Title: Alternative Sweeteners

524 Deis
binding water, thus providing lubrication, slipperiness, body, and mouth-feel.
Carbohydrate adjustments can positively (or negatively) influence shelf-life,
freezing characteristics, and mouth-feel by affecting the physical state of the final
product (Fig. 2). Processing parameters such as pH, temperature, shear, and compatibility
with other ingredients, as well as the rheological character of the carbohydrate,
must be considered. Guar, locust bean, and xanthan gums are effective
thickeners across a number of food categories (15, 16). Pectins can form soft to
hard gels and are widely used in jams, jellies, and tomato-based products. Alginates
and carrageenans are commonly used in ice-creams, puddings, fruit gels,
and salad dressings. Most gums, depending on form and/or processing conditions,
can be used as gelling agents or thickeners.
Gellan gum, approved as a food additive in 1990, is produced by Sphingomonas
elodea (known earlier as Pseudomonas elodea). Gellan exists in two
forms—a native, acylated form and a deacylated form. Both forms have a glucose,
glucuronic acid, rhamnose backbone (2:1:1), forming a linear tetrasaccharide
repeating unit. The acylated from provides elastic gels; the deacylated form
provides a more brittle gel. Gellan is compatible with a number of other gums
(xanthan, locust bean), starches, and gelatin to manipulate the type of gel, elasticity,
and stability and can form strong brittle films exhibiting oil and moisture
barrier properties.
Fiber should always be considered for fat replacement and as a replacement
for flour and other caloric ingredients (17). ‘‘Dietary fiber’’ as a classification
encompasses a wide range of fiber sources that vary in their physical properties.
Two subclasses are recognized—soluble and insoluble—which are very different
in chemistry and physiological effects. Insoluble dietary fibers, the predominant
class, are insoluble in aqueous enzyme solution. About two thirds to three fourths
of the dietary fiber in a typical diet is insoluble. Soluble dietary fiber is soluble
in an aqueous enzyme system but can be precipitated with 4 parts of ethanol to
1 part of the aqueous mixture. Certain nonabsorbable, nondigestible saccharides
are not precipitated in alcohol, and so are not counted as soluble fiber in the
current method, even though they contribute to physiological functions and may
be beneficial to health. These include insoluble resistant starch, polydextrose,
Fibersol-2, fructooligosaccharides, inulin, polyols, and d-tagatose. At this point,
these products cannot be claimed in total dietary fiber (TDF), but work is underway
to change this.
Cellulose is the most abundant source of insoluble dietary fiber, as well as
the most abundant carbohydrate in nature, making up a significant part of the
mass of a plant. Cellulose is a linear polymer of beta-1,4-linked d-glucose undigestible
by the human gastrointestinal tract (in contrast, the alpha-1,4-linked glucose
in starch is highly digestible). Sources are predominantly plant cell walls—
foods high in insoluble fiber are whole grains, cereals, seeds, and skins from fruits
and vegetables. Cellulose is available in a number of forms—from mechani-