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(Circulation. 2007;115:2231-2246.)
© 2007 American Heart Association, Inc.
AHA Conference Proceedings |
| Abstract |
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Key Words: AHA Conference Proceedings diet fatty acids nutrition trans fat trans fatty acids
| Introduction |
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The key objective of the conference was to provide an interactive and collaborative forum to discuss the current status and future implications of reducing the intake of trans fatty acids without increasing saturated fats as part of a balanced dietary approach to reduce the risk of cardiovascular disease while maintaining functionality and consumer acceptance of packaged, processed, and prepared foods.
| History of Trans Fatty Acids in Health |
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The use of partially hydrogenated fats accelerated in the 1960s, 1970s, and 1980s as food producers responded to public health recommendations to move away from animal fats and tropical oils. At the time, partially hydrogenated fats seemed to be a good alternative, particularly because of their stability, cost, availability, and functionality. Before the 1990s, limited data were available on the health effects of trans fatty acids, and the data often were contradictory. For example, an article published in 19571 found no significant effect between coconut oil (iodine value 9) and hydrogenated coconut oil (iodine value 5.2) on plasma cholesterol levels of 9 healthy males, probably because, independently of hydrogenation, the fat was composed of predominantly saturated fatty acids. (Iodine value is a measure of the total number of double bonds present in fats and oils. It is generally expressed in terms of number of grams of iodine that will react with the double bonds in 100 g of fats and oils.) In this same study, researchers reported that compared with coconut oil, the hydrogenated whale oil (iodine value 83) was similar in its effect on plasma cholesterol levels, whereas the nonhydrogenated whale oil (iodine value 118) was found to be hypocholesterolemic. One year later, researchers reported that within the context of a 35% butterfat diet, there was no significant difference between supplemental corn oil and hydrogenated corn oil.2
Between 1960 and 1990, numerous additional studies were published with inconsistent results. This variability is likely attributable to differences in the background diets, starting fatty acid profile of the test oil, differences in the degree and type of hydrogenation, and less-than-optimal comparison fats.
In 1990, Mensink and Katan3 compared the effect of diets rich in oleic acid, saturated fatty acids, and trans fatty acids. They reported that relative to a diet rich in oleic acid, total cholesterol and low-density lipoprotein (LDL) cholesterol levels were higher after subjects consumed diets rich in saturated or trans fatty acids. In contrast, relative to the diet rich in trans fatty acids, high-density lipoprotein (HDL) cholesterol levels were higher after subjects consumed the diets rich in saturated fatty acids or oleic acid. The differential effects on LDL and HDL cholesterol levels resulted in the least favorable total-to-HDL-cholesterol ratio after the subjects consumed the diet rich in trans fatty acids.
The negative effect of partial hydrogenation and resulting trans fatty acids on serum cholesterol levels bears out consistently in multiple research studies conducted throughout the 1990s. A 1999 study4 found that partial hydrogenation had a linear, positive relationship with LDL cholesterol levels in that increasing dietary intake of trans fatty acids increased the levels of LDL cholesterol. In contrast, HDL cholesterol levels remained relatively constant with increasing hydrogenation and decreased only with the highest level of hydrogenation, resulting in the least favorable total-to-HDL-cholesterol ratio. A recent meta-analysis of available data found that a 2% increase in energy intake from trans fatty acids was associated with a 23% increase in the incidence of coronary heart disease.5
The US Food and Drug Administration (FDA) mandated that as of January 1, 2006, the Nutrition Facts panels of all packaged food labels must indicate the quantity of trans fatty acids in a serving of the food product. Since the phasing in of this information, it appears that the regulatory action has catalyzed food manufacturers to reformulate many of their products to decrease levels of partially hydrogenated fats. This regulatory action also has resulted in an increased awareness about dietary trans fatty acids in the general public and in efforts by a number of cities and states to limit the trans fatty acid content of restaurant foods.
| Value of Addressing Trans Fatty Acid Issues to Help Consumers |
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Other highlights of the survey include the following:
| Food Science Behind Fatty Acid Technology |
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The major fatty acids found in food are palmitic, stearic, oleic, linoleic, and linolenic acids. Their structures, physical properties, functionality traits, and health effects are summarized in Table 2.
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Trans fatty acids occur naturally at relatively low levels in meat and dairy products as a result of the fermentation process in the animals rumens. In the US diet, a large proportion of trans fatty acids (
80%) is contributed by the partial hydrogenation of fats. Partial hydrogenation increases the shelf life and flavor stability of foods containing fats and gives the fat a higher melting point. Compared with fatty acids with cis bonds, trans fatty acids tend to be more stable in storage and during frying. Partially hydrogenated fats tend to be more solid than unsaturated fats but less solid than saturated fats. The major dietary sources of trans fatty acids are traditional vegetable shortenings and solid margarines, crackers, candies, cookies, snack foods, fried foods, baked goods, and other processed foods. The actual amount coming from any of these products is changing rapidly as a result of efforts by food producers to decrease the level of trans fatty acids in their foods.
Measurement of Trans Fatty Acids
Two methods approved by the FDA for measuring fatty acid composition to declare the amount of trans fatty acids in the food on food labels are summarized next. There are advantages and disadvantages to both processes.
100 m long. It takes about 1 hour to run a sample with this process, and the method can measure individual trans fatty acid isomers to
0.1 g per serving. The advantage of this method is the ability to measure individual trans fatty acid isomers to as low as 0.1 g per serving, but the disadvantages are the long sample preparation and gas chromatography run times.
1 minute to read the sample with an accuracy of 0.5 g trans fatty acids per serving. The minimum trans fatty acid content of the sample must be 0.8% to 1% to get an accurate reading, depending on sample size. This method makes no distinction among the different trans fatty acid isomers and therefore can give a value only for the total trans fatty acids. Different trans fatty acid isomers may have different effects on health. For example, although trans fatty acids created through partial hydrogenation have been linked with an increased risk of coronary heart disease,5 vaccenic acid, a naturally occurring trans fatty acid in the fat of ruminants, is converted in human beings to rumenic acid, an isomer of conjugated linoleic acid.11 Conjugated linoleic acid has been shown to protect against some types of cancer in animals and humans.12 Therefore, the lack of sensitivity to different trans fatty acid isomers limits the usefulness of ATR-FTIR as an assessment method for other purposes. There are also limitations regarding the type of oil being measured; for example, the oil cannot contain large quantities (>5%) of conjugated unsaturated fatty acids (eg, tung oil), and the oil cannot contain functional groups around the isolated trans double bonds, all of which interfere with the ATR-FTIR measurement. The sample also must be liquid during measurement. Despite its limitations, most food manufacturers use this method because of its speed. | Fats and Oils for Human Consumption |
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Salad and Cooking Oils
Bland flavor, light color, good stability, and manufacturing processing and packaging flexibility are important for salad and cooking oils. Good choices to meet these requirements are polyunsaturated and monounsaturated oils. Less polyunsaturated fat is preferred to minimize the likelihood of rancidity and the need for refrigeration. This type of salad or cooking oils also is suitable for in-home 1-time deep frying and pan frying. The need for trans fatty acid reduction in this type of liquid oils is not an issue because most salad or in-home cooking oils on the market today do not contain trans fatty acids and cooking this type of oil in ones kitchen does not produce trans fatty acids.
Frying Oils
Commercial frying applications include restaurant frying such as the preparation of deep-fried foods and packaged foods such as snack chips.
Oils for commercial frying require stability related to the thermal deterioration processes of oxidation, hydrolysis, and polymerization. For consumer acceptance, the fatty acid composition of the oils needs to have 20% to 30% linoleic acid to produce a desirable full deep-fried flavor to the foods; however, higher levels of linoleic acid might introduce "off"-flavors from oxidation. For restaurant use, oils need to be stable because a long fry life is required and the oil has to withstand the high temperatures of commercial frying. Food manufacturers prefer stable oils that can also tolerate high temperatures and allow an extended shelf life for foods after they are packaged.
Stable frying oils are characterized by increased amounts of oleic acid (preferably in the moderate range of 50% to 65%), decreased amounts of linoleic acid (preferably in the 20% to 30% range), and decreased amounts of linolenic acid (preferably no more than 3%). It has been common to acquire stable commercial frying oils by changing the fatty acid composition by partial hydrogenation. Potential alternatives to partially hydrogenated oils for commercial frying include naturally stable oils such as corn, cottonseed, palm, peanut, and rice bran and modified fatty acid oils such as mid-oleic corn, high-oleic/low-linolenic canola, high-oleic sunflower, mid-oleic sunflower, low-linolenic soybean, and mid-oleic/low-linolenic soybean oils (Figure 1). In choosing trans fatty acidfree frying oils, consider the cost, availability, oxidative stability, functionality in terms of the appearance and texture, flavor, and nutrient composition of the option. Specifically, some of these oils such as animal fats and tropical oils contain high amounts of saturated fats and should not be considered as replacements.
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Solid Fats
Functionality parameters in solid fats (spreads and baking shortenings) include the melting point, lubricity, moisture barrier, and creaming ability. The parameters of fat content, emulsifiers, solid fat in blending, and melting point need to be in place before product development is begun. In the development of solid shortenings to reduce trans fatty acids, functional parameters such as plasticity for extrusion into dough and creaming properties are important. The dough should not be sticky or "oil out" (have the fats separate from the dough) at high temperatures. Solid shortenings packed in cubes need to allow handling without deformation.
Partially hydrogenated fats have been effective in achieving functionality and stability requirements in solid fats. To meet the functionality and stability requirements in solid fats while minimizing trans fatty acids, many of the current options typically include significantly increasing saturated fatty acids.
Several consumer brands of solid trans fatty acidfree margarines have become available in recent years, as have solid shortenings. The availability of these products for commercial use is uncertain at this time.
| Health Sciences of Dietary Fatty Acids |
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In terms of per capita spread consumption, US margarine consumption was minimal before World War II, but after World War II, there was a significant increase. Margarine consumption surpassed the intake of butter during the 1960s, 1970s, and 1980s. In the 1990s, the consumption of margarine decreased, and the intake of butter remained constant. Today, there is essentially an equal intake of margarine and butter. On the basis of a proprietary analysis of AC Nielsen sales data conducted by the National Association of Margarine Manufacturers, there also has been a shift away from stick margarine to soft and liquid margarines, with soft and liquid margarines accounting for 72% of the margarine sales in 2006 compared with 46% in 1990.
The use of shortening increased steadily throughout the 20th century. Salad and cooking oils were separated from other edible oils in the USDA Census Bureau for Added Fats and Oils in the mid-1960s, and they represent the largest single source of fat in the US diet today.
World vegetable oil consumption is about 106 million metric tons, with soybean and palm oil representing
60% of this consumption (Table 3).13 The breakout of edible oil use in the United States is quite different. Americans consume
10% of all the edible oils in the world, and
75% of this is soybean oil.14 Key uses for soybean oil in the United States include baking and frying (44%), salad and cooking oils (44%), and margarine (7%).
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Trans fatty acids have been included in the USDA National Nutrient Database for Standard Reference only since 1994,15 and only since 2002 was national randomized sampling conducted to derive trans fatty acid values. The database now contains trans fatty acid values for >800 food products, but this is only a fraction of the total products in the database. In addition,
50% of these 800-plus products are branded, and many of them have been reformulated since being added to the database. The rapid changes in product formulation led to challenges in maintaining accurate trans fatty acid consumption data.
A 2006 review16 showed that trans fatty acid consumption per person per day in the United States decreased from
10 g per person per day in 1984 to
4 g per person per day in 1995. Comparatively, in Denmark, the per capita consumption of trans fatty acids steadily declined through the 1980s and 1990s from slightly >2 g/d per person in 1992 to <0.5 g/d in 1999.17,18 In June 2003, Denmark introduced protection measures concerning trans fatty acids in food. As of January 2004, the level of industrially produced trans fatty acids in oil and fats intended for the consumer, either alone or as an ingredient in foodstuffs, must not exceed 2%. As a result, trans fatty acids created through partial hydrogenation have virtually been eliminated in Denmark.
Although mean values are available for per-person per-day trans fatty acid consumption, the range is high because of the variability of the trans fatty acid content in foods. For example, a review of 37 different kinds of bread, cake, and related products in the Washington, DC, area showed that the average grams of trans fatty acids (grams per 100 g fat) ranged from 0.0 to 48.8.19 The significant difference in the trans fatty acid content in products within each food category is due to differences in the type of fats and oils used in the manufacturing process.
Dietary Fatty Acids Affecting Cardiovascular Disease and Diabetes
Dietary fat profiles have a significant impact on health. Many studies have shown that trans fatty acids can adversely affect LDL and HDL cholesterol levels, and some data suggest that trans fatty acids adversely affect other outcomes.5
A meta-analysis of 60 controlled trials of dietary fats and blood lipids (Figure 2) show that as carbohydrates are replaced with polyunsaturated or monounsaturated fats, the ratios of total to HDL and LDL cholesterol decrease.20 However, when carbohydrates are replaced with trans fatty acids, the ratio of total to HDL cholesterol increases, as does LDL cholesterol. Trans fatty acids also are the only type of fats that do not raise HDL cholesterol.
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Strong observational and experimental evidence also exists for the increasing risk of coronary heart disease associated with trans fatty acids. Multiple prospective studies and case-control studies have reported a positive association between trans fatty acid intake and the risk of developing coronary heart disease.2123 A less mature data set suggests a positive association between trans fatty acid intake and type 2 diabetes and elevated inflammatory markers.24,25
| Alternatives |
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25 billion pounds of edible oils used, close to 18 billion pounds were soybean oil.
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Soybean oil is commonly used because it is abundantly available, is a versatile base stock, and is cost competitive. However, liquid soybean oil is high in linolenic acid, and for rigorous applications such as commercial frying and baking, it is frequently hydrogenated to increase stability.
Alternatives to Partially Hydrogenated Fat
There are a number of alternatives to partially hydrogenated fat. Table 5 provides a summary and lists some of their advantages and drawbacks.
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| Summary of Trans Fatty Acid Alternatives Presented |
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On the basis of the estimates of the companies in Table 6, the national supply of these key trans fatty acid alternative commercial products would total
3.25 billion pounds in 2007, compared with the
9 billion pounds of partially hydrogenated oils that should be replaced in North America, as shown previously in Table 4.
| Considerations for Evaluating and Choosing Trans Fatty Acid Alternatives |
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The dynamics of industrial marketing can influence the choice of commodity crops versus trait-enhanced oils. As shown in Figure 3, most (
90%) of the soybeans and corn are currently sold as commodities for syrup (corn), meal, feed, alternative fuel, and starch.
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In the meantime, trait-enhanced oils face the following challenges:
There are conceptually many pathways in generating alternatives for trans fatty acids. All of these pathways can lead to a significant reduction in trans fatty acids in the US food supply. Given that many pathways are available and factors of industrial marketing are at play, no perfect oil will dominate, and all of these options will be used.
| Considerations for Food Reformulation |
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For many applications, food reformulation to reduce trans fatty acids is less of a technical challenge and more of a business decision. Several factors were identified that promote the reduction of trans fatty acids in the food supply: (1) leadership and commitment of corporate senior management, (2) collaboration across the supply chain and ongoing interindustry dialogue, (3) adequate supply of alternative ingredients for food reformulation, (4) increased competition in the marketplace to focus on health and wellness, (5) media coverage and consumer demand, and (6) regulation to stimulate changes.
| Use of Alternatives in Food Manufacturing (3 Case Studies) |
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Frito-Lay North America
Summary of Presentation by Robert Brown, PhD, MPH
With the September 2002 release of the Institute of Medicines "Report on Dietary Reference Intakes of Trans Fatty Acids,"9 Frito-Lay responded with a strategic decision in November 2002 to ensure that all of their oils would be "trans fat free" within the year. The companys Nutrition and Regulatory Affairs Division had been doing research and development on options for trans fatty acid alternatives since the late 1990s, and by 2002, viable options had been identified. Frito-Lay based its decision on nutrition using a parameter of unsaturated-to-saturated or trans fatty acid ratio, as well as considerations for flavor, stability, and cost. In 2002, corn oil was identified as a viable option, although it contributed to only 2.2% of the world supply. By July 2003, trans fatty acids had been eliminated from the companys most popular brands, including potato chips, which had been fried in partially hydrogenated oils. Mid-oleic sunflower oil also was identified as a viable option to replace cottonseed oil used in another brand of potato chips. However, it took 4 years of working with farmers in North Dakota to plant mid-oleic instead of regular sunflower seeds to generate an adequate supply. In 2006, the mid-oleic sunflower oil was used instead of cottonseed oil to reduce saturated fats and to increase polyunsaturated fats in one of their major brands of potato chips.
Several significant challenges had to be overcome during the reformulation:
Frito-Lay continues to face challenges that need to be addressed:
Unilever North America
Summary of Presentation by Ravinder Reddy, PhD
Unilever is a multinational company with products in the categories of nutrition, hygiene, health, and beauty. This case study focuses on spreads, of which Unilever is the worlds leading producer. With its global reach, connection with the nutrition science community, and extensive technical capabilities, Unilever was able to assess the emerging science and to act quickly to innovate. Unilever was among the first companies to reformulate spreads to reduce the amount of trans fatty acids.
Unilever has invested in research and development in nutrition and heart health for >40 years, including sponsoring independent research to examine the effects of foods on health. Unilever has expertise and proprietary knowledge in oil application technologies. In the early 1990s, scientific data emerged suggesting that trans fatty acids may have a negative impact on blood cholesterol levels. Unilever initiated an extensive research program that included sponsoring independent scientific research, and by 1993, spreads with very low trans fatty acid content had been developed. These products became readily available by 1995, made with tropical oils in Europe and Latin America. In North America, the science community and consumer groups did not favor using tropical oils to replace trans fatty acids because of concern about increasing the saturated fat content. Therefore, in North America, Unilever developed proprietary solutions using mainly nontropical oils such as soybean, canola, and sunflower oils.
Unilever developed a global position and policy on spreads to ensure that technologies be developed to minimize the combined amount of trans fatty acids and saturated fats for all Unilever products on the market in each country. Spreads and margarine are to be virtually free of trans fatty acid worldwide (<1 g/100 g or as legally defined). After reformulation, the company policy is that the combined amount of saturated fats and trans fatty acids must not exceed existing levels.
However, to make an impact on public health, the food products must be consumed. Unilever invested in research to ensure that these new products met consumer expectations. The products must be sufficiently easy to spread soon after being taken from the refrigerator. The spread must remain stable at room temperatures and have acceptable texture, "mouth feel," and taste. To make the transition, Unilever took a step-by-step approach by screening and sourcing novel raw materials and developing partnerships with suppliers, using technologies such as rearrangement and fractionation to produce trans fatty acidfree hard fats, and using extensive processing knowledge to develop trans fatty acidfree spreads at the lowest costs.
Since the initial phase of product reformulation in 1995, Unilever has developed new fat blends and novel processes to produce trans fatty acidfree spreads that have lower saturated fat and higher unsaturated fat contents. The company continues to have a leading role in nutrition research and has a corporate strategy to provide leadership in the industry to significantly improve public health.
The AIB
Summary of Presentation by Brian L. Strouts
Partially hydrogenated fats have been used extensively in commercial baking processes, resulting in high levels of trans fatty acids in commercially baked goods. AIB is primarily a research and education organization that tests and recommends shortenings and oils to food manufacturers for their baked products.
Fats and oils in baked goods serve multiple functions that are integral to the product, including tenderizing, aerating, allowing a clear definition of structure, ensuring sufficient shelf life, flavoring and flavor carrying, and emulsifying.
Typical types of shortenings include regular hydrogenated shortening, frying shortening, hard fats, emulsified hydrogenated shortening, fluid shortening, butter, and margarine. Challenges to changing from these ingredients to trans fatty acidfree solutions include the following:
The AIB indicates that because of the different functional properties required for the wide variety of baked goods, many types of fats and shortenings may be needed, and the right ingredient may have to be obtained through trial and error. The challenge is especially formidable in the manufacturing of cakes, cookies, biscuits, pie crusts, pastries, and doughnuts.
As an example of the extensive and time-consuming experimentation that often is necessary, the AIB worked with a manufacturer to overcome the problem of a "flat puff pastry" by manipulating and adjusting different fractions of palm oil on the basis of performance for a brand of shortening. The resulting pastry was the same in quality as the one produced by an all-purpose partially hydrogenated puff pastry shortening (Figure 4). In the beginning of the process, the puff pastry was flat and unacceptable, just like the one produced with another no-trans alternative.
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In the food service environment, restaurants and bakeries also have to go through extensive recipe reworking and product testing to ensure that their baked goods made with trans fatty acidfree oils and shortenings meet standards for taste, texture, and shelf life. Challenges appear to exist in finding trans fatty acidfree alternative shortenings without increasing saturated fats to meet the functionality requirements. In food manufacturing and food service, many companies that made a switch to trans fatty acidfree alternatives for their baked goods chose shortenings made with palm oil or butter.
| Use of Alternatives in Food Services (1 Supplier and 3 Case Studies) |
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ACH Food Companies
Summary of Presentation by Pete Friedman, MS
The session began with ACH Food Companies, a fats and oils supplier to both the consumer and food service markets. Given the importance of frying in restaurants, fry studies are conducted by food oil companies on a regular basis. Oils are evaluated during fry tests in the laboratory or in the restaurant on parameters such as color, free-fatty-acid content, polar compound concentrations, flavor, and degree of foaming and polymerization. Of the various oil evaluation parameters, ACH indicates that color is an important measure in restaurant operations because it is fairly practical to implement an oil change schedule with the help of a color testing kit. The ideal frying oil would have a low cost while maintaining a high oil quality for a long period of time. A review of oil costs found that the RBD (refined, bleached, and deodorized) soybean oil is the least costly oil on a per-unit basis, but with the 1- to 2-hour stability under high heat, it often cannot be used in restaurants. In comparison, high-oleic canola oil and high-oleic sunflower oil tend to have the highest initial costs. However, the longer fry life of high-oleic canola oil and sunflower oil is expected to offset some of the initial higher costs to restaurants. In addition, cost is a dynamic issue that tends to change frequently. ACH anticipates that once high-oleic canola and low-linolenic soybean oils reach >1 billion pounds per year, the cost differentials will be reduced.
The choice of frying oils is important to quick-service (fast food) restaurants because fried foods are predominant on their menus. Oil cost has driven many decisions. Customers do not usually ask for trans fatty acidfree oils or foods in quick-service restaurants.
Casual dining restaurants rely less on fried foods than do quick-service restaurants. The lower volume of fried foods and different cooking applications could make it easier to switch to trans fatty acidfree oils in this setting. Fine-dining establishments offer few fried foods, and trans fatty acid oil use is not a typical concern in that sector.
The Holland Inc.
Summary of Presentation by Debe Nagy-Nero, MS, RD
The Holland Inc., a regional chain of 40 quick-service restaurants in the Pacific Northwest, switched to a trans fatty acidfree frying oil in January 2006. The motivating factors were both their mission of "doing the right thing" based on literature documenting the deleterious effects of trans fatty acids and questions from their guests. The decision took 9 months to implement, starting with buying a trans fatty acidfree canola oil from an existing supplier, getting acceptance from the corporate committee, educating personnel about trans fatty acids, setting up oil testing at a pilot restaurant, deciding between current par-fried French fries containing trans fatty acids and trans fatty acidfree fries on the basis of taste, and finally laboratory testing to obtain the nutritional content of the foods. The restaurants advertise using a trans fatty acidfree oil in their kitchens at the front counter, and customer reactions are generally positive. The biggest challenge has involved training cooking staff on the appropriate time to change the frying oil. The Holland Inc. has used expertise from Dow AgroSciences to educate cooking staff about the appropriate schedule to change the frying oil to avoid changing it too quickly. Because The Holland Inc. purchases par-fried French fries containing trans fatty acids, the French fries served at the restaurants still have trans fatty acids. The chain is seeking trans fatty acidfree options for their cookies and seasonal shortcakes, which continue to contain trans fatty acids.
The additional cost of 6 cents per pound for the trans fatty acidfree oil has not been an issue with senior management and has been absorbed by the company. The customer count went up in 2006 compared with 2005. However, it is not clear whether that increase had anything to do with positive customer reactions to the oil change; there was barely any difference in the oil and French fry purchases for the first 6 months of 2006 compared with the same period in 2005.
Ruby Tuesday
Summary of Presentation by Julie Reid, MS
Ruby Tuesday is a nat