From the Archives
of the Rare Fruit Council of Australia
by William F. Whitman
Miracle Fruit
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."
Acknowledgement: Museum of Science, 3280 South Miami Avenue, Miami,
Florida 33129
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