SCIENTIFIC NAME: Synsepalum dulcificum
FAMILY: Sapotaceae

It was back in 1952 that I was making a tour of the Canal Zone Summit Gardens, Panama. My main interest had been fruits of the Asiatic tropics such as mangosteen (Garcinia mangostana), durian (Durio zibethinus) and rambutan (Nephelium lapaceum). Under the guidance of Summit Gardens Director, W.R. Lindsay, we suddenly came upon a small, five-foot-high compact bush with bright red berries that contrasted with the dark green of the small-leaved foliage. A nod of the head from Lindsay confirmed my question as to whether they were edible. I then plucked one of the small, jellybean-size fruit, popping it into my mouth. At his recommendation I ate a second fruit and we then passed on to an adjacent Key lime (Citrus aurantifolia) tree.

The Director explained this was no ordinary Key lime, but a very special one with a wonderfully "sweet" taste. An attempt to pass up sampling this fruit proved futile and at his insistence I hesitatingly took the lime halves he had cut and carefully put one to my tongue. Not only was it sweet, it was delicious! After rapidly consuming several more of the supposedly "sweet" limes, I caught my breath and requested an explanation. The explanation, Lindsay related, lies with the small red berries from the miracle fruit you ate just before we came to the lime tree. Such was my introduction to the Synsepalum dulcificum, the "taste-twister" that causes a sour, acid fruit to appear to become sweet.

The miracle berry, miraculous fruit or miracle fruit, as it has variously been called, is indigenous to tropical West Africa where it can reach a height of 18 feet. Here the natives often use the ¾-inch-long, ellipsoidal-shaped berries to make their maize bread more palatable and to give sweetness to their sour palm wine and beer. W.F. Daniell (Pharm. J. 11,445, dated 1852) was the first to describe the fruit and its unusual effects. He called it "miraculous berry". Since then, there has been considerable interest in this Gold Coast (Nigeria and Ghana today) fruit that is in the Sapotaceae, the same family as the common sapodilla (Manilkara zapota) which is extensively grown in South Florida.

Among those interested in seeing the miracle fruit established in South Florida was the late Dr. David Fairchild. He made a total of four introductions, consisting of both plants and seed, between the years 1929 through 1939, that were planted at the U.S.D.A. Plant Introduction Station on Old Cutler Road, Miami. Two later introductions by others, one in 1940 and another in 1958, were made, and all failed except for the last. Dr. Robert J. Knight, Jr., Research Horticulturist at this station, wrote in a personal letter to the writer, "Apparently the early introductions were established in Puerto Rico and the Panama Canal Zone, in as much as the later introductions to Florida came from these sources." Through the years 1934 to 1957, a total of seven miracle fruit introductions were received at the Sub-Tropical Experiment 5tation, Homestead. Plants which were set out in the field in the existing soils always became chlorotic and finally died.

From the miracle fruit eaten in Panama, the writer brought back three seeds with him upon his return to Florida. Planted and grown in peat moss-filled containers, they fruited four years later in 1956 upon reaching a height of three feet. Shortly thereafter, the plants were set out in a pH. 6.4, acid black hammock sand soil and eventually reached a seven-foot height. Seeds, distributed by birds and children, germinated freely on a volunteer basis in the acid soil wherever conditions were favorable. Dr. Knight further wrote "Since David Fairchild and other U.S.D.A. people were interested in seeing it (miracle fruit) established, I don't believe the first miracle fruit introductions here suffered from neglect; judging from our experience (U.S.D.A. Plant Introduction Station) with the most recent introduction, I believe the early ones failed because our (South Dade's) alkaline-reaction limestone soils are not suited to this species."

The miracle fruit, upon attaining a height of two to three feet in four years or less, can produce fifty or more berries at one time. The main crop comes in winter, with larger plants tending to bear some fruit most of the year. Setting plants out in alkaline soils should be avoided; peat moss is one of the best mediums for potting up these acid-loving fruits. The writer has observed unprotected miracle fruit growing as far north as the Tampa area, and therefore assumes it to have moderate cold resistance. Birds, at times, can become a nuisance for those not caring to share their crops.

What was probably the first large-scale attempt to unlock the unique secrets of the miracle fruit was undertaken by the International Minerals and Chemical Corporation, makers of Ac'cent (monosodiumglutamate). One of the objectives for undertaking this basic research was to find a substitute artificial sweetening agent for that employed in diet cola drinks, which at the time left a bitter aftertaste.

A preliminary start was made, on the part of the Corporation's Food Biochemistry and Analytical Chemistry Research Department, by contacting those known to grow the miracle fruit in Florida. During this period the writer, along with others, cooperated in this project by furnishing both information and a limited supply of the fresh fruit. As the project gained momentum, it became evident that larger quantities of the fruit would be required. Scientists were therefore sent to Nigeria, Africa, to study it horticulturally in its native habitat, to observe its uses, and to obtain an unlimited supply of the fresh fruit.

Unfortunately, work on the entire project was terminated after more than a year of concentrated effort, when researchers failed to see any immediate solution to their goal of isolating in pure form the active principle of the fruit for structure and property studies. A paper "A New Concept in Sweetness-Taste-Modifying Properties of Miracle Fruit", by Inglett and others, summarizing their experiments and findings was delivered at the 148th National Chemical Society Meeting, Chicago on August 31, 1964. In this scientific report they stated, "The quality of the miracle-fruit-induced sweetness is unexcelled. Miracle-fruit-induced sweetness is more desirable than any of the known natural or synthetic sweeteners."

The writer frequently has used the miracle fruit as a sugar substitute when eating other fruit. In spite of the fact that fifty or more of these ¾-inch-long red berries have been consumed at one time, when preparing seeds for potting up, no ill effects have been observed. In the writer's opinion, one fruit worked in the mouth long enough to remove all the pulp from the smooth, shiny single seed, gives maximum results, and consumisng additional berries does not tend to increase its potency. The sweet-inducing properties of this "taste-twister" can linger on for up to three hours and the flavor of fruits, such as fresh strawberries, can be greatly enhanced when certain delicate flavors, formerly masked by table sugar, are released and experienced for the first time.

Under Florida growing conditions, the miracle fruit is usually seen as a small, ornamental shrub which is especially attractive when the shiny red berries appear. It is hoped the Florida nursery trade will make this plant available, as numerous requests are frequently received for seed, fruit and plants from research workers, diabetics and an interested public who have read of the properties of this unusual and interesting West African introduction.

In spite of the failure of the International Minerals and Chemical Corporation's research to succeed in dissolving the miracle fruit's active principle and obtain it in pure form, other scientists continued to wrestle with the problem. Two researchers, Dr. Kenzo Kurihara and Dr. Lloyd M. Beidler at the Florida State University's Dept. of Biological Science, Tallahassee, finally discovered a way to isolate the elusive active principle. Their paper "Taste-Modifying Protein from Miracle Fruit" appeared in the September 20, 1968, issue of Science, Vol.161, No. 3847, on pages 1241-1243. For their experiments, plants of the miracle fruit were grown in the university's greenhouse and the fruit of 300 berries used. In the abstract to their paper they wrote, "The active principle of miracle fruit (Synsepalum dulcificum) is a basic glycoprotein with a probable molecular weight of 44,000. Application of the protein to the tongue modifies the taste so that one tastes sour substances as sweet."

Today, research on the miracle fruit is going on at an accelerated pace. Dr. Lloyd M. Beidler, in personal correspondence addressed to the writer, stated, "One company, Meditron, Inc., was formed to commercially develop the berry. They have built up a large collection of plants and are currently growing them in the United States and four other foreign countries. This company has spent much time learning the growing habits and best methods of pollination of miracle fruit. Our research at FSU has resulted in many companies showing an interest in the use of the product."

William F Whitman
Acknowledgement: Museum of Science, 3280 South Miami Avenue, Miami, Florida 33129

DATE: March 1994

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