By Tony Hao '19
The answer seems to be no. Sour cream, by definition, is sour; and sour and sweet are two opposite tastes.
However, in West Africa, there grows a red fruit called agbayun, or asaa, or taami, or ledidi (different tribes have different names for this fruit). The fruit looks like an enlarged version of goji berry and, similar to goji berry, tastes mildly sour; however, what’s unique about this sour berry is that, after you eat it, everything sour will become sweet. In fact, the sourer something tastes, the sweeter it becomes after eating this berry. So yes, in this case, sour cream can definitely taste sweet!
Probably tasting sweet sour cream doesn’t appear that disturbing--your mind can easily adjust and just consider the white cream as cream cheese or whipped cream. But think about this: you drink some vinegar, and it’s sweet. You enjoy it so much that you drink a lot of vinegar--and it all goes to your stomach. What’s likely to happen next is that your stomach would be burning because of the high amount of H+ ion in the vinegar. Well, sweet stuff can make you feel pain. This is just way too much for your brain to handle.
Let’s explore two things here: what makes something taste sour, and what’s the deal with that weird berry?
In some languages, the word “sour” is the same as “acidic,” so it’s definitely H+ that makes something taste sour. But you may also recall your chemistry teacher telling you that HCl, H2SO4, etc., are strong acids. “So they must taste very sour,” you conclude. Nope, they taste spicy--because they are burning your tongue! (Well, “spicy” is actually a type of pain instead of a type of taste) What actually decides the degree of sourness is the pH value of the food. For example, rice vinegar (acetic acid, Ka=1.8x10^-5), having a pH of approximately 4.3 (a small chemistry exercise here: what would be the molarity of acetic acid in rice vinegar?), tastes just about right to be pleasantly sour for a salad. However, if you drink a 10M solution of H2SO4, whose pH is -1, you probably wouldn’t find the solution pleasantly sour. But can these “strong” acids taste appropriately sour, though? Yes. As this piece of news reports, diluted HCl just tastes like lemon juice, whose pH is about 2.0. Our tongues have a certain range of pH values that we perceive as sour. In addition, chemicals of other tastes can affect of our perception of sourness as well. For example, even though soda has a relatively low pH, thanks to carbonic and phosphoric acids, your tongue would probably not perceive it as sour because different sugars in soda coat and hide the sour taste of the acids (oh yeah, another really cool use of sugar and sweet taste: if something tastes too salty, you can add sugar to make it taste pleasantly umami!). Again, different people may have different perceptions to the same food, and different other chemicals may mess up our taste buds.
Speaking of our taste buds, let’s go back to our second original question: what’s the deal of the berry? Unlike sugar, which combines with sour or salty stuff to create different tastes, the berry, commonly known as “miracle berry” or “M-Berry,” doesn’t combine with your food. Instead, it combines with your taste buds. As you probably know, taste buds in different regions of our tongues are in charge of different tastes--some for sweetness, others for sourness, more others for saltiness/umami, and the rest for bitterness. In the weird berry, whose technical name is synsepalum dulcificum, there exists a protein called “miraculin” (yes, literally the miracle protein) that looks like this:
This protein combines with your sour-tasting taste buds and dons them sweetness receptors! In other words, this protein temporarily removes all your sour-tasting taste buds and make them taste sweetness! As a result, everything sour will taste sweet, and everything sweet will taste really sweet, and everything extra-sour will taste extra sweet!
Think about what would happen if you eat some sour-patch kids after eating a miracle berry! Sad news, though, this protein gets washed away by your saliva, so it only lasts around 30 minutes :( And another sad news: FDA does not approve m-berry as a safe food additive even though the berry is purely natural (and some other nations have actually approved m-berry and deemed it safe!)
Ok, at the end of my article, here’s a link of people tasting sour things before and after eating a M-Berry pill. The difference is, hm, pretty dramatic. Take a look!
Sources:
https://www.seriouseats.com/2016/07/how-do-we-taste-salt-sour-acid-sweet-bitter-flavor.html
https://www.chegg.com/homework-help/questions-and-answers/ka-value-acetic-acid-ch3cooh-aq-18x10-5-calculate-ph-280-m-acetic-acid-solution-ph-calcula-q4820338
https://agardenerstable.com/2012/06/02/rice-vinegar-for-home-canning/
https://en.wikipedia.org/wiki/Miraculin
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