Blackcurrant (Ribes nigrum)
The blackcurrant (Ribes nigrum) is a woody shrub in the family Grossulariaceae grown for its piquant berries. It is native to temperate parts of central and northern Europe and northern Asia where it prefers damp fertile soils and is widely cultivated both commercially and domestically. It is winterhardy, but cold weather at flowering time during the spring reduces the size of the crop. Bunches of small, glossy black fruit develop along the stems in the summer and can be harvested by hand or by machine. The raw fruit is particularly rich in vitamin C and polyphenol phytochemicals. Blackcurrants can be eaten raw but are usually cooked in a variety of sweet or savoury dishes. They are used to make jams, jellies and syrups and are grown commercially for the juice market. The fruit is also used in the preparation of alcoholic beverages and both fruit and foliage have uses in traditional medicine and the preparation of dyes.
As a crop, the blackcurrant suffers from several pests and diseases. The most serious disease is reversion, caused by a virus transmitted by the blackcurrant gall mite. Another is white pine blister rust which alternates between two unrelated hosts, one in the genus Ribes (blackcurrant included) and the other a white pine. This fungus caused damage to forests when the fruit was first introduced into North America, where the native white pines have no genetic resistance to the disease. As a result, the blackcurrant has for most of the 20th century been subject to restrictions in parts of the United States as a disease vector. The effectiveness of these restrictions is questionable, since other Ribes species also host the disease and are native to North America.
Breeding is being undertaken in Scotland, Poland, Lithuania, Norway, and New Zealand to produce fruit with better eating qualities and bushes with greater hardiness and disease resistance.
Scientific classification
Kingdom: Plantae
Clade: Angiosperms
Clade: Eudicots
Order: Saxifragales
Family: Grossulariaceae
Genus: Ribes
Species: R. nigrum
Description
Ribes nigrum, the blackcurrant, is a medium-sized shrub, growing to 1.5 by 1.5 metres (4.9 by 4.9 ft). The leaves are alternate, simple, 3 to 5 cm (1.2 to 2.0 in) broad and long with five palmate lobes and a serrated margin. All parts of the plant are strongly aromatic. The flowers are produced in racemes known as "strigs" up to 8 cm (3 in) long containing ten to twenty flowers, each about 8 mm (0.3 in) in diameter. Each flower has a hairy calyx with yellow glands, the five lobes of which are longer than the inconspicuous petals. There are five stamens surrounding the stigma and style and two fused carpels. The flowers open in succession from the base of the strig and are mostly insect pollinated, but some pollen is distributed by the wind. A pollen grain landing on a stigma will germinate and send a slender pollen tube down the style to the ovule. In warm weather this takes about 48 hours but in cold weather it may take a week, and by that time, the ovule may have passed the stage where it is receptive. If fewer than about 35 ovules are fertilised, the fruit may not be able to develop and will fall prematurely. Frost can damage both unopened and open flowers when the temperature falls below −1.9 °C (28.6 °F). The flowers at the base of the strig are more protected by the foliage and are less likely to be damaged.
In midsummer the strigs of green fruit ripen to edible berries, very dark purple in colour, almost black, with glossy skins and persistent calyxes at the apex, each containing many seeds. An established bush can produce about 4.5 kilograms (10 pounds) of fruit each year.
Plants from Northern Asia are sometimes distinguished as a separate variety, Ribes nigrum var. sibiricum, of which Ribes cyathiforme is considered a synonym.
Uses
Culinary uses
The fruit of blackcurrants can be eaten raw, but it has a strong, tart flavour. It can be made into jams and jellies which set readily because of the fruit's high content of pectin and acid. For culinary use, the fruit is usually cooked with sugar to produce a purée, which can then be passed through muslin to separate the juice. The purée can be used to make blackcurrant preserves and be included in cheesecakes, yogurt, ice cream, desserts, sorbets and many other sweet dishes. The exceptionally strong flavour can be moderated by combining it with other fruits, such as raspberries and strawberries in summer pudding, or apples in crumbles and pies. The juice can be used in syrups and cordials. Blackcurrants are a common ingredient of rødgrød, a popular kissel-like dessert in North German and Danish cuisines.
Blackcurrants are also used in savoury cooking because their astringency creates added flavour in many sauces, meat and other dishes and they are included in some unusual combinations of foods. They can be added to tomato and mint to make a salad, used to accompany roast or grilled lamb, used to accompany seafood and shellfish, used as a dipping sauce at barbecues, blended with mayonnaise, used to invigorate bananas and other tropical fruits, combined with dark chocolate or added to mincemeat in traditional mince pies at Christmas.
Japan imports US$3.6 million of New Zealand blackcurrants for uses as dietary supplements, snacks, functional food products and as quick-frozen (IQF) produce for culinary production as jams, jellies or preserves.
Beverages
The juice forms the basis for various popular cordials, juice drinks, juices and smoothies. Typically blended with apple or other red fruits, it is also mixed with pomegranate and grape juice. Macerated blackcurrants are also the primary ingredient in the apéritif liqueur crème de cassis, which in turn is added to white wine to produce a Kir or to champagne to make a Kir Royale.
In the United Kingdom, blackcurrant cordial is often mixed with cider (hard cider) to make a drink called "cider and black". If made with any common British lager beer, it is known as a "lager and black". The addition of blackcurrant to a mix of cider and lager results in "diesel" or "snakebite and black" available at pubs. A "black 'n' black" can be made by adding a small amount of blackcurrant juice to a pint of stout. The head is purple if the shot of juice is placed in the glass first. Blackcurrant juice is sometimes combined with whey in an endurance/energy-type drink.
In Russia, blackcurrant leaves may be used for flavouring tea or preserves, such as salted cucumbers, and berries for home winemaking. Sweetened vodka may also be infused with blackcurrant leaves making a deep greenish-yellow beverage with a tart flavour and astringent taste. The berries may be infused in a similar manner. In Britain, 95% of the blackcurrants grown end up in Ribena (a brand of fruit juice whose name is derived from Ribes nigrum) and similar fruit syrups and juices.
Food value
Nutrients
Raw blackcurrants are 82% water, 15% carbohydrates, 1% protein and 0.4% fat (table).
Per 100 g serving providing 63 kilocalories, the raw fruit has high vitamin C content (218% of the Daily Value, DV) and moderate levels of iron and manganese (12% DV each). Other nutrients are present in negligible amounts (less than 10% DV, table).
Phytochemicals
Polyphenol phytochemicals present in the fruit, seeds and leaves, are being investigated for their potential biological activities.
Major anthocyanins in blackcurrant pomace are delphinidin-3-O-glucoside, delphinidin-3-O-rutinoside, cyanidin-3-O-glucoside, and cyanidin-3-O-rutinoside, which are retained in the juice concentrate among other yet unidentified polyphenols.
Blackcurrant seed oil is rich in vitamin E and unsaturated fatty acids, including alpha-linolenic acid and gamma-linolenic acid.
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