performed with two-handed comb scoops, dry picking is today accomplished by motorized, walk-behind harvesters which must be small enough to traverse beds without damaging the vines.
White cranberry juice drinks are made from regular cranberries that have been harvested after the fruits are mature, but before they have attained their characteristic dark red color. Yields are lower on beds harvested early and the early flooding tends to damage vines, but not severely.
About 95% of cranberries are processed into products such as juice drinks, sauce, and sweetened dried cranberries. The remaining 5% is sold fresh to consumers. Cranberries destined for processing are usually frozen in bulk containers shortly after arriving at a receiving station. To allow air movement deterring decay, cranberries for fresh market are stored in shallow bins or boxes with perforated or slatted bottoms. Because harvest occurs in late autumn, cranberries for fresh market are frequently stored in thick walled barns without mechanical refrigeration. Temperatures are regulated by opening and closing vents in the barn as needed.
Usually cranberries as fruit are served as a compote or jelly, often known generically as cranberry sauce. Such preparations are traditionally served with roast turkey meat and are considered by some to be a staple of English Christmas dinners, and the Canadian and US holiday Thanksgiving. The berry is also used in baking (muffins, scones and cakes) but, unlike many other berries, is normally considered too sharp to be eaten unaccompanied.
Fresh cranberries can be frozen at home, and will keep up to nine months; they can be used directly in recipes without thawing.[5]
Cranberry juice is a major use of cranberries; it is usually either sweetened to reduce its natural severe tartness and make "cranberry juice cocktail" or blended with other fruit juices.
Nutrients and antioxidant capacity
Cranberries have moderate levels of vitamin C, dietary fiber and the essential dietary mineral, manganese, as well as a balanced profile of other essential micronutrients.[6]
By measure of the Oxygen Radical Absorbance Capacity with an ORAC score of 9,584 units per 100 g, cranberry ranks near the top of 277 commonly consumed foods in the United States.[7]
| Nutrients in raw cranberries[8] | ||
| Nutrient | Value per 100 grams | % Daily Value |
|---|---|---|
| Energy | 46 kcal | |
| Fiber, total dietary | 4.6 g | 15.3% |
| Sugars, total | 4.04 g | |
| Calcium, Ca | 8 mg | 0.8% |
| Magnesium, Mg | 6 mg | 1.9% |
| Manganese, Mn | 0.15 mg | 7% |
| Phosphorus, P | 13 mg | 1.9% |
| Potassium, K | 85 mg | 1.8% |
| Sodium, Na | 2 mg | 0.1% |
| Vitamin C, total ascorbic acid | 13.3 mg | 16% |
| Vitamin A, IU | 60 IU | 9% |
| Vitamin K, mcg | 5.1 mcg | 6.4% |
| Carotene, beta | 36 mcg | ne |
| Lutein + zeaxanthin | 91 mcg | ne |
ne: Daily Value not established
Health benefits and potential health benefits
Phytochemicals
Cranberries are a source of polyphenol antioxidants, phytochemicals under active research for possible benefits to the cardiovascular system, immune system and as anti-cancer agents.[9][10]
Cranberry juice contains a chemical component, a high molecular weight non-dializable material (NDM), as noted above, that is able to inhibit and even reverse the formation of plaque by Streptococcus mutans pathogens that cause tooth decay.[11][12] Cranberry juice components also show efficacy against formation of kidney stones.[13][14]
Raw cranberries and cranberry juice are abundant food sources of the anthocyanidin flavonoids, cyanidin, peonidin and quercetin.[15][16] These compounds have an unknown effect on human health, but are powerful against human cancer cells in vitro. Their effect in humans, however, is unproven, showing poor absorption into human cells and rapid elimination from blood.
Since 2002, there has been an increasing focus on the potential role of cranberry polyphenolic constituents in preventing several types of cancer.[17][18][19][20][21] In a 2001 University of Maine study that compared cranberries with twenty other fruits, cranberries had the largest amount of both free and total phenols, with red grapes at a distant second place.[22] Cranberry tannins have anti-clotting properties and may reduce urinary tract infections and the amount of dental plaque-causing oral bacteria, thus being a prophylaxis for gingivitis.[23]
Anti-adhesion properties
There is potential benefit of cranberry juice consumption against bacterial infections in the urinary system. Research shows that an effect occurs from a component of the juice inhibiting bacterial attachment to the bladder and urethra.[24] [25][26]
Although promising for anti-bacterial activity, long-term consumption of cranberry juice has only limited evidence for beneficial effects against urinary tract infections in women.[27] Similar applications have not been successfully proved in other clinical trials of consuming cranberry juice or tablets by people with spinal cord injury associated with bladder catheterization, neurogenic bladder or infrequent urination, any of which may be associated with increased susceptibility to bacterial infections.
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