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Is Reb-M the holy grail of Sugar Reduction?

Stevia has been the talk of the town for a while, but what has recently subdued this is the hype around the newer steviol glycoside Reb-M. 
 
It is even being marketed as the holy grail of Sugar Reduction. But is that true? And if it is, why hasn’t Reb-M taken over yet? Let’s find out. 
 
Whether you are already developing a low-calorie product using Stevia or considering sugar reduction in your existing product, this blog will help you figure out where Reb M falls into your sugar reduction plans.
 
What is Reb-M?
 
In the present times, several food and beverage businesses are actively seeking and incorporating steviol glycosides into their products to substitute sugar. This helps them manufacture low/no sugar recipe while obtaining consumer interest and labeling benefits.
 

Steviol Glycoside Name Melting Point, °C Mol. Weight % Solubility in Water % in Leaf Relative Sweetness Sensory Attributes
Rebaudioside M 216-218 1291 0.20 < 1% 230-450 Sweeter than Reb-A

 
Looking at the molecular structure of the steviol glycosides.
Stevioside (first generation glycoside) has three glucose units attached to the steviol backbone, Reb-A (second generation steviol glycoside) has four glucose units whereas Reb-M (third-generation steviol glycoside) has six glucose units.
And like the saying the more the merrier, more glucose molecules here means better taste with a declining aftertaste. 
 

Is Reb-M the holy grail of Sugar Reduction?

Fig 1.1: Difference between the molecular structure of generation I, II, and III steviol glycosides. The figure shows that Reb M has more glucose units (6) as compared to Reb-A (4) and Stevioside (3).
 
Source: https://www.researchgate.net/publication/274073985_Development_of_Next_Generation_Stevia_Sweetener_Rebaudioside_M
 
Why is stevia leaf Reb-M considered as a premium extract?
 
The two factors that make Reb-M stevia superior among other extracts are its unique taste and its scarcity in the leaf. 
 
In comparison to the other glycosides obtained from the leaf, Reb-M is the one with the closest taste profile to sugar without any aftertaste or prominent lingering effect.
 
Another factor that accounts for the premium nature of Reb-M is its scarcity in the Stevia leaf. Being one of the minor glycosides, it is present in the Stevia leaves in trace levels; 0.1% of the dry matter to be precise, which makes its extraction from the leaf commercially impossible. Therefore in recent times, stevia Manufacturers are relying on technologies like fermentation and enzyme modification to ramp up production.
 
How is Reb-M produced?
 
Fermentation
 
Reb-M stevia produced using the process of fermentation is identical to its natural counterpart. The fermentation process uses genetically modified yeast and a glucose source, usually cane sugar or corn dextrose to produce the sweet glycoside.
 
Enzyme modification
Minor glycosides like Reb-M can also be produced using enzyme modification via glycosylation or bioconversion, both of which techniques involve adding supplementary glucose units to lower-cost steviol glycosides.

  • Glycosylation

The technique involves the treatment of traditionally extracted, lower-cost, major steviol glycosides with the enzyme cyclodextrin glycosyltransferase that facilitates the transfer of glucose units, modifying the chemical structure of the steviol glycoside. The product obtained at the end of the reaction are glycosides that are dissimilar to the minor glycosides found in nature.

  • Bioconversion/Biotransformation

Bioconversion/Biotransformation is another process that utilizes genetically modified yeast and a glucose source by Stevia Manufacturers to produce minor glycosides like Reb-M. However, unlike fermentation, where no part of the plant is used, the substrate used is traditionally extracted major steviol glycosides and the end product obtained is similar to its natural counterpart. 
 
Characteristics of Reb-M that makes it desirable:
 

  • Taste

The sweetness of Reb-M is defined as sugar-like, with a taste that is pleasant and well perceived, lacking any bitterness or licorice-like aftertaste. The graph attached below describes the taste profile and sugar-like characteristics of Reb-M.
 

Is Reb-M the holy grail of Sugar Reduction?

Fig 1.2: Comparison between different sensory properties of Sugar, Reb-A, Reb-D, and Reb-M. It can be seen that Reb-D and Reb-M have a closer sensory profile to sugar and less bitterness as compared to Reb-A.
 

  • Ease of formulation

 
The sugar-like taste profile of Reb-M significantly reduces the amount of technicality and use of ingredients it takes to successfully manufacture a product with Stevia. The lack of any undesired aftertaste or off-taste, makes it possible for product developers to use the extract on its own up to a certain threshold without having to use a masking agent or additional flavors.
 
Is Reb M always the right choice for your product? 
Before selecting an extract, it is important to make sure you are purchasing a product that works for you in terms of taste as well as cost.

  • Product application

 
In certain product applications such as citrus beverages, 50% sugar reduction can be achieved with the help of Reb-A without any noticeable after-taste or off-taste. In this case, a lower-cost extract such as Reb-A blended with other extracts or ingredients works better than Reb-M Stevia and proves to be economical as well.

  • Binary Sweetness

 

Is Reb-M the holy grail of Sugar Reduction?

Is Reb-M the holy grail of Sugar Reduction?

Fig 1.4: Comparison of the synergistic effects of ArboPure RM and ArboPure RA with Sucrose and Erythritol, to see the binary sweetness quality, implying that ArboPure RM performs better in binary mixtures, although ArboPure RA doesn’t fall far behind.

  • Flavor profile

 
For product applications focusing on replacing/reducing sugar while keeping sugar-like sweetness intensity as a priority, Reb-M stevia may work as a great sugar alternative. Depending on the desired sweetness level, both Reb-M and Reb-A can be great sugar substitutes.
 
How can Arboreal help
 
Reb-M is commercially produced in less than five organizations globally, Arboreal Stevia being one of them. We at Arboreal are reinventing Stevia, with an expertise of over six years and our vertically integrated Stevia supply chain. We manufacture and provide Stevia extracts and solutions developed in India’s first application development center along with free formulations support.
For any questions regarding Stevia, drop us a mail at [email protected], or to book your free consultation call, click here.