Nonhydrogenated Cottonseed Oil Can Be Used as

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RESEARCH

Current Research

Nonhydrogenated Cottonseed Oil Can Be Used as

a Deep Fat Frying Medium to Reduce

Trans-Fatty Acid Content in French Fries

DARLA R. DANIEL, PhD, RD; LESLIE D. THOMPSON, PhD; BRENT J. SHRIVER, PhD; CHIH-KANG WU, PhD; LINDA C. HOOVER, PhD, RD

ABSTRACT

ObjectiveThe purpose of this research study was to eval-uate the fatty acid profile, in particular trans-fatty acids, of french fries fried in nonhydrogenated cottonseed oil as compared with french fries fried in partially hydroge-nated canola oil and french fries fried in partially hydro-genated soybean oil.

DesignCottonseed oil, partially hydrogenated canola oil, and partially hydrogenated soybean oil were subjected to a temperature of 177°C for 8 hours per day, and six batches of french fries were fried per day for 5 consecutive days. French fries were weighed before frying, cooked for 5 minutes, allowed to drain, and reweighed. Oil was not replenished and was filtered once per day. Both the oil and the french fries were evaluated to determine fatty acid profiles, trans-fatty acids, and crude fat.

Statistical analysis A randomized block design with split plot was used to analyze the data collected. Least-squares difference was used as the means separation test. Results No significant differences were found between fries prepared in the three oil types for crude fat. Fatty acid profiles for the french fries remained stable. The french fries prepared in cottonseed oil were significantly lower in trans-fatty acids. The combined total of the trans-fatty acid content and saturated fatty acid content were lower in french fries prepared in cottonseed oil.

Conclusions Because deep fat frying remains a popular cooking technique, health professionals should educate the public and the food service industry on the benefits of using nonhydrogenated cottonseed oil as an alternative to the commonly used hydrogenated oils.

J Am Diet Assoc. 2005;105:1927-1932.

D

espite the negative health effects, deep fat fried snack foods remain very popular among consumers. The unique sensory qualities found in foods that are deep fat fried cannot be duplicated by any other cooking method. In particular, french fries remain a very popular food item in the American diet. On average, each person in the United States consumes approximately 13.6 kg (30 lb) of french fries every year (1). Therefore, the food service industry has the difficult task of providing the popular french fry in the most healthful form possible.

During 1989 and 1990, many restaurants reduced their use of saturated fats and substituted hydrogenated veg-etable oils because of consumer pressure for more health-ful products (2). This decline in the use and consumption of animal fat and tropical oils was attributable to the relationship found between saturated fatty acid intake and heart disease. Oils high in saturated fat, such as lard, were replaced with vegetable oils such as canola oil and soybean oil. However, vegetable oils containing high con-centrations of polyunsaturated fatty acids require hydro-genation to increase their chemical stability. Trans-fatty acids are a byproduct of hydrogenation. Partially hydro-genated vegetable oils contain approximately 30% trans-fatty acids, whereas animal fats contain approximately 3% trans-fatty acids (2).

Both clinical and epidemiological studies indicate that the risk for coronary heart disease increases with increas-ing dietary intake of trans-fatty acids (3). This is probably because trans-fatty acids are metabolized in the same manner as saturated fatty acids. A study by Mensink and Katan (4) found that increased consumption of trans-fatty acids increases blood cholesterol levels. Zock and col-leagues (5) hypothesize that for every additional percent-age of trans-fatty acid in the diet, low-density lipoprotein (LDL) cholesterol is increased by about 1.5 mg/dL and high-density lipoprotein (HDL) cholesterol is decreased by approximately 0.5 mg/dL.

The majority of trans-fatty acids consumed today come from foods fried in partially hydrogenated vegetable oil, as well as margarine, snacks, and baked products (6). Restaurants typically use partially hydrogenated vegeta-D. Daniel is an assistant professor, Department of

Hu-man Sciences, Stephen F. Austin State University, Na-cogdoches, TX; at the time of the study, she was a doc-toral student, Education, Nutrition, and Restaurant, Hotel, Institutional Management, Texas Tech Univer-sity, Lubbock. L. Thompson is an associate professor/ associate chairman, Animal and Food Sciences and In-ternational Center for Food Industry Excellence, Texas Tech University, Lubbock. B. Shriver is an assistant professor, C.-K. Wu is an assistant professor, and L. Hoover is an academic dean, Education, Nutrition, and Restaurant, Hotel, Institutional Management, Texas Tech University, Lubbock.

Address correspondence to Darla R. Daniel, PhD, RD, Department of Human Sciences, Stephen F. Austin State University, Box 13014 –SFA Station, Nacogdoches, TX 75962. E-mail: ddaniel@sfasu.edu

0002-8223/05/10512-0008$30.00/0 doi: 10.1016/j.jada.2005.09.029

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ble oil for deep fat frying french fries. Soybean oil and canola oil rank first and third, respectively, among the oilseed crops (7) and are commonly used as a deep fat frying medium (8). The National Cottonseed Products Association has begun targeting casual dining restau-rants in an advertising campaign to promote the health and taste benefits of cottonseed oil (8). Restaurant chefs, who are profit oriented but are also interested in health, may find cottonseed oil very appealing. The average price for cottonseed oil is just a fraction of a cent higher per pound than that of soybean oil (9). Table 1 shows the typical fatty acid profile of the unhydrogenated forms of cottonseed, canola, and soybean oils (10).

The objective of this study was to determine the fatty acid profile, in particular trans-fatty acids, of french fries fried in cottonseed oil as compared with french fries fried in partially hydrogenated canola oil and french fries fried in partially hydrogenated soybean oil.

METHODS Fat Sources

Cottonseed oil was obtained from PYCO Industries, Lub-bock, TX; both canola oil (Extend) and soybean oil (Mel Fry) were obtained from Ventura Foods LLC, City of Industry, CA. Cottonseed oil was not hydrogenated, whereas the canola and soybean oils were partially hy-drogenated. All three oils contained tertiary butylhydro-quinone and citric acid as antioxidants and dimethyl-polysiloxane as an antifoam agent.

French Fries

This research was conducted using US Department of Agriculture grade A frozen, partially cooked, Russet Bur-bank potatoes produced by Payette Farms (J. R. Simplot Co, Boise, ID), straight cut3_⁄₈⫻3_⁄₈_{inches. The nutritional}

composition of an 86-g (3-oz) serving size is 120 calories, 4 g fat, 1 g saturated fat, 18 g carbohydrate, and 2 g protein. Other ingredients included beef tallow and/or vegetable shortening (partially hydrogenated soybean and/or canola oil), dextrose, and disodium dihydrogen pyrophosphate (to maintain natural color). The french fries were obtained from Watson Sysco Foodservice (Lub-bock, TX).

Fryer

A stainless steel, gas-heated deep fat fryer with three 23-to 27-kg (50- 23-to 60-lb) oil capacity tanks (Pitco Friala23-tor with built-in filter, model AG14S, Pitco Frialator Inc, Concord, NH) was used. For statistical purposes, each tank was considered a block.

Experimental Design

Using a block (tank) design with a split plot (time), each of the three tanks was filled to capacity with its desig-nated fresh oil. The oil was placed into a container tared on a bench scale, and approximately 24 kg (measured to two decimal places) was weighed. After the oil was weighed, it was hand-poured back into the fryer. The oil residue left adhering to the walls of the container was scraped into the tank with a large rubber spatula. After 1 week, oils were rotated to a different tank to correct for any temperature differences among the tanks. Because there were three tanks, three repetitions were required to complete one trial. Three trials (one trial equaling three repetitions) were used to create a stronger statistical model. Oil was heated and used for 5 consecutive days without replenishing. The oil was heated for 8 hours every day for 5 days. After 5 days of heating and frying, the used oil was sampled and discarded and fresh oil was rotated to another tank until each oil had been in each tank during the 3-week repetition. A fresh sample of the oil was taken before the start of the study, and a sample was taken at the end of each day for analysis. The sam-ples were flushed with nitrogen to help retard oxidation and stored frozen in brown Nalgene containers until fur-ther analysis could be performed. At the end of the day, the oil was filtered using the built-in filtering system within the Pitco Model AG14S. Before draining the oil for filtering, 1 cup of filtering powder (Homestyle Hol-N-One, Inc, Fordyce, AR) obtained from Lubbock Restaurant Supply (Lubbock, TX) was added to the oil. As the oil was draining, any food particles left around the sides or in the bottom of the fryer were scraped toward the drain. The oil in the last tank (farthest from the filtering system) was filtered first, the middle tank second, and the tank closest to the filter last. This minimized cross-contamination of the different types of oil. Fresh filter paper was used to filter each oil type. The filtering process was timed using a digital timer for exactly 2 minutes. The oil was pumped back into the same tank by the fryer’s internal pump and allowed to bubble. This signified that the return lines had been cleared. This pumping process was timed for exactly 2 minutes. After the 5-day cycle, the fryer was cleaned first with Drano (SC Johnson, Racine, WI), rinsed with water, cleaned again with apple cider vinegar, rinsed, and dried.

Frozen french fries were taken from the freezer and immediately weighed to the nearest gram. Approximately 2 kg of french fries were added to the deep fat fryer basket and immersed in the hot oil at a temperature of 177°C for exactly 5 minutes. A digital timer was used to accurately record the time. Throughout the day, six batches of fries were cooked, yielding daily a total of 12 kg (26.4 lb) of french fries for each oil. Batches were fried every 30 minutes to 1 hour to allow the temperature of the oil to recover between batches. The fries were then removed Table 1. Typical fatty acid profile of cottonseed oil, canola oil, and

soybean oila Fatty acid composition (%) Cottonseed oil Canola oil Soybean oil Myristic (14:0) 0.5-2.5 0.1 ⬍0.5 Palmitic (16:0) 17-29 3.5 7-12 Stearic (18:0) 1-4 1.5 2-5.5 Oleic (18:1) 13-44 60.1 20-50 Linoleic (18:2) 33-58 20.1 35-60 Linolenic (18:3) 0.1-2.1 9.6 2-13 a_{Source: reference}₁₀_.

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and lower in trans-fatty acids compared with french fries fried in the other two oils. The US Food and Drug Ad-ministration will require the trans-fatty acid content to be included with the saturated fatty acid content on a food label by 2006. If trans- and saturated fatty acids are added together, french fries fried in cottonseed, canola, and soybean oil contained 30%, 36%, and 41% of the total, respectively, using data obtained on day 5 (Table 2). French fries fried in cottonseed oil had a lower combined total of saturated and trans-fatty acids and, more impor-tantly, the percentage of the total contributed by trans-fatty acids was lower. The percentage of the total contrib-uted by trans-fatty acids was 9%, 53%, and 55% for cottonseed, canola, and soybean oil, respectively. If trans-fatty acids, gram for gram, are more dyslipidemic than saturated fatty acids, it would be wise to choose an oil with a lower content of trans-fatty acids, even if it were higher in saturated fatty acids.

Studies have shown that monounsaturated fatty acids and polyunsaturated fatty acids elicit similar lowering effects of LDL cholesterol levels in parallel with total cholesterol; however, monounsaturated fatty acids did not lower HDL cholesterol levels whereas a slight de-crease was seen with polyunsaturated fatty acids (4). French fries fried in both canola and soybean oil had higher monounsaturated fatty acid levels than those fried in cottonseed oil.

Because fried foods contribute a large proportion of trans-fatty acids consumed in the United States, it is advisable to reduce the content of trans-fatty acids in frying oils. Hydrogenation contributes 75% of the trans-fatty acids found in food products. Cottonseed oil can be used in its unhydrogenated state. This will become espe-cially important when the trans-fatty acid content is re-quired to be disclosed on a food label. Cottonseed oil fits this profile. Restaurants will find cottonseed oil to be economically feasible while appealing to customer desires for a healthful product. A limitation to this study was the high variability in the initial trans-fatty acid content of the par-fried french fry. Further studies should be con-ducted on french fries that have not been par-fried or that are par-fried in nonhydrogenated vegetable oil.

It is unknown how much saturated fatty acid it takes to offset the health benefits of using a product with a de-creased amount of trans-fatty acids. Epidemiological studies would need to be performed to determine the health benefits of using oil with a higher saturated fat content but a lower trans-fat content. It is clear that more studies should be done on the effects of the fatty acid profile on health.

CONCLUSIONS

Trans-fatty acids are becoming a major health concern, and the public’s awareness will continue to increase. It is important that dietetics practitioners understand where trans-fatty acids are found in foods and how to plan diets accordingly. If fried foods are going to be a part of a client’s diet, trans-fatty acids can be minimized by the choice of fat used in the preparation of food. Foodservice establishments will be influenced by public health con-cerns, and dietetics professionals can provide these estab-lishments with informed suggestions regarding the use of

cottonseed oil as an alternative to hydrogenated oils to reduce trans-fatty acid consumption.

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