Fermentation Based Steviol Glycoside Production – Demystified

For about an year we are anxiously waiting for commercial launch of steviol glycosides produced through fermentation. At least three commercial companies are working on industrial scale production of fermentation derived products.

 

There has been intense interest and competition to commercialize the fermentation based production of steviol glycosides, driven by two key factors.

 

Firstly, possibility of mass producing rare steviol glycosides like Reb M, Reb D etc., which are said to have better taste profile than Reb A, at cheaper cost.

Secondly, the prospect of getting those fermentation based steviol glycosides legally described and labeled as “Natural”, which may enable producers to quietly incorporate them in profitable natural products markets.

The initiative of developing a production process for stevia sweeteners, which is supposed to make the entire stevia farming sector irrelevant, generated a mixed reaction among the stakeholders. 

Some of the comments are as follows –

 

The mere fact that a product is based on an innocuous raw material is not sufficient to pull the “natural” wool over consumers’ eyes.......Stevia’s already wobbly status as the only “natural” low-calorie sweetener is about to be thrown into even greater jeopardy

 

– Simone Baroke, Euromonitor Analist                                           Link 

 

This is unlikely to have an effect in the short term as consumers still associate fermentation with a natural production process

-David Turner, Analyst, Mintel                                                        Link

 

Of course this will damage the natural reputation of stevia even if (in Europe) stevia extracts are not allowed to be labeled as “Natural” but from Natural Origin

-Monica Lorenzo, Board Member, European Stevia Association         Link

If the commercialization of the fermentation based steviol glycosides happens, the switch in human consumption of a synthetic biology based sweetener will probably not be advertised. Consumers will continue to be told that they are being offered a “natural” product. Already some companies producing leaf stevia have been speaking out against this coming deception. In 2012, Pure Circle unveiled polling data showing that consumers expect stevia to come from a leaf; and in 2015, a number of stevia trade associations openly attacked the new synthetic biology based  stevias as likely to damage the industry’s reputation.

Stevia – the production dilemma

Produced by nutrition from earth, rain and sunshine from a plant…….found by ancient wisdom

Produced by a genetically modified organisms in an industrial setup utilizing inorganic/synthetic nutrients

How it is done

Steviol glycoside synthesis in stevia plants is a multi-step process. Simple molecules produced during photosynthesis and glucose breakdown are combined to make complex steviol glycoside molecules. Each step is catalyzed by specific enzymes. Production of all these enzymes is, in turn, controlled by specific “genes” in the cells of stevia plant.  

If you want to know more about genes and how they work, you may visit this page

For production of steviol glycosides by fermentation, the following method is followed

  1. All these required genes are inserted into micro-organisms like Yeast or E. coli and stable genetically modified organisms with all these genes in working condition in their cells is produced.

  2. The organisms are cultured in large “fermenters” or large stainless steel vessels in sterilized liquid medium. The liquid medium contains all the nutrients required for rapid growth of the organisms.  

  3. The genetically modified organism multiplies and grows in the medium. They produce steviol glycosides and secrets that in the medium. Sometimes, they store the product in their cell.

  4. After certain time, the organisms are separated from the liquid medium and the liquid medium is processed to isolate the steviol glycoside from it. Sometimes the microbial cells are ruptured mechanically or by osmotic shock to facilitate release of the fermentation products in the medium.

  5. The steviol glycoside is purified by conventional method and pure glycosides in solid powder form are produced.  

The process in brief
 
Comments

A study of the present scenario reveals the following facts regarding the completion between fermentation based production and conventional farming based production of stevia sweeteners.


1.    The fermentation based production is mainly aimed for high end Reb M and Reb D. It may not compete against conventionally produced Rab A. Now Reb A is being used more efficiently with development of formulation technology. 


2.    Now, instead of pure steviol glycosides, “Pre-mixes” with taste modifiers and enhancers are being offered to the customers. Custom made Pre-mixes have very high compatibility with the food in which it is used. They are cheap, easy to use and produce good taste profile. In this scenario, there is little incentive for the consumers to switch over to costly Reb M and Reb D overnight. 


3.    There is no data available about the present production cost of fermentation based steviol glycosides. Some of the companies have delayed the commercial launch due to high production cost. 


4.    At present the cost of setting up a fermentation based production unit is higher than expanding new farming area with equivalent steviol glycoside production capacity in emerging areas like Africa, India, South East Asia and Caribbeans.


5.    The cost of production of steviol glycosides through conventional method is also showing downward trend due to enhancement in operational and energy efficiency in newly designed extraction facilities. 


6   Continuous R&D has been developing new stevia cultivars with higher glycoside content, which in turn, is also instrumental in bringing down the extraction cost.


7.    There is also a recent trend of establishing “mini” decentralized extraction plants. These small plants can cater local customers with high cost efficiency. Sometimes, these units are offering low cost purified liquid products to the customers, which have acceptable taste profile. 


8.    Steviol glycosides produced from naturally grown plant based stevia will always have better image in the consumers mind. Till now, steviol glycoside based sweeteners are identified predominantly as a plant based product, with pictures of stevia plants or leaves on the packaging of almost all the products. Fermentation based products may have difficulty in fitting into this image. Cargill has no intention of using fermentation based glycosides in their Truvia business, and they are not marketing the fermentation based products as “Stevia” (Reference).
 

All these factors, in combination, indicate that farming based steviol glycoside production will continue to be an economically viable business for some more time.