Star fruit (carambola), raw (organic?)

The raw star fruit ( Averrhoa carambola), which is also called carambola or Starfruit It is an egg-shaped, sour-sweet berry with pronounced longitudinal ribs, up to 15 cm long. Make sure it is organic quality.

Use in the kitchen

How do you eat star fruit? The cross-cut slices of raw star fruit are ideal for garnishing salads, cocktails, vegan desserts or cakes due to their decorative star shape. In Indian cuisine, star fruit is also used for spicy dishes such as pickles, chutney or dal. You can conjure up 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 type is very sour, and the small, light green fruits are only used for cooking. The sweet variety, on the other hand, should primarily be eaten raw, otherwise it loses its flavor. The light yellow or golden yellow to amber-colored and translucent flesh indicates the ripeness of the exotic star fruit. The yellow (yellow-orange) skin of the ripe fruit can be peeled off before consumption or eaten with it.

In Taiwan, a new cultivar has been in use for some time, the 'Honglong' star fruit: Its skin has a darker color (orange to red) and replaces the former main crop 'Chang Tsey', which is very susceptible to pests and diseases. ⁴

Vegan recipe for ice cream on a stick with star fruit

Ingredients (for 4 servings): 1-2 pieces of raw star fruit (carambola, organic), 500 ml coconut water (not coconut milk!), fresh mint, 50 g strawberries, 50 gblueberries, ice cream stick molds or alternatively spoons and e.g. small yoghurt cups.

Preparation: Wash the raw fruit thoroughly. Then cut the star fruit crosswise into slices so that the star shape is visible. Cut the strawberries into bite-sized pieces and place them in the ice cream molds together with the star fruit, blueberries and mint. Finally, fill the molds with coconut water and freeze overnight.

Vegan recipe for chocolate star fruit tartlets

Star fruit is particularly suitable as a decoration for cakes and tortes, here for tartlets.

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 of raw star fruit (organic).

Preparation: Pit the dates and mix them in a blender together with the nuts and cocoa powder (possibly with maple syrup) to form a homogeneous mass. Then divide into two equal-sized pieces, shape each into a ball and roll out the dough ball into two circles. Press the dough evenly into each tartlet mold. If you don't have tartlet molds, you can use any other shape - just adjust the dough to the shape. Place the filled molds in the fridge for 1-2 hours. Meanwhile, finely chop the chocolate, put it in a bowl and melt it over steam. Finely mix the silken tofu. Then add the melted chocolate and mix until a fine cream has formed. Now fill the tartlets with the chocolate cream. Place in the fridge for a few hours. Peel the star fruit with brown spots on the edges and cut it into slices widthwise. Finally, decorate the vegan tartlets with the stars and serve cold.

Vegan recipes with star fruit can be found under the note: " Recipes that have the most of this ingredient ".

Purchasing - Storage

The exotic star fruit thrives in several to continuous flowering and harvest periods. Therefore, it is in season all year round. In Europe, however, the star fruit is mainly sold during the cooler months in order to avoid domestic competition from other fruits. ⁵

In India, the harvest takes place from January to February and from September to October. ²⁵ In Florida, the star fruit is harvested from June to February; in Malaysia almost all year round - and in Taiwan the fruit is also grown summer and winter. Ideally, there are three harvests per year. ⁴

Star fruit can be bought from major retailers such as Coop, Migros, Denner, Volg, Spar, Aldi, Lidl, Rewe, Edeka, Hofer and Billa. Organic supermarkets such as Denn's Biomarkt or Alnatura also stock some of them. We recommend looking for organic quality, as fruit from conventional cultivation is heavily contaminated with pesticides (see below). Some tropical houses specialize in the organic cultivation of exotic fruits: ask in your region.

The availability of star fruits varies depending on the size of the store, catchment area, etc. Our recorded food prices for the DA-CH countries can be found above under the ingredient image - and by clicking on them you can see their development at different suppliers.

Storage tips

The optimal storage temperature for star fruit depends on the degree of ripeness, but also on the cultivar. Unripe fruits turn yellow at room temperature, but the sugar content does not increase. ²⁸ In general, you can say: Ripe star fruit can be stored at room temperature for about 4-6 days. The storage time is longer under cool conditions. A study reported on the storage of fruit of the varieties 'Fwang' and 'Arkin' at 7.2 °C (in well-ventilated boxes, for 4 weeks) without this having a negative effect on the quality. ²⁵ For longer storage, the refrigerator is suitable, which is usually around 5 °C (up to 8 °C). ²⁸ However, star fruit should not be exposed to temperatures below 5 °C, as it is particularly susceptible to cold damage (except for the 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 mandarin oranges (27 mg/100g) and not far behind lemons (53 mg/100g). However, star fruit cannot compete with raw broccoli (89 mg/100) or rose hips (426 mg/100g). ²³

With 0.39 mg of vitamin B5 per 100 g, star fruit lies between asparagus (0.27 mg/100 g) and broccoli (0.57 mg/100 g). Its vitamin B5 content is therefore not particularly high (7% of the daily requirement). ²³

Among the minerals, star fruit has a relatively high copper content (0.14 mg/100g), similar to kiwi (0.13 mg/100g). Compared to walnuts (1.6 mg/100g), the copper content is very low. The sweet berry has 133 mg/100g of potassium. That is slightly more than in apples (107 mg/100g), but much less than in bananas (358 mg/100g) or kale (491 mg/100g). ²³

The various antioxidants ^8,14,17 and fiber ¹⁰ in star fruit are considered to be particularly beneficial to health. Star fruit also contains sorbitol, a sugar that is suitable for diabetics. ¹⁶

You can find all the ingredients of the 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? Star fruit is said to have numerous positive nutritional and healing effects.

Secondary plant substances

Many of the health effects of star fruit can be attributed to the secondary plant substances it contains. Our article on secondary plant substances provides an overview of the classification of substance groups, their occurrence in foods and possible effects on humans. Star fruit contains the following secondary plant substances, among others:

• Isoprenoids: Sesquiterpenes: Sesquiterpene lactones (7α‐hydroxy‐dihydro‐epideoxyarteannuin, 3‐α‐hydroxy‐dihydro‐epideoxyarteannuin B); Triterpenes: Steroids (Beta-Sitosterol), Saponins, Lupanes (Lupeol), Beta-Amirine; Tetraterpenes: carotenoids (beta-carotene) ^3.10
• Alkaloids ¹⁰
• Polyphenols: Phenolic acids: Hydroxybenzoic acid (gallic acid); Flavonoids: flavonol (quercetin-3-O-β-d-glucoside, rutin), flavanols (epicatechin, catechin), flavones (apigenin fucopyranoside, [apigenin 6-C-(2-deoxy-β-D-galactopyranoside)-7-O-β-dquinovopyranoside, apigenin 6-C-α-L-rhamnopyranosyl- (1-2)-β-L-fucopyranoside, apigenin 6-C-α-L-rhamnopyranosyl-(1-2)-β-L-fucopyranoside, carambalosides], flavonoid glycosides (luteolin 6-C-α-L-rhamnopyranosyl-(1-2)-β-D-fucopyranoside), anthocyanins (cyanidin glucosides); chalcones (phloretin furanosyl glycosides); Tannins (proanthcyanidin) ^10,15,17,19
• Other nitrogen-containing compounds: Phenylalanine derivatives (Caramboxin) ¹⁰
• Other organic compounds: Quinones: Benzoquinone (2-dodecyl-6-methoxycyclohexa-2,5-diene-1,4-dione); Anthraquinone Glucosides, Aldehydes (p-anisaldehyde) ^3.10

However, it should be noted that the composition of secondary plant substances in star fruit can vary depending on the variety, time of harvest and growing conditions. Therefore, quantities are only of limited use and should only be understood roughly.

According to studies, star fruit has antioxidant properties ¹⁴, blood sugar-lowering ²⁰ and cholesterol-lowering effects ¹⁰. The Averrhoa carambola plant also has anti-inflammatory, antimicrobial, antitumor and immune-boosting effects. ^10,13,18 Researchers isolated a total of fourteen compounds, including four flavone glycosides and ten chalcone glycosides, using spectroscopic methods. ¹⁵ Studies show that the residue of the star fruit after juice extraction accounts for about 70% of the total antioxidant activity. The leaves of the star fruit also contain antioxidant compounds, the activity of which correlates significantly with the phenol content. ¹⁰

Using a star fruit extract from the leaves, bark and fruit, researchers demonstrated in the laboratory that star fruit has antimicrobial, antifungal and antioxidant effects. Secondary plant substances such as saponins, tannins and steroids are involved in this. ^18,19 In addition to the high fiber content (micronized fiber), the sesquiterpene lactones contribute to a blood sugar-lowering, antitumor and cholesterol-lowering effect. ¹⁰

The star fruit is rich in antioxidant compounds (flavonoids, proanthocyanidins, carotenoids (beta-carotene), saponins, alkaloids, tannins and gallic acid) and has a high ability to capture reactive oxygen species and free radicals. The flavonoids, proanthocyanidins, beta-carotene, saponins, alkaloids and tannins contained in it have a strong antioxidant effect together with vitamin C (L-ascorbic acid). ^10,17 p-anisaldehyde and the multifunctionalbeta-sitosterol have antimicrobial, antitumor, immune-boosting and anti-inflammatory effects ^10,13,18.

In various studies, the flavones (apigenin fucopyranoside) contained in star fruit leaf extracts reduced blood sugar levels in diabetic rats. They also stimulated insulin secretion and increased glucose-induced insulin secretion in hyperglycemic rats. Furthermore, these flavones improved glycogen synthesis in the soleus muscle and relaxed the thoracic aorta of rats. ¹⁰

One study showed significant improvements in skin inflammation in mice using an extract from the leaves. ^3,10,24 The phenolic composition of the star fruit leaf extracts led to health improvements in obese rats. ¹⁵ The Phenolic compounds are also known for their liver-protective effects. A study with mice found a preventive effect against liver cell cancer. ¹⁹

Several animal and in vitro studies demonstrated anti-inflammatory and cytoprotective properties of the compound 2-dodecyl-6-methoxycyclohexa-2,5-diene-1,4-dione (DMDD). According to the results, DMDD increases glucose-stimulated insulin secretion and lowers blood sugar levels in mice with diabetes. In addition, treatment with DMDD attenuates diabetic nephropathy (kidney disease) and improves kidney function. Further clinical studies are needed to confirm these effects of star fruit in humans. ¹⁰

Another experiment demonstrated in vitro and in vivo (on mice) that an extract from star fruit leaves has the potential to be used against breast cancer due to the DMDD present. ²² In studies, DMDD improved the learning ability and memory performance of mice with symptoms similar to Alzheimer's disease in humans. ²⁰

Another study showed a reduction in blood sugar levels in male mice with diabetes using benzoquinone (obtained from the roots of the star fruit). Extracts from the leaf showed anti-tumor effects due to the quinones. ¹⁰ Here too, further studies are needed to confirm the effectiveness in humans.

Dangers - Intolerances - Side effects

People with kidney problems (renal insufficiency) should not eat star fruit under any circumstances. The high content of oxalic acid and the poison caramboxin can lead to symptoms such as hiccups, altered consciousness, vomiting, psychomotor agitation (unintentional hasty movements, tremors, etc.), epileptic seizures, coma and death. ^{2 ,6}

Caution is also advised for people who take certain sedatives or cardiovascular medications. Star fruit can affect the effect of these medications. ⁷

Even people without a pre-existing condition are advised not to consume large quantities of star fruit. ^1,2

Folk medicine - natural medicine

The roots, leaves and the star fruit itself have a variety of uses in traditional medicine. A tea preparation is used to relieve indigestion, hemorrhoids, fever, headaches, vomiting and coughs. ¹⁰ The tea is also 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 inflammations. ¹⁴ In addition, an extract obtained from the leaves of the star fruit tree is used to treat diabetes. ³ In traditional Chinese medicine ( TCM) the root is used to treat headaches, vomiting, coughs and hangovers. ²⁰ The plant is also used in folk medicine to treat diabetic nephropathy, joint pain, kidney stone formation and chronic paroxysmal headaches. ¹²

Ecological footprint - animal welfare

The main areas where star fruit is grown are in tropical countries such as Taiwan and Indonesia, and regional cultivation in Europe has only taken place sporadically so far. The transport routes for the fruit are therefore very long, which is also reflected in its ecological footprint. Because it spoils quickly, star fruit is often transported by plane, which causes significantly more emissions than transport by ship. Conventional agriculture also uses chemical fertilizers and pesticides, including on star fruit, which is susceptible to pests. ²⁷ However, these pesticides have a negative impact on the environment, including on the star fruit's most important pollinators - honey bees. ^7,26,27 Ideally, when shopping, you should look for products from organic and regional agriculture. ⁹ In the Bavarian tropical house 'Klein Eden', for example, attempts are being made to grow exotic fruits organically - including star fruit. ²¹

For optimal growth, the star fruit needs a lot of water and summer temperatures. To avoid drought stress in the plants, star fruit sometimes needs to be watered artificially. ^5.28 This requires additional energy and thus increases the ecological footprint.

For detailed explanations of various sustainability indicators (such as ecological footprint, _CO2 footprint, water footprint), see our article: What does the ecological footprint mean?

Worldwide occurrence - cultivation

Where does the star fruit come from? The origin of the star fruit is not clearly established; Indochina, Malaysia and Indonesia are considered to be the most likely places of origin. Other possible places of origin are the Moluccas archipelago, India and Sri Lanka. In prehistoric times the star fruit was brought to the Philippines and India. The Sanskrit name 'Karmana' (= food appetizer ⁷) attests to its long-standing presence in India. In 1856 the star fruit was mentioned in Rio de Janeiro and in 1887 in Florida, 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. The main producing countries include Taiwan, Malaysia, Brazil, Guyana, India, the Philippines, Australia, Israel, Florida and Hawaii. ¹¹

Growing your own

The exotic plant can be purchased as a young and grafted tree. As it is not winter hardy and cannot tolerate temperatures below 10 °C, it is best grown in a winter garden in Central Europe. Ripe star fruits can be harvested from October to February.

Further information

The star fruit is a slow-growing, bush-like 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 at night. The star fruit flowers purple. Unripe fruits are dark green; a ripe star fruit is yellow (exception: special cultivated varieties, e.g. the above-mentioned 'Honglong' = Averrhoa carambola L. cv. Honglong). The star fruit belongs to the family of wood sorrel plants (Oxalidaceae) and to the genus of cucumber trees ( Averrhoa). ¹⁵

Alternative names

In German-speaking countries, the star fruit is also called Karambola, Carambola or Karambole. In English, it is known as star fruit or carambola.

Other applications

The star fruit is suitable as a cleaning agent, especially for cleaning metals.