This small citrus fruit is popular in the Philippines and other parts of Southeast Asia. The calamondin is also known as acid orange, calamansi, Chinese orange, kalamansi, musk lime and Panama orange. It's a hybrid whose parentage is unclear; some horticulturists theorize that it's the offspring of a kumquat and mandarin orange, while others speculate that it's a lime-mandarin cross. Calamondins look like round limes with thin green to greenish-yellow skins that turn orange as they mature. The orange pulp has relatively large seeds and is exceedingly sour, which is why this fruit is used as one would lemons. Calamondins, which are high in calcium, potassium and vitamin C, are grown yearround in California and Florida but are more plentiful from November through May. They're not widely available but can be found in some Asian markets, produce stores and upscale supermarkets. Store calamondins in the refrigerator for up to 2 weeks.
From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.