Encapsulates: Providing Protection
April 01, 2010
by Donna Berry
From flavors to leavening agents to nutrients, bakers rely on encapsulation technologies to protect numerous micro-ingredients used in baked foods formulations and, thereby, control their release. The term encapsulation describes the process of enrobing one material in another at the microscopic level. Microencapsulation describes an even finer degree of encapsulation technology and is one of the earliest examples of applied nanotechnology, which is the science of controlling matter at the atomic and molecular physical level.
“For bakers, encapsulation is primarily about delaying the activity of a micro-ingredient until a specified time during the baking process,” said Mike Beavan, director of product development, Watson, Inc., West Haven, CT. “The encapsulating material is like a protective shell, keeping an active ingredient locked in and stabilized until the release of the material is desired.”
Sometimes encapsulation prevents certain critical ingredients from partaking in premature or undesirable interactions in dough or batter. Other times the protective coating secures unstable or fragile ingredients. Encapsulation of certain ingredients can improve processing — at the mixer, in the proofer or in the oven. It can also extend shelf life in some applications.
“Encapsulation has been used to solve a variety of formulation, handling and stability problems for food additives,” said Joseph Persyn, manager, microencapsulation and nanomaterials, Southwest Research Institute, an independent, nonprofit contract research organization based at San Antonio, TX, that specializes in formulation and process development of encapsulated products. “The institute is unique in that it possesses the facilities and equipment to investigate the full range of encapsulation technologies, including spray drying and congealing using disks and nozzles, fluid-bed coating, co-extrusion, coacervation-phase separation, emulsion polymerization, liposomes, micelles and others.”
To properly use encapsulation technologies, it is critical that survival and release catalysts be identified for a specific application. Proper selection of coating materials, carriers, encapsulation process and handling ensures a consistent functional ingredient.
“An ingredient’s water solubility can be a problem in bakery applications because it promotes undesirable reactivity of that ingredient,” said Kristine Lukasik, manager, scientific and technical product support, Balchem Corp., New Hampton, NY. “In this case, spray chilling or a fluidized bed technique can be used to apply a lipid barrier coating to the ingredient, with the goal of providing a water barrier for reduced solubilization.
“Oil-soluble substrates are typically better protected by using spray drying, melt extrusion and coacervation with water-soluble matrices such as proteins (gelatin, zein, etc.), specialty starches, sugars and sugar alcohols, or oligo- and polysaccharides (maltodextrin, gum Arabic, etc.),” she continued.
Mr. Persyn explained, “With a large number of encapsulation processes available and with many variations thereof, along with the thousands of potential formulations, entering the field of encapsulation can be an overwhelming and costly endeavor. And with the push toward healthy, innovative ingredients and food fortification, the number of applications continues to grow. As one quickly learns, most encapsulation solutions are customized for a particular active ingredient and its intended application.”
As the baking industry has become more automated, encapsulation technologies have become more sophisticated and tailored to different plant handling and processing conditions, as well as specific applications.
“We started encapsulating micro-ingredients to meet the needs of our customers who were upgrading to computerized industrial baking processes,” said Jim Watson, president of Watson, Inc. “Most likely the first micro-ingredient we encapsulated was ascorbic acid, a weak acid readily destroyed by mild alkali solutions such as baking soda. However, ascorbic acid adds strength to dough, in particular, the increasingly popular category of frozen dough. Encapsulating the ascorbic acid protects it until baking time, and when released, ascorbic acid improves baking properties and baked product quality.”
Tom Tongue, director of product development, IFP, Inc., Faribault, MN, added, “What we consider ‘true’ encapsulated ingredients got their start in the 1980s. We were mostly spraying fat onto ingredients in those days.
“Coating levels of 30 to 50% were typical, and only one to three different coating materials were available,” he continued. “Today, encapsulation technology is a science that starts with designing an encapsulated particle with properties to survive defined stress conditions such as heat, moisture, pH, abrasion, etc., and release based on available catalysts.
“We must evaluate the active materials to assure that they consistently meet closely defined specifications including particle size, shape and moisture content,” Mr. Tongue said. “Engineering changes to equipment provide more controls for the process. Today’s encapsulates are typically 70 to 85% active, with more consistent survival levels and at lower cost than encapsulates of just five years ago. Most hot-melt encapsulations are still based on three basic hydrogenated or partially hydrogenated vegetable oils, but formulators now have a wider range of coating materials, many of which are added as performance modifiers.”
Coatings must be compatible with the application. An oil-encapsulated ingredient will not release in a water-based system, while a starch-encapsulated ingredient will not be released by the heat of baking.
“Technology has advanced most significantly by making improvements in the coating used to encapsulate the active ingredients,” said Pat Jobe, technical sales manager, Clabber Girl Ingredients Division, Terre Haute, IN. “Establishing variations in the coating allows us to focus on the release and to control when, and to what degree, the active ingredient begins to work.
“Most encapsulation processes today encapsulate 100% of the active ingredient, offering no variation or customization to meet unique applications,” he continued. “However, our patent-pending encapsulation system varies the level of coating used to encapsulate the active ingredient, allowing the release to occur in stages. Much like a double-acting baking powder, the level of coating allows multiple-phase release of the active ingredient, releasing part of the ingredient in the blending stage and a second phase in the oven. The degree of release at each stage of the process is unique to each product and designed to fit the needs of the baking manufacturer.”
Mr. Tongue added, “IFP’s proprietary process involves an angled impact spray pattern. The impact between coating droplet and active particles creates a moving particle that spreads the coating layers evenly over the surface of the active core material. We minimize the gaps and voids that conventional fluid-bed processes create, producing particles with less coating that consistently provide equal or greater protection from moisture or abrasion.”
As with value-added products, encapsulation usually increases the price of an ingredient. Thus, bakers must determine if there is any benefit to using the encapsulated version of an ingredient.
“By using encapsulated fortifying ingredients such as vitamins, minerals and omega-3 oils, a baker ensures the consumer that these nutrients are present in the final product,” said GuoHua Feng, manager of bakery ingredient innovation, Caravan Ingredients, Lenexa, KS. “Not only do they remain viable, they also won’t oxidize and cause offflavors during shelf life.”
The market for frozen and refrigerated dough, for both food service and at-home baking, continues to grow as both operators and home bakers seek out convenience solutions.
“Encapsulated ingredients make sense when the raw ingredient can negatively interact with other ingredients or the environment,” Mr. Tongue said. “For instance, take-and-bake or self-rising pizza crusts are subject to advance preparation and must ensure performance when taken home and baked. Encapsulating either or both of the chemical leavening agents delays interaction until the crust temperature exceeds the melt point of the coating, typically 145°F. This allows perfect leavening every time.
“Similarly, makers of commercial breadings have a quality challenge regarding first and last product produced in a batch,” he continued. “If their batch size is small, there could be minimal deviation in loss of leavening, but if an extended time period is in play, an encapsulated leavening system can provide process time flexibility.”
Ms. Lukasik explained, “Encapsulation of sodium bicarbonate is particularly important in refrigerated and frozen batters and doughs that contain free soluble acids from ingredients such as fruit, cocoa, molasses and buttermilk because encapsulation prevents premature leavening and undesirable color changes. Shelf life can be extended and performance improved, even if these products are freeze-thaw abused.”
Using encapsulated leavening agents in refrigerated dough sold in pressurized tubes allows the manufacturer to mix the dough without gassing prematurely or excessively. “Two different leavening agents are used,” Mr. Watson explained. “The encapsulated acid activates once the dough is in the cardboard tubes, where it quickly rises and excludes the excess air in the tube.”
Sometimes the least likely of ingredients can benefit from encapsulation. “By providing a protective coating on watersoluble ingredients such as sanding sugar and pretzel salt, the problem of ‘melt away’ can be reduced or eliminated, thereby extending the shelf life of fresh baked foods such as muffi ns, donuts and pretzels,” Ms. Lukasik said. “By encapsulated certain acids, it is possible to deliver a vibrant sourdough flavor to delicate laminated doughs while minimizing process time.” Moira Watson, director of corporate communications at Watson, Inc., said, “Highly aromatic seasonings such as onion and garlic will soften dough during processing and storage. Encapsulation prevents this from happening, as well as masks the strong odors these seasonings possess.
“It’s also critical to encapsulate cinnamon in yeast-raised doughs because cinnamon kills yeast,” she continued. “Once baked, the encapsulating material melts and the flavor and aroma are released.”
Bakers often use microbial inhibitors to extend product shelf life, but most preservatives inhibit yeast. “Encapsulation keeps these preservatives away from active yeast,” Mr. Feng said. “When the time is right, they can be released and protect the products from mold growth, which can assist with ensuring quality during shelf life.”
For example, sorbic acid is a very good anti-mold agent with a neutral taste, but it cannot be added directly to dough because it destroys the action of the yeast. When encapsulated, the sorbic acid is not released until the product is baked.
“With fresh baked foods, especially whole-grain products, it is possible to control mold growth by including encapsulated ingredients such as sorbic acid and calcium propionate salts, in combination with organic acids,” Ms. Lukasik said. “These can be added directly with dry ingredients and will not interfere with dough development or leavening. This is especially significant in products such as flatbreads, tortillas and par-baked foods.
“Encapsulation may be used to more effectively control chemical reactions with flour proteins in a dough matrix in applications such as pan breads and flatbreads,” she continued. “The reactivity of oxidants and reducing agents such as ascorbic acid, azodicarbonamide and L-cysteine can be delayed from minutes to hours, thus facilitating dough mixing and maximizing the effect of the conditioners.”
Mr. Jobe said, “Clabber Girl offers a 2-stage ingredient system that improves leavening by having varied levels of a coating around fumaric acid.” The first stage allows release in the bowl, which assists with pH control when mixing dry ingredients with water during the manufacture of tortillas or bread. When the product is baked off, the heat releases the second stage of the encapsulated fumaric acid.
“Most encapsulators use a 1-stage system, which releases only when heat is introduced,” he continued. “Because chemicals in the ingredient start to react in the bowl, having an initial release at this stage in addition to the bake stage results in a more balanced finished product.
“Bread manufacturers who use this 2-stage encapsulated fumaric acid ingredient have been able to eliminate the use of vinegar, an acidulant that is difficult to work with in liquid form, and reduce the amount of yeast required. This provides a cost savings to the baker,” Mr. Jobe continued. “The ingredient has also been shown to extend product shelf life.”
Mark Rice, senior national sales manager at Clabber Girl, added, “Our 2-stage system can improve and extend dough. It controls rising at the bowl and during baking, allowing the baker to balance out the equation, particularly when batter will be refrigerated or frozen for an extended amount of time.”
Sodium is a hot button in the food industry, and bakers are seeking ways to eliminate unnecessary sources of this nutrient such as leavening agents stabilized by being attached to sodium. “When you encapsulate reactive organic acids for release later in the baking process, a baker can eliminate many sodium-based leavening agents,” Mr. Watson said.
According to Ms. Lukasik, “By encapsulating soluble monocalcium phosphate, it is possible to significantly reduce the sodium content of certain leavening systems used in baked foods”
Mr. Rice noted, “We are looking into new ways to use encapsulation to replace expensive sodium-based leavening acids such as sodium acid pyrophosphate (SAPP) and•sodium aluminum phosphate (SALP) in baking powders. This will be a huge advantage for the baking industry since these leavening acids are used in almost all chemically leavened baked foods. Using encapsulation technology will continue to improve cost of goods and the overall quality of products. The sky is the limit.”
In conclusion, Ms. Lukasik said, “As industry knowledge of coating materials and technology improves and new functional ingredients are exploited, we will see improved functionality such as true controlled release and quantitatively better stability of encapsulates to elevated temperature and shear force. As the interest in nutrition via bakery products increases, encapsulation will be used to deliver emerging functional ingredients as well as more traditional ingredients for fortification. The further improvement of microencapsulation technology will make the ingredients more accessible to product developers, thus extending the range of viable applications in cereal foods and broadening technical innovation in the bakery industry.”