Carambola (Averrhoa cannon) is a tropical fruit that has recently started its trade in Europe. It is also called the star fruit, because it is star-shaped when cut on cross section. It has a thin edible skin, of pale yellow colour that turns into golden yellow when the fruit is ripe. It has a translucent, crispy, juicy and acid pulp. The largest varieties are the sweetest. It usually measures between 7 and 12 cm. The larger fruits have a golden colour, they are sweeter and slightly acid. The smallest varieties are quite bitter and have pale, green or yellow tonalities. They are eaten fresh, in salads or juice. They are normally used to garnish all types of sweet and salty dishes.
When cut on cross section we get pretty star-shaped slices. When mature, the skin is easily removed. They become a nice decoration in meat dishes, desserts, cakes or drinks, cocktails and punch. It is an ideal food for its vitamin C and mineral content like calcium, magnesium and phosphorus. Each 100 g of pulp supply 40 calories to the organism. The countries producing this tropical fruit are Malaysia, Thailand, Indonesia and Brazil. The recommended temperature for storage is 5ºC and the optimal relative moisture is around 90 and 95%.
Types and Varieties of Carambola
There are two types of varieties; some of them are adapted to the production areas. From the two varieties distinguished, the smallest is of a green colour and acid taste and comes from Brazil. The other one is a larger variety, of pale green colour and mild taste, and it comes from Malaysia. The varieties of carambola produced in Australia, of which some trials were carried out in the Experimental Station ‘La Mayora’ in Spain are the following: ‘Arkin’, ‘B-6’, ‘B-8 ‘, ‘B-10’, ‘B-16’, ‘Chujuba’, ‘Fwang-Tung’, ‘Kambangan’, ‘Hart’, ‘Maha’, ‘Thai Knight’, ‘8-1 ‘, ‘9-4’, ‘11.1’
The carambola is a small tree. 5 to 12 m high, with a short trunk. It is quite attractive and ornamental, with pale green leaves. The flowers are gathered in clusters. This tree needs a tropical or subtropical climate, with quite a humid weather.
Origin and Production
Carambola is native to the Malaysian Archipelago, Indochina. This fruit is found in most of the tropical countries. The main producing countries are Malaysia, Thailand, Indonesia and Brazil.
This fruit is available almost all the year round in countries like Thailand, Sri Lanka, India, Brazil or even European countries with milder temperatures. The following table is an example of the dates of availability in the United Kingdom market, with the origin and the weight of the packages.
|Origin||Availability in the UK markets||Weight of the packages|
|CANARY ISLANDS||February-March||2 kg|
|COLOMBIA||All the year round||3.5 kg|
|MALAYSIA||All the year round||3 kg|
|MEXICO||All the year round||Various|
|THAILAND||July-September and December-January||2/4 kg|
|THE UNITED STATES||August-February||3 kg|
Source: Fresh Produce Desk Book (2001)
Carambolas are usually wrapped in paper or with a soft plastic protection (mesh) that prevents the angles to become brown.
There is no compulsory quality standard for carambolas. However, there is a Codex Stan 187 standard from the FAO, the United Nations Food and Agriculture Organization. The Codex standards are not compulsory, they are only for reference. The quality factors for carambola, according to the University of California, Davis, are the following: turgescent and yellow fruit, free from brown discolour in the skin and the five angles. Fresh and juicy flesh. There are five cultivars, sweet and acid. The sweet ones have a pH = 3.8-4.1; in this group we find the variety ‘Arkin’. Within the group of acid cultivars we find ‘Golden Start’; they have a pH=2.2-2.6. The produce must be free of bruises, damages caused by insects and birds, and free from rotting.
Postharvest Atmosphere Management
Carambola is well-preserved for 3 to 6 weeks at temperatures between 5 and 7.5ºC. They can be transported by boat. Cooling is the technique with maximum effectiveness in the storage of carambolas. The conditions recommended for storage are between 5 and 7.5 ºC and 90-95% of relative moisture. The green colour tends to disappear, the fruit ripens when it is subject to ethylene and the taste and acidity improves. These changes may be seen accelerated with an exposure to ethylene of 100 ppm for 24 hours. However, similar procedures, if severe, may increase the fruit rotting.
The same environmental conditions for storage (temperature 5-7.5ºC and 90-95% of relative moisture), are the suitable for the transport and distribution stages. The quality problems are evident in the fruit after sea transport, when the period of time between the harvest and the consumption is too long.
After the harvesting some problems caused by chilling injuries may arise; these would bring along the necrosis of the angles, some other alterations are physical damages, blight, damages caused by heating and pathogens.
The chilling injuries symptoms are depressions on the surface of the fruit; some are small, considering those which do not exceed 1 mm, the others are deep and dark or long, 1 to 2 mm. These areas are of a brown colour. These symptoms have been observed in some cultivars of carambola after two weeks at 0ºC or 6 weeks at 5ºC. The most usual damages are clearly defined areas of a greyish colour and somewhat depressed in the skin, a darkening in the pulp, abnormal maturation, greater sensitivity to infections, a faster deterioration, a dull colour and little taste, as well as some spots in the skin.
Necrosis of the angles
The angles of the fruit are very sensitive to any damage caused by their delicate position. This causes undesired brown necrotic tissues in the fruit.
The dark and broken areas are prone to suffer from abrasions and damages. The cracks increase with the fruit’s loss of water. The manual care during the harvesting and subsequent storage and transport is indispensable in order to reduce these physical damages to the maximum.
The symptoms are visible when the carambolas loose around 5% of their weight due to hydric stress.
Damages caused by heating
Dark skin and softening of the flesh may occur in carambolas which have been subject to heat treatments (over 46ºC for 35 to 55 minutes). A better alternative would be irradiation. The application of heat and irradiation is carried out in order to treat insects.
Damages caused by pathogens
Many damages occurring during the storage of carambola would be caused by Alternaria alternata (specially in frozen fruit), Cladosporium cladosporioides or Botryodiplodia theobromae. These damages generally occur during the fruit storage and could diminish with a careful handling during the harvest, storage and transport.
Health Benefits of Carambola
This fruit has a high concentration of vitamin C. An average-sized carambola supplies around 30% of the daily recommended consumption of 60 mg/day.
Historically, the boats’ crews relied on salted meat and dried products, and thus they were severely affected by scurvy (lack of vitamin C). Long shipping expeditions failed because of the lack of men in good conditions of health. Scurvy, in long sea expeditions, was prevented by carrying citrus on board. Epidemiological research indicates that stomach cancer is less frequent in people who follow a diet rich in vitamin C. Due to possible adverse reactions, patients with kidney failure must not consume carambolas.
|Carambola, Averrhoa carambola / Fam.: Oxalidaceae|
| Note: Composition for 100 g. of fresh product
Values in ( min. – max. ) format.
Nutrition and Eating
Fresh carambolas are a great source of vitamin A and C, and minerals like calcium, magnesium and phosphorus.