For many developers of dairy products, hydro-colloids are as important to a formulation as the milk. That’s because the ingredient category has the primary function of managing moisture, of which milk is about 87%. The function is alluded to in the name, where the prefix “hydro” means water and “colloid” means a gelatinous substance.
“Hydrocolloids are typically hydrophilic, high-molecular weight compounds, usually with colloidal properties,” said Jane Whittinghill, a new product development scientist with ICL Food Specialties, St. Louis. “They generally are polysaccharides, but some proteins can be considered hydrocolloids, for example, gelatin. Their primary function is thickening or gelation while secondary functions include emulsification, aeration, suspension and encapsulation.”
In dairy products, hydrocolloids most often are used to stabilize, thicken or gel the system.
“They are especially important in the stabilization of products low in fat, lower in total solids or high in fiber,” Ms. Whittinghill said.
Hydrocolloids work in combination with carbohydrate, protein and fat components, as well as processing parameters, to deliver desired texture and stability to dairy products, explained Donna Klockeman, senior principal food scientist with TIC Gums, White Marsh, Md.
“Blends of hydrocolloids can work synergistically to achieve texture and stability goals with fewer ingredients,” Ms. Klockeman said. “Further, most polysaccharide hydrocolloids contain soluble fiber and therefore can assist with fiber content claims.”
Hydrocolloids also play an important role in keeping ingredients stable in dairy product systems. This includes such identifiable pieces as nuts, fruits and such cereals as oats in yogurt, as well as vitamins, minerals and other nutrients, including fiber and protein.
“With formulating trends moving in the direction of ingredients for health and wellness, hydrocolloids are necessary to keep the inclusions in balanced suspension,” said Corrie Reilly, marketing and communications, Agropur Ingredients, La Crosse, Wis.
Economics are always a product development consideration. Hydrocolloids have proven to have a positive impact on the bottom line.
“Within the hierarchy of cost savings, manufacturers will see improved production economics as hydrocolloids present the ability to produce higher overruns or moisture levels, which can have a positive impact on yields and product output,” said Gerry Buescher, director of business development for Agropur Ingredients.
Varied functions and sources
By definition, all hydrocolloids bind water. After that, they vary in functionality and long-term performance. For example, some hydrocolloids form thermoreversible gels, where gelation occurs after the hydrocolloid dissolves in solution and is cooled. When heat is applied, the gel melts or dissolves. This is best exemplified by gelatin dessert, which melts in the mouth at body temperature. Gelation temperature and melting point varies
Other hydrocolloids form nonthermoreversible gels, also called thermally irreversible gels, and will not liquefy when heated. They may soften or shrink, which also is referred to as retrograde. In other words, the gel remains mostly intact once formed.
There are also some hydrocolloids that do not form any type of gel on their own, but will do so in the presence of other compounds. The challenge lies in finding the right balance between the different gelling characteristics. This allows for products with superior moisture retention and desirable mouthfeel and texture.
For example, xanthan gum, which is produced by microbial fermentation, is a non-gelling hydrocolloid. It hydrates rapidly in cold water to give a reliable viscosity, with a little going a long way. Its consistent water-holding ability makes it an effective tool for controlling syneresis. When used in combination with carrageenan, xanthan contributes synergistically to the formation of a thermoreversible gel, meaning that less carrageenan is required to form the gel.
Guar gum, which is obtained from plant seeds, will disperse and swell almost completely in cold water to form a highly viscous solution. Like xanthan, it is not self-gelling. It has an extremely high water-binding capacity, making it useful in cultured dairy applications where standing water is undesirable.
“Within the world of systems, there are certain hydrocolloid synergies that exist,” said Phil Rakes, senior food technologist at Agropur Ingredients. “Most notably, xanthan gum and locust bean gum are very popular. This combination can be successful in several applications and is incredibly flexible. Dependent upon ratios and application, this synergy can produce ranges in viscosity and gelling characteristics.”
In general, native starches form non-thermoreversible gels and will retrograde over time, which results in syneresis. Hence, historically chemically modified food starches have been used to bind moisture in dairy products, as modification adds stability and resistance to retrogradation and syneresis. With the trend toward cleaner labels, formulators are revisiting the use of native starches, in particular those that have been physically modified for improved functionality.
“For products promoted as clean label, synergies between hydrocolloids and other product components can be leveraged to allow for simplified ingredient lists,” Ms. Klockeman said.
Many hydrocolloids are available as 100% certified organic. Some, such as pectin and carrageenan, are approved for use in organic products.
“With the food and beverage industry trending toward cleaner labels and increased sustainability, product developers are often limited in their choices of hydrocolloids,” said Amanda Wagner, food scientist, Fiberstar Inc., River Falls, Wis. “They are unaware of other ingredients that can function as well as or better than their current hydrocolloid formulation.
“For instance, we offer an all-natural, clean label functional fiber product line derived from orange pulp that can deliver similar functionalities as hydrocolloids in dairy applications with the ability to provide a clean nutritional label. These functionalities include thickening, emulsifying stabilization, reduced syneresis and fat reduction.”
Useful and innovative applications
Beyond white milk and natural cheese, almost all dairy products may benefit from the addition of hydrocolloids. And as Ms. Whittinghill said, hydrocolloids are especially useful in the stabilization of dairy products with lower fat or solids content.
“For example, in full-fat or cream-style yogurt, fat is entrapped in the protein network and upon consumption, yields a lubricating effect on the tongue and palate, imparting a creamy sensation,” she said. “When fat is reduced or removed, there’s a change in the texture and mouthfeel. To achieve the creamy sensation associated with full-fat yogurt, gelatin is often the hydrocolloid of choice.”
This is because gelatin may absorb 5 to 10 times its weight in cold water. Specifically with yogurt, gelatin prevents whey from being expelled from the casein gel. This is because the gelatin molecules form a lattice in the casein gel during the gelling process that gets stabilized by hydrogen bonding.
“The texture of yogurt relies on the formation of casein networks induced by culture fermentation,” said Ana Maria Garavito Rojas, food chemist, Gum Technology, a business unit of Penford Food Ingredients, Tucson, Ariz. “These networks are easily broken down by shear during processing. This results in water being squeezed out, which then causes the yogurt to have a weak texture. Hydrocolloids that form gels, such as agar, pectin, and blends of locust bean gum and xanthan gum, can be particularly useful to reinforce the casein networks as well as to bind any excess water.
“The acidic nature of products such as fruit-flavored yogurt, fermented dairy and fruit beverages, and sour cream, along with the heat treatment they are subjected to, tend to cause aggregation and precipitation of milk proteins. This can result in grainy textures, separation and syneresis. High-methoxyl pectins are especially useful in these instances.”
Ms. Klockeman said, “In yogurt, sour cream and other cultured dairy products, hydrocolloids modify texture by emulsifying, thickening and gelling, in addition to controlling syneresis.”
There is a growing demand for low-fat cheese sauce, Hopeton Watson, a new product development scientist, said.
“Getting a low-fat cheese sauce to have the mouthfeel and texture of full-fat sauce is difficult,” he said. “Hydrocolloids can help to capture those specific attributes and give low-fat cheese sauces the ability to mimic the full-fat versions.”
With frozen desserts, hydrocolloids play an important role in the product at two separate junctions in its lifecycle, at both the mix and frozen stages, explained Mr. Rakes.
“With the mix, hydrocolloids aid in suspension and help to provide emulsion stability,” he said. “When the mix gets processed to a frozen state, the hydrocolloids reduce iciness, prevent a coarse texture and bind water during heat-shock cycles.”
Just like gelatin is a protein that functions similar to a polysaccharide hydrocolloid, some dairy proteins exert comparable hydrocolloid functionality. In some dairy applications, the addition of specialty dairy proteins may substitute for traditional polysaccharide hydrocolloids.
“Our highly functional dairy proteins are very compatible in frozen dessert systems for boosting nutrition and improving product quality,” said Terese O’Neill, director of sales-ingredients with Agropur Ingredients. “They are labeled simply as whey protein concentrate and can be used in conjunction with hydrocolloids or as a full alternative.”
In dairy beverages, most notably chocolate milk, carrageenan is the hydrocolloid of choice, as it provides optimal suspension of cocoa particles.
“This can be an impactful hydrocolloid for dairy beverages packaged in clear containers, as the carrageenan prevents solids from separating and settling to the bottom of the container,” said Carla Fabian, director of sales-health and wellness at Agropur Ingredients. “Manufacturers with opaque containers will be less likely to encounter this appearance issue, but there is something to say regarding consumer preference for transparency.”
Mr. Buescher added that gellan gum has become a popular beverage ingredient alternative to carrageenan, which in some circles has come under scrutiny as being an undesirable ingredient.
“Gellan gum forms an adjustable gel that aids in suspension and prevention of separation over the shelf life of the product making it a suitable replacement,” he said.
With the trend toward high-protein formulations comes additional compatibility issues.
“In dairy product formulations, hydrocolloids can have distinct reactions with different sets of proteins,” Ms. Reilly said. “It is important to take note of potential ingredient interactions and choose the hydrocolloid system wisely.”
This is particularly true in high-protein dairy beverages. These often contain a blend of dairy proteins, sometimes with plant proteins, which come with their own set of sensory issues, some of which can be addressed through the addition of hydrocolloids.
“We recently introduced a new stabilizer system for low pH ready-to-drink beverages,” Ms. Klockeman said. “It stabilizes
protein with minimal impact on viscosity. It also increases color uniformity and the rate at which the product clears the mouth while reducing awareness of gritty particulates, such as those encountered in high-protein beverages.”
Ms. Rojas said, “One of our new products is a blend containing modified food starch, xanthan gum and carrageenan. This blend promotes a creamy texture and mouthfeel in dairy-based meal replacement beverages. It also improves suspension of cocoa particles and contributes to the fiber content.”
The functional fiber derived from orange pulp that Ms. Wagner mentioned has been shown to extend fruit or partially replace pectin in fruit-based preparations.
“It can reduce syneresis in yogurt, maintain a full-fat texture in low-fat ice cream or yogurt, sour creams or cheese applications and improve yield in processed cheeses,” she said.
Formulators must remember hydrocolloids are complex, both in their pure form and when combined as a system. It is important to work closely with an ingredient supplier for each and every product formulation.
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