There are a few proteins from Africa that are similar but do not turn sour into sweet like Miraculin.
Brazzein is a sweet tasting protein, unlike Miraculin. It is derived from the plant Oubli (Pentadiplandra brazzeana Baillon) in West Africa. This protein is found to be 500-2000 times sweeter than sucrose, Miraculin is 400,000 times sweeter. Brazzein is commonly consumed by monkeys, bonobos and humans and these were the first to test its sweet properties. The fruits from the Oubli are sweet tasting alongside the protein and are safe for use for people with diabetes. Brazzein can withstand heat the best which makes it the top protein to use in foods. Unfortunately, it is not considered “Generally Recognized As Safe” by the FDA as of December 2021.
Monellin, also known as the serendipity berry, is eaten by old world primates (mostly different species of monkey) and humans in West Africa. This protein is 800-2000 times sweeter than sucrose, but differs in that the sweet effect is slow. Unlike Miraculin, which is immediate, it takes time for Monellin to sweeten your taste buds. Similar to Miraculin, this protein is pH dependent and cannot be heated as it will destroy the sweet properties. Monellin is best used as a tabletop sweetener, since it is water soluble, and is safe for those with diabetes. This is one of the only proteins that can be grown in yeast which produces a sweetening agent that is 4000 times more potent than sucrose. Luckily, Monellin has been deemed safe for consumption in Japan but not in the EU or the United States.
Thaumatin is different from these proteins above in that it is a flavoring agent and not necessarily a sweetener, even though it is 100,000 times sweeter than sucrose. It is derived from the Katemfe fruit in West Africa. Similar to Monellin, its sweetness effects builds very slowly and lasts an adequate amount of time. Thaumatin has an after taste similar to liquorice. This protein is the best for foods as it is water soluble and stable to heating and acids. The downside to thaumatin is that it is crystallized very easily and when converted into a powder form, can be an allergen for people. However, this diminishes when it is turned into a liquid. Thaumatin has been deemed “Generally Recognized As Safe”, but the U.S. but only as a flavoring agent and not as a sweetener. In Israel, Japan, and the EU, it is considered safe for consumption as a sweetener.