Article: Nutritional Productsí Flavors and Flavor Masking -- June 2008
Food stimulates the senses. When foods are enhanced with extra nutrients, technology may be required to impart a positive stimulation of the senses. Product developers today almost need to be experts in the nutritional properties and flavor dynamics of a wide array of botanicals, supplements, vitamins and minerals. As the functional food trend unfolds, delivering nutritional compounds in palatable products continues to challenge food formulators and flavor chemists alike.
Vitamins, Minerals and Botanical Flavor IssuesIt seems the consensus among nutritional ingredient suppliers, flavor experts and food manufacturers is that B vitamins, especially thiamin, minerals like iron and copper, as well as certain fatty acids, botanicals, proteins, peptides and omega-3s can present technical challenges to formulators of various food matrices. Some food products are more difficult than others to fortify while providing good taste, as products differ by water activity, pH and expected storage time. In some cases, nutrients are water-insoluble (e.g., omega-3s, lycopene, phytosterols and some minerals), making these more difficult to provide in a beverage.
Vitamins like thiamin (vitamin B1) can be challenging in some products, as it imparts a sulfur note similar to a rotten egg. This is due to the thiamin molecule’s sulfur-containing portion. Minerals like phosphorus, potassium, magnesium, zinc and iron, as well as the sulfur-containing amino acids like methionine, cystine and cysteine, also can bring about lingering metallic flavor issues. Calcium does not have a metallic flavor, but may precipitate out and give a chalky texture or flavor when used at higher levels.
Oil-soluble vitamins A, D, E and K have been known to impart off-notes at higher concentrations, depending on the product. Flavored waters may contain up to 15-25% of the recommended daily intake per serving of these fat-soluble vitamins, but most products typically do not use high doses because the body stores them and there is a potential for a harmful overdose with long-term use.
At high levels, carotenoids can “ring” and cause color changes. Even so, energy drinks, enhanced flavored waters, fortified teas and sports drinks often incorporate fat-soluble vitamins and antioxidants, so formulators do meet these challenges.
Botanicals can be bitter, depending on several factors. The standardization of the active component, the particular part of the plant used, processing methods and the level of fortification in the finished product all impact flavor. “For example,” contributes Frank Del Corso, senior food technologist for a flavor house specializing in fortified beverages and supplements, “Ginkgo biloba leaf extract standardized to a high level of ginkolides (an active component in Ginkgo biloba) may be too bitter to use in some applications, so a simple 4:1 or 5:1 extract would provide the right flavor.”
Longer chain nutritional lipids also can cause issues. “Omega-3 fatty acids oxidize, causing rancidity flavor and odor issues. Fish oil is not an easy flavor to mask, but nanotechnology and microencapsulation are good at protecting these very unstable molecules, and there is a lot more going on behind the scenes [in regards to new technology],” notes Ram Chaudhari, Ph.D., FACN, CNS, senior executive vice president, chief scientific officer, for a supplier who creates custom-blended nutrient pre-mixes for the food, beverage and pharmaceutical industries.
ProteinsHigh levels of protein can invite flavor issues; soy often is problematic when it comes to off-notes. But all proteins have amino acids and an amine backbone that allow them to participate in Maillard reactions along with sugars, so all proteins will “get you in the end,” offers Gary Reineccius, Ph.D., professor and flavor expert at the University of Minnesota, and head of the Department of Food Science and Nutrition.
The Maillard reaction can be a problem, if there is even a tiny amount of sugar in a formula. The reducing end of the sugar reacts with the protein to create “gluey” flavor notes reminiscent of the old brown glue packaged with a rubber top. “It can be very difficult to get rid of these notes,” states Reineccius.
“People may try to add a lot of other flavors to cover up any off-notes, but it really comes down to the fact that ‘you can’t make a silk purse out of a sow’s ear,’” he explains. In other words, high-quality ingredients--those of the best flavor quality--are the way to go, he adds.
Technical Solutions: Masking to NanotechnologyThe solutions to flavor issues range from edible films, encapsulation and masking agents to nanotechnology. Flavor companies have been very creative with masking systems, and many of the technologies are patented and/or proprietary. “Solutions are product-dependent. For example, encapsulation or even a basic fat coating over B vitamins and minerals can improve stability and flavor in a bar, although that would not work in a beverage,” explains Diane Hnat, senior technical marketing manager at a well-known nutrient supplier.
Masking off-notes inherent in nutritional ingredients can be done by encapsulating the nutrients. At times, it also may be useful to encapsulate the flavors themselves. Capsules containing nutrients must stay intact during the entire stages of food processing and mastication, but then the nutrients must be released for digestion. Encapsulation is typically very expensive; however, it may be very difficult to mask off-flavors otherwise.
A lot of suppliers have developed their own encapsulating technologies for improvement of flavor and functionality. “Protection of omega-3s from oxidation with a gelatin or starch coating allows their incorporation into milk. These types of coatings protect EPA and DHA from oxidation during the shelflife of the milk, retaining good flavor while allowing the dispersion of the fatty acids throughout the milk,” Hnat adds.
Normally, the encapsulation process limits exposure to oxygen, extending the shelflife of the nutrient. Recent research on various starches as encapsulation agents may offer a less-expensive approach for encapsulating both flavor compounds and nutritional ingredients. Starches may react uniquely with specific ingredients, holding in flavor compounds and protecting fats from oxidation.
One nutritional ingredient supplier has patented a “beadlet” technology, where active ingredients are formulated into micro-sized particles at 0.2µm. These particles are then encapsulated and stabilized in a patented, protective matrix (typically gelatin), resulting in a particle with a diameter of 400µm covered in cornstarch.
Flavor and masking ingredients can be very specific; for example, ingredients can be formulated to block “burn” or bitterness from preservatives or soy protein. “Blockers,” as they are called, are available to mask a number of other flavors as well. “Flavor houses have become experts in specific areas of fortification,” says Del Corso. “For example, we work almost exclusively with beverages, so we have become very good at formulating systems that can support various levels and types of fortification.”
Patents exist for certain nucleotides that are able to decrease the perception of bitterness. “Adenosine monophosphate, a nucleotide with bitter masking properties, is becoming a common masking agent for lingering metallic flavors,” notes Chaudhari. Other ingredients are also able to address unpleasant bitter tastes by overpowering the senses with strong tastes (such as menthol).
“Any nutritional in-gredient improperly mixed--at too high a use rate or with incompatibility issues--can cause problems. But on a case-by-case basis, product-specific masking ingredients can be used,” explains Scott Rayburn, beverage applications manager at a well-known flavor supplier. The choice of which masking agent to employ depends on ingredient interactions, effects on color, turbidity or cloudiness in beverages and other parameters.
“Nanotechnology is a powerful masking technology that uses very fine particles (with hydrophobic and hydrophilic properties) to protect nutrients from interactions with other components in a food,” explains Chaudhari. In the range of approximately 1-100 nanometers, particles or systems may have novel properties due to their small size. These properties have the ability to be controlled or manipulated on the atomic or molecular level.
“Mono and diglycerides, whey proteins and other molecules with hydrophobic and hydrophilic properties can [potentially be used as part of these systems]. It is still expensive, but becoming more mainstream; it should become less expensive and more applicable with time,” Chaudhari adds.
End Products: Powders, Bars and Beverages“Since moisture, in general, can accelerate oxidation, there are some advantages to working with dry systems--when it comes to some nutrients. However, certain minerals (for example, in foods with low water activity) can interact and produce off-flavors,” notes Hnat. Protecting B vitamins and certain minerals with a fat coating provides flavor masking and can reduce interactions of these nutrients with other ingredients (such as in nutritional bar matrices).
In liquid applications, there can be problems when using hydrophobic or hydrophilic masking agents. In beverages, solubility issues can result in flocculation, precipitation and problems with turbidity. However, when it comes to concerns with proteins and peptides participating in the Maillard reaction, it is easier to stabilize these nutritional ingredients in a liquid form (as compared to a dry form). Many bars are intermediate-moisture foods; this is the most optimal moisture level for Maillard reactions to occur, says Reneccius. In contrast, the very, very high moisture level of a beverage offers some protection.
Encapsulation is a good way to stabilize nutrients in a bar, to which it is relatively easy to add higher amounts of nutrients. “However, the challenge is that many nutrition bars start out with good flavor, but as the bar is stored, the good flavor goes away and the bad flavor appears,” notes Reneccius.
Chocolate can be good at masking some flavors. “Sometimes people try to build flavors around an off-note,” Reneccius explains. “For example, Americans who grew up on Hershey bars are content with an oxidized milk flavor in a milk chocolate, so it may be easier to add certain nutrients with oxidized flavors to chocolate. However, Europeans would likely think the same oxidized flavor was horrible. It comes down to what we have grown up with,” he explains.
Depending on the finished product or on the specific off-note created from a particular nutrient, vitamin or other flavor, a different approach would be taken for masking. Increasing the acidity in a beverage can help “clean up” the aftertaste of artificial sweetener blends. However, in some cases, increasing the acidity of the beverage can also intensify an off-note.
Natural and OrganicMany consumers are all for things that are good for the environment and that support sustainability. “But, people also do not want to spend a whole lot more for them. Suppliers are recognizing this and so the availability of [less expensive] organic flavoring compounds and masking ingredients is sure to grow,” Del Corso offers.
Organic formulations can be very challenging, since artificial flavorings cannot be used. It is easier to manage flavor issues when a customer is just looking for natural flavors, since more natural than organic ingredients are available at this time, says Del Corso. For organic flavors, all of the ingredients must be 100% organic; additionally, an organic-certifying body such as QAI or CCOF must certify the facility or production plant. An increasing number of organic flavoring compounds are becoming available as suppliers are seeing their demand grow.
According to Rayburn, “it is easier to make natural and artificial flavors; however, organic flavors are very possible, with somewhat higher cost.” It is often useful to remember that “natural flavor” and “all-natural” products have two different meanings. Natural flavor is defined in 21CFR 101.22. But an “all-natural” product is much less well-defined. While a product could utilize a “natural flavor,” its carrier may not be considered “all-natural,” possibly making the flavor inappropriate for a product claiming “all-natural” status. “Organic flavors create even more issues with supply chains in both raw materials and solvents. Masking flavors in organic products have pretty much the same issues as all-natural products,” Rayburn adds.
“Providing organic ingredients can be complicated. It involves details about the origins and processing of the ingredients. But, without an official definition, natural has a bit more flexibility in what a customer can and will accept,” explains Hnat.
(For more information on organic ingredients, see the article, “A New Approach to Organic Ingredients” in this June 2008 issue of Prepared Foods.--Eds.)
Website Resourceswww.nano.gov/html/facts/whatIsNano.html -- Website of the National Nanotechnology Initiative program established to coordinate federal nanotechnology R&D
www.fda.gov/nanotechnology/faqs.html -- The FDA’s webpage, with Frequently Asked Questions on nanotechnology
www.fortitech.com -- Website with articles and podcasts on nutritional ingredients and RDIs from various countries around the world
www.cargillflavorsystems.com -- Home of a newly organized flavor supplier
www.allenflavors.com -- Home page of one flavor supplier
SIDEBAR: When Flavors Don a MaskWhen preparing new dishes, many food innovators strive to enhance taste, while retaining nutritional value. It calls for the right blend of ingredients, which not only adds to the flavor directly, but also can intensify other ingredients’ flavors. To add flavors to a wider range of foods, the industry leverages different techniques to modify the flavors of nutritional ingredients. Below are some examples, along with a few safety considerations.
* Bitter Blocker: “Flavor modifiers” either intensify or block flavors. for instance, “coolant flavors” have little or no taste, but stimulate cold receptors in the mouth to make the flavor of menthol in candy more intense.
Conversely, flavor modifiers can block flavors. in savory dishes where a sweet taste is typically not desired, sugar can enhance other relevant characteristics. In this case, a chemical such as lactisole will temporarily block sweetness receptors on the tongue, allowing the savory flavor to dominate.
Adenosine monophosphate (AMP), a naturally occurring nucleotide substance, can block bitter food flavors, including those found in coffee. AMP works much like lactisole. It will not directly alter the bitter flavor, but instead alters human perception of “bitter” by blocking the associated receptor.
* Sweet Deal: Artificial or added sweeteners, such as aspartame or glycyrrhizin (a licorice root extract), can be used at concentrations not normally perceived as sweet to enhance other, more costly flavor ingredients or the natural sweetness inherent in foods. Other ingredients contribute to “mouthfeel,” such as the creamy or fatty taste of butter, the heat of chili peppers or the bite of horseradish, complementing the flavor.
* Nano-encapsulation: To mask omega-3 fatty acids and other flavors, the industry has started to encapsulate ingredients, either through micro or nanotechnology. Encapsulation is basically the art of encasing an ingredient in a starch or other material, such as natural gums, proteins or hydrocolloids, and then spray-drying the mixture to form a capsule around the ingredient. Recently, difficult-to-add nutrients, such as omega-3 fatty acids and certain vitamins, have been altered to nano-particle size (typically less than 100 nanometers) and encapsulated.
Nano-encapsulation may also increase nutrient bioavailability and, if not monitored, there is a concern that ingestion of nano-sized nutrients could possibly reach toxic levels. Unfortunately, relatively few safety studies exist on nano-sized nutrient consumption to fully expose the actions of nano-sized nutrients. Therefore, the FDA stated it will evaluate nano-sized food additives on a case-by-case basis to determine their safety.
--Ray A. Matulka, PH.D., assistant director of toxicology, Burdock Group, firstname.lastname@example.org.