In the 1970s, the Miracle Berry was poised to become the sugar replacement of choice. It was hailed as the solution to the diabetes epidemic, and was preferred to every other sugar alternative in blind taste tests. The fruit contains a taste-altering protein, miraculin, that makes sour foods taste sweet. So why haven't you heard of it? Did "big sugar" engineer its downfall? And can modern food entrepreneurs reposition the miracle berry as the future of sweet?