Researchers claim to have identified the bitter taste receptors activated by specific stevia extracts, potentially leading the way to development of better taste modulators and more selective stevia plant breeding.
Published in the Journal of Agricultural and Food Chemistry, the researchers wrote that there has been little research into the taste profiles of specific steviol glycosides – the sweet components of the stevia leaf – and how they interact with taste receptors in the mouth.
They examined differences in how individual steviol glycosides are perceived in terms of bitterness and sweetness, and characterized the most common glycosides accordingly.
“Our ﬁndings could help to eﬀectively navigate breeding of Stevia rebaudiana and improve postharvest downstream processing toward the production of sweet taste-optimized and bitter taste-minimized Stevia extracts,” they wrote.
The researchers added that understanding how specific stevia extracts work to elicit bitter tastes could help with the development of better taste modulators to block bitter flavors associated with stevia sweeteners.
Among the findings, they identified two receptors, hTAS2R4 and hTAS2R14, which they claim account for the detection of stevia’s bitter taste. While sweet taste – whether from nutritive, non-nutritive, artificial or natural sources – is detected by a single type of receptor within taste buds, people have about 25 different bitter taste receptors, so understanding which of these account for perception of the bitterness associated with stevia could help formulators modulate this perception, while increasing perception of sweetness.
Different sweetness curves
Stevia supplier PureCircle has also pointed to the promise of isolating and combining different steviol glycosides according to their taste profiles.
Speaking to FoodNavigator-USA at IFT in Las Vegas last month, PureCircle’s vp of global marketing and innovation Jason Hecker said: “People are interested in how the different glycosides work together in particular applications. …All of these glycosides have different taste profiles. They have different sweetness curves and they interact differently with each other. You don’t need major changes to make a major difference.”
While stevioside has been reported to be the most abundant of the sweet components, rebaudioside A, also known as Reb A, has been identified as the most potent. Rebaudioside C has been identified as imparting a lingering bitter taste, after the sweet sensation has disappeared.
Glycosides include stevioside, rebaudiosides A-F, steviolbioside, and dulcoside A, among others.
The authors of this latest study characterized the most common steviol glycosides by combining human sensory studies with cell-based functional taste receptor expression assays.
Source: Journal of Agricultural and Food Chemistry
2012, Vol. 60, pp. 6782−6793 dx.doi.org/10.1021/jf301297n
“Human Psychometric and Taste Receptor Responses to Steviol Glycosides”
Authors: Caroline Hellfritsch, Anne Brockhoﬀ, Frauke Stahler, Wolfgang Meyerhof, and Thomas Hofmann.