In-depth understanding of how stevia works with different flavour systems, bulking agents, and other ingredients is required to optimise NPD or reformulation of existing food and drinks using the natural sweetener.
In the third part of our special edition on stevia, FoodNavigator caught up with technical experts from stevia supplier Pure Circle and flavour giants Firmenich and Wild to investigate the technical challenges associated with formulating a reduced calorie product with the natural sweetener.
Sidd Purkayastha, vice president of global technical development and support at Pure Circle, told this publication that stevia has a threshold level of sweetness, which once crossed gives a poor return on investment and can lead to technical challenges.
He said that every steviol glycoside has a different flavour and sweetness profile. “Each of those [glycosides] has a very interesting sensory profile, and we are beginning to understand that, and select them preferentially, to bring together a better overall taste profile,” he explained.
The Pure Circle expert said such an approach will benefit manufacturers in the long run:
“Stevia is more like a spice, that has a blend of molecules, rather than a single molecule,” continued Purkayastha. “Sucralose, aspartame, ace-k, are single molecules. Here [with stevia] we have a number of molecules, and when you combine them, overall they can provide a better sweetness profile.”
Meanwhile, Bill Swanhart, principle food technologist at Firmenich, said stevia on its own will never be able to fully replace sugar one for one. However, in combination with other flavours it is possible to create great tasting products with stevia, he stressed.
“The sweetness is definitely there with stevia, but our challenge is to try and get something more similar to the profile of sucrose,” he continued.
“Right now we have a good toolbox to help build sugar tastes back in,” said Swanhart, but he noted that fundamental understanding of the role of other ingredients in a formulation, in terms of how they impact flavours and mouth feel perceptions, is critical.
In addition to the challenges of reducing sugar, Peter Naylor, director of strategic business development at Wild Flavours, noted that many manufacturers have begun to realise that when it comes to swapping sweeteners in a product, it is not as straight forward as one might think.
“If for example you have an existing diet or calorie free product, you can’t just take out the existing artificial sweeteners and replace them with stevia. The formulation will need a total re-work, or at least looking at again,” he explained.
Sugar is an important part of any food or drink product, and has several functionalities – with Swanhart noting that in many products “sugar is not just there for sweetness.”
Noting sugar’s role in terms of flavour and texture in products, he explained that stevia cannot deliver that functionality.
Also with sugar, continued Swanhart, you have an upfront, middle and end sweetness. “Stevia has more of a slower onset so it takes a little longer to come in than sugar, and also it has a longer duration so therefore it lingers.”
The Firmenich technologist said the formulation challenge around stevia is the ability to build back the functionalities in a positive way in order to develop a flavour that has some of those up-front notes and in this way counter some of the lingering sweetness effect associated with the natural sweetener.
Stevia can sometimes, however, be associated with metallic and bitter aftertastes, including liquorice and astringent notes.
Naylor said that one way of dealing with off-notes is through the use of bitterness blockers, “so any potential bitter flavours do not come through as strongly.”
However Swanhart says that blocking any bitterness is not the right solution in all cases:
“Sometimes you can incorporate the bitter notes as part of the flavour. For example you have bitterness in say a cranberry or grapefruit, so you can use that slight bitter note as a positive rather than a negative,” he explained.
“In these applications the bitterness comes through in the taste but it makes up a part of the overall flavour profile.”
Naylor commented that small amounts of carbohydrate in a finished product can help to better hold together the sweetness profile of a stevia product, and can also assist with boosting mouth feel.
As a result, he said that mid-calorie range products are “an area that may start to be of more and more interest to manufacturers as stevia advances.”