Table of contents
The raw star fruit (Averrhoa carambola), which is also commonly known as carambola, is an egg-shaped, sweet-sour berry that is up to 15 cm long and has pronounced longitudinal ribs. It is available in organic quality.
Culinary uses of star fruit
How do you eat star fruit? The cross-sectional slices of the raw star fruit are suitable for garnishing salads, cocktails, vegan desserts or cakes due to their decorative star shape. In Indian cuisine, the star fruit is also used for spicy dishes such as pickle, chutney or dal. You can make an aromatic main course in the form of a carpaccio, for example: fruity carpaccio with melon, mango and star fruit.
It should be noted that there are two main types of star fruit.7,28 One variety is small, light green and very acidic; these fruits are used for cooking. The sweet variety, on the other hand, should primarily be eaten raw, otherwise it will lose its taste. The light yellow or golden yellow to amber-color and shimmering flesh indicates the ripeness of this exotic fruit. The yellow (yellow-orange) skin of the ripe fruit can be peeled off before consumption or eaten with it.
In Taiwan, a variety of star fruit called 'Honglong' has been in use for some time: its skin is darker (orange to red) and replaces the former main crop 'Chang Tsey', which is very susceptible to pests and diseases.4
Vegan recipe for Star Fruit Popsicle
Ingredients (for 4 servings): 1-2 raw star fruit (carambola, organic), 500 ml coconut water (not coconut milk!), fresh mint, 50 g strawberries, 50 g blueberries, popsicle molds or small yogurt cups.
Procedure: Wash the raw fruit thoroughly. Then cut the star fruit crosswise into slices so that you can see the star shape. Cut the strawberries into bite-sized pieces and place in the molds along with the star fruit, blueberries and mint. Finally, fill the molds with coconut water and freeze overnight.
Vegan recipe for Chocolate Star Fruit Tartlets
The star fruit is particularly suitable as a decoration for cakes and tarts.
Ingredients (for 2 people): 100 g Medjool dates (pitted), 30 g walnuts, 40 g almonds, 2 tbsp cocoa powder (unsweetened), 1 tbsp maple syrup (optional), 50 g dark chocolate, 100 g silken tofu, 1-2 pieces raw star fruit (organic).
Procedure: Stone the dates and grind them together with the nuts and the cocoa powder (possibly with maple syrup) in the blender to a homogeneous mass. Then divide into two equally sized portions; shape each into a ball and roll out the dough ball into two circles. Press the dough evenly into the shape of a tartlet. If you don't have any tartlet molds, you can use any other mold - simply adapt the dough to the mold. Place the filled molds in the fridge for 1–2 hours. Meanwhile, finely chop the chocolate, place in a bowl and melt over steam. Mix the silken tofu finely. Then add the melted chocolate and mix until a fine cream has formed. Fill the tartlets with the chocolate cream. Put in the fridge for a few hours. If necessary, peel the star fruit (especially if there are brown spots on the edges) and slice across. Finally, decorate the vegan tartlets with the stars and serve cold.
To find vegan recipes with star fruit follow the reference: "Recipes that have the most of this ingredient".
Not only vegans and vegetarians should read this: A Vegan Diet Can Be Unhealthy. Nutrition Mistakes. |
Purchasing - storage
The exotic star fruit has multiple to continuous flowering and harvest periods. So, it is in season all year round. In Europe, however, star fruit is mainly marketed during the cooler months to avoid local competition.5
In India, harvest occurs from January to February and from September to October.25 In Florida, star fruit is harvested from June to February; in Malaysia almost all year round - and in Taiwan the fruit is grown in both summer and winter. Ideally, there are three harvests per year.4
Star fruit can be bought from major retailers such as Walmart, Costco, Whole Foods Markets, Kroger, Target, Albertsons and Safeway (United States); Asda, Sainsbury’s, Tesco, Morrisons, Aldi, Lidl, and Holland & Barret (Great Britain); Metro, Extra Foods, Real Canadian Superstore and Goodness Me (Canada); and Coles, Woolworths, and Harris Farm (Australia). Organic supermarkets may also have them. We recommend looking for organic star fruits, as conventionally grown fruits are heavily contaminated with pesticides (see below). Some tropical farms specialize in the organic cultivation of exotic fruits: inquire in your region.
Storage tips
The optimal storage temperature for star fruit depends on the degree of ripeness and the cultivar. Fruit that is picked unripe turns yellow at room temperature, but the sugar content no longer increases.28 In general, you can store the ripe star fruit at room temperature for around 4–6 days. Storage life is extended under cool conditions. One study reports storing 'Fwang' and 'Arkin' fruit at 7.2 °C (in well-ventilated boxes), for 4 weeks without any negative impact on quality.25 If you want to store longer, you can put the fruits in the refrigerator, which is usually around 5 °C.28 However, the ripe star fruit should not be kept at temperatures below 5 °C; unripe fruits only tolerate temperatures above 5 °C, as they are particularly susceptible to cold damage (except cultivar 'Arkin').4,5
Ingredients - nutritional values - calories
100 g of raw star fruit consists of 91.4% water, 1 g protein and 0.33 g fat. The energy content is 31 kcal.23
Star fruit is a good source of vitamin C (34 mg/100g), similar to tangerines (27 mg/100g) and not far off from lemon (53 mg/100g). However, raw broccoli (89 mg/100g) and rosehip (426 mg/100g) have much higher vitamin C content.23
With 0.39 mg of vitamin B5 per 100 g, star fruit lies between asparagus (0.27 mg/100g) and broccoli (0.57 mg/100g). Their vitamin B5 content is therefore not particularly high (7% of the daily requirement).23
Among the minerals, star fruit has a relatively large amount of copper (0.14 mg/100g), similar to the kiwi (0.13 mg/100g). However, the copper content is very low compared to walnuts (1.6 mg/100g). The sweet star fruit has 133 mg/100g of potassium which is slightly more than apple (107 mg/100g) but much less than banana (358 mg/100g) or kale (491 mg/100g).23
Star fruit contains various antioxidants8,14,17 and dietary fiber,10 which are considered to be health-promoting. In addition, star fruit contains sorbitol; a sugar suitable for diabetics.16
You can find the total ingredients of star fruit, the coverage of the daily requirement and comparison values with other ingredients in our nutrient tables. In the article Nutrients explained you will get a detailed insight into the topic.
Health effects
Is star fruit healthy? Antioxidant properties14 (mediated by vitamin C, epicatechin17 and gallic acid) as well as hypoglycemic effects (mediated by high fiber content and 2-dodecyl-6-methoxycyclohexa-2,5-diene-1,4-dione20) and cholesterol-lowering effects (mediated by micronized fiber10) are attributed to star fruit. In addition, the plant shows antihypertensive (mediated by apigenin), anti-inflammatory, antimicrobial,13,18 antitumor and immune-boosting effects.10
The following is a list of key findings from animal studies:
- Researchers demonstrated the antimicrobial, antifungal and antioxidant effect of star fruit by using extracts from the leaves, the bark and the fruit. Secondary plant substances such as saponins, tannins or steroids are involved.18
- A study with mice showed an anti-inflammatory effect. The researchers applied an extract from the leaves of the star fruit tree to the affected areas of the skin. The extract led to significant inhibition of skin inflammation.3
- Another study with mice showed a liver cell cancer preventive effect of star fruit.19
- Another experiment demonstrated in vitro and in vivo (on mice) that an extract from star fruit leaves can potentially be used against breast cancer.22
- Researchers administered DMDD (a compound isolated from star fruit root) to mice with symptoms similar to human Alzheimer's disease. DMDD improved the learning ability and memory of the sick mice.20
- Researchers found a positive health effect of star fruit leaves in obese rats. When the rats consumed the leaves, the negative effects of excess weight improved.15
- The flavonoid 'apigenin-6-C-β-L-fucopyranoside' contained in star fruit leaves lowered blood sugar levels in diabetic rats, stimulated "insulinsecretion" and enhanced glucose-induced "insulinsecretion" in hyperglycemic rats. In addition, these flavonoids can stimulate glycogen synthesis in the soleus muscle of rats by mechanisms known for "insulinsignaling".24
Dangers - intolerances - side effects
People with kidney problems (kidney failure) should never eat star fruit. The high content of oxalic acid and caramboxin can lead to symptoms such as hiccups, altered consciousness, vomiting, psychomotor agitation (unwanted hasty movements, tremors, etc.), epileptic seizures, coma and death.2,6
Caution is also advised for people taking certain tranquilizers or cardiovascular medications. Carambola can affect the effects of these drugs.7
Even people without any previous illness should not eat large amounts of the star fruit.1,2
Traditional medicine - naturopathy
The roots, leaves, and the star fruit itself find a variety of uses in traditional medicine. A tea preparation is used to relieve indigestion, hemorrhoids, fever, headache, vomiting and cough. In addition, the tea is used as an appetite stimulant, diuretic and to treat diarrhea.16 In India, Malaysia and Taiwan, the fruit is used as a remedy for fever, coughs, asthma, chronic headaches and skin inflammation.14 Extract of the leaves is used to treat diabetes.3 In Traditional Chinese Medicine (TCM), the root is used to treat headaches, vomiting, coughs and hangovers.20 Star fruit is also used in folk medicine for the treatment of diabetic nephropathy, joint pain, kidney stone formation and chronic paroxysmal headaches.12
Ecological footprint - animal welfare
The main growing areas of the star fruit are in tropical countries such as Taiwan and Indonesia, while regional cultivation in Europe has only been done sporadically so far. Accordingly, the transport routes of the fruit are very long, which is also reflected in their ecological footprint. Due to their high perishability, star fruit is often transported by plane, which leads to significantly more emissions than transport by ship. Conventional farming also uses chemical fertilizers and pesticides because star fruit is vulnerable to pests.27 However, these pesticides have a negative impact on the environment, including the star fruit's main pollinator - honey bees.7,26,27 Ideally, when shopping, look for products from organic and regional agriculture.9 In the Bavarian tropical house 'Klein Eden', for example, attempts are being made successfully to grow exotic fruits, including star fruit, organically.21
Star fruit needs a lot of water and warm temperatures for optimal "growing". To avoid drought stress on the plants, star fruits sometimes also have to be irrigated artificially.5,28 This requires additional energy and thus increases the ecological footprint.
Worldwide occurrence - cultivation
Where does star fruit come from? The origin of star fruit is not clear. Indochina, Malaysia and Indonesia are considered the most likely places of origin. Other possible places of origin are the Moluccan Archipelago, India and Sri Lanka. Star fruit was brought to the Philippines and India in prehistoric times. The Sanskrit name 'Karmana' (meaning food appetizer7) proves its long-standing occurrence in India. In 1856 star fruit was mentioned in Rio de Janeiro and in 1887 in Florida, and Trinidad and Tobago. The cultivated plant was probably introduced to Hawaii around 1789 and to Australia at the end of the 19th century.11
Today, star fruit is grown in many areas of the tropics and subtropics. Major producing countries include Taiwan, Malaysia, Brazil, Guyana, India, Philippines, Australia, Israel, Florida and Hawaii.11
Cultivation - harvest
This exotic plant can be purchased as a young and grafted tree. Since this is not hardy and does not tolerate less than 10 °C, it does best in a winter garden in Central Europe, where star fruits are ripe for harvest and consumption from October to February.
Additional information
Star fruit is a slow-growing, bushy tree with a short trunk. The tree reaches a height of 6 to 9 m and a diameter of up to 15 cm. When stressed, the leaves fold up during the night. The flowers are purple. Immature fruits are dark green; a ripe star fruit has a yellow color (exception: special cultivars, e.g., the above-mentioned 'Honglong' = Averrhoa carambola L. cv. Honglong). Star fruit belongs to the sorrel family (Oxalidaceae).15
Alternate names
Star fruit is also called carambola in German-speaking countries. In English they are known as star fruit or carambola.
Other applications
Star fruit is used as a cleaning agent, especially for cleaning metals.
Bibliography - 28 Sources
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20. | Wei X, Xu X, Chen Z et al. Protective Effects of 2-Dodecyl-6-Methoxycyclohexa-2,5 -Diene-1,4-Dione Isolated from Averrhoa Carambola L. (Oxalidaceae) Roots on Neuron Apoptosis and Memory Deficits in Alzheimer's Disease. Cellular Physiology and Biochemistry. 2018; 49(3):1064–73. |
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