What Formulators Need to Know About Natural Flavorings with Modulating Properties

High Potency Sweetener (HPS) Taste Challenges

Human flavor perception is a crossmodal integration of all five senses: taste, smell, sight, sound and touch. 

There are five taste challenges when we formulate reduced-sugar foods and beverages with HPS. The first three problems are in the “sweetness time-intensity curve” (Figure 1, upper left). Sugar is in green and stevia in blue. Stevia sweeteners have delayed sweetness onset, lower sweetness peak, and lingering sweetness. This is due to HPS being more hydrophobic, less water soluble and having slower diffusion in the saliva to the sweetness receptor. 

Figure 1 - 5 HPS perception problems that sweetness modulators can fix: Sweetness onset, peak, linger, bitter, mouthfeelCourtesy of W2O Food Innovation

The fourth problem is “bitterness” (Figure 1, lower left). Stevia Reb A 95%/97% (RA) sweetness was nearly linear for the first 200ppm but plateaued at around 8% sugar equivalence (SE), while RA bitterness started above 300ppm and increased dramatically in beverages. This is because RA triggers not only the sweetness receptor T1R2, but also two bitterness receptors TAS2R4 and 14 above 300ppm.

The fifth perception problem is lack of “sugar mouthfeel”. The descriptive analysis data (Figure 1, right) demonstrated that RA had negative oral touch sensations (astringent and metallic) and lacked desirable sugar mouthfeel. This is because HPS, unlike sugar, does not bind enough water to create viscosity that is described as sugar mouthfeel.

Sweetness modulators is a cottage industry that grew up together with plant-based HPS. There are seven types based on different modulation mechanisms. Most plant-based sweetness modulators are labeled as natural flavor in the US.

Flavorings with Modifying Properties (FMP) and FEMA Guidelines

“Sweetness modulator” in general is defined as substances that are themselves tasteless but increase, decrease or otherwise change sweetness detection in the mouth and perception in the brain. It is critical to understand that FMP- designated technical effect for FEMA GRAS status is limited to flavor modification.

So what do we must know before we formulate with FMPs?

There are approximately 2,800 flavor ingredients on the FEMA GRAS list. The vast majority of these are flavoring substances (>2,400 individual chemically-defined flavor substances and >300 natural flavor complexes) that impart flavor, and a relatively small number of these are FMPs (less than 3%). 1,100 are also FDA GRAS.

FMPs may be used in flavorings (i.e. compounded flavors/flavor systems) to modify the flavor profile by altering the flavor attributes of the flavoring and the food to which it is added but may not impart a specific characteristic flavor on their own. The FMP-designated technical effect for FEMA GRAS status is limited to flavor modification.

It is important to understand the proper labeling for compounded flavors containing flavorings with modifying properties (FMPs), and the foods containing these compounded flavors. FMPs that have FEMA GRAS status as their sole regulatory authority to use in the U.S. are GRAS only for their technical effect of flavoring. The technical effect of individual FMPs can be verified through appropriate sensory testing conducted under the FMP’s specified conditions of intended use as a flavoring substance.

Guidance for the Sensory Testing of Flavorings with Modifying Properties within the FEMA GRAS Program

• ^“Test 1 is used to demonstrate that the FMP does not have inherent sweetness or saltiness under conditions of intended use as an FMP in the finished food product.
• Test 2 assesses the effect of the FMP on the finished food product.

FEMA FMP Fact Sheet

FMPs have FEMA GRAS status for technical effect of flavoring and the conditions of intended use are consistent with FEMA GRAS levels. The FMP is used with other FEMA GRAS FMP’s in the compounded flavor or in the finished food consistent with FEMA GRAS levels, and the combination (i.e. stacking) of FMP’s results in a sweetening technical effect in the finished food. In this scenario, the technical effect is sweetening rather than flavoring, and appropriate regulatory authority to use would have to exist for the FMP(s), and declaration would be required on the finished food if appropriate regulatory authority to use was available for the sweetening technical effect.⁶

Table 1 shows the most common or the newest FMP. 

Table 1 - New and common flavorings with modifying propertiesCourtesy of W2O Food Innovation

Glucosyl Steviol Glycosides (GSG) FEMA 4728. It’s made by glycosylation of stevia leaf extracts. Non-alcoholic beverages' usual use and maximum use levels are 125ppm and 175ppm, respectively. 

Reb M 95% FEMA 4922. It’s made by stevia leaf extraction. Non-alcoholic beverages' usual use and maximum use levels are 10ppm and 24ppm, respectively.

Erythritol FEMA 4819. It’s made by glucose fermentation. Non-alcoholic beverages' usual use and maximum use levels are 0.5% and 2.5%, respectively.

Allulose FEMA 4897. It’s made by bioconversion. Non-alcoholic beverages' usual use and maximum use levels are 1.5% and 2%, respectively.

Thaumatin FEMA 3732. It’s made by extraction. Non-alcoholic beverages' usual use and maximum use levels are both 7ppm.

Brazzein FEMA 5035. It’s made by yeast precision fermentation. Non-alcoholic beverages' usual use and maximum use levels are both 7ppm.

Applications in Foods and Beverages

Figure 2 - Blending as a sugar reduction strategyCourtesy of W2O Food Innovation

Blending is the umbrella strategy (Figure 2). It’s about combining sweeteners and modulators to get to sweetness target level while formulated at low usage so to avoid the off flavor from each. Now that Reb M stevia sweetener is available, blending is necessary only in high SE (12% SE) zero sugar beverages like carbonated soft drinks (Figure 3). This is possible because 350ppm Reb M delivers 8% SE without the typical licorice and bitter RA off flavors. 

Figure 3 - Formulating zero-sugar cola with FMPsCourtesy of W2O Food Innovation

Summary

Sweetness modulators are defined as substances that increase, decrease or otherwise change the detection and perception of sweetness. Sweetness modulators are substances themselves tasteless, but make sweeteners sweeter. They are based on neuroscience and work on seven mechanisms that can include FMPs. FMP-designated technical effect for FEMA GRAS status is limited to flavor modification. As neuroscience and ingredient technologies advance, it’s definitely possible to make reduced sugar foods and beverages taste better. 

References

1. Molecular Mechanism of Sweetness Sensation. DuBois, 2016. https://pubmed.ncbi.nlm.nih.gov/26992959/Consumer-Based
2. Sensory Characterization of Steviol Glycosides (Rebaudioside A, D, and M). Tao and Cho, 2020. https://www.mdpi.com/2304-8158/9/8/1026
3. Sugar substitutes not so super sweet after all. Antenucci and Hayes, 2014. https://www.sciencedaily.com/releases/2014/09/140905090817.htm
4. Non-Caloric Sweeteners, Sweetness Modulators, and Sweetener Enhancers. DuBois and Prakash, 2012. https://www.researchgate.net/publication/221728746_Non-Caloric_Sweeteners_Sweetness_Modulators_and_Sweetener_Enhancers
5. Human Psychometric and Taste Receptor Responses to Steviol Glycosides. Meyerhof and Hofmann 2012. https://pubmed.ncbi.nlm.nih.gov/22616809/
6. FEMA FMP Fact Sheet. The use, regulatory status and labeling of FMP in the US. Scenario 4. 2020.
7. FEMA FMP. (FMP Fact Sheet, FMP FEMA GRAS Use Levels and Food Categories, Sensory Guidance, US Flavor and Food Labeling Implications, 2018 Flavor Labeling Workshop, 2022 FEMA FMP Workshop). https://www.femaflavor.org/topic/fmp
8. FEMA Flavor Labeling Workshop 2025. https://www.femaflavor.org/events/fema-2025-flavor-labeling-workshop-33726
9. FEMA Flavor Labeling Workshop: Focus on FMPs. 2018. https://www.femaflavor.org/flavor-labeling-workshop-focus-fmps
10. FEMA GRAS and U.S. Regulatory Authority: U.S. Flavor and Food Labeling Implications. Hallagan et al 2018. https://foreverest.net/news-list/fema-gras-and-u-s-regulatory-authority-u-s-flavor-and-food-labeling-implications
11. Sensory Testing for FMP. Harman and Hallagan, FEMA Science Committee Sensory Data Task Force. November 2013, Volume 67, No.11. https://www.femaflavor.org/sites/default/files/2019-07/harman_et_al_2013.pdf. Updated 2022. https://www.femaflavor.org/sites/default/files/2023-01/harman_et_al_2022.pdf.
12. Sensory Testing for FMP. In Food Tech. https://www.ift.org/news-and-publications/food-technology-magazine/issues/2013/november/features/fema-sensory
13. Under the conditions of intended use – New developments in the FEMA GRAS program and the safety assessment of flavor ingredients. Hallagan and Hall 2009. https://www.femaflavor.org/sites/default/files/Hallagan%20and%20Hall%2C%202009.pdf
14. FEMA website 2025. GRAS 33, 32, 31, 30, 29, 28 lists. https://www.femaflavor.org/fema-gras
15. Natural Sweetness Modulators. BCF Sweetness Reimagined conference presentation. Woo, 2025.