Biomedical Engineering Reference
In-Depth Information
Polyglycerol Esters
These are generally prepared by polymerization of glycerol under alkaline conditions
at elevated temperatures (approximately 230°C)
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by direct esterification of the
polyol with selected free fatty acids. PGEs can also be made by interesterification
of the polyol in the presence of an alkaline catalyst. In general, PGEs contain from
two to ten glycerol moieties in length and are used in many food applications. To
obtain the desired physical characteristics and functional properties, the polymer-
ization and esterification reactions are carefully controlled and the final product can
provide a broad range of HLB values.
PGEs are multifunctional, a property that allows them to be used as fat substitutes
as well as emulsifiers. For example, they are used as surfactants in whipped toppings
and frozen desserts, as anti-bloom agents in confectioneries, as anti-spattering agents
in cooking oils, as flavor dispersants and stabilizers in beverages, as texture enhancers
in prepared cake mixes, and as binders of ingredients and lubricants in extruded snacks.
When used in liquid salad dressings, PGE can prevent oil and water separation, make
products creamy, and aid color and flavor dispersion. They also aid in getting oil-based
flavors into solution in oil-based mixes and often allow mixing of incompatible ingre-
dients in hard to emulsify mixes.
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PGEs (mainly di-, tri-, and tetraglycerols) are used
in aerated foods containing fat, such as cakes and sponges. PGEs impart excellent
properties to cake batter by increasing the cake volume and uniform structure when
used in cake margarine in combinations with distilled MG. Triglycerol monostearate
(4G1S), for example, can be used as a whipping agent and as an aerator in non-aqueous
lipid systems. In this capacity it reduces costs by eliminating the need for egg whites
and vegetable protein as foaming agents, eliminates an extra processing step, and
enhances shelf stability since no water is required for functionality. By aerating readily
in either batch or continuous automatic whipping equipment, 4G1S sets rapidly after
whipping, which allows product extrusion through various shaped dies.
Octaglycerol monooleate (8G1O) and octaglycerol monostearate (8G1S) are also
commercially available as emulsifiers. 8G1O is used as a viscosity reducer in high
protein systems, as an emulsion stabilizer, and as a beverage clouding agent. It is
also used in imitation cheese products to retard oiling-off or separation of fat and
casein, and to improve the melt-down characteristics of the finished cheese with a
dramatic reduction in the viscosity of the product. In ice cream toppings, 8G1O can
be used to provide emulsion stability and improve gloss. 8G1O can also be used to
reduce the cholesterol content of casein, which would make the product useful as
an ingredient in imitation meats, cheeses, and other dairy products. In food analogs,
such as imitation bacon, 8G1O can be used to prevent the vegetable oils from
separating during storage and to improve the texture of the product. 8G1S is used
as a whipping agent, and an emulsion and freeze-thaw stabilizer. In pet foods, 8G1S
can be used to produce a glossy, moist appearance, which makes the product more
appealing. Both products, 8G1O and 8G1S, can be used as polysorbate replacers.
They are also used to disperse flavors and colors into aqueous systems as they are
relatively free of any flavor character note.
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A new line of PGEs bland in taste, mild color, and with excellent melt color
have become commercially available. These compounds range in appearance from
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