and these may have been their original attraction, well before human selection developed varieties with sweet juices The improved varieties do have a refreshing, tart to sweet-tart juice that can be extracted with little pulp The peel is rich in gel-making pectins And citrus fruits are also fairly robust They’re nonclimacteric, so they retain their quality for some time after harvest, and the meaty peel offers good protection against physical damage and attack by spoilage microbes Citrus Anatomy Each segment of a citrus fruit is a compartment of the ovary, and is stuffed with small, elongated bags called vesicles, each of which contains many individual microscopic juice cells that fill with water and dissolved substances as the fruit develops Surrounding the segments is a thick, white, spongy layer called the albedo, usually rich in both bitter substances and in pectin And riding atop the albedo is the skin, a thin, pigmented layer with tiny spherical glands that create and store volatile oils Flexing a piece of citrus peel will burst the oil glands and send a visible, aromatic — and flammable! — spray into the air Citrus Color and Flavor Citrus fruits owe their yellow and orange colors (orange comes ultimately from the Sanskrit word for the fruit) to a complex mixture of carotenoids, only a small portion of which has vitamin A activity The fruit peels start out green, and in the tropics often stay that way even when the fruit ripens In other regions, cold temperatures trigger destruction of chlorophyll in the peel, and the carotenoids become visible Fruits of commerce are often picked green and treated with ethylene to improve their color, and coated with an edible wax to slow moisture loss Pink and red grapefruit are colored by lycopene, and red ... mixture of carotenoids, only a small portion of which has vitamin A activity The fruit peels start out green, and in the tropics often stay that way even when the fruit ripens In other regions,... trigger destruction of chlorophyll in the peel, and the carotenoids become visible Fruits of commerce are often picked green and treated with ethylene to improve their color, and coated with an edible...pectin And riding atop the albedo is the skin, a thin, pigmented layer with tiny spherical glands that create and store volatile oils Flexing a piece of citrus peel will burst the oil glands and