Technical Talk: April 2012

Know your artificial sweeteners and what they can do to help you produce lower-calorie baked goods.

Obesity is the global epidemic driving the demand for the next great zero-calorie sweetener. Obesity has more than doubled worldwide since 1980, according to the World Health Organization (WHO), which defines obesity as a body mass index (BMI) greater than or equal to 30. Obesity is often named as an underlying cause of many chronic diseases, such as diabetes, cancer and cardiovascular disease.

Sugar plays a functional role in improving the shelf life of your baked goods.

Many attribute the cause of obesity to the high-calorie modern diet. Sugar (and its many forms) is one of the main caloric contributors. Baked goods are notorious among calorie-rich foods. Desserts contribute the most calories, followed by the breads. Many sweetener alternatives have been developed over the years because sugar is such a calorie culprit. These artificial sweeteners are often much more powerful in their sweetness than common sugar and are therefore used in small quantities. My April 2009  Tech Talk column dealt with the technical issues of replacing sugar in baked goods. In this column, I will explore some of the ingredients in the market that can be used for imparting sweetness in baked goods: mainly high-intensity sweeteners.

The use of sugar (sucrose) in baking not only provides sweetness, but also plays a functional role. Sugar provides food for the yeast, bulk, colour, texture, volume, and increases the shelf life of baked goods. During mixing, it competes with gluten in the dough or batter to bind water, so there is less gluten development and the final product has a tender crumb and good volume. Its water-binding properties also increase batter viscosity. Sugar promotes air incorporation and the production of a more viscous and stable foam. During baking, it increases dough fluidity because it melts with heat. In addition, it delays starch gelatinization so air bubbles have time to expand properly before the product sets. Air bubbles are produced by carbon dioxide and water vapour. For example, in cakes in which the sugar concentration is 55 to 60 per cent, the starch gelatinization is delayed from occurring at 57 C to 92 C. Sugar also delays protein coagulation by dispersing the proteins and interfering with bond formation. As a result, the proteins coagulate at a higher temperature.

The functional properties of sugar in baked goods cannot be replaced with high-intensity sweeteners alone. Therefore, it is necessary to use high-intensity sweeteners in combination with other ingredients to compensate the removal of sugar (such ingredients and their functions were also described in the April 2009 column). They can be digestible (sugar alcohol, maltodextrins), partially digestible (polydextrose, fructooligosaccharides and galactooligosaccharides), or non-digestible (cellulose). The fructooligosaccharides and galactooligosaccharides are of particular interest, which may benefit health more because of their prebiotic activity.

A number of high-intensity sweeteners have been developed over the years. These are many times sweeter than sugar but they essentially provide zero calories. A bitter metallic aftertaste is experienced with some of these intensive sweeteners. Many of them are slower than sucrose to trigger the sensation of sweetness, and the flavour lingers longer after swallowing. In addition, some intensive sweeteners are affected by heat, so they cannot be used in baked goods. In order to overcome these problems, some artificial sweeteners are used in combi-nation with others.

Aspartame is approximately 200 times sweeter than common sugar. It is composed of two amino acids: aspartic acid and phenylalanine. Because it is a dipeptide (chain of two amino acids), it may break down into the two amino acids under elevated temperatures and high pH. For this reason, it is not normally used in baked goods. Neotame is chemically similar to aspartame, but much sweeter and more stable. Saccharin is 300 to 400 times as sweet as sucrose, heat stable, readily soluble but has a bitter, metallic aftertaste. Acesulfame-K is 200 times sweeter than sucrose, heat and pH stable, and fairly soluble, therefore making it possible to use it in baking formulations. Sucralose is 400 to 800 times sweeter than sucrose; heat and pH stable, and has a similar sensory profile to sucrose. Sucralose is available in various forms and can be used in baked goods. One of the sources of intensive sweeteners that has received a lot of attention lately is the plant stevia rebaudiana.

Several compounds called steviol glycosides are present in the leaves of this plant and provide the intense sweetness. The most abundant and well known is the steviol glycoside. However, another, less common glycoside, called rebaudioside A, has a better taste than the others found in the stevia plant.

The leaves of the stevia plant can be extracted with water to produce a powder to be used as a sweetener.

Several ingredients are available as sweeteners from stevia. The leaves of the stevia plant can be extracted with water and the extract is either concentrated (liquid form) or dried to produce a generic form of powder that is used as a sweetener. Steviol glycosides (specifically rebaudioside A, which is considered to be the best tasting) are also isolated and purified and sold as ingredients. On the regulatory side, stevia and its extracts have been produced and approved in some countries for a long time; however, it has only recently received more attention in North America and Europe. In July 2011, the European Union Standing Committee on Food recommended the approval of high-purity stevia extracts for use as a food ingredient throughout Europe. The United States banned stevia in the early 1990s, but in 2008 the rebaudioside A extract was approved as a food additive. Canada’s regulatory climate is different. The Health Canada website states:

Stevia leaves (fresh, dried or powdered) without health claims CAN be sold in Canada to a consumer wishing to use this product for personal culinary use only.

Foods containing stevia leaves (fresh, dried or powdered) have not been accepted for sale in Canada. To date, Health Canada has approved the use of stevia and its extracts as a non-medicinal ingredient (sweetener) in 108 natural health products, and as a medicinal ingredient in three natural health products (NHPs).

Becoming familiar with how to use various alternative sweeteners in your baked goods will help you provide your customers with lower-calorie options.

For more information, or fee-for-service help with food technical and processing issues and needs, please contact Dr. John Michaelides at John Michaelides & Associates at 519-743-8956, or at Bioenterprise 519-821-2960 ext. 226, or by e-mail at j.jmichaelides@gmail.com. Bioenterprise is a company of experienced professionals that coach and mentor emerging agri-technology companies from planning to startup to profitability and beyond.