Finding Trans Fat
Everyone involved with food nutrition, production or consumption is becoming aware of the presence, prevalence and implications of trans fat in our food supply.
The processing vehicle used to impart certain functionality to food ingredients, the hydrogenation process that produces trans fat has become synonymous with “bad fat” in the eye of the consumer. Trans fat has been linked to elevated blood cholesterol and triglycerides, increasing the risk of heart disease and certain cancers. All of these factors have prompted the FDA to require the declaration of the level of trans fat on the Nutrition Facts panel, the first major change to the panel format since its inception in NLEA 1993 final rule.
“Imparting truthful, factual, non-controversial information about the presence or absence and amount of trans fat in food products on the label will provide consumers with information to help them reduce their risk of coronary heart disease,” notes the Final Rule on Trans Fat Declaration FDA, HHS, which will be made effective January 1, 2006.
As a result, the FDA is revising Section 101.9(c) by adding paragraph Section 101.9(c)(2)ii to require the quantitative declaration of trans fat on the Nutrition Facts panel.
What are Trans Fats?There are four major categories of dietary fat for labeling purposes: saturated, monounsaturated, polyunsaturated and trans fat. The FDA considers the terms “trans fat” and “trans fatty acids” as interchangeable. When listed on a Nutrition Facts panel, it must be termed “trans fat” and be declared directly below the amount of saturated fat. Listing unhealthy fats, such as saturated and trans fats, will be mandatory. Mono- and polyunsaturated fats, which are considered “healthy” fats, are voluntary nutrients. They may or may not be declared on a Nutrition Facts panel.
Saturated fat is so called because all of the carbons have the maximum number of hydrogen atoms attached. The carbons are saturated with hydrogen. Unsaturated fats have one (mono-) or more (poly-) double bonds between carbons in the carbon chain backbone of the fatty acid. Cis configuration double bonds have hydrogens attached to the carbons involved in a double bond--both on the same side.
Trans configuration double bonds have the hydrogens on opposing sides--about the carbon double bond. This simple change in stereochemistry allows for many different properties of the oil or fat. Trans fat is used to impart many different functionalities to foods.
Hydrogenation is the process that creates trans fatty acids. Basically, it takes vegetable oils and reconfigures their mono- and polyunsaturated fatty acids into more double bonds of the trans configuration. These hydrogenated oils have many advantages for food formulations. Hydrogenation increases the melt point of fats, allowing them to stay solid at room temperature. They allow food products to last longer, cost less and encounter less rancidity. Hydrogenated oils provide a certain firmness and plasticity to foods, and are well suited for creaming/aerating applications. All of these properties have been used extensively in food processing, especially with cookie and cracker formulations. However, hydrogenated oils and fats are not as healthy as natural vegetable oils.
It is important to note that certain foods of animal origin contain a small amount of naturally occurring trans fat. All dairy and beef products contain a small amount of trans fat, resultant from the ruminant bacteria that allows for cellulose digestion. Fish also may contain a small amount of trans fat, believed to be caused by bacterial degradation. These naturally occurring trans fats will have a minimal impact on a Nutrition Facts panel, and may or may not calculate as “less than” on the label.
Hydrogenated oils are distinguished easily from naturally occurring trans fat by their distribution in the fatty acid profile. Hydrogenation creates a significant amount of C18:1 and C18:2 trans fatty acids, and reduces the amount of linoleic and linolenic fatty acids. The reduction of linoleic and linolenic fatty acid is the reason hydrogenated oils have a greater shelflife and less instance of rancidity; the breakdown of these polyunsaturates may cause undesirable byproducts.
It also is important to note the FDA makes a distinction between isolated or interrupted and conjugated polyunsaturates containing one or more double bonds with a trans configuration. These so called conjugated fatty acids--most notably conjugated linoleic acid, or CLA--have been found to have healthy benefits in the diet, and are excluded from the total trans tally. CLA is prevalent in butterfat, and may be found in beef tissue fat also. Only isolated polyunsaturated fats with one or more trans double bonds are included in the total trans fat quantification.
Trans fatty acid is primarily quantified by capillary gas chromatography with flame ionization detection techniques. Fats are extracted from foods, derivatized to form fatty acid methyl esters (FAMEs), and the resultant FAMEs are quantified on a GC system capable of sufficiently separating the cis and trans isomers. The FDA specifically is recommending a 100m fused silica column (SP-2560, 100m x 0.25mm id, 0.20um film thickness). Modification of existing American Organization of Analytical Chemists (AOAC) and American Oil Chemists Society (AOCS) methods is the basis for protocols that may quantify trans fat. The most critical elements of the suitability of a protocol are extraction without fatty acid reconfiguration, and sufficient separation of cis and trans isomers, which allows for correct identification of each fatty acid species.
There are many options and strategies for food manufacturers who wish to reduce or eliminate the amount of trans fat in their product formulations. These include the use of tropical oils, which generally have a higher melt point. They can be used alone, in blends, and also as fractionated fats. Many oil manufacturers have sought greater fat stability through breeding, both natural and genetically modified, that takes normally liquid oils and gives them properties of greater stability and firmness, without the presence of trans fat. Molecular interesterification, both chemical and enzymatic, can produce solid fats without hydrogenation. And the use of fat replacers and other functional ingredients such as gums and emulsifiers are an option to reduce trans fat levels while maintaining certain functionalities.
Trans fat is in the news these days, as well as on the minds of consumers seeking a healthier diet and lifestyle. And as of January 1, 2006, look more closely to see trans fat on the Nutrition Facts panel of foods and dietary supplements in the U.S.
Marty Kotvas is the senior food chemist with Microbac Labs, Pittsburgh division, and has been analyzing fatty acids for 15 years; he has 20 years of experience in analytical chemistry. He can be reached at 724-772-0610.
More than Trans Fat-freeEveryone in the food industry is feeling the pressure to reduce or eliminate trans fat. However, in addition to limiting or eliminating trans fats, many suppliers hope also to address high cholesterol, diabetes, obesity and other diseases that find their beginnings in fatty foods. Omega-3 fatty acids and plant sterols are increasingly added to many oils and foods.
With the help of breeders at Iowa State University (Ames, Iowa), one company follows International Organization for Standardization (ISO)-certified procedures to grow and process ultra-low linolenic acid soybeans. Linolenic acid is the most unstable component in soybean oil. Decreasing linolenic acid reduces the oil's tendency to oxidize, thereby increasing shelflife. Rich Lineback, vice president of sales and marketing at the company, says that aside from being trans fat-free, the ultra-low linolenic soybean oil made from non-genetically modified (GM) soybeans has less than 1.5% linolenic acid compared to 7% normally. “Low-lin oil performs better than its oxidized stability index (OSI) would lead you to believe,” says Lineback. This neutral-tasting oil with low taste transferability has extended fryer life in foodservice operations and can be used in a variety of other applications including spray-finishing, non-dairy creamers, cheese sauces and cheese powders. Lineback says that even pharmaceutical companies are using low-linolenic oil in softgel tablets that had previously used partially hydrogenated vegetable oils.
“Another exciting area for oil chemistry is the area of structured lipid research, which is supported by advances in biotechnology,” says Marialuci Almeida, Ph.D., a project manager and scientist at an oil supplier. “It will have promising benefits for human nutrition and a positive impact toward the reduction of cholesterol levels,” says Almeida.
Marcia A. Wade, Technical Editor
Blend Back to the FutureIn this soon to be trans-reduced world, blending fractionated palm oils could be one of the solutions to formulating baked goods. “The reality is that semi-solid fats, either saturated fat or trans fat, are essential for the functionality of most baked goods,” says Gerald McNeill, Ph.D., technical director at a palm oil supplier. It is necessary to choose one of the two, or do not make baked products, he jokes. In baked goods, fat melting point and crystal formation is extremely important to texture, creaming and the incorporation of air bubbles during the whipping and mixing process.
Palm oil is well suited for the task because it is a naturally hard fat that is low in polyunsaturates (linoleic acid) and, therefore, maintains a stable shelflife, without the need for further processing. There are many palm oil-based alternatives to hydrogenated fats. Palm oil and palm kernel oil (from the pit found in the center of the fleshy palm fruit) produce two distinct and different products. Fractionation further differentiates palm-based oil and separates palm oil into its two most influential components: palm stearin, formed from crystals that are filtered off after fractionation, and palm olein, which is liquid at room temperature. Fractions are retrieved by raising the temperature in five degree increments with each subsequent heating and cooling process, instructs McNeill.
Stearin is solid and waxy but can be blended with olein, vegetable oils or [emulsified with] water or air to produce any type of consistency. In baking, broad melting ranges are desirable. Since palm kernel oil melts very quickly when warmed, it is not appropriate as a bakery shortening, but excellent for confectionery. It can be very hard and brittle like chocolate and melt quickly in the mouth. Blending fractions of stearin and olein at varying percentages can produce an assortment of textures from liquid to solid and all those in between.
Marcia A. Wade, Technical Editor