February 1, 1999

30 Min Read
Spread's the Word

Spread's the Word
February 1999 -- Cover Story

By: Staff and
Contributing Editors

  Nothing beats eating a warm piece of homemade bread with plenty of butter gradually melting over the surface. However, while butter's delicious, so are the alternatives. Health, taste, ease of use and a quest for diversity and new flavor sensations direct their development. Favorite spreads range from dairy-based butters and cheese spreads to vegetable-based margarines and nut butters. Many have a long history of use, but as always, technology has found room for improvement.

Buttering it up

  The butter typically used for home, foodservice or industrial use is referred to as sweet cream butter. It is usually classified as salted, unsalted or extra salted. According to its standard of identity, butter must contain at least 80% milkfat, and all of the fat must come from milk. The rest consists of water (not more than 16%) and milk solids. Annatto or carotene can act as artificial colorants to produce a richer yellow hue. FDA also allows the manufacture of products labeled as reduced-fat butter. These may contain skim milk, water and gelatin, and must contain 40% or less milkfat.

  Butter was originally made with a butter churn, and while churns are still used in large-scale butter manufacture, they are quickly being replaced by continuous buttermaking machines. To make butter, whole milk is preheated to 63°C in a pasteurizer, and then is divided into skim milk and cream by a separator. The cream continues on to pasteurization, at a temperature of 95°C or higher, which destroys enzymes and microorganisms that impair butter's shelf life. In-line vacuum de-aeration can also be used, to remove any undesirable flavors or aromas. The cream goes on to either a continuous buttermaker or to a churn, where it is violently agitated to break down the fat globules, causing the fat to coalesce into butter grains. As a result, the fat content of the remaining liquid, the buttermilk, decreases. In a churn process, the machine is stopped when the butter grains have reached a certain size, and the buttermilk is drained off.

  After drainage, the butter is worked to a continuous fat phase containing a finely dispersed water phase. Salt is then added. Further working ensures uniform salt distribution and also affects the butter's aroma, taste, keeping quality, appearance and color. Whipped butter has air or nitrogen gas beaten into it, which increases volume and creates a slightly softer consistency at lower temperatures.

  As many consumers go back to butter for its "natural" appeal, they may also rediscover another of its attributes - butter, even the whipped variety, just doesn't perform like spreadable margarine at refrigeration temperatures. So, how to make a butter that spreads more easily?

Better-spreading butter

  To make cold butter spreadable, it is necessary to understand milkfat's chemical composition. "Over 100 fatty acids have been identified in milkfat," says Kerry Kaylegian, researcher, Wisconsin Center for Dairy Research, Madison. "Approximately 12 of these make up 90% of the fatty-acid composition. The fatty acids are arranged on the triglyceride molecule in an orderly fashion by the dairy cow. This arrangement influences the melting properties of the milkfat."

  With over 60% saturated fatty acids, milkfat's oxidative stability is higher than that of most vegetable oils. Increasing the total unsaturated fat content by removing the middle-melting triglycerides improves butter's spreadability. "Fractionating milkfat into several fractions allows the recombination of lower-melting fractions for spreadability and higher-melting fractions for structure, to yield a spreadable butter," says Kaylegian. "Cold-spreadable butter should be easy to spread right of the refrigerator but the product must also retain its physical integrity at room temperature."

  The technology used to produce milkfat fractions is not new - it has been practiced in Europe for 20 years. Fractionation, blending fractions and texturization provide the ability to tailor milkfat in ways that are not possible with conventional dairy processing equipment.

  Dry crystallization achieves the primary goal of changing the physical properties while keeping flavor intact. Dry crystallization involves melting anhydrous milkfat in a temperature-controlled, jacketed tank with agitation. The milkfat is cooled under controlled conditions until it crystallizes, forming a slurry of solid milkfat crystals suspended in liquid milkfat. The slurry is pumped to a filter and the solid and liquid fractions are separated using either pressure or vacuum.

  Blending low-melting and high-melting fractions, typically in a ratio of 3:1, meets a selected solid-fat profile. The fat blend is mixed with skim milk to a fat content of 80% and then is texturized in a scraped-surface heat exchanger. Fats that are approximately 30% to 40% solid at 5°C and 7% to 15% solid at 25°C demonstrate good cold-spreadability. Although processing is different for spreadable butter, it is still considered a natural product, complete with all the good flavors of butter.

Spreading definitions

  Margarines, reduced-fat spreads, light spreads, ultra-fat-free margarine, 85% less saturated fat, trans fat free, no cholesterol, all natural. Why the variety in descriptors for a product that was invented in 1869 as a replacement for butter, and is now a staple in our diets? Response to food-industry trends has created an innovation explosion in the category. Designing better-tasting foods, healthier products, reduced fat, and more-convenient packaging has resulted in a wealth of products, and a category now worth over $1.3 billion per year.

  According to the National Association of Margarine Manufacturers, Washington, D.C., margarine products are used primarily as bread spreads (65%) and as a topping on a variety of foods (10%). The remaining 25% is used by consumers for cooking and baking. In addition, a large volume of margarine is also sold to professional users, such as bakers. These margarines can be tailored to a specific end use. For example, in a baking margarine, a specific melting profile is needed, which enhances the eating quality of the baked goods in which it is used.

  Margarine is an emulsion of oil and water. With higher-fat products, 25% to 80% fat, the product is fat-continuous, a water-in-oil emulsion. Basically, water droplets are dispersed through an oil phase, which contains both liquid oil and solid fat crystals. However, in very low-fat spread products, less than 25% fat, the product is water-continuous, an oil-in-water emulsion.

  Processing is relatively simple. A water-in-oil emulsion is prepared by mixing the aqueous phase into the oil phase, using high shear. The water droplets formed range from 0.2 to 50.0 µm - their size in the finished product affects mouthfeel and flavor release. The emulsion is then cooled in a scraped-surface heat exchanger and worked in a crystallization unit, which allows fat crystals to form.

  Control of the crystallization unit helps determine the physical properties of the margarine. This is achieved by a balance between the liquid and solid oil fractions in the end product. Quick crystallization fosters the formation of stable, small beta-prime crystals. The resulting crystal lattice traps the liquid oil fraction.

What's in margarine?

  Margarine's standard of identity, as established in the Code of Federal Regulations (CFR), in 21 CFR 166.110, requires more than 80% fat and at least 10% of the RDA for vitamin A per serving. Take some of the fat out, and it's no longer a margarine.

  Ingredients for a typical margarine include the following:

  Fats. Margarine typically contains vegetable oil, but can also contain rendered animal fats or menhaden fish oil since this ingredient was affirmed as GRAS. The predominant oil used for margarine in the United States is soybean oil, both liquid RDB (refined, deodorized and bleached) oil and hydrogenated oil. Others used include canola (low-erucic rapeseed), sunflower and corn oil. In Canada and Europe, palm oil and other tropical oils replace hydrogenated soybean oil.

  Water provides the aqueous phase. Milk may also be used.

  Whey, a dairy protein, gives some flavor to the product. Protein destabilizes the emulsion, improving salt and flavor release. Other proteins used include buttermilk, non-fat dry milk and yogurt. Vegetable proteins such as soy protein isolate also are allowed.

  Salt enhances flavor and has a preservative effect. Potassium chloride may be used in place of sodium chloride.

  Mono- and diglycerides promote and maintain the emulsion formed by the mixture of the two immiscible phases - oil and water. Other emulsifiers are also allowed by the standards.

  Lecithin improves margarine's frying performance and acts as an emulsifier.

  Potassium sorbate and EDTA act as preservatives. All preservatives have a maximum use level in the finished food: Sorbic acid, benzoic acid and their sodium, potassium, and calcium salts, individually or in combination, 0.1%, or 0.2% as the acids; calcium disodium EDTA, 0.0075%; propyl, octyl, and dodecyl gallates, BHT, BHA, ascorbyl palmitate and ascorbyl stearate, individually or in combination, 0.02%; stearyl citrate, 0.15%; and isopropyl citrate mixture, 0.02%.

  Citric acid controls the pH of the product, ensuring that preservatives are effective. Other acidulants or alkalizers also are allowed.

  Natural and artificial flavors can be used to mimic the flavor of butter. If flavors other than those similar to butter are added, the characterizing flavor must be declared as part of the name of the product.

  Beta-carotene is the most widely used colorant in margarines and spreads. Occasionally, annatto is used.

  Vitamin A is added per the regulations, at not less than 15,000 international units (IU) per pound in the finished product. Vitamin D may be added at levels to not less than 1,500 IU of vitamin D per pound of margarine.

  Nutritive carbohydrate sweeteners can also be added, according to margarine's standard of identity.

Product forms

  Until the mid 1960s, retail margarine was only sold as sticks. The development of plastic tubs allowed soft margarine to be dispensed in a tub form, and margarine gained a significant advantage over butter's spreadability straight from the refrigerator. Products have followed the lower-fat trend, so that now, the average fat content of margarines and spreads is around 53%.

  Light margarines (40% fat, half that of butter or margarine) were first developed in the late 1960s, but did not really penetrate the market until the early 1980s, when other ingredients, particularly gelatin, starch and/or high levels of dairy proteins, were used to improve quality.

  Liquid margarines were developed in the late 1980s. These are either true liquids, used mostly for frying, or "squeeze" margarines used for topping. Both use a much higher level of liquid oil than standard margarines to give them a liquid texture. In the early 1990s this technology was applied to spray margarines, with Lipton's I Can't Believe It's Not Butter Spray®.

  Driven by demand for lower fat, ultra-low-fat spreads and fat-free spreads were developed in the early 1990s. Fat-free spreads use very different ingredients than standard margarines; the predominant fat-mimetic ingredients are gelatin and starch.

  Depending on the fat level and the method of processing, these may be water-in-oil or oil-in-water emulsions, or merely a hydrated slurry designed to mimic an emulsion.

Healthier choices

  Margarine and related spreads have been positioned as a more-healthful alternative to butter, due to lack of animal fats, or more importantly, cholesterol. While this still holds true, thinking has undergone a shift due to emerging information from innumerable studies on diet and health. Most show that consumption of saturated fatty acids (SAFAs) increases cholesterol levels, while consumption of polyunsaturated fatty acids (PUFAs) lowers cholesterol levels. As a consequence, nutrition experts consistently state that we need to eat less fat and saturated fat, and reduce intake of dietary cholesterol. Recent studies show trans fat, containing a type of fatty acid often formed during hydrogenation, has an effect similar to that of saturated fat - increased consumption can raise cholesterol levels. Current dietary advice includes reducing intake of trans fats.

  When compared to butter, today's margarines and spreads have lower levels of fat, much lower levels of saturated fat and no cholesterol. In fact, clinical trials have shown repeatedly that switching from butter to margarine lowers cholesterol levels. A clinical study recently conducted by Dr. Joseph Judd, a nutrition researcher at the USDA Agricultural Research Services' Human Nutrition Research Center, Beltsville, MD, compared the effect of butter with two types of margarines - one with a moderate amount of trans fat and one with none. The margarine with moderate amounts of trans fat lowered levels of "bad" cholesterol compared to butter, and the trans-free margarine did slightly better. Neither of the margarines lowered the levels of "good" cholesterol.

  Soft margarines provide essential fats (linoleic and linolenic acid) and are a good source of vitamin A and sometimes vitamin E. "Compared to butter, margarine products contain at least one-third less saturated and trans fat combined, and many margarine products actually have little or no trans fat," says Sue Taylor, R.D., director of nutrition communications for the National Association of Margarine Manufacturers. "For those interested in reducing their intake of trans fat, some margarine products, including liquid margarine, some soft products and a new generation of sticks, are completely trans-free."

  Although low-fat and soft margarines contain only small amounts of trans fats, high-fat stick margarines can contain up to 2 grams trans fat per serving. In 1997, Promise®, made by Lipton, a U.S.-based subsidiary of the Anglo-Dutch conglomerate Unilever, became the first U.S. national brand to remove trans fats from the entire line of products. The stick product contains 0 grams trans fat per serving, yet is still good for cooking and baking. It is produced through an undisclosed proprietary technology.

  In 1995, Raisio Tehtaat Oy (the Rasio Group) of Finland used margarine made with canola oil, and containing no trans fatty acids, as a vehicle for cholesterol-lowering plant sterols. The product, Benecol®, seems to be a success in Finland and has been followed up with a low-fat version. In 1998, Lipton and McNeil Consumer Healthcare, Port Washington, PA, also announced the U.S. launch of sterol-fortified margarines. Also in 1998, the Raisio Group and McNeil signed a cooperative agreement to market Benecol worldwide - McNeil Consumer Healthcare, a Johnson & Johnson company, manufactures and markets Benecol end-products worldwide, while Raisio supplies stanol ester and markets Benecol products in its home markets. One other company, Forbes Medi-Tech, a Vancouver biotechnology company, has developed a plant stanol ingredient, Phytrol (FCP Food Supplement). The company has signed an option agreement with Novartis, Basel, Switzerland, for exclusive worldwide rights to license and sub-license FCP in food products. The product is derived from tall-oil soap, the fatty and resin acids produced from certain species of trees during the paper-pulping process.

  Benecol and Take Control from Lipton have been planned for market introduction in early 1999, but Benecol in particular is encountering opposition by the FDA. (See the January 1999 Food Product Design Regulatory Insight: "Cholesterol-Buster Status Clogged.")  The active ingredients in the sterol-enhanced products are minor components of oil, known as plant sterols. These substances, which are widespread in plants and in edible vegetable oils, are already consumed as part of our daily diet. Sitostanol ester is derived from wood or vegetable sterols. Sitosterol is a fat-soluble plant sterol; the hardened form of sitosterol is called sitostanol, which has a demonstrated cholesterol-lowering effect and can be incorporated into food without changing the food's physical properties or flavor. It acts by blocking dietary cholesterol and cholesterol secreted in the bile from being absorbed by the intestine.

  Over the last 40 years, clinical studies have shown that 1 to 2 grams of plant sterols can lower LDL, or bad cholesterol, by up to 10% without reducing HDL, or good cholesterol, levels. One study in the November 16, 1995 issue of The New England Journal of Medicine showed that those using the margarine for a year decreased their total cholesterol by 10% and decreased LDL by nearly 15%. Mayo Clinic endocrinologist Dr. Tu T. Nguyen is currently leading a team researching a margarine fortified with plant sterols. The study involves more than 300 people at six medical centers across the United States. Preliminary findings presented on Sept. 29, 1998 at the Fourth Cardiovascular Disease Prevention Conference in London also reflect sitostanol ester's ability to significantly reduce LDL levels.

  Other products made with less-controversial ingredients appeal to the health- and flavor-conscious. For example, Schratter Foods, Montvale, NJ, has introduced a cholesterol-reduced spread created by its sister company in Belgium. The butter/margarine hybrid, marketed as Corman Light Butter, is made from real butterfat, but is spreadable at refrigeration temperatures. It's formulated to contain six times less cholesterol and one-half the fat of regular butter.

Say cheese

  Although found more often on a cracker than on a slice of bread, cheese spreads provide another opportunity for product designers. Pasteurized process cheese spreads and products are consumed as a table spread as well as an ingredient in a variety of foods. Tasty cracker spreads might include bits of fruit, meat, vegetables or pimento, and added onion, bacon or smoke flavor. Cheese spreads lend taste and functionality to many formulations, including cheese balls, snack fillings, sauces, soups, macaroni and cheese, entrees and vegetable dishes.

  Variations on the cheese spread theme include pasteurized process cheese spread, pasteurized process cheese product, cold pack cheese and cold pack cheese food. The FDA defines standards of identity for some cheese spreads, while other products fall outside the CFR.

Some like it hot

  Pasteurized process cheese spread, as defined in 21 CFR 133.79, is prepared by comminuting and mixing, with heat, one or more varieties of cheese with emulsifying agents at levels of 3% or less. They may include the following optional ingredients: specified dairy products; gums not to exceed 0.8%; acidulants to achieve a pH 4.0 or higher; sweetening agent; water; salt; artificial coloring; spices or non-cheese flavorings; enzyme-modified cheese; and preservatives, such as sorbic acid (less than 0.2%), propionates (less than 0.3%), or nisin (not more than 250 ppm). Process cheese spread may contain fruit, vegetables and meat.

  Pasteurized process cheese spread must be heated at a minimum of 150°F for 30 seconds or longer and should be spreadable at 70°F. The product must contain a minimum of 51% cheese ingredients, 44% to 60% moisture and not less than 20% milkfat.

  Pasteurized process cheese product does not meet the CFR requirements for natural cheese usage, moisture and/or minimum milkfat content. Products include reduced-fat or no-fat spreads.

  Pasteurized processed cheese spreads are designed to provide functionality and consistency. Heat processing plus formulation furnish uniform flavor and texture without ingredient separation. The ingredients allowed as optional in the CFR help achieve this end.
  Optional dairy ingredients contribute solids and can assist in attaining the minimum fat requirement. Specified dairy products, used as-is or in dry form, include cream, milk, skim milk, buttermilk, cheese whey, anhydrous milkfat, albumin from cheese whey and dehydrated cream.

  Emulsifiers influence the texture and spreadability of processed cheese products. Phosphates and citrates bind the cheese proteins to the fat and water, which prevents ingredient separation. "In processed cheese spreads, the casein in the cheese emulsifies the fat," explains Bill Wendorff, associate professor Food Science, University of Wisconsin, Madison. "Emulsifying salts adjust the pH of the system, which controls how well the casein ties up the fat. Optimum casein functionality is achieved at a pH between 5.4 and 5.8."

  In addition to conditioning the casein to act as an emulsifier, acids also contribute to the flavor and shelf stability of a cheese spread. If the target pH of 5.4 to 5.8 is not achieved with the emulsifying salts and acid content of the natural cheeses, an acidulant can be added. This can be one or a mixture of two or more of the following: vinegar, lactic acid, citric acid, acetic acid and phosphoric acid. "Lactic acid is commonly used since it is the primary acid of many natural cheeses," notes Jim Podolske, assistant vice president applications and service, Opta Food Ingredients, Inc., Bedford, MA.

  Gums and stabilizers bind free moisture, contribute viscosity to the system, and affect the melt and consistency of a cheese spread. Ingredients used include: guar gum, gelatin, carrageenan, carboxymethylcellulose, xanthan gum and alginates.

Enzyme-modified cheese can enhance the flavor of a cheese spread or product. Wendorff cautions, however, that "adding too much EMC can give a different profile than the flavor achieved with aged cheddar cheese."

The cold pack choice

  Cold pack cheeses are commonly served as a table spread. "The foodservice industry might use a cold pack cheese food as an ingredient," notes Wendorff. "Since the product is not heated, it generally has a fresher flavor than a pasteurized processed cheese. The disadvantage is that cold pack products do not have the same smooth consistency as a processed cheese."

  Spreads labeled as cold pack differ slightly from pasteurized products in composition and processing.

  Cold pack cheese (club cheese), as defined in 21 CFR 133.123, is prepared by comminuting a blend of cheeses without heat. These must come from pasteurized milk. Optional ingredients include: acidulants that result in a finished product pH of 4.5 or higher; water; salt; artificial coloring; spices or flavorings that do not simulate a cheese flavor, and sorbic acid or propionates (not more than 0.3%) as a preservative. The moisture content of cold pack cheese cannot exceed the maximum moisture content prescribed for the individual cheeses in the blend. They must contain not less than 47% fat on a solids basis with the exceptions of Swiss (not less than 43%) and Gruyère (not less than 45%).

  Cold pack cheese food, as defined in 21 CFR 133.124, is produced by comminuting a blend of cheeses, also made from pasteurized milk, without heat. The product may contain the following optional ingredients: dairy products such as cream, milk, buttermilk, whey solids, anhydrous milkfat and whey protein; acidulants to achieve a final pH of not less than 4.5; water; salt; sweetener; guar or xanthan gum (0.3% maximum); sorbic acid or propionate (not more than 0.3%) as preservatives; artificial coloring; spices and non-cheese flavoring. Cold pack cheese food may contain fruits, vegetables and meats. Cold pack cheese food must consist of 51% or more of cheese. The maximum allowable moisture content is 44% with a 23% minimum fat level.

  Cold pack cheese spread does not have a standard of identity. "This product generally has a higher moisture content and less fat than cold pack cheese food," says Wendorff. "Milk ingredients, such as anhydrous milkfat and cream, can provide fat solids. Other ingredients might include whey solids for additional protein, gums to build viscosity and an acidulant to limit microbial growth."

  The body and consistency of cold pack cheese products depend on the selection of cheese ingredients and the comminuting process. The age of a Cheddar cheese, for example, influences the texture of the cheese particles. Grinding speed and time determine the particle size, which impacts product smoothness.

Getting the fat out

  Developing a reduced-fat or fat-free cheese product is not a simple afternoon's task. The fat must be replaced with ingredients that will deliver an acceptable mouthfeel and desired physical characteristics, such as spreadability, without adversely affecting processing.

  Replacing full-fat cheese ingredients with skim milk natural cheese reduces the fat content. Desired texture and stability can then be built into the system with additional solids, gums, stabilizers and water. Dairy ingredients, such as whey protein concentrate and non-fat dry milk, can contribute solids.

  Added moisture makes the system more dependent on gums and stabilizers to maintain physical characteristics. "It is important not to overextend the system with too much moisture to ensure the functionality and safety of the product," says Wendorff. "In a cheese spread, the moisture and protein form a matrix which emulsifies the fat. In a reduced-fat product, this matrix continues to dictate the functionality of the system and it is desirable to maintain approximately the same moisture-to-protein ratio." Replacing fat with too much water introduces the potential for microbial growth.

  Sodium chloride provides flavor and preservation. "Reducing the fat in a cheese often enhances the sharpness of the salt, which might lead to a reduction in the salt level," continues Wendorff. "A lower salt content combined with additional water can increase water availability and encourage the growth of spoilage organisms."

  Adding whey protein to a reduced-fat cheese spread contributes functionality, since the protein binds with water. Fat solids can be replaced with whey solids and whey protein concentrate. "There is the potential for lactose crystallization with whey solids, which can be eliminated by using delactosed whey," says Wendorff. "Lactose has low solubility in a cheese spread system. If lactose reaches the saturation level, it begins to crystallize into sharp particles."

  Starch can replace a portion of the fat solids. For example, a fat-mimetic corn starch that is not chemically or enzymatically modified is available from Opta for use in reduced-fat cheese products, and can be used at a 1% to 2% level to achieve about a 50% reduction in fat, says Podolske. "Cheese products made with the starch typically include additional solids, such as maltodextrin, and cheese flavor or lipolyzed butter oil." This ingredient easily disperses in cold or warm water and can withstand homogenization temperatures and pressures. "The starch does not increase in viscosity during processing, and thickens upon cooling," Podolske adds. "Reheated products become flowable."

  Altering the fat content of a cheese-spread product often results in a firmer product with reduced melt, which can impact processing. For example, "it takes longer to melt and incorporate skim milk cheese into a formulation," notes Wendorff. "The use of additional gums and stabilizers can alter the point at which the water within the system is totally bound."

Nuttin' but nuts

  History credits the invention of peanut butter, over 100 years ago, to a St. Louis physician. Of the 2.4 billion pounds of peanuts consumed in the U.S. each year, 46% is consumed as peanut butter. Are you picturing millions of children enjoying their peanut butter and jelly sandwiches as part of their school lunch? The facts might surprise you. Leslie Wagner, public relations director, Peanut Advisory Board, Atlanta, GA, reports that adults consume more peanut butter than children do.

  Peanut butter conforms to standards of identity requiring 90% of the product to be made up of peanuts. The remaining 10% is composed of sweeteners, stabilizers, emulsifiers and salt. Sweeteners used include sugar, honey, corn syrup or combinations of these. Molasses is also added, but more to complement the roasted-nut flavor rather than for sweetening.

  Within the last five years, an additional standard of identity was established for peanut spread, in which the peanut contribution was reduced from 90% to 60%. The protein content of peanut spread remains equivalent to that of peanut butter, as do the calories. Reduced-fat peanut butters and spreads generally incorporate additional protein from either soybeans or deoiled peanut solids. If the more-costly peanut solids are utilized, it is possible to formulate a reduced-fat product that is still 90% peanuts, labeled peanut butter, while the use of soybean protein results in a reduced-fat peanut spread containing 60% peanuts. The new standard of identity for spread was developed to provide a peanut butter or reasonable facsimile for those consumers who viewed fat as the enemy - in spite of all the information indicating that legume and nut fats have an important function in the overall diet.

Nut-butter stabilizers

  As early as 1923, peanut-butter innovators discovered that the tendency of peanut oil to migrate to the top of the tin could be mitigated through the addition of a peanut-butter stabilizer. Stabilizing the peanut oil not only results in creamier, easy-to-use product, it also protects unsaturated peanut oil from oxidation, thereby extending shelf life.

  Peanut oil contains 55% monounsaturated and 28% polyunsaturated fatty acids, with only 17% of the fat contributed by saturated fatty acids. The mono- and polyunsaturates make it liquid at room temperature, and subject to oxidation reactions. Stabilizers are made of hydrogenated seed oils, which prevent the migration of peanut oil - the majority of the allowable 55% fat in the product. Emulsifiers such as mono- and diglycerides are also useful in peanut butter, in spite of its obvious lack of moisture, usually less than 2%. It has been speculated that the emulsifiers interact with the protein in the absence of water, helping to suspend them within the oil base.

  Today's peanut-butter stabilizers are based on a blend of hydrogenated oils from rapeseed, cottonseed and soybean. Another hard fat with functionality similar to that of rapeseed is hydrogenated palm oil; however, consumer aversion to tropical oils has diminished its use.

  The use of these three hydrogenated seed oils to stabilize the oil, as well as optimize flavor release and consistency, forms the basis for an interesting exception in the food industry. In most foods, the use of rapeseed oil has been discontinued since the advent of canola oil. However, a small quantity of rapeseed oil with erucic acid is still widely used as a peanut-butter stabilizer. What makes erucic acid so valuable in this application? The answer is in the structure of this 22-carbon monounsaturate, which after hydrogenation to its saturated form, develops a very effective crystal lattice structure called a beta-prime polymorph. This network of linked fatty acids entraps peanut oil within the peanut butter matrix at very low levels of addition, typically at less than 1% of the final butter. Considered safe at this level, hydrogenated rapeseed oil is blended with hydrogenated cottonseed and soybean oils in specified ratios to extend the melting-point range and facilitate spreadability at room temperature and mouthmelt at body temperature. The stabilizer also controls stickiness without compromising the peanut flavor release.

  Stabilizing peanut oil not only controls oil migration, but also offers oxidation protection by encapsulating oil in the beta-prime matrix. In old-fashioned, or natural, peanut butters where oil separation is not prevented, the oil is more accessible to oxidation once the container is opened. These products require refrigeration after opening. In stabilized peanut butter, the shelf life is increased up to one year, even without refrigeration.

  For product developers who wish to gain a better understanding of the role of stabilizers and emulsifiers in nut butters, Art Rittenberg, group leader confectionery technology, AC HUMKO, Memphis, provides an excellent technical summary entitled "Peanut Butter - A Classic Fat Migration Challenge." In this summary of patents and other texts, the effects of the grind size - or the milled peanut particle size - on oil migration are discussed: "Smaller particle size produces a much slower gravitational separation rate." In finely ground butters, the large specific surface area and the reduced space between particles impedes oil transit throughout the matrix. Three known techniques stabilize oil in nut butter:
minimizing oil release by a coarser grind; increasing particle concentration to reduce oil mobility; and formation of a network using hydrogenated oil and emulsifiers to entrap oil.

Beyond peanuts

  Regular smooth or chunky-style peanut butter appear to be the preferred spreads in terms of cost and nutrition, but the food industry is continually improving the flavor and variety, and introducing other options. Recent product introductions focus on flavor enhancements, either improving the classic roasted-peanut flavor or adding complementary flavor favorites. "Honey and peanut butter sandwiches account for 5.3 million sandwiches each year" states Hunt-Wesson Foods, Fullerton, CA, in a press release announcing the new Honey Roast flavor of Peter Pan peanut butter in December of 1998. Another major brand is test marketing peanut-butter/chocolate and peanut-butter/apple/cinnamon flavor combinations. The gourmet specialty market is also offering some interesting new flavor combinations, with more grown-up savory flavors that feature garlic and Worcestershire.

  For the 25% of households that do not stock peanut butter as a staple, there are other varieties of nut-butter spreads to tempt their palate. Bud McDonald, vice president sales, Westnut, L.L.C., Dundee, OR, has seen extraordinary growth in the sales of hazelnut butter since it was introduced by his firm in 1994. Hazelnut butter is milled from roasted hazelnut kernels in a process similar to that of old-fashioned or natural peanut butter. It is generally sold unstabilized and without preservatives, and requires refrigeration to minimize oxidation. In industrial processing, it is used quickly enough that shelf life and oil separation are rarely an issue. Hazelnut butter has a higher oil content - about 60% - making it thinner than peanut butter.

  "The hazelnut is the most widely consumed nut on a worldwide basis," states McDonald. He points out that hazelnuts are eaten in Europe much the same as peanuts are eaten in the United States. Hazelnut butter is frequently enjoyed in Europe as a bread spread for toast. As Americans adopt European styles in coffee and confection, gourmet spreads based on hazelnuts are likely to find a new niche. Flavors known to complement hazelnuts take their cue from confections, including coffee, chocolate, mocha and vanilla creme.

  Almond butter, available as stabilized almond butter through the addition of hydrogenated cottonseed oil, is one of many food ingredients processed by Blue Diamond Growers, Sacramento. Sold in bulk, industrial almond butters are blended to customer specifications with added sweeteners or flavors as required. Almond butter can be prepared from either blanched or unblanched toasted almonds. Unblanched almonds give a characteristic brown texture to the butter that some customers prefer. Complementary flavors added to almond butter include honey, cinnamon, vanilla, chocolate and salt.

  An increased interest in almonds is developing as their health benefits become better known, says Sam Cunningham, Ph.D., Blue Diamond's director of research and development. "Consumer health magazines are extolling the health benefits of eating almonds, reversing the formerly held belief that nuts only add fat the diet. Almond butter spreads are another product consumers can use to increase almond consumption."

  The market for almond and hazelnut butters destined to be formulated into spreads is relatively small when compared to the use of nut butters as food ingredients. In applications where nut flavors are desired, nut butters deliver more nut flavor than do nut pieces, and they do it in an easy-to-use form. Nut spreads will continue to provide a flavor powerhouse that delivers sound nutrition, whether in a retail spread, or as food ingredients.

  Whether made from vegetable oil, milk, cheese, nuts or other raw ingredients, spreads enhance many of our favorite foods. Tackling trends and technology gives product designers the opportunity to spread their imaginations as well as expand their expertise in keeping spreads on top.

Testing Margarines and Spreads
  Most of the analytical work on margarines and spreads is completed on the ingredients prior to processing. The oil blend, in particular, receives most attention, as good-quality oil is essential to maintaining a good-tasting product throughout the shelf life.

Analytical methods for oil include:
Solid Fat Index (SFI). This measures the amount of solid fat in the oil blend at different temperatures. Normally, SFI will be measured at 50°F, 70°F, 92°F and 100°F. Stick and soft margarines have different SFI profiles. In Europe, and to a degree in the United States, the solid fat content of oils is measured by NMR, in which case the solids content is referred to as N values. Typically, degrees Centigrade is also used, so the measurements are normally N10, N20, N30 and N35.
Free Fatty Acids (FFA). FFA is used as a marker to determine that the oil has been deodorized correctly. A typical value is less than 0.1%.
Peroxide Value (PV). PV measures the oxidative stability of a fat blend. Typical value is less than 1.
Metal content. It is important that copper and iron, particularly, are removed from the oil blend, because they facilitate oxidation and the development of off-flavors. Standards for metal levels vary.
Gas Chromatography (GC). GC is widely used to determine the overall fatty-acid profile of the blend; i.e., the amount of saturated fat, trans fat and unsaturated fat in the blend. This is normally required for labeling purposes.

Analytical methods for margarines and spreads include:
Taste. It is important that the margarine taste remains constant throughout each production run and over shelf life. In some cases, individuals are trained to perceive small variations between different products.
Microbiology. Margarines and spreads, while posing a very low microbial risk, are tested for the presence of spoilage organisms and/or pathogens.
Texture. Different margarines and spreads will be manufactured to different specifications for hardness. Product hardness is usually measure by a cone penetrometer.
Salt/pH/Moisture content are all measured by standard techniques.

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