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Is sugar reduction an impossible dream?

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A trans-Tasman team of researchers from Melbourne University, Massey University New Zealand, and Deakin University Victoria have investigated the sensory success of reducing sugar in foods and found it lacking. Despite much technical innovation, there are still challenges for consumer acceptability; the bottom line being foods without sugar don’t taste as good. Their paper is published in Critical Reviews in Food Science and Nutrition

Here we interview lead author Scott Hutchings.

 

Dr Scott Hutchings is a sensory scientist originally from New Zealand with an Honours degree in Food Technology and a PhD in Food Science (Food Structure/Oral Processing) from Massey University. He has worked as a food technologist in the food industry, and as a research fellow in the area of sensory science and food structure at University College Dublin, lreland. He is now a lecturer in sensory science at the University of Melbourne. His research seeks to develop novel food structure-based approaches to enhance the sensory properties of new food products. He is also interested in the development of rapid sensory profiling techniques, sensory perception and oral processing in aging consumers, and sensory modification to influence appetite and food intake.

Alternative sweeteners are seen as the solution that offers sweetness without the kilojoules. Are there any sensory downsides?

Most alternative sweeteners have a slight bitter aftertaste, particularly at higher concentrations. Astringent and metallic side tastes can also be an issue. Often more than one sweetener is combined in a product for a synergistic effect to reduce some of these issues. The time intensity profile of alternative sweeteners also differs from sugar – sometimes you find it takes a few more seconds to detect the peak sweetness of a product with an alternative sweetener, and a sweet taste can also linger for a longer period of time in the mouth.

What other technical solutions are being used to make up for using less sugar in food and how successful are they?

The two main alternatives being used to make up for less sugar are (1) the use of increased flavour, and (2) processing innovation in the area of food structure. Both these methods can achieve a sugar reduction of around 20% without changing the perceived intensity of sweetness.

The use of flavour is the most practical option. Nestle for example have recently reduced sugar content in some of their chocolate by increasing the cocoa content. By increasing the intensity of flavour in a product (the flavour must of course match and be familiar in the type of product), we can lead the brain into perceiving the sweetness intensity to be higher than it really is. The downside to this approach is that the addition of more flavour can add ingredient costs for a manufacturer.

Innovation in food structure is also promising. The most effective approach is through heterogeneously distributing sugar in products (where sugar is not blended evenly in the product – but located in highly concentrated, specific portions of a product). This type of structure fools taste receptors into perceiving a higher intensity of sweetness as a product is chewed (taste receptors are stimulated with an ‘on-off’ effect). However, a food manufacturer would have to invest a lot of money in redesigning a production process to achieve this. It also rather difficult to apply a heterogeneous distribution of sugar in beverages or semi solids – much easier in solid food products. Some food structure research is also investigating techniques to increase sugar release from food while it is consumed in the mouth (thereby increasing sweetness), but this work is early in its development.

Innovation in the food industry has focussed on how to ‘trick the taste buds’ into thinking food contains sugar when it doesn’t. Is there any value in the idea we should just train our tastebuds to enjoy foods that are less sweet?

There is certainly some value in ‘tricking the taste buds’ for some consumers and segments of the market who still want to enjoy foods at the same level of sweetness that they are used to. While we are yet to fully understand the health effects of reduced sugar products versus full sugar options, and current approaches to trick the taste buds have their draw backs as discussed above (alternative sweeteners, using increased flavour, technology in food structure), these options nonetheless can provide a lower calorie alternative that is still enjoyable enough from a sensory point of view - many consumers around the world are satisfied with this.

For other consumers slowly training themselves to consume foods with less sugar and sweetness might be a preferred option. This can be achieved for an individual with food prepared at home, however the widespread availability of processed foods with a high sugar content and/or sweetness intensity does make a gradual reduction in the sweetness of food consumed difficult for many people. Industry-wide reduction of sugar (even relatively small levels of reduction) in processed food could be a good long-term option to assist with this approach.

The way sugar impacts central taste and reward pathways is very complex. How far advanced are we in outsmarting our own physiology?

My understanding is that we still do not completely understand the difference between how sugar and alternative sweeteners differ in their effect on reward pathways in the brain, and that the use of alternative sweeteners to reduce overall calorific intake in people is only partly successful. 

Current research suggests that alternative sweeteners will not deliver the same level of satisfaction and pleasure compared to sugar in the reward pathways of the brain. Furthermore, while both sugar and alternative sweeteners stimulate sweet taste receptors in the mouth, alternative sweeteners do not stimulate the gut receptors involved in satiety like sugar does.

You are a sensory researcher and your paper describes the many challenges to replicate the taste of sugar, but what are the other technical qualities sugar has in food and how well can they be replicated?

Sugar provides a wide range of benefits to a food product in addition to taste. Sugar decreases water activity, reduces microbial growth, and increases shelf life. It has an important role to play in how dough rises during baking, prevents ice crystal growth in ice-cream, and thickens the viscosity in many beverages.

Alternative sweeteners don’t provide the same body and mouthfeel of sugar. That crispy crunch you get from your favourite biscuit, or that smooth sensation of your favourite ice-cream, is very difficult to replicate without sugar. Particular sugar alcohols, starches, and gums can be used to substitute this textural effect, but cannot replicate it very well, as of yet.

In your opinion, is a continued quest for reduced sugar products that taste great an impossible dream? What future developments would you advocate?

A significant (i.e. greater than 30%) reduction in sugar content without compromising sensory perception is very difficult to achieve. Perhaps not an impossible dream, but technically very challenging with the current food formulation options available!

But even small reductions in sugar intake have been shown to have a positive impact on health. Consequently, I believe continued developments in the area of flavours and food structure to achieve small but realistic reductions in sugar are the most promising avenues to reduce sugar but maintain a great taste. These approaches avoid the unwanted side tastes of alternative sweeteners and also appeal to consumers who are wary of the perceived heath impact of alternative sweeteners. 

NEXT: Food addiction behaviour - how can we help?

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