Structure and Function of Food Hydrocolloids
With all of the choices of hydrocolloids in food applications, it is easy to see why a little explanation is helpful. When looking for gelation, alginates, carrageenan, pectin, agar, xanthan gum and gellan gum are the right choices. For synergistic gelation, developers should consider pectin plus alginate (H+), kappa carrageenan plus LBG, xanthan plus LBG or guar gum. If viscosity addition is required, pectin, alginates, locust bean gum, guar gum, carrageenan, xanthan gum, carboxymethylcellulose (CMC), hydroxypropyl methyl cellulose (HPMC) or starches can do the trick.
The functionality of these compounds is dependent on molecular weight, explained Tracy Mosteller, team leader--frozen desserts and beverages, of Danisco USA Inc., during a presentation titled, “Structure and Function of Food Hydrocolloids,” at the 2008 Prepared Foods’ R&D Application Seminar-East. She noted that when dispersed in water, the long chains unfold to form open, flexible, random coils. With increased concentration, the polysaccharide chains intertwine and entangle. The longer the molecule and more extended its conformation, the greater degree of entanglement, which means stronger interaction and higher viscosity. Conversely, a lower molecular weight molecule will have lower viscosity, due to less entanglement and weaker interactions.
LBG and guar gums are both non-ionic hydrocolloids, but they have different characteristics, notes Mosteller. LBG is scarcely branched, while guar is highly branched. Guar is cold-soluble with a long, “slimy” texture, and LBG needs heat to hydrate and has a short, creamy texture. LBG provides synergy to kappa carrageenan and xanthan, while guar is synergistic with xanthan gum. The pH compatibility of the hydrocolloid to the food system should be considered. Each hydrocolloid has an optimum pH range. LBG and guar gum have an optimum pH range of 4-10. Carrageenan is a sulfated polysaccharide derived from red seaweed. It can be primarily used in neutral pH applications and is reactive with milk and other proteins. Kappa carrageenan produces rigid, high-strength gels that are thermally reversible, with the highest degree of milk reactivity [This is defined as a gum’s ability to produce significantly higher viscosity in milk than in water.--Eds.]. Iota carrageenan produces elastic gels, is thermally reversible, has a high salt tolerance, is thixotropic, and produces gels with calcium and low milk reactivity. Lambda carrageenan is non-gelling, as its structure prevents helix formation, and it forms high water viscosities with little or no milk reactivity. Applications for carrageenan include meats, gelled desserts and drinkable jellies; and dairy systems like chocolate milk and other beverages, ice cream, process cheese, culture products, puddings and aerated desserts.
Xanthan gum is a cold water-soluble, viscoelastic hydrocolloid with a high viscosity at low concentrations and a high degree of pseudoplasticity, Mosteller went on to explain. Xanthan is stable under various ionic strengths, heat, a pH range of 1-13, shear, enzymes and salts. It is freeze/thaw stable, and compatible and synergistic with other stabilizers. Xanthan gum has a neutral taste, is easy to use and makes food mixes easier to process during sheeting, pumping, emulsifying, filling, whipping and extruding. In baked goods, it suspends particles, increases volume and reinforces the gluten network. In sauces and dressings, it prevents creaming-off, suspends particles and improves texture. Texture is improved in dairy products, beverages and fruit preparations through use of xanthan gum. “Xanthan gum is the most effective hydrocolloid for dispersing particulates for a long shelflife,” Mosteller offered.
Pectin is derived from citrus peel and apple pomace. It is a polygalacturonic acid chain, partly esterified with methyl ester groups, interrupted by neutral sugar areas. There are both low- and high-methoxyl pectins, with the high-ester pectins providing stability to beverages and acidified milk drinks, medium-rapid or slow-set to jams, and extra-slow set for confectionery jellies. With so many choices, finding the right hydrocolloids can sometimes be tricky.
“Structure and Function of Food Hydrocolloids,” Tracy M. Mosteller, team leader-Frozen Desserts & Beverage, Danisco USA Inc., email@example.com
--Summary by Elizabeth Mannie, Contributing Editor
Fiber Combinations as Nutritional Stabilizers
Nutritionists agree that recommended dietary fiber intake should be 25-30g/day. A balanced combination of soluble and insoluble fiber is also optional. Fiber consumption has decreased to 10-20g/day in many Western countries, and it is closer to 11g/day in the U.S., according to the American Dietetic Association. Yet, there appears to be a strong understanding by consumers of a link between fiber and overall health, as indicated by reports from the International Food Information Council. Some 78% of Americans believe fibers are healthful, and 73% are trying to increase fiber consumption.
One proprietary ingredient that combines acacia fiber (a soluble fiber) with wheat fiber (an insoluble fiber) applies a technical innovation for a unique fiber. It is different from a simple, dry blend, because the insoluble fiber particles are uniformly encapsulated into the soluble fiber matrix. The innovative fiber combination is manufactured using a proprietary, state-of-the-art, co-drying technology, explained Sebastien Baray, technical manager, Colloides Naturels Inc., during a presentation titled, “Optimized Combinations of Fibers Used as Nutritional Stabilizers,” at Prepared Foods’ R&D Applications Seminar-East.
Cold water-dispersible, this fiber develops its viscosity immediately after dissolution in water. In order to develop its unique, smooth texture, it requires no heating or shearing for activation.
More than 80 in vitro and in vivo clinical studies support the nutritional properties of acacia gum. Acacia gum is highly tolerated and has prebiotic properties, a positive impact on glycemic index, improved gut transit function and antioxidant properties. It is all-natural and GMO-free, with no chemical or enzymatic modification.
Wheat fiber’s mechanical action increases transit speed through the digestive system, improving regularity. This wheat fiber is also all-natural, GMO-free and gluten-free.
Functions of the ingredient include thickening, stabilizing, water-binding, replacing fat and enhancing mouthfeel. The main applications are as a fat replacer and for freeze/thaw stability in bakery; as a fat and sugar replacer in ice cream; as a fat reducer, egg replacer and mouthfeel enhancer in sauces and mayonnaise; and as a texturizer in confectionery products.
In muffins, 50% of the fat was replaced with 1 or 2% of the innovative fiber ingredient. Taste panels found it similar to control over a 10-day shelflife. In light mayonnaise, substitution of the egg yolks with 4% of this innovative fiber ingredient provided a smooth, creamy texture, lowered cholesterol, and addressed vegan and egg allergy concerns. In pepper sauce, 5% of the innovative fiber ingredient replaces 50% of the fat, providing high viscosity, comparable taste and improved freeze/thaw stability.
Ice cream does well with a partial fat replacement (11% vs. 20% cream), with an added 1.7% innovative fiber. There are no differences in viscosity, whipping, freezing or molding. Panels found no difference in color, taste or texture. There was a slightly lower melt point.
“Optimized Combinations of Fibers Used as Nutritional Stabilizers,” Sebastien Baray, technical manager, Colloides Naturels Inc., firstname.lastname@example.org
--Summary by Elizabeth Mannie, Contributing Editor
Modified Starch 101
Modified starches are products whose properties have been altered by physical or chemical means, but whose granular and molecular structure may be more or less retained. FDA regulations for modified starch can be found in 21 CFR 172.892.
Eric Shinsato, technical sales support manager, Corn Products U.S., discussed different types of modified cornstarch, their functions and applications in a presentation titled, “Modified Starch 101.” Starch modification can impart stability under low pH, high temperature, extended processing time, shear and storage conditions ranging from frozen to shelf-stable. Selected functional characteristics can be imparted, such as altered viscosity, timing of viscosity development during processing and aesthetic properties, including texture and clarity. Specific attributes, like emulsification and encapsulation properties, may also be imparted.
Acid thinning is one way to modify starch. The hot viscosity of such cornstarch is reduced after acid hydrolyzes (i.e., “cuts”) the starch’s molecular structure, thus weakening the starch granule. This results in reduced viscosity, allowing the starch to be used at higher concentrations while still maintaining its gelling characteristics, said Shinsato.
Other types of starch modification include oxidation with sodium hypochlorite and dextrinization. Dextrins are created when starch is heated in the presence of acid and a small amount of water, broken into hydrolyzed fragments, then repolymerized into dextrins of varying degrees of solubility.
Applications for acid-thinned, oxidized starch and dextrins include coatings and glazes, jelled confectionery, paper and corrugating. These starches function to impart crispness, lower hot viscosity at high concentrations and adhesive properties, respectively, offers Shinsato.
Cross-linking starch increases starch granule stability after gelatinization. The initial viscosity is decreased, and the final viscosity is improved under acid, heat and shear conditions. Paste rheology may be altered from cohesive to short texture. Applications for cross-linked starches include emulsified products like salad dressings; aseptic or pasteurized dairy products like yogurt, cheese sauces and puddings; retorted canned sauces, gravies and soups; and low-pH products like pie fillings and barbecue sauce.
Substitution as a means of starch modification increases water-holding capacity, improving freeze/thaw and cold storage stability. Substitution decreases retrogradation and increases paste clarity, lowers starch gelatinization temperature, improves ease of cooking and may impart specific functional properties. Applications for substituted starches are frozen foods, prepared meals, sauces, gravies, refrigerated foods, meat products, sauces, puddings, flavor emulsions and encapsulation.
Shinsato also explained that pregelatinized starches are cold water-hydrating, low-moisture products. They provide instant viscosity development, without additional cooking. They may have a gelled, fluid or short texture; opaque to clear appearance; stability in acid, shear and freeze/thaw conditions; and a smooth to slightly pulpy texture. Pre-gelatinized starches have applications in bakery fillings, cold process salad dressings and mayonnaise, dry mix soups, sauces and gravies.
Cold-water swelling starches are granular instant starches that swell in cold systems to develop viscosity. They may be produced by cooking and spray-drying, or by slurrying starch in alcohol and subjecting it to high temperature and pressure. The goal is to achieve uniform, intact swollen granules. The benefit is a very smooth, textured product similar to one that has used a cook-up starch.
“Modified Starch 101,” Eric Shinsato, technical sales support manager, Corn Products U.S., email@example.com
--Summary by Elizabeth Mannie, Contributing Editor
Innovative Stabilizers for Beverages
Gum Arabic, used as a stabilizer for beverages for many years, comes from the Acacia tree, grown in the gum belt of the sub-Saharan Africa region. Gum Arabic is a highly branched arabino-galactan-protein complex. Concerns on the global gum Arabic market include political instability in the major growing countries. The plant is also sensitive to climatic changes and insect attacks, affecting yield, supply and quality. Irregularity of supply has caused wide fluctuations in price. “More resources are needed to assure the quality of incoming material,” explained Wen Shieh, technical manager, fruit, beverage and confection, Cargill Texturizing Solutions, during a speech titled, “Innovative Stabilizer for Flavor Beverage Emulsion and Beverage Cloud.”
The main applications of gum Arabic in foods are as an emulsifier for beverages and flavor emulsions. It also provides good adhesive properties in confections, pan coatings, snack foods and icings/frostings for baked goods. Alternatives used include modified food starch, sugar beet pectin and whey protein isolate. However, sugar beet pectin is costly, and whey protein introduces allergens and has stability issues.
A modified starch that provides a good replacement for gum Arabic in beverage applications is made by substitution with n-octenyl succinic anhydride (n-OSA), said Shieh. This modified starch is based on the natural and renewable raw material, waxy cornstarch. This raw material offers consistent quality, supply and price stability, while providing a similar functionality as gum Arabic. N-OSA is approved for use by 3% of n-OSA treatment. Additional modifications allowed in combination with n-OSA substitution include acid thinning, enzymatic thinning, dextrinization and pregelatinization.
Shieh noted that beverage emulsion stability is affected by emulsifier-to-oil ratio. Water quality also plays a part in stability. Alkalinity affects flavor and reduces emulsion stability. Hardness or high mineral content (calcium and magnesium) reduces emulsion stability, especially in finished beverages. Emulsions, which are thermodynamically unstable, can either exhibit flocculation, aggregates of particles or coalescence. Emulsions can also break into oil and water, or exhibit creaming, when the emulsion is not properly formulated and processed.
The emulsifying performance of traditional n-OSA starch, gum Arabic and a new and improved n-OSA starch was established by the preparation of weighted orange oil in water emulsions, stabilized with either gum Arabic or one of the n-OSA starches. Rheological parameters, such as storage modulus (G’) and loss modulus (G”), and particle size distribution of the emulsion, were measured initially and at extended refrigerated storage conditions.
When preparing emulsions for beverages, preservatives, colorings, starch and acid were dissolved in water. The weighing agent was dissolved in flavor oil. Then these two components were mixed to form a pre-emulsion. The mix was then homogenized.
Results showed that the new, improved n-OSA starch had the most effective emulsification and stabilizing properties, with the smallest particle sizes compared to the other stabilizers, offered Shieh. Additionally, there was no gelation after 100 days of cold storage or 300 days of room temperature storage, when compared with gum Arabic, which showed significant coalescence after 50 days.
“Innovative Stabilizer for Flavor Beverage Emulsion and Beverage Cloud,” Wen Shieh, technical manager, fruit, beverage and confection, Cargill Texturizing Solutions, firstname.lastname@example.org
--Summary by Elizabeth Mannie, Contributing Editor
Understanding how food ingredients can assist with product formulations requires knowledge of both ingredient characteristics and applied food science. Prepared Foods,I> is now open for both speaker and attendee registration for its R&D Applications Seminar-Chicago on October 19-21, 2009, in Itasca, Ill. For more information, see www.PreparedFoods.com/rd.