Harvested sour oranges (a.k.a. Seville or bitter) at the JB Ranch in Seville,… (David Karp / For The Times )
Reporting from Seville, Calif. — Tucked away along a canal beside an imposing mountain grows an 80-acre orchard of oranges so enchanting that each winter I make a pilgrimage to its secluded site. What I find so special is not just the beauty of the grove, typically shrouded in tule mist, with sticky, reddish-brown clay soil, and dark green trees radiant with neon-orange, intensely aromatic fruits. It's also the curious history behind this planting, little known even to longtime locals, though it recently has become California's primary source for sour oranges, the kind used in marmalade.
This super-flavorful culinary citrus, also known as the bitter or Seville orange and beloved by Middle Easterners, Latinos and high-end chefs, was previously hard to find here, but the 8-year-old orchard -- aptly located in Seville, a small community northeast of Visalia -- is now bearing so abundantly that Sunkist, for the first time, is marketing the fruit domestically.
Sour oranges play an important role in citrus cultivation and ethnic cooking, but since they are too bitter and acidic to eat fresh, many citrus lovers are unfamiliar with them. They're round and about the same size as sweet oranges but have a thicker, rougher, darker red rind and a spicier aroma; the peel and the seedy, juicy, yellow flesh owe their bitterness to two polyphenolic compounds, neohesperidin and naringin.
Early citrus scientists conjectured that sour oranges might be the ancestors of sweet oranges such as navels and Valencias, but studies of DNA markers have shown that sweet and sour types arose separately from crosses of pummelo and mandarin, probably from different clones of each. Sour orange is actually a 50/50 hybrid of those two species, while sweet orange seems to be a backcross, a second-generation hybrid that's more mandarin than pummelo, according to a recent analysis by Mikeal L. Roose, professor of citrus genetics at UC Riverside.
Like most cultivated citrus, sour oranges originated in the area of southern China and northeastern India. They may have been known to the Romans but were not widely cultivated in the Mediterranean basin until the Arabs spread them late in the first millennium A.D. -- some 500 years before the cultivation of sweet oranges in the region. In medieval times, Arab cooks used the juice to flavor meat stews; today Persians typically use it as a souring agent on fish.
Sour orange cultivation is emblematic of the Seville region of southern Spain, which has exported the fruits to Britain for making marmalade since the 18th century. The Spanish also brought sour oranges to the New World, where the trees grew wild in some areas, and Cuban and Dominican cooks came to use the juice in garlicky mojo sauce to marinate pork and chicken.
Starting in the 19th century, sour orange became the leading rootstock used for other citrus worldwide, because it is relatively cold-hardy, tolerant to root rot and can adapt to many soils. Its use for this purpose has declined in recent decades, because trees grafted on sour orange are susceptible to the increasingly prevalent tristeza virus, but many a California farm or garden has a sour orange tree that grew up after the scion, the upper part of the tree, died.
For at least a century, sour orange trees have been widely grown as ornamentals in Arizona, particularly in the Phoenix area, because they provide shade, produce fragrant blossoms and thrive despite neglect. An odd trade arose in which students and Boy Scout troops, as well as hired laborers, harvested the fruit from trees grown in and around streets, golf courses, backyards, cemeteries and the like.
A longtime kingpin of this business, Bob Baker, 83, remembers that back in the 1960s he used to buy and ship more than 50,000 cartons of the fruit, largely to Canada, where marmalade making traditionally was strong; but that gradually decreased to 1,000 or so this year, as home preserving declined and harvests and quality proved inconsistent.
In 1962, seeking a more assured supply, the owners of California Citrus Pulp Co., based in Colton, planted 40 acres of seedling sour orange trees in Bard, Calif., near Yuma, where land and water were cheap at the time. Harley Berryman, now 80, farmed and eventually bought this orchard, which was long the main domestic source. But as the trees aged, production diminished, and Berryman found he could make more money renting the land for winter vegetables, so in 2006 he bulldozed the grove.
Around 2000, Vita-Pakt, a former juice processor (and briefly, in 1964, a skateboard maker), which had become the dominant domestic supplier of sour orange peel for marmalade, recognized that the Bard orchard was on the way out and asked growers near its factory in the San Joaquin Valley to plant sour oranges.