Kumquats

Find - Kumquats are usually fairly easy to find in season, though they won’t dominate store shelves the way the large and better known citrus fruits will. They tend to be especially popular (and more easily found) in areas with a large East Asian diaspora. They are grown in warm parts of Asia, the Middle East, the Mediterranean, and North America.

Kumquats are in generally only in season for a few months in the winter and early spring (generally December to May in the Northern Hemisphere).

Choose - The shape of the fruit can vary depending on the variety, but will generally be either spherical or ovoid. Kumquats are small for a citrus fruit – generally about the size of a large green olive.

Look for bright orange kumquats with a highly fragrant peel. There are some cultivars that do not become bright orange, instead remaining yellow, greenish, or combination of the two, but most of these are not commercially common. You may find that your kumquats look like tiny oranges when cut open (i.e. they have a juicy interior), but don’t be surprised if they’re actually quite dry and solid throughout. Either type is normal, and may vary depending on the variety and the growing conditions. In either case, the sweetness doesn’t come from the juice, so don’t worry too much about what type you get.

Unlike most citrus, the peel of the kumquat is always eaten, and is actually the primary source of sweetness. This means you want to ensure that your kumquats are clean and blemish-free. The thickness of the rind can vary somewhat, and the fruit usually has 2-6 seeds. If you’re lucky, the seeds will be large and easy to pick out, though there are often small, thin seeds that are a little trickier to extract.

Store - Kumquats can be kept at room temperature (e.g. in a fruit bowl) for at least a few days assuming that they are not already over-ripe, but (as with any citrus) keep watch for any powdery mould growth on the skins. If you want to keep them a little longer (or stop them from ripening further), they can be kept in the refrigerator for at least two weeks.

Kumquats also freeze very well if kept whole or simmered in a simple syrup. Candied kumquats will store in the refrigerator for at least several months.

If you have an overabundance of kumquats, they can also be stored in alcohol to make an infused liqueur or salted and refrigerated (like preserved lemons).

Because kumquats are unique among citrus in that they’re generally eaten in their entirety, they’re somewhat difficult to replace. The ideal replacement for kumquats is another small citrus fruit called a calamondin or calamansi. The small calamondin fruits are actually a hybrid of kumquat and mandarin orange, and they feature a fragrant skin and sweet/sour fruit. Calamondin peels are highly fragrant, but not as soft or thin as those of kumquats, so only the zest should be used when substituting. Bottled calamondin juice is often available at Asian grocery stores, but make sure you don’t buy a sweetened variety.

All that being said, if you can’t find kumquats, you’re probably not going to be able to find a lot of calamondin, so a second, easier substitution is possible. If you have a recipe that calls for kumquats and you only have access to common citrus fruits, try using a mixture of orange juice, lemon juice, and a little lime juice to replicate the sweet/sour element, plus orange zest to bring in the aromatic element of the peel. You could experiment with other citrus as well, including sour oranges and tangerines (if you can find them).

If you’re trying to substitute for kumquats, take care not to overdo it with the juice. Kumquats are not overly juicy, so they don’t give up a lot of liquid/juice when cooking. If you do use a combination of citrus fruits as a replacement, be judicious with the volume.

I've done my best to present some key information, but kumquat taxonomy (like most citrus taxonomy) is a matter of contention. There are several varieties, many of which are treated as species in some situations. That being said, from a flavour perspective, there’s not a great deal of difference between the varieties, so the complexity shouldn't discourage any culinary exploration.

ROUND (MARUMI) KUMQUAT  - Any of several round, golden-yellow varieties. These kumquats are frequently encountered as ornamental houseplants. The fruit is pleasant, with a sweet rind and a rather sour flesh. Most of these varieties are less popular for eating raw, with the exception of the Meiwa (see below). In some cases, the rind is too tough to eat raw.

MEIWA KUMQUAT  - A pale-orange, round kumquat variety, particularly popular raw (eaten out-of-hand). This is one of the most commonly available kumquats in grocery stores, and is the most commonly encountered round variety. Sometimes known as Fortunella crassifolia.

OVAL (NAGAMI) KUMQUAT - A very popular oblong kumquat variety with deep orange fruit. These were the first kumquats imported to the West, and have remained a very popular variety throughout the world. The entire fruit is always eaten, and is popular both raw and cooked. These kumquats are one of the most commonly encountered varieties in grocery stores. Sometimes known as Fortunella margarita.

JIANGSU (FUKUSHU) KUMQUAT - A very thin-skinned, acidic/sour kumquat with large round fruit and bright orange skin. Most likely a hybrid of two other kumquat varieties.

NORDMANN & OTHER SEEDLESS KUMQUATS - Many of these varieties are fairly new and uncommon commercially, but if you can get the fruit, or you’re looking for a variety to grow, these ones are ideal for the simple reason that the fruits are seedless. This makes them absolutely ideal for candying or making marmalades and other preserves. Nordmann Seedless is the most easily found variety in North America, but there is also a Japanese variety called Puchimaru.

KUMQUAT HYBRIDS - Kumquats hybridize readily with other citrus fruits, and there are many unusual hybrids available for culinary and decorative purposes that have kumquat as one parent. Most of the newer varieties have “quat” in their name. In general, these hybrids are not interchangeable for kumquats from a flavour perspective, but they do have enough in common to be used in similar fashions. Some of these include:

• Calamondin – A very important fruit in the cuisine of the Philippines. The fruit is quite sour, and can be sold green or orange, though the flesh will generally be an orange-yellow color. Calamondins are thought to be a naturally occurring hybrid of kumquat and mandarin orange. See the ‘Substitutions’ section for more information.
• Orangequat/Mandarinquat – Any of several mandarin or sweet orange hybrids. Larger than a kumquat, and somewhat like a calamondin.
• Limequat – Any of several key (Mexican) lime hybrids. Much more like a lime than a kumquat. Uncommon as a commercial fruit, but increasingly common as an ornamental plant.