Real Food Right Now and How to Cook It: Kumquats

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Everything is adorable about kumquats. From their diminutive size to their cheery color, and even their name - all as cute as a button, and a welcome sight in the dead of winter when there is little fun to be had at the market. (Don't worry, I still love you potatoes and rutabagas!) Pick up a basket of these wee citrus-that-aren't-citrus (more on that below) and dream of warmer climes.

A Brief History of Kumquats

Kumquats are native to Southeast China, where, according to the Oxford Companion to Food, they were first domesticated but can still be found growing wild. The fruit was described in Ancient Chinese scholar Han Yen-chih's Monograph of Citrus in 1178 BCE. (My favorite line about kumquats in the monograph says, "[w]hen served on the table they glisten like golden bullets.") They were brought from China to Japan, where they became (and still remain) a popular fruit. In 1846, Robert Fortune, a Scottish botanist with a remarkable history of his own, brought kumquats to London. Later, Fortune would be sent back to China by the British East India Company to steal Chinese trade secrets about tea production, as this fascinating article explains. Kumquats made their way to the southern US around 1850.

Factual Nibbles

  • Kumquat trees are popular as displays and gifts for Chinese Lunar New Year - the plant symbolizes wealth and good luck. (Chinese New Year falls on February 19th this year - get your kumquats, quick!)
  • I literally can't even with this kumquats on cats video. Or this one
  • Pangrams are sentences that use all of the letters in the alphabet. Weirdly, kumquats appear quite a bit in pangrams, like this one: "Hazel's kumquat flavored jellybeans were exceptionally good." Or this one: "Butter & kumquat jelly sandwiches: a zany way of expressing love." (Both from The Daily Pangram.)

Kumquat Cultivation

Kumquats are in the Rutaceae (rue) family, which includes the Citrus genus and all of its corresponding familiar fruits - but kumquats technically are not citrus, although they share obvious citrus-y attributes. They are classified in a genus all their own, Fortunella, named after noted kumquat importer and tea-secret thief Robert Fortune. They grow on adorable small trees, usually between eight and fifteen feet high, but dwarf specimens can be found in order to grow in pots. Kumquat trees have dark, glossy green leaves and beautiful fragrant flowers. A single tree can produce hundreds to thousands of kumquats per year. There are a couple of different varieties of kumquat - most common are the Marumi (F. japonica), which is round, and the Nagami (F. margarita), which is oval in shape and the variety introduced to London by our old pal Robert Fortune. The Nagami variety is by far the most common kumquat type seen in markets in the US.

The cute little fruits are cultivated in China, Taiwan, Southeast Asia, Japan, Greece and Florida. If you are lucky, you may also find them at farmers' markets in Texas and California. There are also a number of interesting kumquat hybrids, including the limequat (key lime x kumquat), lemonquat (lemon x kumquat) and the calamondin (calamansi) (thought to be mandarin orange x kumquat).

Kumquat Seasonality

Like most other citrus(y) fruits, kumquats are in season in the winter - usually from December through March.

Environmental Impact of Kumquats

Kumquats are a majorly niche fruit in the United States, so their environmental impact is minimal. However, it is extremely difficult to find organic kumquats. As this article from Purdue University explains, kumquats are susceptible to most citrus pests (except for citrus canker, to which they are highly resistant), so I can only speculate that pesticide use is common in non-organic fruit.

Here's a list of pesticides used on kumquats in California and here's a list of approved pesticides for kumquat cultivation in Florida (see Table 10 ) - as you can see, there are quite a few. If you are lucky enough to find organic kumquats, snap them up. (*And check out our Real Food rule of thumb, below, for more information.) In Florida, citrus production is part of a larger water use problem. Citrus and strawberry farmers spray their crops with immense amounts of water in years when their crops are in danger of freezing. As this article explains, this kind of excessive water use causes aquifer depletion and sinkholes, neither of which are any fun. Agricultural irrigation and water use (for things like lawn watering) in Florida is also causing saltwater to infiltrate local aquifers.

Kumquat Characteristics

Most of the kumquats we see at markets in the US are the bright-orange Nagami variety - they are oval shaped, between two and three inches long. Kumquats are the only citrus(y) fruit that can be eaten peel and all; indeed, kumquat peels are sweeter than the tart juice inside. They do sometimes have large and bitter seeds, however, so I find them more delicious sliced than whole, so I can pop the seeds out. Look for kumquats without mushy or brown spots, and if you can, choose fruit that aren't tinged with green, as these tend to be more bitter.

Kumquat Nutrition and Effects on the Body

There is a lot of good stuff in teeny kumquats. They are packed with fiber and Vitamin C and are low in calories. They've got some calcium, Vitamin A, riboflavin, iron, manganese and potassium, to boot. In traditional Chinese medicine, kumquats are said to help with sore throats, excessive phlegm and coughs.

What to Do with Kumquats

Kumquats are usually eaten raw, made into preserves or candied (see below for more on this). The peel and the pulp together make a lovely sweet-tart contrast, and although they aren't very common, they are actually a versatile fruit, performing well in both sweet and savory dishes. On the sweet side, they pair beautifully with chocolate, vanilla, mint and other fruit, like pears and cranberries. For savory dishes, think about pairing kumquats with duck, pork, chicken, fish, cheese, greens and grains. I like to slice kumquats very thinly (removing any seeds) and toss into kale salads, along with toasted sunflower seeds or almonds. Or toss sliced kumquats into your favorite grain salad (think farro, quinoa or brown rice). They are also delicious as a topping for fish (like salmon) and make a great chutney to pair with hard, salty cheeses. Or make this kumquat salsa to make boring grilled chicken a bit more interesting. For dessert, kumquat-lemongrass ice cream sounds fantastic, as does this kumquat upside down cake (or the yogurt-olive oil cake with candied kumquats, below!). You can even make tea out of fresh kumquats, which is said to help heal those nasty winter colds.

How to Store Kumquats

Kumquats store well - kept in the refrigerator, they'll keep for at least ten days.

How to Preserve Kumquats

Kumquats make excellent preserves - here is a lovely kumquat marmalade from David Lebovitz, or if you'd like to be a bit more experimental, check out this kumquat habenero marmalade. Here's another marmalade recipe for preserving the whole fruit, rather than slicing them, as most marmalade recipes call for. Here is an excellent recipe for candied kumquats that will keep in your refrigerator for at least three months - top vanilla ice cream with warmed kumquat syrup and some candied kumquats and prepare for bliss. Commercially produced kumquat liqueur is available - but you can easily make your own. (If you're interested, here are pictures of a kumquat liqueur distillery in Corfu, Greece, where kumquats are apparently one of the major agricultural products.)

Recipe: Yogurt-Olive Oil Cake with Quick Candied Kumquats

This recipe is fast and delicious. The kumquats are essentially just macerated until they "candy" on their own - no saucepan or candy thermometer needed. And the cake is simple, too: no stand mixer required, no creaming of butter and sugar - it is very, very quick and very, very good. I usually use regular whole-milk yogurt (don't use low fat here), but you can use whole milk Greek yogurt just as successfully. The recipe is loosely based on this one from Bon Appétit .

For the quick-candied kumquats:
1 pint kumquats, washed and dried
1 tablespoon water or light rum
12 cup sugar

For the yogurt cake:
112 cups all-purpose flour
2 teaspoons baking powder
34 teaspoon kosher salt
The quick candied kumquats (above)
12 cup sugar
34 cup whole-milk yogurt
12 cup fruity extra virgin olive oil
2 large eggs
1 tablespoon orange or lemon juice
1 teaspoon real vanilla extract

For the quick-candied kumquats:

  1. Cut the kumquats into 18 inch slices, popping out any seeds as you go. (There will be big, greenish seeds and little tiny seeds; make sure you get rid of both.)
  2. Combine the sliced kumquats with the water or rum and 12 cup of sugar in a small bowl. Let stand at room temperature for at least an hour, or as long as 8 hours. (If you are going to let them stand for over an hour, cover the bowl with plastic wrap and stick in the refrigerator.)

For the yogurt cake:

  1. Preheat the oven to 350°F. Spray a standard (812x414) loaf pan with cooking spray. Set aside.
  2. Whisk together the flour, baking powder and salt in a medium bowl. 
  3. In a large bowl, combine the candied kumquats and any liquid they've produced, along with the remaining 12 cup of sugar. Toss well to mix. Add the yogurt, oil, eggs and vanilla extract and whisk well to combine. 
  4. Fold in the dry ingredients and stir to blend (do not over mix). 
  5. Pour the batter into the prepared loaf pan and smooth the top. Bake for about 55 minutes, or until a cake tester comes out clean and the cake is golden brown on top.
  6. Let cool 15 minutes, then invert on a cooling rack. Cool completely before slicing. A bit of whipped cream on top would be nice.

(*Real Food rule of thumb: We think that first and foremost, in terms of nutrition, people should eat lots of fruits and vegetables whether they are organic or not. The EWG's guide is a handy list, but we will point out here that the impacts of pesticides are not limited to your ingestion of them - agricultural chemicals also affect farmworkers and local waterways, both good reasons to buy organic, even those vegetables that carry a light pesticide load. Also, it has been demonstrated that produce grown by small-scale farmers, even those who are not certified organic, tends to have a lighter pesticide load than its industrially-produced counterpart, owing to industry's tendency toward large monocrops.)


This post was originally published in February 2015.