Grapefruit

grapefruitBy Kurt Nolte

When it comes to choosing grapefruit, some like to think pink. Grapefruit come in two varieties: white and pink. Pink grapefruit gets its color from carotenoids (carotene), pink grapefruit contains over fifty times the carotenoid of white grapefruit. In the body, carotenoids are partially converted to vitamin A so; eating pink grapefruit adds vitamin A to your diet. Vitamin A is an antioxidant that is required in the diet for good growth, skin development and is important in the maintenance of peripheral vision.

Pummelos, the largest of the citrus fruit varieties, are also called Chinese grapefruit. They are very popular during Chinese New Year celebrations because of their resemblance to the full moon.

You can eat grapefruit just like an orange by peeling it and dividing it into segments. Each medium grapefruit has between 10 to 12 sections.

Grapefruit juice freshly squeezed and stored covered in the refrigerator will retain 98% of its vitamin C for up to a week.

A grapefruit is 75% juice. One medium grapefruit will give you 2/3 of a cup of fresh-squeezed juice.

Since the early part of the 20th century, mutant strains of white grapefruit have appeared with pink to slightly reddish color, and have been propagated by citrus breeders into several strains of grapefruit that are now best known as the Ruby Red.

The grapefruit got its name from the way it grows in clusters (like grapes) on the tree. There is no mistaking a grapefruit tree – they are large with glossy dark green leaves and the fruit hangs in clusters on the tree.

The majority of grapefruit are packed into a standard two-piece fiberboard carton holding approximately thirty-two (32) pounds. The number of fruit packed into a standard carton includes the large 18’s, 23’s, 27’s, 32’s, 36’s, 40’s, 48’s and the smallest 56’s, based on the number of fruit packed in a carton.

Grapefruit trees are beautiful and a member of the citrus family offering about 69% of the RDA for vitamin C. Grapefruit also provides about 250 mg of potassium and pectin, a soluble fiber effective in lowering cholesterol levels.

World production of grapefruit is almost 6 million tons, the United States produces over 60% of this total.

Yuma County produced about 250,000 cartons of grapefruit on 150 acres in 2005 valued at over $155,000.

Some mature grapefruit trees can yield up to 1500 pounds of fruit in a season. The average yield is 350 pounds per tree. Grapefruit require high heat during the growing season in order to reach maximum eating quality.

The Rio Red grapefruit has almost five times more red pigment both in exterior as well as interior color as the original Ruby Red.

There are three major types of grapefruit, white, pink/red, and star ruby/rio red varieties.

All grapefruit have a similar tangy-sweet flavor and are very juicy.

The grapefruits that are used to make juice are those which contain seeds. The pink or red variety contains more vitamins than the white.

Store grapefruit at room temperature up to a week, or up to 8 weeks in a refrigerator.

The principal ancestor of the grapefruit – a subtropical evergreen – was called Pummelo, brought by a captain Shaddock to Barbados from the Malay Archipelago.

The West Indies were the point of origin for grapefruit, probably as a natural cross between the Pummelo and a sweet orange and was later propagated in 1830 as the seedy Duncan variety. The first seedless grapefruit variety was the Marsh white which through bud mutation was the progenitor of the Pink varieties.

More than 20 varieties of grapefruit have been propagated in the United States. The major white-pulped varieties are Duncan and marsh; the major pink-pulped varieties are Ruby and Webb. The grapefruit is readily crossed with other members of the citrus genus. The tangelo, a Florida juice fruit, was produced by fertilization of grapefruit flowers with mandarin orange pollen.

Grapefruit achieves its best quality under conditions of hot days and warm to hot nights, which results in higher sugars and lower acids than grapefruit produced in the cooler night temperatures common in Arizona.

Mature, healthy grapefruit trees that are well-hardened by previous cool to cold weather can probably tolerate temperatures in the mid-20’s without leaf or twig damage, although ice will form in the fruit of the grapefruit after about 3 to 5 hours at 27 degrees.

Budded grapefruit trees, if properly established and grown, should bear in the third season after transplanting.

Generally, a grapefruit does not “ripen” in the normal sense of the word, rather, it matures to good eating quality. Yuma grapefruit will usually achieve legal maturity in late October, although the peel color will likely still be quite green (plus the red blushing of red-fleshed varieties). The color development of the rind is linked to cooler nighttime temperatures.

The longer the fruit remains on tree, the larger it becomes and the sweeter it becomes. A grapefruit holds very well on the tree, so fruit can be harvested as needed from late October through May.

A grapefruit tree may bear 20,000 – 50,000 flowers each spring yet only 0.5-2.5% develop into a mature fruit.

Only about 10% of the sugars produced by the tree via photosynthesis are used for fruit growth.

As with all citrus trees grown in the Yuma area, grapefruit trees require a deep irrigation every 10 days to 2 weeks during the summer.

Source: Kurt Nolte is an agriculture agent and Yuma County Cooperative Extension director. He can be reached at knolte@cals.arizona.edu or 726-3904. For additional information please visit https://extension.arizona.edu/yuma.