Carambola - Fruit of R.Borgacci

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What is carambola?

Carambola - in English "starfruit" - is the name of a fleshy fruit produced by the homonymous arboreal plant - of the botanical family Oxalidaceae, Genus Averrhoa and carambola species - native to the Asian continent; today it is also cultivated in South America, the Middle East, islands of the Pacific Ocean, Australia and Africa.

Succulent, slightly sour and not too sweet, that of carambola is a very characteristic looking fruit. It is greenish from unripe and yellow when ripe. It has an oval shape with five longitudinal protuberances, each with a triangular section; cutting it transversely, the slices take on the shape of a star. The size changes, even by a lot, depending on the variety.

The carambola has organoleptic and taste peculiarities that leave something to be desired. It is usually eaten raw but, in some local traditions, it is transformed into sauce, jam or fruit juice.

Did you know that ...

The carambola trees are also cultivated for the ornamental role of their beautiful dark green leaves, pink flowers and the characteristic and abundant fruits.

Like that of bilimbi fruits, carambola juice can be used to clean rusted or oxidized metal - in particular brass - and rust stains on fabrics. It can also be used as a mordant in dyeing.

The same applies to the nutritional properties, with only exceptions represented by the levels of water and vitamin C (ascorbic acid); for this reason the carambola is framed in the VII fundamental group of foods. The content of provitamin A - RAE, especially of carotenoids such as lutein and zexanthin, is appreciable - and the concentration of folates may be useful. The latter, like the potassium and magnesium minerals, are not as high as in most meaty sweet fruits.

The caloric intake of the carambola is low since, in the presence of a high degree of hydration, the concentration of energy macronutrients is still moderate; the most abundant is fructose. For this reason the carambola lends itself to the diet against overweight and certain metabolic pathologies, for example diabetes mellitus type 2 and hypertriglyceridemia. In the next paragraphs we will go into more detail.

Nutritional Properties

Nutritional properties of the carambola

We begin by specifying that there are mainly two varieties of carambola: one sweet and one sour. The sour type has a higher content of oxalic acid, while the sweet one has a higher percentage of fructose - even if they rarely contain more than 4% of sugar.

The carambola belongs to the VII fundamental group of foods, because it contains considerable doses of vitamin C or ascorbic acid. It should however be emphasized that also the percentage of RAE (provitamin A) is not negligible, consisting mainly of the carotenoids zeaxanthin and lutein.

The carambola has a low caloric intake. Energy is supplied mainly by carbohydrates, followed by negligible amounts of proteins and lipids. Carbohydrates consist entirely of fructose - simple, soluble, monosaccharide sugar. Peptides have a low biological value, ie they do not contain - in the right quantities and proportions - the essential amino acids of the human protein model. Fatty acids are, in theory, predominantly unsaturated.

The carambola also contains dietary fiber, part of which is certainly soluble; the relationship with insolubles is not known.

Cholesterol-free, it does not even contain the molecules mainly responsible for scientifically diagnosable food intolerances, such as celiac disease, adverse reactions to lactose and histamine. The carambola is low in phenylalanine. Purines are also very scarce, but we should remember that any excess fructose in the diet - difficult to make by eating carambola only - can promote the retention of uric acid in the body.

As for the vitamins, the carambola boasts excellent concentrations of vitamin C (ascorbic acid) and discrete levels of equivalent retinol (RAE - provitamin A, consisting mainly of luteins and zexanthin); the dose of folate may be useful, although not particularly high. With regard to mineral salts, on the other hand, they are appreciable, but not as high as one would expect from a sweet fleshy fruit, potassium and magnesium levels.

The carambola also contains unwanted molecules. We are talking about oxalic acid, which can give rise to oxalates, and caramboxine. In the paragraph referring to the correlation between carom and health we will go into more detail.

Diet

Carambola in the diet

Carambola fruits, like most foods in this category, lend themselves to almost all diets; some clinical conditions of nephrological interest are exceptions, as we shall see in the next paragraph.

Being low in sugar and energy, they have very few contraindications for: overweight, type 2 diabetes mellitus and hypertriglyceridemia.

Dietary fibers, of which we do not know the details concerning the composition / breakdown, perform numerous functions useful to the organism. First and foremost, properly associated with water - of which the carambola fruits are rich - the fibers can:

• increase the mechanical stimulus of satiety - even if fructose is a carbohydrate that weakly triggers the hormonal feedback of satiety
• modulate nutritional absorption - reducing the insulin glycemic surge and hindering the absorption and reabsorption of cholesterol and bile salts
• prevent or treat constipation / constipation.

This latter aspect contributes to decreasing the chances of carcinogenesis of the large intestine and of many other discomforts such as hemorrhoids, anal fissures and anal prolapse, diverticulosis and diverticulitis, etc. It should also be remembered that soluble fibers constitute a nutritional substrate for intestinal bacterial flora; maintaining the trophism of the microbiota, whose metabolism releases important nutritional factors for the mucosa, further promotes the health of the colon.

Vitamin C, carotenoids (lutein and zexanthin - RAE, provitamin A) and polyphenols - primary and secondary - have an important antioxidant role. In addition to counteracting the action of free radicals responsible for cellular aging, these nutritional elements are considered useful for treating various metabolic pathologies.

The richness of water contributes to maintaining the state of hydration - which becomes precarious above all with increasing sweating, in the presence of insufficient thirst stimulation (as in old age) or following certain diuretic pharmacological therapies (for example against hypertension primary arterial).

There are no contraindications for the conditions of: celiac disease, lactose intolerance, histamine intolerance, phenylketonuria and hyperuricemia or gout - although, as we have already said, it is known that too much fructose in the diet can aggravate the retention of uric acid. Recall that the carambola is rich in oxalic acid, an anti-nutritional factor that reduces the absorption of some minerals such as calcium and a predisposing element for kidney stones (renal lithiasis) of the same composition.

The carambola has no limitation in the vegetarian, vegan and raw food diet; the same applies to philosophies and / or religions of all kinds.

The average portion of carambola is 100-200 g (about 30-60 kcal).

Health

Carambola: is it good?

Antioxidant carambola

The carambola is rich in antioxidants and mineral potassium; moreover, it is rather low in sugar and sodium. Antioxidants include vitamin C or ascorbic acid, retinol equivalents (RAE - provitamin A) and primary and secondary polyphenols.

Antibacterial carambola

In addition to a strong antioxidant activity, the carambola also seems to possess a certain antimicrobial power; this would be due to the presence of nitric oxide (nitrogen monoxide - NO) - whose presence varies according to the state of maturation. This derivative of the amino acid arginine is known above all for its vasodilator effect and mediator of nerve impulses, but not everyone knows that it also has an antibacterial effect. To be precise, the microorganisms of the genus Escherichia ( coli species), Klebsiella, Staphylococcus (species aureus ) and Pseudomonas ( aeruginosa species) seem sensitive to nitrogen monoxide.

Carambola: does it hurt?

Carambola and diseases of the kidneys

Carambola also contain "caramboxina" and oxalic acid. Both substances are considered harmful for those suffering from kidney failure and kidney stones, and generally for all subjects on dialysis.

deepening

Caramboxine is a neurotoxin structurally similar to phenylalanine, which nevertheless plays the role of glutamatergic agonist.

Oxalic acid, on the other hand, is an anti-nutrient that binds certain minerals and prevents intestinal absorption (for example calcium oxalate). If captured and poured into the blood, during renal filtration, oxalic acid has the same effect and promotes the synthesis of stones or renal lithiasis.

People with kidney failure who eat considerable amounts of carambola may experience: hiccups, vomiting, nausea, mental confusion and sometimes death.

For healthy people, the levels of oxalic acid and caramboxine in the carom are low enough to be considered safe. However, some researchers hypothesize that the fruit and juice may cause kidney damage or, rarely, kidney failure in people with normal function; this is why the carambola fruit should be avoided or consumed with extreme moderation. Obviously these assumptions have not yet been confirmed and, for the moment, no danger has been attributed to the consumption of carambola.

Interactions

Pharmacological interactions of carambola

Like grapefruit, carambola is also considered a powerful inhibitor of seven cytochrome P450 isoforms. These enzymes are indispensable in the first step of eliminating many drugs; therefore, the consumption of carambola or its juice combined with some prescription drugs can significantly increase their permanence in the blood favoring the risk of superdosaggio.

Kitchen

Carambola in the kitchen

The carambola is totally edible, including peel - despite being slightly waxy. These fruits are best consumed shortly after ripening, when they are yellow and possibly with a slight shade of green.

The carambola is consumed mainly raw but, in some local traditions, it is processed into real recipes.

In Southeast Asia, carambola are stewed with cloves and sugar, sometimes in combination with apples. In China they often accompany fish recipes. In Australia, they can be cooked as real vegetables, preserved in brine or turned into jam. In Jamaica they are sometimes dried. In the food industry, especially in India, carambola is frequently used to prepare fruit juices; that of the sour varieties is used to prepare alcoholic and non-alcoholic cocktails. In Australia, the sour carambola, with a sour taste, can be mixed with various chopped spices. In the Philippines, unripe carambola is eaten dipped in rock salt. In Thailand, they are cooked together with shrimp. In the Philippines they can be used as a condiment.

Description

Description of the carambola

The fruit of the carambola has a length of 5 - 15 cm - depending on the variety - and is oval in shape. It is usually characterized by five prominent longitudinal protrusions, with a triangular section; rarely only four or up to eight. In cross section, the carambola has the shape of a stylized star. The color of the skin, which is thin, smooth and waxy, is between yellow and green in an unripe phase, and intense yellow when fully ripe. The flesh is crunchy, firm and extremely juicy; the appearance is translucent and of a variable color between light and intense yellow. It is somewhat vaguely similar to grapes. The unripe harvested fruits, slightly green, turn yellow at room temperature but do not increase the fructose content. The overripe carambola is typically yellow with brown spots. Each fruit can contain from 10 to 12 light brown seeds, flat shape and length from 6 to 13 mm, enclosed in a gelatinous aril. Once removed from the fruit, they lose profitability in a few days - that is, they are no longer able to sprout.

The prevailing taste changes according to the variety; it can be sweet or sour. The taste is typical, difficult to compare, but some compare it to a mix of fruit including apples, pears, grapes and citrus fruits. On the other hand, unripe fruits have a similar taste to green apples (Granny Smith).

Botany

Elements of botany of the carambola

Of the botanical family Oxalidaceae, genus Averrhoa and carambola species, this plant is a tree originating from the Asian continent. It is still uncertain whether he was born in Sri Lanka or the Moluccas, but it seems to be naturally distributed in the Philippines, Malaysia, Vietnam, Nepal, India, Bangladesh, Mauritius and the Seychelles. Today it is also cultivated in the islands of the South Pacific Ocean, in Africa, Australia, in the Middle East and in South America.

As for the bilimbi tree (genus Boanico Averrhoa and bilimbi species), closely related to it, there are two varieties of carambola: small sour and large sweet. In recent years various cultivars of both have been developed; the most common are:

• sweet types "Arkin" (Florida), "Dah Pon" (Taiwan), "Ma fueng" (Thailand), "Maha" (Malaysia) and "Demak" (Indonesia)
• acidulous types "Golden Star", "Newcomb", "Star King" and "Thayer" (all from Florida).

Some of the harsh varieties like the "Golden Star" can become sweet if they are left to mature.

Cultivation

Notes on carambola cultivation

The carambola is a tropical and subtropical fruit that can be grown up to 1200 meters of altitude. It prefers complete exposure to the sun but requires sufficient humidity and annual rainfall of at least 1800 mm. It has no preference for the type of soil but requires good drainage.

Carom trees must be planted at least 6 m apart and fertilized three times a year. The tree grows rapidly and begins production at four or five years. Too much spring rain reduces fruiting but, under ideal conditions, a single plant can deliver 90 to 180 kg of carambola per year. In Malaysia, flowering occurs throughout the year, with greater production between April and June, and between October and December. In South Florida, for example, the rhythms of this cultivation are quite different.

The main adversities of the carambola are fruit flies, fruit moths, ants and birds. The crops are also susceptible to frost.

The main producers of carambola in the world market are: Australia, Guyana, India, Israel, Malaysia, Philippines, Taiwan and the United States. Malaysia is a world leader in this production and ships the product throughout Asia and Europe - including Italy. Due to concerns about pests and pathogens, however, it is not yet possible to export to the United States - under the current regulations of the Department of Agriculture. In the USA, carambola are grown in tropical and semi-tropical areas, such as Texas, South Carolina, Louisiana, California, Virginia, Florida and Hawaii.