and Its Derivatives
September 1997 -- Applications
By: Ronald C. Deis, Ph.D.
While many new types of products were introduced to accelerate sales, time-tested, but hard-to-change methods produce many favorite candies. Confectionery is still largely an art; most changes in ingredient technology accommodate the need to increase line speed. Starch and its derivatives comprise an integral part of this, controlling the effects of moisture migration during processing and shelf life.
Gelled candies. These include jellies, gummy bears, licorice, gum drops, jelly beans and pastilles. Products in this category contain a gelatinizing agent, such as starch, gelatin, pectin or gum arabic.
Caramels, fudge and toffees. These are boiled confections, grained or non-grained.
Within confections, starch and its derivatives see use in a broad range of functionalities, including use as: sweeteners, texture stabilizers, gelling agents, crystallization inhibitors, thickening agents, film formers, dusting agents, glazing agents, adhesives, flow agents, moulding agents, and foam stabilizers.
Setting the stage
Within these granules are two distinct molecular types of starch, amylose and amylopectin - polymers of glucose. Amylose is a linear polysaccharide composed of up to 10,000 glucose residues connected by alpha-1,4 glucosidic bonds. Amylopectin is a larger, extremely branched molecule with short alpha-1,4 linked chains connected by alpha-1,6 glucosidic bonds.
Modified cook-up starches. These are produced by chemically modifying starch by thin-boiling; cross-linking for acid shear and heat stability; and/or further modification (esterification or etherification) for control of retrogradation.
Down to the basics
To produce any of the range of hydrolysate products, a starch suspension is treated with acids and/or enzymes to reduce molecular weight. By varying the extent of conversion and the degree of acid (random cleavage of glucosidic bonds) or enzyme (more controlled cleavage) hydrolysis, a wide range of products can be produced. These are commonly differentiated by dextrose equivalent (DE), defined as the percentage of reducing sugar calculated as dextrose on a dry weight basis.
More than sweet things
An extremely important ingredient in candies, corn syrup assumes a much broader role than mere "sweetener." Corn syrup controls crystallization of sucrose-inhibiting "graining," moisture retention, viscosity development, browning inhibition, and microbial spoilage.
Technically, corn syrups and their dried forms, corn syrup solids, can be found in a DE range of 20 to 95. The lower the DE, the lower the hygroscopicity, but also the higher the viscosity. The lower-DE syrups can prove difficult to handle, but they may be effective in decreasing moisture pickup or development of stickiness in candies. Corn syrups as low as 36 DE are commonly found in the industry.
High-maltose syrup is used to some degree, because it contains a minimum amount of dextrose. This translates into increased color stability by reducing browning, and a lowered hygroscopicity in hard candies.
In gums and jellies, corn syrup may contribute 35% to 100% of the sweetener solids. Marshmallows may contain 35% to 80% of the sweetener as corn syrup (while fondants, creams, and fudges contain 10% to 40%). Blends of corn syrups and sucrose, dextrose, invert or HFCS are common, available from ingredient suppliers or mixed in-plant.
Moulding, not moldy
The use of moulding starches is well-known, and not much has changed over the years. Manufacturers use moulding starches as a medium to form deposit-candy impressions in starch trays. Utilized for many years, this process takes the name "Mogul process." In general, the process consists of a tray destacker, which places finished deposit products - jellies, for example - on a chain-driven tray conveyor. Trays are emptied, and product is separated from starch. Empty trays are re-filled with conditioned starch, smoothed, then stamped with plaster stamps. A piston depositing system delivers molten candy into the moulds. The trays are stacked, then the product is staged to a drying room. After drying, the product separated from starch is finished (sugar-sanded, oiled, etc.), then packaged.
The identity of moulding starch is simple: it typically consists of an unmodified common corn starch, supplemented with a white mineral oil or high-stability vegetable oil. Mineral oil sees the widest use, due to its stability; up to 0.30% may be used, but 0.05% to 0.10% is most common. No-oil varieties also have become available due to demand.
Since the starch is re-used, it must be "conditioned" - sifted to remove candy pieces and starch agglomerates; dried to the proper moisture for the product to be moulded; cooled to 90° to 160(F; and properly buffered because many fruit candies are acidic. Starch moisture and temperature ranges are recommended for each candy type so the rate of moisture migration out of the product can be controlled. For example, gums and jellies require 5% to 7% moisture starch at 120° to 160(F; cream centers require 6% to 8% moisture starch at 90° to 115(F; and soft marshmallows require 5% to 7% moisture at 90° to 100(F. Starch manufacturers can supply information for the type of product desired.
Forming a gel
Thin-boiled starches are designated further by "fluidity" - the inverse of viscosity. This means that an unmodified starch has a "zero" fluidity. Further thinning results in a "60," then a "65," "72," "75" or a "90" fluidity. As starches are acid-thinned, viscosity decreases, and gel strength decreases, but at a slower rate. A "90" fluidity starch has the lowest viscosity of the acid-thinned starches, as well as the lowest gel strength. Thin-boiling starches with lower fluidities will boil with a heavy viscosity, and produce a short texture; gel strength decreases as hydrolysis continues. Higher-fluidity starches boil thinner, but produce a more stringy texture and a weaker gel.
"For deposited jelly candies, you want a thin hot viscosity," says Moore, "followed by quick gelling properties once you get it into the mold. In the case of high amylose starch, the gelling speed and the final gel strength are related."
"With cold-water-swelling starch technology, you can develop formulations that will gel in the mould without cooking," explains Moore. "You disperse it into a liquid corn syrup - it has to be primarily high fructose - mix it cold, and there is a certain length of time where the starch doesn't have enough moisture available to gel, so you can deposit it. Then, in a short length of time it will gel. This gel varies from a classic short-textured starch candy to a more resilient gelatin-like candy."
The panning process coats candies by rotating them in a coating material in a revolving pan. Hard-coated products start with a center, such as a sugar pellet or a nut, then panned in sugar/corn syrup blends. Layers are panned on, then dried successively until enough layers are applied to reach the proper size. Color can be introduced in any layer(s). Once the last coating has been applied, the product is "polished" with a wax and/or confectioner's glaze. In certain products, such as nonpareils, dusting starch between layers prevents sticking and whitens the product. Hard coatings are applied with heat and air for drying.
Both hard- and soft-panned centers are commonly pre-coated with gum arabic, a low-viscosity, highly soluble exudate gum that serves as a binder, thickener, crystallization inhibitor, film former and emulsion stabilizer. As much as 10% to 40% gum arabic can be used as a binder in some products. Gum arabic has displayed seasonal variations in quality, availability and cost, so starch suppliers have focused on its replacement for some time. Several starch products have been developed that can be used in this application.
Starch can also help the bottom line by shortening process time. "Gum arabic can be replaced as a pre-coating on sugar-free gum," says Cerestar's Shinsato. The company has developed a product that "considerably lowers coating time, since the viscosity of this acid-thinned, hydroxypropylated tapioca starch is low, even at 50% of the total layer amount, vs. a maximum 40% concentration for gum arabic. This results in less layers required, resulting in lower coating time."
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© 1997 by Weeks Publishing Company