Reb-D (Rebaudioside D) has a “better sugar character and more desirable taste” than Reb-A in many beverage applications, but is difficult to use because of its low solubility in water at room temperature, says PepsiCo.
Writing in patent application #20130251881, ‘Method For Enhancing Rebaudioside D Solubility In Water’ (published Sept 26, 2013 - click here), it adds: “For instance, Reb D needs to be heated to near boiling water temperature for two hours in order to achieve complete dissolution at 0.8% concentration. At most only 300 to 450 ppm can be solubilized in water at 23°C.”
Reb-D and the solubility challenge
Due to this low solubility, if Reb D is used in beverages, it needs to be combined with other sweeteners that are more soluble in water, says the application.
“There is business interest now in developing sweetener compositions higher in Reb D… [But] such development is impeded, in part by the low solubility… It would be advantageous, therefore, to develop improved methods to enhance solubility of Reb D in water at room temperature (20-25°C.).”
Traditionally, many beverages are manufactured by developing a concentrate/syrup that is later diluted in water (typically one part syrup, five parts water), says the application.
However, owing to the solubility challenge, “Reb D cannot be provided in a syrup or concentrate in amounts sufficient to provide a sweetened beverage.“
The treated Reb-D powder maintains the sweetness characteristics of the untreated Reb-D
The patent application describes methods of enhancing the solubility of Reb D in aqueous-based liquids comprising:
1 - Preparing a clear Reb D solution by adding Reb D powder to water and heating to completely dissolve it, or by extracting Reb D from the stevia plant using hot/boiling water or water/ethanol, wherein the temperature of the clear Reb D solution is above 70°C.
2 - Mixing the clear Reb D solution with a solubilizing enhancer, wherein the temperature of the enhanced Reb D solution is maintained above 70°C and wherein the solubilizing enhancer is a water soluble organic acid salt, a water soluble organic acid, or a hydroxyl-containing sweetener.
3 - Adding a stabilizer to the enhanced Reb D solution to produce a stabilized Reb D solution; wherein the stabilizer comprises a thickener or anti-agglomeration agent.
4 - Spray-drying the stabilized Reb D solution to form a powder.
Depending on the process used, the solubility can be increased up to 1,500 ppm, or 3,000 ppm, or 7,000 ppm, and even up to 8,000 ppm at 23°C (room temperature), says PepsiCo.
“Beverages made with modified Reb-D powder have a comparable taste profile to beverages made with untreated Reb-D. That is, the treated Reb-D powder maintains the sweetness characteristics of the untreated Reb-D.”
PepsiCo: Reb-D provides significantly lower bitterness than the same concentration of reb-A in otherwise identical formulations
In a separate patent application #13605644 published in March (click here), PepsiCo noted "that rebaudioside D in an aqueous solution, an acidic aqueous solution, and an acidic aqueous carbonated solution, provides the same or significantly higher sweetness than the same concentration of rebaudioside A in otherwise identical formulations".
Reb-D also "provides significantly lower bitterness than the same concentration of rebaudioside A in otherwise identical formulations”, said PepsiCo.
Reb-D has ‘one of the best sweetness profiles of any steviol glycoside’
According to leading stevia supplier PureCircle, Reb D has "one of the best sweetness profiles of any steviol glycoside”.
The firm, which has developed proprietary varieties of stevia plants containing high levels of Reb-D, has secured process, method and application patents to protect its Reb D extracts, which it aims to commercialize in 2014.
The regulatory path in the US at least is also cleared, with the FDA issuing a ‘No Objection’ letter to PureCircle’s GRAS determination for Reb D over the summer.
Reb D will be particularly important in enabling customers to develop naturally sweetened formulations with very low to no calories
In a recent interview with FoodNavigator-USA, PureCircle vice president global marketing & innovation Jason Hecker said his firm’s Reb-D had "generated interest among a number of customers" although he didn’t name names.
He added: "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, like carbonated soft drinks."
Click here to read PepsiCo’s patent application in full.