Stevia Sweeteners

What are stevia sweeteners? what is reb M? A few ways are available to produce reb M and each has its own advantages and disadvantages. In addition, product label may tell how reb M is made

2/1/20244 min read

reb M by leaf extract, bioconversion and fermentation
reb M by leaf extract, bioconversion and fermentation

Stevia sweeteners are natural sugar substitutes derived from the leaves of the Stevia rebaudiana plant, native to South America, now mostly planted in Asia. These leaves contain steviol glycosides, a group of zero-calorie sweet molecules about 200 to 400 times sweeter than sucrose. Stevia extract was used as a dietary supplement for years in USA before the high purity form of rebaudioside A (reb A), the most abundant steviol glycoside in stevia leaf, was granted GRAS status by FDA in 2008.

Over 60 steviol glycosides have been identified so far. Over the past 15 years, many hopes and hypes come and go whenever a new molecule becomes commercially feasible. The occurrence mirrors precisely what is happening in the hemp cannabinoid industry today. As reality sets in, the predominant stevia sweetener remains reb A and its blends, while rebaudioside M (reb M) shows promise as a potential future blockbuster (1).

Numerous resources about stevia sweeteners are available on the internet, so we won’t reiterate what is already plenty. In this context, we will focus primarily on reb M and its current regulatory landscape and labelling guidance, of which information is scarce.

There are three ways to produce reb M commercially: 1) extract reb M from stevia leaves, 2) convert reb A or other steviol glycoside extracted from stevia leave to reb M by enzymatic conversion (bioconversion); 3) produce reb M from simple sugar by fermentation (fermented reb M). All three methods are deemed natural. The natural abundance of reb M in stevia leaf is below 0.1%, although advanced agronomy has managed to increase this level up to approximately 2%, as claimed in some patents and by certain growers, large-scale plantations remain impractical due to inherent constraints. In contrast, stevia cultivars with 10% or higher reb A content have been extensively planted. Reb M can be made by chemical synthesis, but its cost is much higher those of bioconversion or fermentation, therefore product adulteration with artificial reb M is not an immediate concern. In comparison, reb A and related products on the market are exclusively extracted from stevia leaves. Fermented reb A is technically feasible, but the cost is not competitive.

Due to its low abundance, leaf extracted reb M is very expensive and its supply is limited (the supply may not be enough for Coca-Cola to replace 10% of its artificial sweeteners by leaf-extracted reb M). Technical advances make both bioconversion and fermented reb M affordable, the choices may depend on their different regulatory and labeling landscapes in different countries. Focus in this article is on USA and Canada.

Non-GMO status: there are no obstacles for leaf extract or bioconversion reb M to obtain non-GMO status. However, Non-GMO Project raised concern regarding non-GMO status for fermented reb M.

Labelling as food ingredients:

  • Leaf extracted reb M: can be labelled as stevia extract, stevia leaf extract in both USA and Canada

  • Bioconversion reb M: may be labelled as reb M (or its full name, same below), stevia extract, stevia leaf extract in Canada; or stevia leaf sweetener, stevia leaf reb M, stevia reb M, reb M in USA

  • Fermented reb M: may be as labelled reb M, stevia sweetener in USA; or reb M, steviol glycoside in Canada.

A Cargill study found consumers associate stevia and stevia extract positively with health perception and purchase impact, while their view is negative toward steviol glycosides. All steviol glycosides and their blends extracted from stevia leaf can be labelled as stevia extract or stevia leaf extract, which include stevioside, reb A, reb B, reb C, reb D, reb M and others included in the JECFA monograph. Famous products using leaf-extracted reb M include Chobani ZeroSugar yogurt.

All three types of reb M may be labelled as natural flavor under USA FEMA (Flavor Extract Manufacturers Association) guidline. Another type of stevia sweetener, enzyme modified stevia (EMS) or glucosylated steviol glycosides (GSG), is commonly (or exclusively) labeled as natural flavor according to FEMA guidance. Please be aware that the ingredient labelling is complicated, incorrectly labeled ingredients may lead to bad consequences. The information provided here is based on recommendations from manufacturers and is for reference purposes only, therefore should not be construed as legal advice.

News emerged in late 2023 that a stevia company alleged some reb M products sold in USA are not made through extraction or bioconversion as labelled. The accusation did not clarify which item is incorrectly labeled as what, as previously discussed, it appears unlikely that adulteration of synthetic Reb M is at play. It remains a technical challenge to unequivocally distinguish reb M made through extraction versus bioconversion or between bioconversion and fermentation. Our team of experts possesses the necessary know-how and expertise to help you combat economic-driven misconducts.

As more players enter the natural high intensity sweeteners market, the competition becomes intense and arises from other sweeteners like monk fruit or between bioconversion and fermented reb M. Other natural high intensity sweeteners such as sweet proteins brazzein and thaumatin, and glycyrrhizin are still at early stage of commercialization and consumer acceptance, they won't post noticeable threat to stevia.

It is worth noting that neohesperidin dihydrochalcone (NHDC), while claimed as natural by certain manufacturers and considered semi-natural in some literature, is in fact an artificial sweetener derived from citrus.

Reb M WAS the hope for 100% sugar replacement in beverages and other food applications. However, its lingering sweetness and bitter aftertaste make the formulation extremely challenging. Add poor solubility if reb M is used in concentrated syrup for beverage bottling and retail dispensing. Many commercially available solutions, including those from renowned companies and expensive ones, may fall short of fulfilling their promises. Exercise caution when encountering "one-can-do-anything" claims. Feel free to reach out if you need guidance on how to select the right sweeteners for your applications.

ren M and reb A sweetness and bitterness comparison
ren M and reb A sweetness and bitterness comparison