December 28, 2006
Using Fibers in Beverages for Functional and Health BenefitsDietary fibers long have been acknowledged as food components that are beneficial to health. Dietary fibers can be either soluble in water or insoluble. These products are not digested in the human small intestine but may be fermented in the large intestine.
Insoluble fibers increase bulk and speed passage of foods through the gastrointestinal tract. These fibers have been associated with a reduction in the risk of diverticulitis and colon cancer. Insoluble fibers include cellulose, hemicellulose, lignin, resistant starches and other macromolecules. The main commercial products are oat fiber, soy fiber, wheat fiber, cellulose fiber and resistant starch.
Soluble fibers form a gel when mixed with liquids. They have been associated with reducing the glycemic index and blood cholesterol levels. Soluble fibers include pectins, beta-glucans, polydextrose, partially hydrolyzed guar gum and other carbohydrates.
The 2005 FDA dietary guidelines have a goal of attaining 28g fiber in a 2,000-calorie diet. However, the current median intake is only 14.5g per day. This translates into a shortfall of 13.5g of fiber per day. The American Dietetic Association recommends that dietary fiber provided by mixed diets contain two-thirds to three-quarters insoluble fiber and one-third to one-quarter soluble fiber. Many leading experts in the field concur that formulating with a balance of insoluble and soluble fibers is necessary to obtain the optimal physiological benefits of both types of fibers.
Fiber in beverages can enhance total dietary fiber intake, reduce calories, add stability, increase viscosity and mouthfeel, enhance or modify flavor, and improve satiety. A number of soluble fibers currently on the market are used in beverages. The objective of this article is to demonstrate that insoluble fibers also can be used very effectively in beverages. Just like soluble fibers, not all insoluble fibers are the same, and thus not all will work universally in a beverage. The functional attributes of insoluble fibers can be manipulated during the manufacturing process of these fibers by changing the ratios of cellulose, hemicellulose and lignin. These manipulations change the amount of water the fiber will absorb, which then affects viscosity imparted when used in a beverage system. The alterations also can reduce lignin content in the fiber that, in turn, makes the fiber softer, imparting a more acceptable mouthfeel. Insoluble fibers also can be ground to different fiber lengths, again imparting different perceptions in the mouth when used in a beverage formulation.
By selecting the appropriate insoluble fiber (low water absorption, low lignin content and short in length), insoluble fibers can be used effectively in a thinner, more liquid-type beverage. Formulators can thicken smoothie-type beverages by using a fiber with higher levels of water absorption that will increase the product’s viscosity in a beneficial manner.
When used in beverages, insoluble fibers require suspension to stay in solution. In some cases, this is not an issue because the product is already thick and viscous, or the beverage is consumed immediately after preparation before settling occurs. In most liquid beverages, though, low concentrations of gellan gum and xanthan gum will need to be added to suspend the insoluble fiber particles. Carrageenan also is effective at suspending particles and works synergistically with cellulose gel/cellulose gum.
There are multiple benefits of using insoluble fibers such as oat fiber and soy fiber in beverages. They include dietary fiber enrichment, texture modification and control, calorie reduction and physiological benefits. They are available to beverage manufacturers who can carefully select insoluble fibers already on the market today.
“Using Fibers in Beverages for Functional and Health Benefits,” Melanie Dineen, SunOpta Ingredients Group, firstname.lastname@example.org, www.sunopta.com.
—Summary by Elizabeth Mannie, Contributing Ed.
Particle Suspension Using Fluid Gel TechnologyGellan gum fluid gel is a weak gel network which is highly pseudoplastic. It demonstrates elastic properties at rest but becomes as thin as liquid when disturbed. When used in beverages, it keeps healthful ingredients like large protein aggregates, fruit pulp, calcium minerals and fibers in stable suspension, says C. Ronnie Yuan, principle scientist at CP Kelco.
Adjustments do need to be made, depending upon the gel’s particular application. In coffee beverages, a buffering salt is required to bring the pH to 6.5-6.8 for best performance. Acidified protein drinks containing milk or soy protein can be stabilized further with pectin or CMC. However, these ingredients do not have sufficient properties to maintain long-term stability.
Gellan gum can be either low-acyl or high-acyl and demonstrates different characteristics accordingly. Low-acyl gellan gum requires Ca++ to form a stable fluid gel, and hydration temperatures vary from 25°C to 100°C, depending on the ions present and the use of sequestrants. The gel sets between 40°C and 25°C, and shear is required during or after gelation to form fluid gels. However, once formed, the fluid gel is more resistant to further shear or agitation. Low-acyl fluid gels also provide a lower mouthfeel viscosity than high-acyl gels.
Conversely, high-acyl gellan gum is not sensitive to ions, and no added Ca++ is required to form a fluid gel. Hydration temperatures range from 80°C to 90°C, and no sequestrants are needed. The high-acyl gel sets between 80°C and 70°C, and shear is not needed to form the gel. Once formed, the high-acyl fluid gel network will weaken with shear. Easy to disperse with mild mixing, hydration is achieved using typical juice heat treatment conditions of approximately 185°F to 190°F for 30 seconds or neutral dairy HTST/UHT process conditions.
In summary, incorporation of gellan gum fluid gel is an appropriate method for suspending proteins, minerals, fibers and vitamins in healthful beverages—thanks to its weak gel structure, highly pseudoplastic nature, flexible hydration methods and low use level requirements. The gel is also pourable, pumpable and gives a low mouthfeel viscosity. Additionally, it is compatible with many existing processes and has excellent flavor release and clarity.
“Protein Stabilization and Particle Suspension in Beverages Using Fluid Gel Technology,” C. Ronnie Yuan, CP Kelco, Ronnie.email@example.com, www.cpkelco.com.
—Summary by Elizabeth Mannie, Contributing Ed.
Stabilization and Fortification of Beverages with Acacia GumAcacia gum (also known as gum Arabic) is one of the most common and versatile food ingredients in the world. This natural gum comes from two trees in sub-Saharan Africa, the acacia senegal and the acacia seyal. The purification of acacia gum involves no chemical or enzymatic treatments: the raw exudates are processed naturally by dissolving them in water, followed by filtering, pasteurizing and spray drying.
Gum acacia has a wide range of applications in beverages. It can act as an emulsifier, enhances mouthfeel in fruit juices and teas, can serve as a protective carrier for encapsulation of vitamins or colors, helps stabilize foam in beer or polyphenols in wine, and serves as a source of soluble dietary fiber.
To ensure proper emulsification, the oil-in-water emulsions stabilized with acacia gum must be homogenized at high pressures. Typical formulations of flavor emulsion for soft drinks include essential oils and a form of ester gum in the oil phase and acacia gum, preservatives, colors and water in the aqueous phase. Overall stability is affected by both emulsification and stabilization factors.
Acacia gum’s role in enhanced mouthfeel is a function of its low viscosity. Compared to other gums (such as guar, carrageenan and locust bean), a 1% solution of acacia gum is significantly lower in viscosity. Acacia gum also imparts a roundness to match the texture brought by sucrose or fruit juice and has excellent stability at low pH values and extreme temperatures.
Acacia gum is an essential ingredient in brewing that can enhance foam stability, a key element for consumer acceptance. Foam stability is influenced by hop acids, protein, carbon dioxide, viscosity, alcohol content, presence of metal ions, as well as by a lower surface tension, which the addition of acacia gum will help achieve. Foam stabilizers are added after filtration but before bottling and pasteurization.
Acacia gum is also added to wine as a stabilizer. It should be added approximately 72 hours prior to the last filtration and/or immediately before bottling after filtration. The presence of gum acacia will help stabilize tartaric acid, protein, cupric and ferric ions; mouthfeel will be enhanced; overall astringency may be reduced; and color will be stabilized.
Gum acacia is an excellent source of soluble dietary fiber. It can be used in juices, drinks, milk and dairy products, meal substitutes, liquid breakfasts and foods for enteral nutrition. It may also function as a prebiotic. In one clinical study conducted by Cherbut, et al. in 1999, the researchers determined that acacia gum significantly increased the growth of Lactobacillus and bifidobacteria in the human intestinal tract from 10g per day. In a similar study performed by Rochat, et al. in 2001, it was shown that acacia gum has a prebiotic effect with consumption levels as low as 6g per day.
“Stabilization and Fortification of Beverages with Acacia Gum,” Sebastien Baray, Colloides Naturels Inc., firstname.lastname@example.org, www.cniworld.com.
—Summary by Rick Stier, Contributing Ed.