Synsepalum dulcificum (miracle fruit)

A photo showing the foliage and berry of Synsepalum dulcificum

Synsepalum dulcificum is a nondescript little west African shrub with nondescript little white flowers. From an ornamental point of view, its attractive red berries are its only appealing feature, but it is the content of the fruit, not their appearance, that makes the plant really interesting. The berries of S. dulcificum contain a unique glycoprotein called miraculin which is capable of binding to the sweet taste receptors located on taste buds. Binding of sweet-tasting molecules like sucrose to the sweet receptor activates a cellular response resulting in perception of sweetness. Miraculin, in contrast, binds to the sweet receptor but does not necessarily activate it, meaning that it is not intrinsically sweet-tasting. Only under acidic conditions does a conformational change in the miraculin protein cause activation of the sweet receptor. Thus, for about an hour after one has chewed a miracle fruit, any acidic (i.e. sour) food will taste sweet.

I obtained a small S. dulcificum plant about five years ago, but I can’t say I have mastered growing it–at least, I haven’t figured out how to reliably produce berries. The tiny flowers bloom intermittently year-round but I rarely see any fruit. This year, by diligently brushing the little flowers to release pollen, I managed to obtain four berries, one for each member of our family. The berries finally ripened this week, so we had a little tasting party. The berries themselves aren’t particularly exciting–the skins are tart, and the thin layer of whitish pulp surrounding the single large seed is vaguely sweet. But the effect on our taste buds was immediate. We ate fresh lemons and limes like oranges; they tasted like lemonade or limeade, sugary sweet but with underlying sourness because the acid was still activating our sour receptors as well as sweet receptors. Apple cider vinegar tasted like a sweet, complex cider. Malt vinegar tasted like…well, like sweetened malt vinegar. It was really quite nasty.

If you get hold of an S. dulcificum plant, give it acidic soil and keep it warm and well watered. My plant goes outside in the spring when night temperatures are reliably above 60 F (15.5 C), and it seems to do most of its growing in summer when daytime temperatures are in the upper 80s and 90s (30-35 C). Although the plant can tolerate considerable sun, the thin leaves are easily burned if a shade-grown plant isn’t given time to acclimate. I typically keep my plant under 40% shade cloth.

I previously failed to germinate seed in the greenhouse. Perhaps the winter nights were too cold. This time, I’ll try starting the seed indoors under lights. It occurs to me that if I can grow at least one more plant, I might get more berries by cross-pollination rather than selfing.

2 thoughts on “Synsepalum dulcificum (miracle fruit)

  1. If you try growing under lights, please let us know the result. I never expected to be able to grow miniature orchids that way, but many of them flowered very well.

    Liked by 1 person

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