Polydextrose has an accepted caloric value of 1.0 kcal per gram and works very well with the lower-MW polyols, contributing vis-cosity without adding calories. Polydextrose is hygroscopic and can easily pick up moisture. This is a great property for controlling wa-ter activity and shelf-life in certain applications, such as meal and snack bars, and fudge. But, in something like hard candy, this water-loving property could be counterproductive by increasing stickiness and limiting shelf life. Knowing the requirements of the application will help the product developer understand where this ingredient can provide the most benefit for a finished candy.
Inulin defines a group of low-digestible carbohydrates found naturally in many sources, such as agave, onions, bananas, asparagus, garlic and Jerusalem root, although commercial sources are primarily produced from chicory root and agave. It is self-affirmed GRAS and has a caloric value between 1.0 and 1.2 kcal per gram. Inulin is composed of fructose molecules linked together, ending with a glu-cose molecule, to form polymers of various lengths—ranging anywhere between 2 and 70 units long. When the polymers are broken down to the point where they range from 2 to 10 units in length, they are referred to as fructooligosaccharides (FOS). They can also be built up from sucrose, as in the case of short-chain fructooligosaccharides (scFOS). Typically, the smaller the polymers, the more solu-ble and sweet they become. Also, depending upon the source, inulin can be either highly branched (as in agave) or linear. As a result, the more branched the polymers, the more soluble they will become (up to 230.0 grams in 100.0 grams of water)—but still offering slightly less viscosity than linear polymers.
Resistant maltodextrin is metabolized dramatically slower than traditional maltodextrins, reducing its effect on elevating blood glu-cose levels. Although scientific data indicates resistant maltodextrin ranges from 1.0 to 1.5 kcal per gram, in the United States it is still considered 4.0 kcal per gram. The molecules of resistant maltodextrin are typically large in size and highly branched. This allows them to be very soluble while contributing viscosity comparable to that of traditional maltodextrin in applications like meal and snack bars, as well as hard and soft confectionery.
A sweet boost
Most of these bulking agents are less sweet, some considerably less, than sucrose. In most cases, the product designer must consider adding one or more high-potency sweeteners (HPS) to supplement the loss of sweetness.
In the past decade, formulators have gotten creative in their use of combinations of approved nonnutritive sweeteners and sweetness enhancers. Although many types of HPS exist, only a few are approved for use as a sole source of sweetness in the United States: sac-charine, sucralose, acesulfame K, aspartame, neotame and rebaudioside A. Of these, the HPS most often used in the confectionery indus-try are aspartame, acesulfame K and sucralose due to cost and ingredient synergy. Neotame has been used primarily in pressed mints and chewing gum. Acesulfame K is heat-stable and has an early sweetness onset, which combines well with the lingering sweetness of aspar-tame and sucralose. Aspartame has limited stability to heat and acidity, so it is usually added late in a process or at elevated levels. An example of this would be in hard candies, where aspartame is added post-cook, prior to the cooling table.