Dada a diferenciação e discussão do que são na realidade os frutos de casca rija, de casca dura ou "Nuts" (também por vezes chamados de frutos secos, nozes, amêndoas, sementes oleaginosas, etc), apresentamos um pequeno resumo dos mais conhecidos frutos de casca rija, mas em função do seu teor em proteína, gordura e hidratos de carbono.
O termo noz (nut) designa em geral um fruto de casca rija. Em botânica, é um fruto seco com apenas uma semente (raramente duas) no qual a parede do ovário ou parte dela se torna muito dura na maturidade. A maioria dos frutos de casca rija vem dos pistilos (conjunto de órgãos femininos das flores das Angiospermas: o estigma, o estilete, e o ovário) com ovários inferiores e não abrem na maturidade.
Entre os chamados frutos de casca rija, podemos assinalar a bolota (fruto do carvalho), a avelã ou a castanha. Outros podem ser sementes, como a castanha do Brasil (ou castanha do Pará). O amendoim também por vezes chamado de fruto seco é na realidade um legume. Há ainda as drupas secas ou seja os caroços de frutas de caroço (como a amêndoa da amendoeira, o coco, a noz da nogueira, e a noz pecã. Em seguida, reunimos todos estes frutos de casca rija, independentemente da sua natureza morfológica. Todos eles serão classificados de acordo com o seu teor de proteína, gordura e hidratos de carbono.
Refª: estas informações foram compiladas a partir da informação disponibilizada no website http://www.faculty.ucr.edu/~legneref/discover.htm.
The term “nut” is used loosely to describe a number of related or unrelated plant structures. Officially a nut is a one-celled, one-seeded dry fruit with a hard pericarp or shell. Some of the so-called nuts of commerce correspond to this description. Among them are the acorn, filbert, chestnut and hazelnut. The others may be seeds, as the Brazil nut; legumes, such as the peanut; or dry drupes from which the outer parts of the fruit have been removed, such as the almond, coconut, pecan and walnut. The following discussion will group all of these together regardless of their morphological nature. They will be classified according to their fat, protein and carbohydrate contents.
Refª: information compiled from the website website http://www.faculty.ucr.edu/~legneref/discover.htm.
Frutos de casca rija com elevado teor de gordura
Nuts with High Fat Content
The Brazil-nut tree, Bertholletia excelsa, is a giant with a rough bark in the Amazon forests in South America. It bears 18-24 hard, brown, spherical, woody fruits from 4-6 inches in diameter and weighing 2-4 pounds. Each fruit contains 12-24 seeds with a hard bony covering. These are the Brazil nuts of commerce, also called Cream Nuts. They have served as human food for centuries. The food value is very high with a fat content of 65-70 percent and protein content of 17 percent. Collection and shipping of these nuts is an important industry in South America. Trees are rarely cultivated and most of the output is obtained from the wild trees. There are also similar nuts of finer quality and more delicate flavor obtained from the Sapucaia orParadise-nut trees, Lecythis usitata, Zabucajo sp., and other species.
The cashew nut tree, Anacardium occidentale, is a handsome native of Brazil that is now extensively cultivated in tropical countries from Mexico to Peru and Brazil, in the West Indies, southern Florida and the Mediterranean area, Mozambique, India, and the East Indies. It bears a thin-skinned, pear-shaped, yellow or reddish, juicy “fruit” known as the Cashew Apple. This is actually the swollen peduncle and disk. The true fruit, a small curved or kidney-shaped structure, is borne on the outside of the “apple” at the distal end. This is the cashew “nut.” The rich kernel is delicately flavored and contains nutritious oil. The grayish-brown coat, or shell, contains oil that blisters the skin. The ripe fruit, which as a characteristic aroma, is consumed in many countries or used for preserves. The fermented juice makes a wine, Kaju that is sometimes bottled. The leaves, the light close-grained wood, the sap and the bark are also useful.
This is one of the most important economic plants especially in the South Pacific and other tropical areas. Coconut is a palm, Cocosnucifera, probably native to the Malay archipelago, but possibly of Ecuadorian and Central American origin. It grows best near the seashore, but can occur at altitudes of 5,000 ft. It is undoubtedly one of the most graceful and beautiful of all palms, often with a typical leaning habit. The bases of the slender trunks are swollen. The large pinnate leaves are 6-12 ft. long and 18 in. wide. They are borne in a cluster at the top of the stem. The flowers are formed in a large compound spadix, enclosed by a spathe. The fruit is a 3-sided dry drupe. It consists of a smooth rind, or exocarp; a reddish-brown fibrous mesocarp; and a hard stony endocarp, or shell that encloses the seed. The white meat and milk represent the endosperm of the seed; the embryo is embedded in the hard endosperm.
The coconut plants have many uses. The leaves are highly incendiary that when burned produce a bed of coals which imparts a delicious flavor to grilled meats. The fibrous husk yields Coir, a textile fiber. The hard shell, or endocarp, is used for fuel, vessels and other containers, and a fine grade of charcoal. The water of the green coconut makes an agreeable and refreshing drink. The meat may be eaten raw or shredded and dried to form desiccated coconut. It is frequently ground and pressed through a cloth after water has been added. The resulting coconut milk is very palatable and a good substitute for cow’s milk as it contains several vitamins. However, the main use of the meat is for copra, the source of coconut oil and oil cake. The unopened inflorescences yield a sweet liquid that is converted into palm sugar or fermented to make palm wine, arrack, or vinegar. The leaves are also used for thatching, baskets, hats, mats and curtains. The petioles and midribs are used for fence posts, canes, brooms, needles and pins. The trunk furnishes a strong, durable wood for houses and bridges. Some of the porcupine wood of commerce, much used for cabinetwork, is from the coconut. The heart of bud at the apex of the stem is used in salads or is cooked. The bark contains a resin and the roots a drug.
Coconuts thrive best within the true tropics, but they will grow at higher latitudes. They grow best in fertile soils. Wild trees are an important source of coconuts, but commercial plantations abound. Mature nuts are planted in a nursery and barely covered. They germinate in a few months and the seedlings are transplanted when about a year old. Proper spacing, clean cultivation and intercropping improve growth. Cover crops, fertilization and irrigation also help to maintain the yield. Flowering and fruiting at tropical latitudes are continuous and ripe nuts can be obtained during every month of the year. Harvest is usually every two months. The yield and size of the nuts vary with the spacing and the variety planted. About 3,000-7,000 nuts are required to produce one ton of copra, which yields 1,200 lbs. of coconut oil and 800 lbs. of oil cake. One thousand nuts can yield 165 lbs. of coir fiber. Great care must be taken not to lie beneath the trees, as the fruit is very heavy and can cause grave injury when falling.
Driving them against a sharp spike fastened to a piece of wood and wrenching them apart husk the coconuts. An experienced person can husk 1,200-2,500 nuts per day. The nuts are broken into two halves with a blow of a heavy dull knife. The dried meat or copra, the most important product, is prepared in different ways. About half the supply is dried by simple methods, using the sun or drying on racks over fires made from coconut shells. After a few days the meat curls away from the shell and can readily be detached. Copra prepared in this way is dark colored and has an oil content of about 50 percent. Plantation copra is dried within 24 hours in the sun followed by heat from fires in drying houses. This copra is white and has a high oil content (60-65 percent). The best grade of copra has traditionally come from Sri Lanka.
Desiccated coconut is used by confectionery and candy makers and in cooking. It is prepared from the best grade of nuts. These are cured for several weeks and then carefully cracked and the meat is removed while fresh. This is washed and cut into threads and dried in a vacuum for one hour at 160 deg. Fahrenheit.
Hazelnuts, Corylus spp., are found in cool temperate regions of both hemispheres. The native American shrubs, Corylus americana and C. cornuta, produce small nutritious and palatable nuts of no commercial importance. Larger European species, C. avellana and C. maxima, are the source of Filberts, Cob Nuts andBarcelona Nuts. Filberts are cultivated in Southern Europe and Oregon.
Hickories, Carya spp., are native American trees common throughout the eastern deciduous forest. Butternut hickories contain a large amount of tannin and are not suitable for food but are eaten by livestock. Another group has sweetish edible nuts, the best of these being the Shagbark Hickory, Carya ovata andShellbark Hickory, Carya laciniosa. These can be some of the finest of the wild nuts in North America and they have excellent storage qualities. The trees show promise under selection and experimentation. They can be grafted and crossed and many new varieties adapted to a wide range of soil and climatic conditions have been produced. The nuts yield a fine salad oil and the wood is a valuable timber. The bark, which frequently sloughs off, is used in smoking meats.
Macadamia trees, Macadamia ternifolia, are native to northeastern Australia. They produce a nut also known as Queensland Nuts. The tree has been introduced into other subtropical areas of both hemispheres. It has become of considerable commercial importance in Hawaii. Both thin-shelled and thick-shelled varieties are grown. The kernels have a sweet flavor that is enhanced by roasting and a rich oil.
The Pecan Tree, Carya illinoensis, is indigenous to the southeastern United States and northeastern Mexico. It is in the same genus as Hickory. The trees are extensively cultivated in both the Southern states and points west all the way to California, in the latter under irrigation. New varieties have extended the production northward into the upper Mississippi valley, Indiana and Virginia. Harvesting begins when trees are only 3-4 years of age. Paper-shelled varieties have been developed from East Texas stock. Pecans have a high fat content of 70% and they are used in desserts, candy, ice cream, cakes, etc. Pralines, consisting of brown sugar, vinegar and nuts, are a favorite confection in the South. Pecan pie is a delicious blend of nuts with a brown sugar custard base. Pecan oil and tannin obtained from the shells are by-products.
The seeds of Canarium ovatum, a native tree of the Philippines are Pili Nuts. They are very similar to Java almonds from C. commune of Eastern Asia and the East Indies. The seeds of both are consumed raw or after roasting. They have a spindle shape with a very thick hard shell. Fatty oil is expressed from the seed and used for human consumption and in oil lamps, and a resin is extracted from the tree. The plum-like fruit of the Pili is also edible.
Pine nuts or Piñons are obtained from the seeds of several species of Pinus, native to Western North America. Included are the Nut Pines, P. cembroides var. edulis and P. edulis var. monophylla; the Digger Pine, P. sabiniana; and the Torrey Pine, P. torreyana. These bean-sized nuts have a thin brownish-red shell and a slightly resinous flavor. Amerindians have always harvested piñons. The pinecones are harvested before they would open naturally. They are then roasted so that the scales will fall apart, which allows the seeds to separate. Wild birds and rodents quickly gather them when they open naturally in nature. The production is entirely from wild trees.
Pignolia Nuts are the seed of Pinus pinea of Southern Europe. These are longer and more yellow than piñons and have a rich delicious taste. Other species of pine provide edible nuts in India and Eastern Asia. China has increased its export of such nuts in the latter 20th Century.
Walnut trees provide both nuts and timber. They are native trees of North America and Europe.
Black Walnut, Juglans nigra, is an abundant tree of the eastern deciduous forest region of North America. It is a tall handsome tree that is often used for ornamental purposes. The large spherical fruits are green when ripe and the outer covering has to disintegrate or be physically removed to free the nuts. The walnut kernels have high oil content and were a favorite food of Amerindians. They retain their flavor when cooked and have a food value four times as great as meat. They are very difficult to crack and the husk stains the hands a dark brown so their wild harvest today is restricted to the very dedicated. These nuts are used mainly in the candy and ice cream industries. The tree is very productive and can be grown in a variety of soils and climates. Walnuts provide a valuable timber and also a brownish-black dye that was used by early settlers to dye hair.
Butternut, Juglans cinerea, is native to area with limestone soil in eastern North America. The tree is smaller than Black Walnut with elliptical nuts that have a deeply corrugated shell. Butternuts are high in fat content and are often preferred to walnuts because of their finer and richer flavor. The kernels are more readily separated. Sugar is sometimes obtained from the sap. They have often been used in the candy industry.
English Walnut, Juglans regia, is indigenous to Iran and is widely cultivated in Southern Europe, China and other parts of Asia. In North America California and Oregon are leading producers. English walnut has been under cultivation for ages and many varieties exist. The attractive trees are usually planted in rows. Only the outer limbs produce perfect nuts. The kernels are easily freed from the pericarps and are bleached and polished. The furrowed kernels are the cotyledons of the seed, no endosperm being present. Walnuts yield excellent oil and the oil cake is a good livestock feed. The codling moth, Carpocapsa pomonella and Navel Orangeworm, Amyelois transitella, often attack the crop in North America and biological agents (parasitic insects) have been partially successful in control.
Frutos de casca rija com elevado teor de proteínas
Nuts with High Protein Content
Almonds are probably the most popular of the high protein nuts. They are obtained from a medium-sized tree, Prunus amygdalus that is related to the peach and closely resembles it in blossoms and young fruit. Almond trees are also cultivated as ornamentals. The almond fruit is an edible drupe, with a tough fibrous rind surrounding the stone or “shell” and the seed or “nut.” There are two major types of almonds.
Sweet Almonds, Prunus amygdalus var. dulcis, have an edible seed and are the main source of the commercial product. The tree is native to the eastern Mediterranean where it has been cultivated for centuries. It is grown throughout Southern Europe and in California, Australia and South Africa. The seeds are especially delicious when eaten green. However, they are usually roasted or salted or made into a paste to be used for cake and bread. An extract is also prepared for flavoring. There are many varieties, some with think shells and some with hard shells. Jordan almonds are hard-shelled with a thinner integument on the seed and a finer flavor. In California a successful biological control effort against the Navel Orangeworm, Amyelois transitella, reduced harvest losses to below four percent.
Bitter Almonds, Prunus amygdalus var. amara, possess a bitter glucoside, Amygdalin that readily breaks down into prussic acid and thus prevents their use as food. Nevertheless, they are grown in Southern Europe as a source of the oil. During the extraction process the prussic acid is eliminated and the oil can then be used for flavoring. Bitter almonds are also used as a rootstock for sweet almonds.
The beech tree, Fagus grandifolia, is abundant in the eastern deciduous forest of North America. The high protein nuts are small, triangular and very sweet. They are of minor importance for human food, but are eagerly sought after by cattle, pigs, squirrels, poultry and other birds. They impart a fine flavor to pork, and razorback hogs are fed on the mast, which is a mixture of beechnuts, chestnuts and acorns. The European beech, Fagus sylvatica, yields slightly larger nuts that are consumed by humans and used for the edible oil of beechnuts.
Pistachio, Pistacia vera, also known as Green Almond, is a small tree indigenous to Western Asia. It has been cultivated in the Mediterranean region since before 2,000 B.C. It is now grown in Iran, Afghanistan, the southern United States and irrigated areas of the West, especially California. The fruit is a drupe. The seed contain two large green cotyledons with a reddish covering. These high protein “nuts” are salted in brine while still in the shell. They are highly prized for their color and resinous flavor and are combined with other nuts as mixed nuts and as a flavoring material for ice cream and candy. Their quality varies with the kind of culture. Restricting water reduces yield be improves flavor.
Frutos de casca rija com elevado teor de hidratos de carbono
Nuts with High Carbohydrate Content
Acorns are the fruits of oak trees, Quercus spp. They are true nuts. Acorns have been used in America for fattening livestock, especially hogs. They are an excellent human food, but are rarely used except by indigenous people. The white oak, Quercus alba, and the live oak, Q. virginiana, are the best of the twelve or more species with edible fruit. The Amerindians have always used acorn flour. They ground the nuts, leached them to remove the tannin and other bitter qualities, pounded them into a meal and used them in porridge, mush and other ways. Acorns have been used in other areas of the world, for example they once furnished 25 percent of the food of the poorer classes in Italy and Spain in the form of acorn bread or cake. This is highly nutritious and may be stored indefinitely. Any species of acorn is edible after the tannin has been removed, but the holm oak, Q. ilex, is the main source. Oak trees are very productive and adapted to poor soil. The problem with acceptance of this food is its unaccustomed flavor, which is probably related to few persons being able to prepare it properly.
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