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| Citrus depressa | |
|---|---|
 | |
| Shiikwāsā on a tree | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Rosids |
| Order: | Sapindales |
| Family: | Rutaceae |
| Genus: | Citrus |
| Species: | C. depressa |
| Binomial name | |
| Citrus depressa | |
Citrus depressa (Citrus ×depressa, formerlyC. pectinifera,Okinawan:シークヮーサー/シークァーサー,romanized: shiikwaasa,Japanese:ヒラミレモン,romanized: hirami remon orシークヮーサー,shīkwāsā, in English sometimes calledshikwasa,seaquarser,shiikuwasha,shequasar,Taiwan tangerine,sheer-quoarserre,Okinawa lime,[1]flat lemon,hirami lemon, orthin-skinned flat lemon,[citation needed] is a smallcitrus fruit often harvested and used when green, rich inflavonoids and native toEast Asia (Taiwan andOkinawa Islands,Japan).
Very sour, it is often used likelemon orlime togarnish dishes, but is also used to make jams, or a yellowjuice, which can be thinned or sweetened.
Its name is occasionally translated into English ascalamansi (calamondin,Citrus ×microcarpa), but this is a different fruit.
Shiikwaasa is primarily produced in southwest Japan, in the northern region of themain Okinawa island, along with another indigenousJapanese citrus, thetachibana orange (Citrus tachibana). The two are not the only species of citrus currently growing on the island, as there have been foreign species introduced and have since been crossbred alongsideCitrus depressa. Despite the varying diversity of citrus currently found in the region, onlyshiikwasa andtachibana are native to this region, originating in the Ryukyu Islands.[2]
Citrus depressa is grown in Okinawa and Taiwan.Shiikwaasa is grown in Okinawa. This flat lemon is a flowering tree with an average height of 3–5 m (9.8–16.4 ft). The appearance is similar tocalamansi. The flowers, white and about 3 cm (1.2 in) in diameter, usually bloom in April. The fruit, which appear around July, weigh about 25–60 g (0.88–2.12 oz). Unripe, the skin is a dark green, which becomes yellow during ripening. The fruits have a very low sugar content and are very sour in September, but gradually become sweeter as they ripen.[1]
Genetic analysis ofshiikwaasa and other Asian island mandarin orange varieties revealed this group to be a family of independent clonalF1 hybrids, arising from multiple crosses between a native Ryukyu Islands mandarin species,C. ryukyuensis, and a mainland-Asian mandarinC. reticulata still found onOkinawa, designated RK3 by the researchers. This mainland parent is related to the ChineseSun Chu Sha mandarin but has small amounts ofpomelointrogression that was passed on to theshiikwaasa. The mainland parent reproduces clonally, as do theshiikwaasa progeny of numerous independent hybridization events with distinct individual sexually-reproducing Ryukyu mandarin parents, sometimes serving as seed parent and sometimes as pollen parent. This varied origin, plus the fact thatshiikwaasa grow wild and are referred to in some of the earliest poetry of the island kingdoms, suggest that the hybridizations occurred naturally.[3]
Shiikwaasa is often used as a fruit juice and has been used for alternative health practices frequently. Though the pulp has some beneficial nutrients, most health-benefitting compounds present in the fruit's peel are:
Though commonly used as a fruit juice and considered an aid in metabolic health,C. depressa can potentially also aid in fat regulation. The addition ofC. depressa alongside a high-fat diet has been demonstrated to decrease fat mass, though this is based on a study done on rat models, and little study has been done to determine a similar correlation in humans.[7] Driedshiikwaasa, however, is often mixed with teas for its therapeutic benefits, and can be mixed into a fruit paste with chili pepper as a garnish on grilled meats.Shiikwaasa paste has also been demonstrated to decrease plasma glucose levels in lab rats and human volunteers.[4]
High levels of flavonoids provide the bitter taste often associated with the fruit. To makeshiikwaasa juice more palatable, sugar is commonly added excessively. However, fermentation ofCitrus depressa juice has also been demonstrated to cause a significant decrease in the umami, bitterness and astringent tastes of the fruit,[8] to aid in creating a more flavorful drink while maintaining the nutritional content of the fruit.
Shiikwaasa fruits are also a significant source of antioxidants. Anin vitro study used antioxidant assays to determine that in 100 g (3.5 oz) of unripenedshiikwaasa peels, there is either, approximately, 225.4 mg to 294.2 mg of total phenolic compounds – composed ofβ‐Carotene andDPPH – which varied due to differing extraction methods.[9]
Data related toCitrus depressa at Wikispecies
