Published Saturday, April 14,
2001, in the Contra Costa Newspapers
runs deep for blood oranges
Q: I was told
recently that the blood orange is a cross between an orange and a
pomegranate. Is this true?
A: No, the blood orange (Citrus sinensis L. Speck)
and the pomegranate (Punica granatum) are genetically incompatible,
and cross-fertilization will not occur.
in the citrus field believe that blood oranges are a natural mutation. At
some time in the past, a sweet orange underwent a change at the genetic
level that produced an orange with red coloration in the flesh and juice
and on the rind. This new trait was interesting enough to someone that they
continued to propagate the variety.
recently it was believed that the blood orange originated in the
Mediterranean, possibly Sicily or Malta. However, there is documented
evidence that red oranges were in China as early as the fourth century. A
Chinese poem from the eighth century translates as follows:
Kiang-Nan in the Kiangsu
are small scarlet oranges
the winter doesn't kill
the air is truly sweet
mention of red oranges in Sicily came nine centuries later in the opera
"Hesperides" by the Jesuit Ferrari (1646). He describes the fruit
Aurantium indicum with pigmented pulp brought to Italy from the
Philippines by a Genovese missionary. Blood oranges also appear in a
painting by Bartolomeo Bimbi, an artist in Tuscany during the 17th and 18th
centuries. And the Florentine botanist Micheli (1679-1737) included
illustrations of the characteristics of the wine-colored juice Aurantium
hierochunticum in one of his manuscripts.
oranges, along with navel oranges and Valencia oranges, are one of the most
cultivated types of oranges. However, they exist as a commercial crop,
primarily in the Mediterranean basin where conditions appear to be best for
consistent color and flavor. They do not do as well in the cool
citrus-growing areas of Southern California or in the humidity of Florida.
Strangely enough, the rind coloration is best when the fruit is not exposed
to the sun; thus, some growers shade the lower portion of the trees by
growing a tall cover-crop such as sesbania.
color of blood oranges is due to the presence of chemicals called
anthocyanins. These pigments are present in a variety of familiar plants,
including hydrangeas, purple cabbage and red grapes. Gardeners are probably
familiar with the dependence of hydrangea color on the pH (a measure of
acidity) of the soil. The flowers are pink in acidic soil and blue in basic
soil. It is the anthocyanins that change color with changes in pH. (To
observe this dependency, add a small amount of baking soda --which is
"basic" -- to a teaspoon of grape juice or red wine. The liquid
will change color from red to purple, but probably will not get basic
enough to actually turn blue.)
the pink in pigmented grapefruits is caused by lycopene rather than
anthocyanins. Blood oranges do not yield an appealing juice, since the
pigments tend to deteriorate during processing and become muddy. But if you
try this orange -- with its unique interior color and rich orange flavor
with overtones of fresh berries -- you are in for a tasty treat.