Choosing an Alternative Sweetener

With obesity and overweight problems reaching epidemic proportions worldwide, the good news is that more and more consumers are choosing foods that promote wellness. They want to feel good, vibrant, and invigorated throughout their lives. At the same time, they don’t want to give up flavor and texture, which raises the challenge of developing food products that fit into an active, health-oriented life-style. This challenge extends to alternative sweeteners to sugar, which not only must help ensure enjoyable taste but also must contribute significantly to a food’s nutritive value as part of a healthy diet.

We’ve all heard of low-carb diets. Typically, these diets are focused on restricting simple carbohydrate (primarily sugar) intake. In this way, blood sugar (glucose) and insulin levels are maintained, which is termed low glycemic.

The World Health Organization (Geneva) and the Food and Agriculture Organization of the United Nations (New York City) have stressed the importance of a low-glycemic diet since 1997. In addition, research studies of the scientific evidence related to the glycemic effect of carbohydrates and its role in chronic Western diseases suggests that a low-glycemic diet may lead not only to improved blood glucose control but also to lower insulin levels, a reduced insulin demand, and reduced blood lipid levels. Moreover, long-term consumption of a diet based on low-glycemic foods may not only be useful for weight control, but may also make an important contribution to the prevention of Western diseases like obesity, coronary heart disease, and diabetes.

From a physiological standpoint, carbohydrates may be defined in terms of their digestibility, which in turn describes their impact on blood glucose levels.

• Carbohydrates that are hydrolyzed and absorbed in the small intestine, then metabolized by the human body-these include the sugars glucose, fructose, and sucrose, as well as cooked starches.
• Carbohydrates that are not fully hydrolyzed and metabolized-lactitol, maltitol, isomalt, sorbitol, and xylitol.
• Carbohydrates that are absorbed but not metabolized and excreted via urine-erythritol and mannitol.
• Carbohydrates that pass through the small intestine unchanged and are fermented totally or partially by the gut bacteria-polydextrose, pectin, fructose-oligosaccharides, inulin, and resistant starch.

Consequently, carbohydrates that are easily digested, including glucose and other simple sugars, will have a relatively high impact on blood glucose levels. On the other hand, carbohydrates that are low- or nondigestible will have a lower impact on blood glucose levels. This group includes a number of polyols (sugar alcohols) that are used as sugar replacers, including lactitol, isomalt, sorbitol, xylitol, erythritol, and mannitol.

Therefore, one way to evaluate an alternative sweetener is to gauge the impact of its glycemic effect on a food’s overall glycemic response-an important consideration given that there is a growing body of research showing that a low-glycemic diet can provide significant health benefits to the consumer.

START WITH GLYCEMIC INDEX

Glycemic index (GI) is a mathematical calculation that measures the effect of a carbohydrate on a person’s blood sugar (glucose) level. Over the past 20 years, GI values have been determined for a large number of foods, and commercial GI testing has been conducted by a number of laboratories worldwide. In addition, the second edition of the “International Tables of Glycemic Index,” published by a research team led by Janette Brand-Miller of the Sydney University Glycemic Index Research Service (SUGiRS) in Australia, covered approximately 1300 different foods.

At SUGiRS, glycemic index is measured against glucose, which corresponds to a reference value of 100. Foods can generally be classified according to their GI value as high (70–100), moderate (56–69), low (41–55), and very low (maximum of 40). According to SUGiRS, the GI values of several types of sugar are 68 for saccharose, 46 for lactose, and 20 for fructose. In addition, the sucrose substitute maltose is rated even higher than glucose, at 105.

A study conducted by SUGiRS on the sugar replacer isomalt, with glucose as the reference, indicated a GI value of 2 (±1%). Furthermore, its report on isomalt concluded the following: “Results from previous studies performed by SUGiRS, in which GI values of jams, biscuits, and confectionery containing various sweeteners have been measured, indicate that the relatively low glycemic effect of isomalt would still be apparent if it was used in place, for instance, of sucrose or glucose syrups in real foods. The reduction of the food’s GI value would depend on the amount of isomalt used and the glycemic effect of its other ingredients.” In other words, the glycemic response of a food may be significantly directed toward low-glycemic by replacing sugars and/or easily digestible starches by replacers like polyols or fibers.

This conclusion was reinforced in 2003, when equal amounts of traditional and sugar-free products from the German food manufacturer Schneekoppe (Seevtal, Germany) were compared for GI values.

• The GI of a jam made with fructose was determined to have a very low GI of 35, compared with a higher value of 59 for its sugar-based counterpart.
• The GI of a candy made with a combination of lactitol and polydextrose was determined to be a very low 5, compared with a higher value of 62 for a sugar-based candy.
• The GI of a chocolate made with maltitol and fructose was determined to be a very low 37, compared with a higher value of 56 for a sugar-based chocolate.

As has been described, by using polyols as an alternative sweetener to replace sugars and other ingredients with higher blood glucose effects, a significant reduction of the glycemic effect of the final food can be achieved.