Article: Dairy Solutions to Application Challenges -- October 2008
October 1, 2008
It has been rumored that Marco Polo first encountered sun-dried milk in his travels through Mongolia in the 13th century. In 1855, the first commercial patent for drying milk was granted, and since that time, milk has been evaporated, dried, filtered, cultured and otherwise manipulated into a wide range of functional food additives. In the 1980s, whey protein concentrates (WPC) first appeared on the market, followed by whey protein isolates (WPI). The 21st century has ushered in a new generation of dairy ingredients with improved heat stability, gelling capability and flavor superiority.
There is a dairy ingredient for almost any application problem. In today’s market, often the first challenge is to meet a specific nutrition goal; in many cases, it is to make a nutrient content or structure-function claim. Dairy ingredients can boost the protein content of foods, while delivering on the promise of superior flavor with minimal guilt. Diets higher in protein have been associated with increased satiety, so foods fortified with dairy protein show great promise in foods intended for the weight-management market.
A Dairy Ingredient for Every ChallengeThe two primary dairy proteins are whey and casein. Caseins precipitate at a pH of 4.6 and comprise approximately 80% of total protein. Whey proteins remain soluble across a wide range of pH levels and have superior gelling and water-binding capability, unless they are heated and become denatured. Dairy proteins, with their hydrophilic and hydrophobic polar nature, function as emulsifiers and can be used to replace fat, improve texture and increase shelflife in a variety of breads, meats and frozen desserts. Caseins have good heat stability and emulsification properties, and both milk protein concentrates (MPC) and caseinates can be tailored to provide specific functionality. The following is a list of some of the newer categories of dairy ingredients.
* Specialty whey protein concentrates and isolates abound. Whether a food formulator needs to develop a clear beverage that “takes the heat,” pack a “20g protein punch” into a bar or create a low-carb sauce, there probably is a heat-stable, high-gelling, partially hydrolyzed or other specialty whey ingredient that is tailored to meet the challenge. Consult with Dairy Management Inc.’s (DMI) technical support team for a supplier referral by sending an e-mail to: email@example.com.
* Milk protein concentrate (MPC) can be used to boost the protein content and reduce the sugar levels of a wide variety of puddings, nutritional beverages, process cheeses and frozen desserts. In the past five years, the supply of domestic ingredients has been steadily increasing. This may be significant to food companies looking for safe and reliable ingredient sources in an uncertain world market.
* Whey phospholipids (WP) are a fairly new class of ingredients that have exceptional emulsification properties. They are high in phosphatidylcholine (PC), also known as lecithin, and can be used in emulsified and processed foods, frozen desserts, bakery products, pumping hams and other meats.
* Cultured dairy ingredients include not only yogurt powder (cultured non-fat dry milk), but also a wide variety of blends of cultured ingredients that can provide the tangy taste of yogurt, reduce sodium levels and serve as antimicrobials.
* Specialty and ethnic cheeses are increasingly being produced in the U.S. Traditionally, cheese was either processed or natural, but now some cheese manufacturers are producing a type of hybrid cheese with some emulsifying salts and improved functionality over a purely natural cheese. Examples include process Havarti and process feta. Cheese is also showing up in new forms. At this year’s IFT Food Expo, one manufacturer showed a freeze-dried mozzarella that could be used as a component of a shelf-stable snack.
Benefits in BeveragesBecause of their versatility, whey proteins can be used to boost the protein content of a wide variety of beverages. They can be used in meal replacers, smoothies, isotonics, protein waters and sports drinks. Developing a powdered drink mix is relatively simple. The challenges usually arise when companies try to develop a ready-to-drink (RTD) product. One of the first considerations when selecting the appropriate dairy ingredient is the desired appearance of the beverage.
Clarity/Opacity: If clarity is the goal, then the ingredient of choice is a whey protein isolate, which has over 90% protein and very low levels of fat. Isolates also work well in opaque beverages, but, in these applications, an MPC70 or a WPC80 (the number designates the level of protein) may be more cost-effective and also provide good opacity. Understanding a bit of whey chemistry helps. The isoelectric point for beta-lactoglobulin is 5.2, and for alpha-lactalbumin, 4.1. Large random aggregates of whey protein occur in beverages with high salt content or pH levels near the isoelectric point, resulting in opaque beverages. Conversely, at low salts or at pH levels below the isoelectric point, clear beverages can be produced. K. J. Burrington, whey applications specialist at the Wisconsin Center for Dairy Research, in Madison, Wis., suggests, “For hot-fill products, clear beverages can be formulated in the pH range of 2.8-3.4, and cloudy beverages in the pH range of 3.5-4.5.”
Solubility: Often, the next challenge is solubility. In protein waters and isotonics, whey proteins are easily soluble at a pH of 3.4, where soy and casein would precipitate out. Whey proteins also work well at a neutral pH of around 7.0. Burrington adds, “Use a max of 2g of protein per ounce at pH 3.0 under hot-fill conditions. If higher protein levels are desired, a partially hydrolyzed whey protein may be needed.” Whey proteins are least stable near their isoelectric point, but they are quite soluble either above or below this pH. Solubility can also decrease with more severe heat treatments that denature whey proteins, making them less soluble.
Processing: Other factors that affect the appearance and stability of whey protein beverages include ionic strength, hydration time, sugar and water. The heat treatment and shear also determine whey protein functionality. Other components in the system, including protein, fats and salts, will also affect the final product. “Adequate hydration of whey proteins can usually be accomplished by blending the whey with other dry ingredients in the formula, mixing with water and allowing to hydrate 20-30 mins. Then the beverage can be heated to 190° for two minutes, or using approved hot-fill process parameters. In many instances, adequate hydration will reduce turbidity by as much as 50%,” notes Burrington.
Yogurt ImprovementsYogurt is increasingly becoming a vehicle for delivering a wide variety of functional food ingredients. The yogurt industry adds a number of different dairy and non-dairy ingredients to yogurt to improve body and consistency.
Ironically, one way to reduce syneresis or “wheying off” is to incorporate whey proteins and adjust heat treatment. Researchers at the Wisconsin Center for Dairy Research have explored this mechanism. High-heat treatment of 90-95°C for 5-10 minutes denatures the majority of whey proteins. John Lucey, Ph.D., associate professor at the University of Wisconsin-Madison, explains, “Some denatured whey proteins (DWP) remain in the serum and will be ‘soluble.’ The majority of DWP become attached or ‘bound’ to the casein micelle. Having some of the bound DWP attached to the micelle surface during heating reinforces the gel matrix and increases viscosity in the finished yogurt.”
Processing parameters such as pH at heating, salts and subsequent pH adjustment will affect the amount of DWP that become bound to the casein micelle. When milk is heated at a pH of 6.5, a greater percent of the denatured whey proteins are associated with micelles. Lowering the incubation temperature also helps improve texture and reduce whey separation, thus reducing syneresis. Lucey recommends using around 2% of WPC34 or 0.4-0.75% of WPC80/WPI for fortification of the milk solids content of the yogurt mix, along with some skim milk powder. Going beyond these levels of whey protein can lead to graininess, lumpiness and a short, brittle texture, although this depends upon the yogurt processing conditions. Dairy ingredients can boost nutrition and lower carbohydrate count, while providing a “clean” label.
Key Uses in BakeryA popular trend is to produce products with higher levels of protein and fiber to enhance satiety. Recent market research by DMI indicates that two-thirds of consumers believe satiety is extremely or somewhat important. Laura Gottschalk, DMI’s vice president of strategic research, explains, “Morning is seen as the most important time to eat or drink something satiating. Our research further suggests that about one third of consumers reach for a healthy snack when the hunger urge strikes. They feel that nutrition bars are one food that would do a better job of satisfying their hunger, if they were fortified with protein.” To develop products that qualify as a good source of protein, WPI or WPC80 might be the ingredient of choice.
Structure and browning: If the emphasis is to improve grain structure, retain moisture, enhance crust browning and improve flavor, then high-heat, non-fat dry milk, WPC34 or a specialty dairy blend might be good choices. Whey-based ingredients can be customized to meet specific protein, minerals and lactose compositions. Structure development is inversely correlated to the undenatured whey protein nitrogen (WPN) value in NFDM (the lower the WPN value, the greater the foaming functionality). High-heat NFDM prevents loaf volume depression in breads. On the other hand, low-heat NFDM reduces dough extensibility and gives poor loaf volume. Ingredients with higher levels of lactose can aid in browning.
Meeting Challenges in MeatsWhey ingredients can be used in processed meats as partial replacements for meat, as binders, flavor enhancers and meat analogs. Whey ingredients can improve yield and prevent moisture loss in ham and surimi. In meat applications, the binding of myofibrillar meat proteins decreases during cooking, due to protein denaturation. Under appropriate heating conditions, WPCs can form irreversible gels by restructuring into extended, three-dimensional networks. By entrapping water within the capillaries of the gel matrix, WPCs provide additional water-binding capacity.
Since most Americans prefer white chicken meat, one challenge was to find a use for the dark meat. A study presented by Gits Prabhu, Ph.D., at the 2007 IFT Annual Meeting, showed that WPC and pre-gelatinized WPI can be used to lighten the appearance of chicken dark meat in ground and restructured chicken products, while maintaining finished product texture and composition.
Entrées and Ethnic Foods IssuesThe water-binding capability of whey proteins makes them useful in a wide variety of soups and sauces. For products that will be exposed to higher temperatures, either an MPC or special heat-stable whey proteins may be needed. Calcium is required for gelling to occur, and free calcium concentration will determine gel hardness and water-retention properties. In some situations, chelating agents can be used to reduce free calcium to optimal levels. Other formula parameters, including heating time, heating temperature, salt levels and pH, will all influence the heat-induced changes to the secondary structure of the whey protein. Dairy proteins are showing up in unexpected places. A recent project by the U.S. Dairy Export Council taught Asian noodle manufacturers how to formulate their products with whey protein to boost nutrition.
In recent years, the U.S. has produced a wide variety of specialty and ethnic cheeses that rival those of many European countries. If the challenge is to add pizzazz to a product line, an ethnic cheese such as Asiago may be the answer. If the task is to fine-tune melt and flow, the cheese experts at the Wisconsin Center for Dairy Research can suggest a solution. One example is to incorporate non-melting Hispanic cheeses such as queso fresco, queso blanco and queso para freir into processed Hispanic cheese, which is pumpable.
Assisting with Frozen Dessert TrendsLower-fat ice cream products are very popular and part of the popular trend toward “permissible indulgence.” Sam Adapa, product development manager, consumer brands and innovation, Safeway Inc., notes, “We improved our light ice creams to the slow-churn type by deploying a combination of simple, novel ingredient technologies using a combination of whey protein, stabilizers and emulsifiers. This approach rendered our light ice creams with 5% butterfat to taste like full-fat (10% or greater) with creamy, rich mouthfeel. We are impressed with the outcome and are expanding the lines of application to other package forms.”
Both MPC and WPC are used in Weight Watchers Smart Ones® Peanut Butter Cup Sundae. This dessert combines low-fat vanilla ice cream, a crumbled chocolate cookie crust, fudge sauce and mini-peanut butter cups. It is touted as: “So delicious, so satisfying...and another little way you can be good today.”
A Plethora of New IdeasAdding whey to ice cream was just one topic covered in the Fifth International Whey Conference in September 2008. Food formulators from around the world congregated in Paris to explore the latest functional whey ingredients. The theme was “WheyVolution.” The conference also explored the use of whey in confections, infant formula, sports gels and bars, other applications where dairy can help food formulators overcome challenges and create healthy and indulgent new products.
Milk is a source of potentially problem-solving ingredients, ranging from traditional cheese to increasingly sophisticated proteins, for a variety of applications.pf