Midwinter is prime citrus season for both the San Joaquin Valley and Southern California districts, with an abundance of excellent mandarins, oranges, tangelos and lemons. The one laggard is conventional grapefruit, which, as grown in these two areas will be too sour for most palates for a couple of months or more. By compensation, we have three fine locally adapted grapefruit-like hybrids, Oroblanco, Melogold and Cocktail "grapefruit," which are at their peak right now.
The Oroblanco is the most widely grown and flavorful of the three. It originated in the 1950s, when R.K. Soost and J.W. Cameron, citrus breeders at UC Riverside, recognized that regular grapefruit does not get enough heat in California, outside the desert, to sweeten in the main winter citrus season.
In what turned out to be an inspired choice, they crossed Siamese Sweet pummelo, an acidless form of the parent species of the grapefruit, with Duncan grapefruit, which is the seedy, white-fleshed variety from which all other commercial grapefruit originated, mostly by mutation. Siamese Sweet itself is insipid, but as a parent it lowered the acidity of its daughter varieties, so that their flavor balance is ideal under conditions of moderate heat; and Duncan contributed much of its intense, distinctive taste, which is rightly considered by experts to be the finest of all grapefruit.
To read the rest of the story, please go to: Los Angeles Times