Bulking and Fat-Replacing Agents - Sweeteners: Nutritional Aspects, Applications, and Production Technology - page 404

presumably longer amylose molecules, reducing the tendency for turbidity and structural deforma-
tion (Roller 1996). This starch has additional properties that include the creation of thermorevers-
ible gels that are pH stable (pH 3-7) with a plastic and shortening-like texture, fairly resistant to
shearing and heating (Fuentes-Zaragoza et al. 2010). As such, maltodextrins can be used in a variety
of products. The resulting texture of potato maltodextrins suits them ideally with applications in
baking goods such as cakes, mufins, and cookies, where they increase dough viscosity and improve
aeration. Furthermore, low-DE maltodextrins enhance the emulsiication capacity, thus stabilizing
water-in-oil emulsion, which makes them suitable in such applications as low-fat cheeses, spreads,
soups, and salad dressings (Marchal et al. 1999).
13.5 pOLYDeXtrOSe
Market trends for low-energy dense foods have led to the discovery and development of sev-
eral high-intensity sweeteners, as depicted in Table 13.1. By the rule of thumb, these products can
replace the sweetness of sucrose; however, due to their sweetness intensity, their use is restricted to
low concentrations, which ultimately means that the bulk of sugar requires additional replacement.
Therefore, the need for bulking agents with physical properties equal to sucrose but substantially
reduced energy content arose. Early bulking agents were usually insoluble ibers such as cellulose
powders or high-viscosity food hydrocolloids, which often detrimentally affected the sensory per-
ception by promoting a gritty texture or a gummy mouthfeel. By design, PD was developed to be
functionally superior to these products. It is highly soluble in water, with low solution viscosity, very
low taste intensity, and low digestibility, with almost absent or minimal adverse gastrointestinal
effects at high levels of use (Auerbach et al. 2007). Therefore, PD is an ingredient designed to be
the ultimate companion ingredient to high-intensity sweeteners. The key characteristic of PD, with
regard to its bulking performance, is its energy value of 4.1 kJ/g. This attribute, in combination with
the excellent solubility in aqueous systems, makes it almost irreplaceable in the development and
processing of low-energy foods. As a sucrose or fat replacer, PD contributes only 25% or 11% of the
energy content of the sucrose or fat, respectively (Shah et al. 2010).
The invention of PD was not accidental, but the result of a targeted research by scientists at
Pizer in 1970, in an attempt to develop a low-energy bulking agent. The objective was to develop an
ingredient that could be used in conjunction with intense sweeteners when replacing fully digestible
and, thus, energy dense carbohydrates in processed foods, and its production has been patented. PD
is a highly branched, low-molecular-weight, randomly bonded polysaccharide composed of glucose
units. An average DP is approximately 12 glucose units (Auerbach et al. 2007). As described in the
patent, it is prepared commercially by the vacuum bulk polycondensation of a molten mixture of
food-grade ingredients in an appropriate proportion. These ingredients are glucose, sorbitol as a
plasticizer, and either citric or phosphoric acid as a catalyst, mixed in approximately 89:10:1 propor-
tion. The resulting product is a mixture of different polymers with various types of glucosidic bonds
in the structure (α-1,6 bonds predominate), which are weakly acidic and water soluble. The mixture
usually contains minor amounts of sorbitol and citric or phosphoric acid. The theoretical chemical
structure of PD is illustrated in Figure 13.1. The R group may be hydrogen, glucose, or a continu-
ation of the PD polymer. As evidenced by this representative structure, PD is a very complex mol-
ecule, more highly branched than other carbohydrates, such as amylopectin, which contains mainly
α-1,4 linkages, with about 4%-5% of α-1,6 linkages as branch points. The structural compactness
and complexity of PD prevents digestive enzymes from readily hydrolyzing the molecule, resulting
in reduced energy content (Figure 13.2).
PDs are often regarded as ROs, which escape the hydrolytic activity of human digestive enzymes
and reach the lower intestine. It has been accepted in several countries that ROs are actually fer-
mented in the large intestine. On the other hand, resistant polysaccharides (RPs) are also resistant