Thick on the Quick

APPLICATIONS

Thick on the Quick

By Donna Berry
Contributing Editor

From institutional cooks to commercialmanufacturers, ease of use and speed are two of the most important criteria whenselecting ingredients that develop viscosity in food systems. Of course,performance is imperative. Application-specific instant starches offer all ofthis and more. “For food products where heating or cooking is a necessarypart of product formulation and processing, native starches and modified cook-upstarches are, in most cases, practical and pragmatic solutions,” says Joni Simms, manager, technical services, Tate & LyleFood Ingredients, Decatur, IL. “The use of instant starches can offer bothconvenience and, often, by the elimination of an entire processing step,significant savings in time, labor, energy and equipment, as well as improvementin delicate products normally harmed by heat.”

From plant to powder

Plantsproduce starch through the photosynthesis of sugar. A wet-milling process removesthe food starches from arrowroot, corn, potato, rice, tapioca and wheat.Regardless of the source, the same basic chemical and physical considerationsapply to all plant starches prior to processing. They consist of large molecules composed of chains of glucoseunits linked together to form one of two inherently incompatible molecules: amylose and amylopectin.

Amylose is a mostly straight-chain polymer with long chains ofglucose units joined by alpha 1,4 linkages. The chains vary in length, starting with about 200 glucoseunits to more than 20,000. Amylose has a lower molecular weight than amylopectinand an extended shape.

Amylopectin consists of branched chains of 20 to 30 glucoseunits, with each amylopectin molecule containing as many as 2 million glucoseunits. The short chains are linked by some alpha 1,4 linkages and many alpha 1,6branch points. Although quite large, because of the branching, amylopectin isalso compact.

The proportion of these two polymers in any given starchgranule depends on the plant of origin, which also influences the number ofglucose units. For the most part, traditional native starch is approximately 20%to 30% amylose with the remainder amylopectin. Tapioca can be one exception;occasionally, it has lower amounts of amylose.

Plant-breeding technology has resulted in starches withvarying ratios of amylose to amylopectin. For example, the term “waxy”describes starch that is almost completely amylopectin. This takes advantage ofamylopectin’s unique functionality, as waxy starches form thick, clear pastes,but gel only at very high concentrations, such as 30%. On the other hand,standard corn starch, at 25% amylose, forms a gel at a level of 4% to 5%.High-amylose starches, which contain 50% to 70% amylose, have their own set ofunique properties: film formers, oxygen and fat barriers, ingredient binders,and quick-setting, stable gels.

Instantize to solubilize

Ordinarystarch granules are not soluble in cold water. They form an opaque suspension,which, upon heating, slowly becomes translucent as the granules swell and thesuspension transforms into a viscous solution, a process referred to asgelatinization. This process is the basis of the first type of instant starch:pregelatinized starch, or pregel.

Pregels have been manipulated so that they swell in coldwater. The most-common processing method involves heating a starch paste to itsgelatinization temperature, drying on a drum dryer and grinding the dried starchto a powder.

“Due to heat and high shear during the instantizing process,the basic starch granules are fragmented and can lose some of the qualitycharacteristics of surface gloss and smooth texture of the parent cook-upstarch,” says Simms. “Pregels work in applications requiring more-rapidhydration or room-temperature preparation, such as instant dessert mixes andsoups.”

The standard drum-drying process used to instantize starchalters granular structure. The ensuing particles are irregular with no definitesize or shape, which often results in a grainy texture in finished products. Thus, certain product formulations require more than a basicpregel.

Using advanced technology, suppliers have developed the secondbasic type of instant starch: coldwater- swelling, or cold-water-hydratingstarch. Granules remain intact and have a definite size, structure and roundedshape.

“Cold-water-swelling instant starches provide the foodmanufacturer with the properties of cook-up starches without the need to cook,” says Tom Luallen, technical director, Cargill Food &Pharma Specialties, Minneapolis. “In the manufacturing environment, thistranslates to saving time and reducing energy costs. Ideal applications includefruit filling, pastry fillings and instant mixes.”

Another application for coldwater- swelling andhot-water-dispersible instant starches is to extend shelf life and enhance thetextural properties of cakes, cookies and other sweet goods, says Dan Putnam,technical manager Grain Processing Corporation (GPC), Muscatine, IA. “This intact granule helps to increase moisture retentionand decrease product shrinkage, undesirable wet top surfaces and large air cellsor tunnels,” he says. “It also provides excellent stability for frozenproduct distribution.” Recommended usage level of this starch for cakes consumed inone to three days is 0.5% (total batch weight). For extended shelf life infrozen storage, bakers should use 0.75% to 1.00%.

GPC designs its specialty instant starch to “manage any freemoisture, as well as hydrate rapidly in cold liquids,” says Putnam. Its smoothsurface appearance and clean flavor profile “also makes it useful for buildingviscosity in soups, sauces, marinades, dressings and fruit fillings whereinstant hydration and steam table stability are required,” he notes.

Signature functionalities

Withinthe two basic instant-starch categories—pregels and cold-water-swelling —suppliersoffer numerous signature ingredients that possess different degrees offunctionalities such as gelling, thickening or fat binding. For example, instantlipophilic starches can emulsify or encapsulate fats and oils in food systems.In emulsified systems, these starches offer a cleaner ingredient label and alsocan reduce or replace more-expensive emulsifiers.

Some instant starches provide lubricity to a food system, thusmimicking fat. A cold-water-soluble modified tapioca starch from National StarchFood Innovation, Bridgewater, NJ, exhibits oil-like properties in liquid food systems. “Itfunctions as a low-viscosity mouth-feel enhancer and remains stable in solutionat low temperatures where conventional starches might gel,” says Shana Brewer,principal food scientist, at the company. She notes it can both improve the mouth-feel of reduced-sugarfruit beverages, and enhance the adhesion of sauces, providing more flavor to afinished food item.

Replacing food solids with starch is not a new way to obtain acost savings; however, doing so with instant products is becomingincreasingly popular in today’s fast-paced world. For example, National StarchFood Innovation has developed a pregelatinized potato starch with a coarsegranulation that contributes a grainy texture to applications. Adding it to formed potato products and mashed potatoesreduces the level of potato solids, providing a cost savings while maintainingthe necessary thick, creamy texture.

This pregel potato starch “also provides excellent bindingproperties in formed meat and veggie patties, absorbing excess moisture andreducing stickiness during the forming process,” says Brewer.

Another pregelatinized potato-based native starch fromNational Starch forms a firm, cuttable gel without heating in as little as twohours and delivers its full strength in less than 10 hours. It also providesmoderate to high viscosity and short, creamy textures at 1% to 3% usage levels,and gels stronger and faster in pH-neutral and refrigerated applications. “It is recommended as a structuring agent for a wide rangeof cold and hot prepared food products,” Brewer says. “It can also be usedas a partial egg replacement in cheesecakes and similar products. And withcookie dough, it reduces cookie spread and prevents surface cracking duringbaking, which enhances uniformity.”

Indeed, instant potato starch is very desirable in dessertapplications, as it is extremely stable under high heat and provides excellentviscosity. Philippe Benyair, vice president, sales and technicalservices, American Key Food Products, Closter, NJ, says of a line of instantpotato starches manufactured by the company’s partner, Emsland GmbH: “Theyexert excellent water-binding, thickening and texturizing properties to bakeryfillings. In fact, potato starch, in general, is one of the best waterbinders in the food-starch category.”

Benyair adds instant potato starch is very convenient becauseit functions in most applications, serving as a universal binding andfood-thickening agent and coating. Its good texture and moisture regulation,along with good expansion and taste regulation, allows instant potato starch tobe used as a fat replacer, as well as for many other applications in the foodindustry.

Advanced breeding techniques have enabled Avebe Group,Veendam, the Netherlands, to produce a GMO-free waxy potato starch with morethan 99% amylopectin. The line of starches combines the functionality thatpotato starch is known for with a unique twist—a short, shiny texture. Onesuch Avebe starch provides excellent baking stability and high viscosity ininstant bakery-cream applications, according to the company. The potato starchbase not only provides excellent visual appeal, but allows the taste to shinethrough since it doesn’t mask flavors. Due to its high viscosity and texture stability, a substantialreduction in dosage level of gelling agents, such as alginates, can be achieved.

Instant rice starch, too, has benefits in hydration and flavorrelease. Hydration time in an ambient condition takes about 10 minutesuntil peak viscosity is reached; this can vary depending on how muchmodification has occurred, according to Remy- Industries NV, Belgium, which usesFairfield, NJ–based A&B Ingredients to market its rice starches in theUnited States. “Our experience shows that flavor release occurs more easilywith rice starch gels compared with starches from other plant sources,” saysGil Bakal, managing director, A&B Ingredients. “In addition, rice starchis very compatible with baby foods and other minimally processed foods such asdairy desserts because of its very white color, neutral flavor, soft gelstructure and exceptional creamy texture.”

In the thick of it

One functionof instant starches is to increase viscosity to various degrees, depending onthe given application. However, not every starch is suited to every system.

For example, Tate & Lyle offers a nonchemically-modifiedcorn starch that quickly produces firm, stable, short-textured gels, even inhigh concentrations of sweeteners, and acts as a texture modifier at lower usagerates, says Simms. The company also offers an instant modified food starch thatsets slowly to a soft gel, which Simms notes provides excellent handlingcharacteristics for the manufacture of frostings, fillings, confections andsalad dressings.

In other applications, a gel is not the target; rather, thefood designer wants to bulk up the system. Simms describes a line of instantmodified food starches that provide “smoothness without graininess, as well asgood resistance to syneresis.” This includes one product that “develops highviscosity and was designed for neutral to mildly acidic foods that are processedunder mild conditions, including gravies, sauces and dairy products,” shesays.

If the desired viscosity resembles pulp, National Starchoffers a coarsely ground pregel that can replace solids in products such astomato sauces or fruit fillings, simulating the texture of the solids whileallowing the food manufacturer to reduce the amount of more costly ingredients,Brewer says. This medium-viscosity texturizer can be used in applicationsrequiring both instant thickening and pulpiness.

Instant starches can also bind or coat. For example, GPC makesa low-viscosity starch that provides excellent film-forming and adhesiveproperties, according to Putnam. He notes the starch forms a fast-drying,flavor-free, flexible film that provides a smooth, glossy coating to confectionsand baked goods. “It also functions as a strong binder for seasoning adherenceonto snacks and cereals that resists cracking and peeling,” he says.

Slowing down hydration

Instantstarches vary in how they disperse in a food system. “To prevent lumping, itis important to slow down hydration,” says Simms. “By nature, instantstarches want to hydrate as soon as water is available, and the trick is toseparate the individual starch particles from one another so that each particlecan hydrate separately from its neighbor.”

The trick is using a diluent to separate the particles, Simmsnotes. “The diluent could be a dry material such as sugar or maltodextrin thatphysically separates the particles. For optimal dispersion, we suggest fourparts other dry material to one part starch. A liquid sweetener can also be usedfor dispersion, provided that the solids are high— at least 75%—and thetemperature is not high (room temperature). Three parts syrup to one part starchis a good ratio. Oil, too, can be used as a diluent. The oil will coat thesurface of the starch granule and slow the hydration rate of the starch oncewater is introduced. With oil, we recommend three parts to two parts starch.”

Sometimes the particle size of an instant starch becomes anasset in terms of dispersion. For example, a coarsely ground pregel starch canoften disperse without any other diluent because the surface area of eachparticle is less than that of a finely ground starch.

Modification can help slow hydration. Tate & Lyle produces“a unique cold-water-swelling modified waxy corn starch that hydrates slowlyto allow ease of dispersion,” says Simms. “It is designed for neutral ormildly acidic food systems. No diluent is needed to slow hydration. The starch binds the water in the food system, providingexcellent moisture-management properties, as well as a smooth, creamy texture anda high degree of surface sheen.”

Increasing particle size through agglomeration is anotheroption to delay hydration and viscosity development. “Agglomeration allows for proper dispersion, eliminatesdusting and improves flow properties,” says Brewer. “Agglomerated instantstarches are commonly used to prevent lumping when a limited amount of dryingredients are available to preblend with the starch or when mixingcapabilities are limited.”

Functionality also depends on the base starch prior toinstantizing. “Stability is generally dependent on the modification type and level on the base starch prior toinstantization, but is also affected by the instantization process,” saysSimms. Given the same level of modification and starch type, granular instantstarches tend to be more stable than pregelatinized starches, she adds.

The use of a pregel or granular instant starch can impactfinal appearance of an application. “The shape and irregular edges onpregelatinized starches cause a more-grainy appearance in a high-waterapplication such as a sauce or filling,” Simms notes. “A granular instantstarch will provide a much-smoother, glossy appearance on the surface of thesefood products due to the maintained integrity of the granule during theinstantization process. The appearance is mostly due to the way the eye perceiveslight as it is reflected or refracted off the surface of the food product.”

The process parameter

As withall product-development efforts, food scientists need to factor in scale-upprocessing variables and adjust the formulation accordingly. For example, with high-shear applications, starch granules caneasily fragment if they do not have the proper process tolerance. Whenfragmented, the starch granules can no longer hold as much water as they couldbefore shear. The result is a thinner-than-expected product.

“If a starch is used that has superior shear resistance ormore process tolerance, the starch will resist breaking down when exposed tohigh shear and provide optimal functionality, such as thickening, creaminess,shelf stability, cold-temperature stability and mouth-feel,” says Brewer. National Starch designed a modified, cold-water swelling waxymaize starch, with a very clean flavor profile, creamy mouth-feel andexcellent surface sheen that can “withstand the most-shearing of processes,such as the colloid mill, and even those processes with recirculation,” shesays. “With its superior resistance to shear, more intact granules are able tohold in water over time and give an improved stability. In many cases, up to 10%less starch can be used compared to conventional starches to achieve the sameviscosity.”

Sometimes the finished-product manufacturing involves someheat and requires a low-pasting-temperature starch. “Such starches are uniquein that they are not true instants, as they must be heated to develop maximumviscosity; however, full viscosity is achieved at 120° to 140°F. This is much lower than temperatures needed for typicalcook-up starches,” says Simms. “This characteristic makes these starchesparticularly suitable for microwaveable applications. They will thicken while a high-solids filling is baking in theproduct to prevent boil-out.”

Many of today’s specialized instant starches perform likecook-up starches and provide time, labor, energy and equipment savings. With so many instant-starch choices, food-product designersshould work closely with their suppliers to identify the best option forfunctionality and convenience.

Donna Berry, president of Chicago-based Dairy & FoodCommunications, Inc., a network of professionals in business-to-businesstechnical and trade communications, has been writing about product developmentand marketing for 11 years. Prior to that, she worked for Kraft Foods in thenatural-cheese division. She has a B.S. in Food Science from the University ofIllinois in Urbana- Champaign. She can be reached at [email protected].