Stevia: The Next Generation

June 3, 2013
Jennifer Grebow
Jennifer Grebow

Jennifer Grebow is editor-in-chief of Nutritional Outlook.

Reb D, plus nature-identical glycosides.

Not so long ago, a global stevia market was just a promise. Today, stevia is just a store shelf away in most key markets.

Worldwide, CPG firms are sinking their teeth into stevia where it has the most bite-as a no-calorie, high-intensity sweetener in packaged food and drinks. As regulatory approvals unlock new markets, ramped-up demand has stevia suppliers intent on figuring out how to make stevia better-taste better, easier to formulate with, more sustainable, and scalable to supply.

A wave of new steviol glycosides and glycoside technologies may hold the answers. Nutritional Outlook talked to several stevia firms who clued us in on what the not-so-distant future holds.

 

There’s a New Glycoside in Town

Before going further, rest assured that Reb A, or rebaudioside A, is still stevia’s bestseller. Reb A is considered the sweetest, least bitter of the steviol glycosides on the market today. (Steviol glycosides are the stevia leaf’s sweetness constituents.)

Still, suppliers are continually on the hunt to tease out new glycosides from the stevia leaf (Stevia rebaudiana Bertoni).

How many steviol glycosides does the stevia leaf hold? Researchers are still finding out. There are at least 10 known steviol glycosides, according to stevia trade association the International Stevia Council (ISC; Brussels). This is, of course, aside from any other glycosides companies may be secretly exploring. ISC explains what technically comprises a glycoside: “These sweet components consist of glucose molecules and, in some instances, rhamnose and xylose molecules attached to the aglycone steviol (diterpene type).”

Stevioside and Reb A are the most prevalent steviol glycosides in the leaf. Others include Reb B, C, D, and F; dulcoside A; rubusoside; and steviolbioside.

Of those, Reb D may just be the next big thing.

In March, stevia supplier PureCircle (Chicago) announced plans to commercialize high-purity Reb D extracts in the very near future. At press time, Jason Hecker, PureCircle’s vice president, global marketing and innovation, was not able to divulge more specifically what makes Reb D so promising. However, he did say this via a company press release back in March: “PureCircle research has identified high-purity Reb D as having one of the best sweetness profiles of any steviol glycoside from the stevia leaf.” He adds that Reb D is part of PureCircle’s new trademarked platform, Stevia 3.0,  which aims to provide manufacturers with new glycoside blends using existing and new glycosides, such as Reb D.

PureCircle has numerous process, method, and application patents locking down its high-purity Reb D. As the company explains, it took more than a decade of research and plant breeding to develop stevia leaves with high enough Reb D content to make high-purity Reb D scalable.

“Historically, Reb D has been found at very low levels within the stevia leaf and at a fraction of the amount of well-known steviol glycosides such as Reb A,” Hecker says. “Through our Comprehensive Breeding Program, using conventional breeding methods, we have continued to discover leaf varieties with significantly higher content of Reb D.”

PureCircle is now moving forward exploring product applications with select customers and says we could see high-purity Reb D on the market any day now.

Hecker adds, “We anticipate that PureCircle’s Reb D will be used in a broad range of products and concepts over time as part of our innovative ingredient portfolio. However, given its clean profile, PureCircle Reb D will be particularly important in enabling customers to develop naturally sweetened formulations with very low to no calories, particularly in food and beverages with higher sweetness levels, such as carbonated soft drinks.”

As for regulatory approvals, PureCircle is now seeking U.S. FDA GRAS affirmation for its high-purity Reb D extracts. (It already has GRAS self-affirmation.) While Reb D has already gained FDA GRAS affirmation in the past, it has only done so as part of an overall glycoside blend (PureCircle’s SG95 ingredient) and not as a standalone food/beverage ingredient-which is what PureCircle is now seeking.

 

Production by Fermentation

As companies continue coaxing rarer glycosides from the stevia leaf, one crucial question will always stand between exploration and commercialization: can the leaf yield enough of a glycoside for mass production? Unlike stevioside and Reb A, other steviol glycosides are present at much lower levels in the stevia leaf. Extracting an equivalent amount of those glycosides thus requires more leaf material to start with. When you think about what that means-more land for crops, more water and energy input, and more cost, in general-some companies are starting to look for other options.

Specialized breeding is one way to raise the level of a particular glycoside in a leaf, as PureCircle did with Reb D. But the process can take years to accomplish.

There may be a quicker and simpler way to produce exactly the amount of a steviol glycoside one needs: microbial fermentation.

Very simply put, fermentation involves a microorganism growth medium such as yeast or bacteria to convert carbohydrates to alcohol, gases, and organic acids. The food industry employs fermentation in many beneficial ways. Fermentation, for instance, can be used to help improve an ingredient’s digestibility and absorption in the body.

In the case of stevia, some are proposing fermentation as a way to create steviol glycosides that are, as some call it, “nature identical”-or molecularly the same-to those glycosides obtained through traditional leaf extraction.

A few companies are exploring this space. In March, Cargill (Minneapolis) and Evolva (Reinach, Switzerland) announced a joint partnership to develop fermentation-derived steviol glycosides. Cargill has invested $5.4 million equity in smaller company Evolva, which specializes in fermented ingredients, including vanilla and saffron. Additionally, in 2012, Evolva acquired the fermented-resveratrol business of Danish firm Fluxome. In turn, Cargill brings to the partnership its commercial stevia experience, and for good reason; in April, Cargill’s Truvia sweetener, combining stevia and erythritol, held almost 60% market share in the tabletop stevia market.

Cargill and Evolva aren’t the only ones interested in stevia fermentation. In May, another company, Stevia First Corp. (Yuba City, CA)-self-described as an “early-stage agribusiness,” and unrelated to Cargill or Evolva-announced it had reached pilot-scale testing of its own stevia fermentation process.

Stevia First CEO Robert Brooke paints a broad picture of how his company’s fermentation process works. It centers on the use of an enzyme obtained from the stevia plant, called steviol synthetase. (Another name for the enzyme is kaurenoic acid hydroxylase.) Stevia First licenses this enzyme from agricultural research firm Vineland Research and Innovation Centre (Ontario, BC, Canada), which discovered the enzyme in 2007.

During Stevia First’s fermentation reaction process, which also involves a yeast medium, steviol synthetase yields steviol. Steviol is the starting point from which all steviol glycosides-Reb A, Reb D, etc.-are born. From this point, “You can produce the same, identical steviol glycosides that are found in nature,” Brooke says. (Stevia First has exclusive, worldwide rights to the steviol synthetase enzyme, Brooke says, meaning other companies cannot use the enzyme in their stevia fermentation processes.)

Unlike traditional stevia agriculture and extraction, the fermentation process takes place in closed vessels, where steviol glycosides are produced solely from the starting materials-yeast, enzyme, etc. “You can think of brewing beer or wine in which you have large vessels that are completely contained,” Brooke says. “So you can work on something in the lab at a 1-liter scale, and then you can quickly move up to 10 liters, 100 liters, and then 10,000 liters or more. And you can do it with pretty good reliability, meaning that if production works at 1 liter, it’s going to work at 100 and 10,000 liters.”

If stevia fermentation takes off, it proposes numerous benefits.

First and foremost, it theoretically should allow companies to produce only the glycosides they want, in exactly the quantity they need. Brooke says, “A strength of fermentation is that you have the potential to produce only the desired steviol glycoside that has the best taste profile, such as Reb A or some next-generation stevia sweetener. Or, alternatively, you can convert less desirable steviol glycosides into better-tasting and more valuable ones.”

Stevia First’s challenge is now experimenting with different types of yeasts, for instance, so that it can produce a broad portfolio of steviol glycosides. In March, the company said it is working to “better characterize the newer steviol glycosides (there are more than 30 in total, and less than half are well-characterized), evaluate their properties, and to develop methods for the production of the most desirable products using microbial fermentation.”

Making a broader range of glycosides commercially producible also makes possible new glycoside blends. On its website, Evolva points out, “Several of the most attractive stevia components are present at very low concentrations in the plant and are very hard to extract. Fermentation allows the production of individual components in any required volume-making entirely new blends possible. This opens up the possibility for food and drink manufacturers to fine-tune their products to local tastes.”

It also allows manufacturers to find more obscure glycosides that might work better for a particular application. As Brooke says, each glycoside has specific characteristics, including sweetness intensity, that dictate its usefulness for a particular application. “And that’s different for every single steviol glycoside.”

Another option Stevia First can offer, Brooke says, is transforming, via fermentation, less-desirable, leaf-derived steviol glycosides in a steviol glycoside mix into some of the more-desirable glycosides, such as Reb A or Reb D.

Additionally, fermentation empowers firms to meet forward demand for other glycosides. For instance, says Brooke, although Reb A is the glycoside most common today, “We really don’t know what the future is going to bring. In five or 10 years, consumers may want something very different. Or, 50% of the market could want Reb A, 25% could want Reb D, and 25% could want something else altogether.” Being able to produce glycosides to spec via fermentation would let companies meet every need.

Furthermore, fermentation sidesteps the limitations of traditional stevia farming and extraction-land, soil, weather-that might prevent a company from being able to produce more of an obscure glycoside. “There’s essentially no guarantee that you won’t need dramatically more land in the future for traditional leaf production if consumers start moving to other steviol glycosides that are present in much lower quantities in the stevia leaf, because you would need to produce five or 10 times as much leaf to get the same amount of product,” Brooke says.

Aside from more efficient land and leaf use, fermentation could improve stevia’s sustainability footprint even further, in terms of other inputs. As it stands, stevia is said to be a more sustainable crop to produce compared to other sweeteners like sugar, requiring less water, land, and energy to grow, extract, and purify. In 2012, in what PureCircle says was the stevia industry’s first-ever published farm-to-sweetener carbon and water footprint supply chain report, the company reported that its stevia has a carbon footprint that is up to 71% lower than beet sugar and 43% lower than cane sugar, and a water footprint that is 92% lower than beet sugar, 95% lower than cane sugar, and 93% lower than high-fructose corn syrup. (Cargill is also documenting the footprint of its Truvia sweetener. This January, the company announced Truvia had become the first stevia-based sweetener to be awarded carbon footprint certification from UK-based Carbon Trust.)

“Fermentation brings stevia sustainability to a whole new level,” Brooke says.

For instance, Evolva says that its process uses “sustainable, low-cost carbohydrate feedstocks, which can be sourced virtually anywhere on the planet.”

And Brooke says, “You’re essentially using water, glucose or some simple sugar, enough energy to power your facility, your fermenters, and some amount of media. It’s a very low-cost and low-energy process.”

“Fermentation represents the potential to create a highly sustainable supply chain because, among other things, it is likely that fewer resources will be needed to produce low-volume, high-quality ingredients like steviol glycosides,” echoes Scott Fabro, part of the global business development team for Cargill’s Truvia. He does specify that at this early stage, Cargill hasn’t yet fully determined the water or carbon footprint its own fermentation process would have.

All of this boils down to cost savings-something the stevia industry could use. Why? Stevia is still more expensive to produce today than other artificial sweeteners, and stevia companies want to bring that price down.

In the end, if it delivers on its promises, stevia fermentation seems infinitely scalable, with few limitations. And when you’re looking at a world of demand from consumers, scalability is just what the stevia industry needs.

So, when might we see the first fermentation-derived stevia products come to market? It’s unclear. Stevia First says pilot stage means the company is working on its engineering parameters to scale up production. But Brooke says stevia extracts could be available as soon as 2014. Meanwhile, Evolva predicts its first stevia product could be available in 2015.

Others are also dipping their toes into fermentation. Chris Tower, president of stevia and Go-Luo monk fruit supplier Layn USA (Newport Beach, CA), says, “Manufacturing technology [including conventional stevia extraction] can only take us so far on this quest to produce varying steviol glycoside extracts; there are physical and/or economic limitations and diminishing returns. As the saying goes, ‘You can’t squeeze blood from a turnip.’”

Layn has done some R&D with fermentation. In Tower’s opinion, the technology “is a few years out on a commercially feasible basis, both in respect to commercial scalability and regulatory approvals for any particular molecule, but definitely a technology Layn is entertaining on a complementary level.”

He and Brooke talked about whether regulatory agencies like FDA, which has already declared steviol glycosides as generally recognized as safe (GRAS), would regard fermented glycosides as likewise GRAS for food and beverages.

Brooke says the process should be relatively simple. “We still must convene a panel of regulatory and food science experts to independently review and determine the safety of our products before launch. But the process is expected to be very straightforward, mostly because stevia already has a robust and clean track record on safety, and we’re producing nature-identical stevia sweeteners.”

Tower adds, “Since the safety toxicity of steviol glycosides is well proven in numerous GRAS dossiers published under FDA’s GRAS Notice Inventory, I think clinical work specific to fermentation-derived stevia molecules wouldn’t require additional, expensive, and time-intensive toxicity studies. Rather, likely the clinical work would be centered on safety substantiation of the particular yeasts and/or other source materials in the fermentation procedure, and basic taxonomic profile and chemistry residue work of the molecule and any of its metabolites-essentially proof of chemical equivalence to the naturally occurring steviol compound existent in the leaf/extract.”

 

A Bigger Toolbox

With new-generation stevia options on the horizon, stevia companies shouldn’t think of the newcomers as an “either/or” proposition-e.g., Reb A or Reb D; traditional farming or fermentation. Rather, think of the newer options as simply expanding a food and drink formulator’s stevia toolbox.

Cargill’s Fabro reminds that today’s existing stevia tools like Reb A are still on the table and very effective. Is there need for more?

“Should customers hold out for next-generation stevia? Before we answer that question, we always ask, ‘What is the objective?’” He tells manufacturers, “In many instances, we already have a readily available solution to meet the customer’s needs.”

Still, as the stevia market advances, suppliers can’t deny that new glycosides and technologies will round out stevia’s possibilities. Even Fabro says, “A variety of technologies, fermentation being one of many, are being investigated to give Cargill and our customers access to more options to meet a range of business objectives. To help our customers reach their goals, we must continue to invest heavily in research, both in harvesting glycosides from the leaf and in other areas such as fermentation, to deliver the best solutions.”

Stevia is growing up. 

 

Also read: If fermented steviol glycosides are nature-identical, can stevia still be called "natural"?

 

 

Sidebar: Tate & Lyle Enters Stevia Market

Tate & Lyle (London) is now a stevia player, with its first-ever stevia launch, Tasteva, debuting last fall. Tasteva adds to the company’s natural sweetener portfolio, which also includes PureFruit monk fruit extract, which the company exclusively markets and distributes on behalf of BioVittoria Ltd. (Hamilton, New Zealand).

“Tasteva is a stevia extract with an optimized steviol glycoside composition designed to provide a cleaner taste and allow higher sugar reduction levels versus the more commonly used extracts with high concentrations of rebaudioside A,” says Amy Lauer, marketing manager, North America. In fact, the firm says, Tasteva outperformed high-purity Reb A extracts on taste in multiple food and beverage formulations.

Lauer adds, “The development of Tasteva was a process that occurred over a number of years. It began with evaluation of over 80 different stevia extracts from the market, looking at their glycoside composition analytically and through detailed sensory evaluations. The result was a deep understanding of how different glycosides impact taste in both positive and negative ways.”

 

Also discussed: Can we still call stevia natural if it's nature-identical?