To the casual observer, sugar replacement in processed food may seem to be primarily about compensating for loss of sweetness. But sugar performs a wide range of functions all of which need to be considered when reformulation to reduce caloric content is attempted.
In addition to adding sweetness, enhancing flavour and suppressing bitterness and acidity, sugar is used to affect colour and texture. It has a fundamental effect on mouthfeel, acts as a preservative and also alters the freezing and boiling points of processed foods.
Sugar replacers can be divided into two types: intense sweeteners, such as acesulfame K, aspartame, saccharin and sucralose, and bulk ingredients, such as polyols and polydextrose.
Intense sweeteners contribute taste but are used in very small quantities and make no significant contribution to total calorific value.
Intense sweeteners can therefore be used most effectively in products such as soft drinks, where a relatively small change in viscosity and mouthfeel will result but not an effect that undermines the viability of the product. They are also used in tabletop sweeteners. Where a ‘spoon-for-spoon’ granular tabletop application is required, intense sweeteners are often combined with a polysaccharide called maltodextrin.
Bulk sweeteners contribute to the bulk, viscosity and texture of foods and usually contribute some calories too. They are used in products such as sugar-free confectionery, cakes, pastries and biscuits where replacing the bulking function of the absent sugar is critical.
Primary challenges in replacing or reducing sugar content
Matching the sweetness profile of sugar
This is clearly a desirable aim but has proved hard to achieve with a single product. Different substitutes have different sweetness profiles so blending sweeteners has become a common practice.
Retaining the flavour profile of the product
Retaining precisely the same flavour in a reduced-sugar variant or reformulated product has been found quite difficult to achieve. Modern practitioners tend to accept that greater success can be achieved by accepting from the outset that there will be some alteration in the flavour profile. The aim therefore is re-optimisation, to develop a new flavour profile as close to the original as possible.
Maintaining the same texture and mouthfeel of the product
Sugar does not just contribute flavour but also adds bulk. Intense sweeteners used in very small quantities do not achieve this, so only bulking agents and bulk sweeteners are appropriate for this task.
Compensating for preservative qualities of sugar
Taking out sugar which is there to extend shelf life may necessitate the addition of a chemical preservative. Manufacturers can also facilitate sugar reduction by shortening ‘use by’ periods and requiring that products be stored in the fridge. While many bulk sweeteners and bulking agents are heat-stable, they do not have the browning properties of sugar which creates another problem in developing reduced-sugar baked goods.
While lower-calorie reformulation may have originally been focused on developing new artificial ingredients to replace sugar, there has been something of a backlash against this approach. Whereas at one stage the negative health impacts of consuming too many calories may have dominated the agenda, today food scientists are increasingly aware of consumer concerns about artificial ingredients and highly-processed foods. As the desire for ‘clean label’ solutions has increased, there has been an increasing emphasis on the search for ‘natural’ ingredients and processes to reduce sugar levels.
Acesulfame K, or acesulfame potassium, is a synthetic heat-stable sweetener discovered around 40 years ago. AceK is 180 to 200 times sweeter than sugar but has a slightly bitter aftertaste in high concentrations. It is therefore usually blended with other sweeteners.
Aspartame is a synthetic sweetener consisting of two amino acids, namely aspartic acid and phenylalanine. First developed more than 25 years ago, aspartame is sometimes referred to by its original trade name, NutraSweet. In addition to NutraSweet, another prominent aspartame-based tabletop sweetener is Canderel.
Aspartame is also about 200 times as sweet as sugar. It has no bitter aftertaste but its sweetness can linger longer than is the case with sugar. It is less stable than Acesulfame-K and unsuited to processes such as canning.
Over the years, aspartame has attracted a significant amount of controversy and adverse publicity regarding alleged health risks. But after many investigations, regulators have concluded that the product is safe for human consumption.
However, aspartame cannot be consumed by people who suffer from a condition known as phenylketonuria (PKU) who are unable to metabolise phenylalanine.
Saccharin is the common name for benzoic sulfimide and is usually used in its sodium salt form for improved solubility. First discovered more than 100 years ago, it is between 300 and 500 times sweeter than sugar. It is the lowest cost sweetener available, though some expect that position to be challenged in coming years by neotame (q.v.). Like acesulfame-K it has a bitter aftertaste so tends to be used in combination with other sweeteners, such as cyclamate (q.v.) or aspartame (q.v.).
Saccharin can be used in products with a long shelf life. The development of saccharin was significant for diabetics as it passes through the system without being digested. The tabletop sweetener, Sweet ‘n Low, is saccharin-based in the US, where it was launched in 1957. However, the brand is cyclamate-based in Canada and is a blend of aspartame and AceK in the UK and EU.
Sucralose is highly potent intense sweetener, being around 600 times sweeter than sugar. Sucralose is stable when heated so can be used in a wide range of heat-processed and shelf-stable food products. In addition to offering stability advantages, sucralose has no bitter taste, although its sweetness is even more lasting than that of aspartame.
While many of the health concerns raised about other artificial sweeteners have not been borne out in research by regulators, sucralose does have the advantage that it has had a comparatively uncontroversial history. Among the sucralose-based tabletop products on the market are Tate & Lyle’s Splenda, SucraPlus, Cukren and Nevella.
Sodium cyclamate, generally referred to as cyclamate when used as a sweetener, is nowhere near as sweet as some of the other artificial sweeteners available, being only about 30 to 50 times sweeter than sugar.
It is also often considered to have an unappealing aftertaste and is therefore generally used in combination with other sweeteners, very often aspartame or saccharin. Such blends have excellent sweetness but the EU limits quite severely the amount of cylcamate that can be used. Its principal advantages are that it is cheaper than most sweeteners and is stable when heated.
Neotame is an artificial sweetener developed by NutraSweet. It is an example of a ‘super-potent’ sweetener, being between 7,000 and 13,000 times sweeter than sugar. With broadly the same stability as aspartame, Neotame is very low cost and is used as a blending sweetener to keep costs down.
A comparatively new addition to the list of sweetener options, stevia has generated great interest particularly as the ‘clean label’ trend has gathered momentum. Derived from a plant called Stevia Rebaudiana, ‘stevia’ is actually a group of natural intense sweeteners called steviol glycosides.
The best known is stevioside, but the best-tasting is rebaudioside A or ‘rebiana’ which is around 200 times sweeter than sugar.
As in all areas of the reformulation space, synthetic sugar replacements have tended to attract controversy related to possible negative side-effects. The search for additives that can be labelled as ‘natural’ has therefore intensified.
Stevia has been used for more than 30 years in Japan and is widely permitted in Asia and Latin America. It gained regulatory approval in the US in 2008 and since then has increasingly been used as an intense sweetener in food and drink products there. It has also been granted approval in several non-EU European countries and while still awaiting official approval in the EU was ruled as safe by the European Food Safety Authority (EFSA) in April.
Polydextrose is a synthetic polymer of dextrose which in itself is not sweet but is used in combination with other artificial sweeteners to provide the bulking properties of sugar while contributing fewer calories.
Also known as sugar alcohols, polyols are chemically modified sugars which can mimic the bulking properties of sucrose with a lower caloric contribution.
The six polyols most commonly used for sugar replacement are erythritol, sorbitol (sometimes known as glucitol), mannitol, lactitol, xylitol and maltitol.
The polyols have distinct differences and are used for different types of product. They also differ in their sweetness and the calorie reduction they offer. Lactitol has only around 40% of the sweetness of table sugar, while xylitol is almost as sweet as sugar. Erythritol has about 60% of the sweetness of sugar.
Erythritol has such a small calorie content that it is legally regarded as ‘zero calories’ in the EU, Japan and the US. In contrast, all the other polyols are – in the EU – legally obliged to assume 60% of the energy content of sugar. The US recognises that each polyol has a somewhat different energy content.
Polyols tend to share the same drawback that they have laxative effects particularly when used in significant quantities. When polyols are used above a certain level, it is mandatory to include a warning of this on the label. The product which produces the least laxative effect is erythritol.
Hydrocolloids – gels and thickeners – are also used in combination with artificial sweeteners to provide a bulking function when sugar is removed.
The ‘clean label’ trend is arguably the most important influence affecting the sweetener arena at the moment, underlined by the huge interest being shown in stevia. While many of the health scares around artificial sweeteners have remained unsupported by exhaustive research, the impact on consumer sensibilities is clear. Products which offer a calorie reduction with the minimal amount of technical processing and artificial substances will have far greater consumer appeal. This attitude has also been reflected in the views taken by major retailers.
That said, there is research interest in developing other super-potent sweeteners along the lines of neotame which can be used in microscopic quantities usually in combination with other sweeteners.
Indeed, there is a continuing research emphasis on blending in general. Blending has always been a facet of sweetener development and it has increasingly been recognised that the best results – in functionality, texture, sweetness and overall taste profile – are more likely to be achieved through a combination of ingredients.
just-food gratefully acknowledges the assistance of Dr John Fry of Connect Consulting in the preparation of this article.
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