What Protein Tastes Sweet? Exploring Natural & Engineered Sweeteners

November 20, 2025 •

3 min read

Over the past decade, a remarkable amount of information has been uncovered about the molecular basis of taste, and a small but fascinating group of proteins that elicit a sweet sensation has been identified. While most people associate sweetness with sugars, there exists a unique class of proteins, such as Thaumatin and Monellin, sourced from exotic plants that offer a potent, low-calorie alternative.

Quick Summary

Several proteins sourced from tropical plants, including Thaumatin, Monellin, and Brazzein, are known to taste intensely sweet and are used as sugar substitutes. Taste-modifying proteins like Miraculin can also change the perception of sour foods to sweet.

Key Points

Thaumatin: Sourced from the katemfe fruit, this protein is up to 3,000 times sweeter than sugar and is heat-stable and water-soluble, making it a versatile flavor enhancer and sweetener.
Monellin: Originating from the serendipity berry, monellin is 1,500-2,000 times sweeter than sucrose but is heat-sensitive and unstable at low pH, which limits its application in many processed foods.
Brazzein: Extracted from the oubli fruit, this protein is the smallest and most thermally stable of the sweet proteins, offering a clean, sugar-like taste.
Miraculin: A taste-modifying protein from the miracle fruit, miraculin itself is not sweet but binds to sweet receptors and causes sour foods to taste sweet when acid is present.
Protein Engineering: Scientists use genetic engineering to produce sweet proteins in microorganisms or plants, improving scalability, cost-efficiency, and stability for wider commercial use.

Introduction to Naturally Occurring Sweet Proteins

In the search for healthier, low-calorie alternatives to sugar, a fascinating category of compounds has emerged: sweet-tasting proteins. These proteins are derived primarily from tropical plants and can be thousands of times sweeter than sucrose, or table sugar, on a weight basis. Unlike artificial sweeteners, which are chemically synthesized, these are natural macromolecules that bind to and activate the sweet taste receptors on the tongue. While many sweeteners are synthetic small molecules, the existence of large, sweet proteins that bind to the same receptor highlights the complexity and diversity of the human taste system. Some of the most well-known examples come from West Africa and other tropical regions, where they have been used for centuries to sweeten foods and drinks.

Leading Natural Sweet Proteins

Several sweet proteins have been isolated and characterized, each with unique properties regarding intensity, onset, and aftertaste.

Thaumatin

Found in the arils of the katemfe fruit ($Thaumatococcus daniellii$), a plant native to West Africa, thaumatin is one of the most intensely sweet proteins known, estimated to be up to 3,000 times sweeter than sucrose. It is approved as a sweetener and flavor enhancer (E957) in various countries, including Europe and the U.S.. Its properties include high water-solubility and heat stability, though it has a slow sweetness onset and a lingering aftertaste. Thaumatin is used in products like chewing gum, dairy, and beverages.

Monellin

Isolated from the serendipity berry ($Dioscoreophyllum cumminsii$) in West Africa, monellin is another potent sweet protein, approximately 1,500 to 2,000 times sweeter than sucrose. It is unstable to heat and low pH, which limits its use in many processed foods. Research is focused on creating more stable engineered versions.

Brazzein

Discovered in the oubli fruit ($Pentadiplandra brazzeana$) from Central Africa, brazzein is the smallest sweet protein, consisting of just 54 amino acid residues. It is approximately 500 to 2,000 times sweeter than sucrose and is notably stable across a wide pH range and under heat, making it suitable for various food products.

Taste-Modifying Proteins

Taste-modifying proteins alter the perception of other tastes rather than tasting sweet themselves. Miraculin, from the miracle fruit ($Synsepalum dulcificum$), makes sour foods taste sweet by activating sweet receptors in acidic conditions. Curculin, from the Malaysian fruit ($Curculigo latifolia$), also makes acidic solutions taste sweet.

Engineered Sweet Proteins

Challenges in natural extraction and protein stability have led to protein engineering. Techniques like genetic engineering and microbial fermentation are used to produce these proteins sustainably and at scale in microorganisms or plants. This approach allows for modifications to enhance properties like thermal stability. Engineered versions, such as single-chain monellin, show improved resilience.

Comparison of Prominent Sweet Proteins


Protein	Source Plant	Geographic Origin	Sweetness Factor (vs. Sucrose, weight basis)	Heat Stability	Aftertaste
Thaumatin	Katemfe fruit ($T. daniellii$)	West Africa	1,600-3,000x	Excellent	Licorice-like, lingering
Monellin	Serendipity berry ($D. cumminsii$)	West Africa	1,500-2,000x	Poor (denatures > 50°C)	Lingering
Brazzein	Oubli fruit ($P. brazzeana$)	Central/West Africa	500-2,000x	Excellent (stable to 98°C)	Clean, like sucrose
Miraculin	Miracle fruit ($S. dulcificum$)	West Africa	N/A (Taste Modifier)	Poor (denatures at low pH/high temp)	N/A

The Role of Sweet Proteins in Diet and Health

Sweet proteins offer health benefits as they are non-caloric and non-glycemic. They provide sweetness without affecting blood sugar, making them suitable for individuals managing diabetes or weight. Sweet proteins do not promote tooth decay and may offer antioxidant benefits. They are processed like other dietary proteins and do not have the same potential concerns as some artificial sweeteners.

Conclusion

Sweet-tasting proteins like thaumatin, monellin, and brazzein offer a compelling natural and low-calorie alternative to sugar. Through protein engineering, these compounds can be produced sustainably and with improved properties, making them increasingly viable for the food industry. These sweet proteins, along with taste-modifiers like miraculin, provide a diverse range of tools for creating flavorful and healthier food and beverage products.

For more in-depth information on food additives and sweeteners, explore comprehensive research available on ScienceDirect.

Frequently Asked Questions

The most common sweet-tasting proteins are Thaumatin, Monellin, and Brazzein, all originating from tropical plants in West and Central Africa.

Yes, sweet proteins are generally considered a healthy alternative to sugar. They are low-calorie, do not impact blood sugar levels, and are processed by the body like any other dietary protein.

Brazzein is considered the most heat-stable sweet protein, withstanding temperatures of up to 98°C, making it suitable for use in a variety of processed foods and beverages.

A sweet protein, like Thaumatin, has an intrinsically sweet taste. A taste-modifying protein, like Miraculin, is tasteless but alters how the taste buds perceive other flavors, such as making sour foods taste sweet.

Yes, sweet proteins like Thaumatin are produced commercially. Due to high extraction costs and other limitations, many are now produced through genetic engineering in yeast or plants for increased efficiency.

Many sweet proteins have a different taste profile than sugar, including a slower onset and a lingering aftertaste. For example, Thaumatin can have a licorice-like aftertaste at higher concentrations.

No, not all sweet proteins are approved for widespread use globally. Approval status varies by country and protein. Thaumatin is widely approved in the U.S. and EU, while others like Monellin and Brazzein face more complex regulatory hurdles.

Yes, sweet proteins are safe for diabetics. They do not increase blood sugar or insulin levels, offering a low-calorie sweetness option that does not interfere with glucose management.

While generally safe, some traditional concerns exist. Monellin's heat instability limits its use, and Thaumatin has a distinct licorice aftertaste at higher concentrations. However, they lack the significant metabolic concerns linked to some artificial sweeteners.

Most sweet proteins, with the exception of Thaumatin which is used commercially, are not found in common, everyday foods. They originate from exotic tropical fruits that are not widely distributed. Engineered versions, however, are being used in some specialized products.

Producing sweet proteins via precision fermentation is more sustainable and environmentally friendly than traditional sugar production. It requires less land and water and produces lower CO2 emissions.

Sweetness can come from specific proteins like Thaumatin, Monellin, and Brazzein, as well as proteins like Miraculin that modify your taste receptors to perceive sweetness from sour substances.

Yes, egg white lysozyme has been shown to exhibit a sweet taste, although it also has an astringent aftertaste. Its sweetness potency is considerably lower than the intensely sweet proteins like Thaumatin and Monellin.