June 18, 2012
By Cindy Hazen, Contributing Editor
My grandmother loved fried doughnuts. My dad ordered fried clams whenever possible. Fried chicken hits my weak spot.
My familys memories aren't the only ones punctuated with lots of fried foods. And while this enjoyment is cross-generational, the mediums used for frying are not. Frying oils are evolving to fit the needs of a new generation of health-conscious consumers who speak a language our predecessors did not.
Trans fat and saturated fatty acids are relatively new nutrition buzzwords among consumers. For decades, partially hydrogenated oila source of trans fatwas the stable, reliable workhorse, particularly as saturated fats became associated with increases in blood cholesterol. It produces a flavor that many of us identify with, and it helped the oil stay fresher longer but unfortunately, it has been proven to have negative health consequences.
Today, the trends are to utilize oil or oil blends that provide 0 grams trans fat per serving, along with a moderate level of saturates," says Tom Tiffany, senior technical manager, ADM, Decatur, IL.
Scientists are proving that saturated fats are not all bad. Saturated fats raise high-density lipoprotein (HDL) cholesterol. The ratio of total cholesterol to HDL cholesterol is a more specific marker of coronary artery disease than is low-density liopoprotein (LDL) cholesterol (American Journal of Clinical Nutrition, 2003; 77(5):1,146-1,155). In a study of 340,000 subjects over a 25-year period, scientists found no correlation between saturated fat and the risk of heart disease (American Journal of Clinical Nutrition, 2010; 91(3):535-546).
Saturated fatty acids as well as hydrogenation are important because they impact frying-fat stability. Oil stability may be less of a concern in the home kitchen where it might be used once and tossed. The rigors of industrial or foodservice operations demand fry life to extend beyond a couple of batches.
In a commercial setting, its a wonder that oils survive at all considering the ways in which they are abused. Large surface areas of industrial fryers expose the oil to air and oxidative stress. Accumulation of crumbs from cooked food further abuses the oil. High temperatures used in frying break down oil faster than lower temperature applications.
Some oils are more susceptible to an early demise. Polyunsaturated fats, such as soybean oil, corn oil and cottonseed oil, break down quickly when exposed to air.
Polyunsaturated fats are typically touted as being the healthiest oils. That isnt true," says Gerald McNeill, Ph.D., vice president, R&D, Loders Croklaan USA, Channahon, IL. That is only true if you dont heat it. If you heat it up, then you degrade it and create much more reactive substances than monounsaturated or saturated fat. For me, the biggest issue in frying today is the incorrect use of polyunsaturated oils for deep fat frying. Its pretty cheap. The downside is, and people dont realize it, it goes off faster."
Polyunsaturated fats have been used widely in fast-food restaurants and momand-pop stores as an alternative to partially hydrogenated oil. Polymer buildup in the fryer is one consequence. But theres also a mist of oxidized fat that comes out of the fryer. Thats very difficult to remove," he continues. "The walls, the furniture over time get coated with a sticky deposit." It coats workers clothes. Its likely inhaled.
The breakdown products from polyunsaturates, aldehydes, are much more reactive than those of monounsaturated or saturated fats. Their consequences to human health are of concern. One recent study revealed the presence of toxic aldehydes in foods following prolonged heating at frying temperatures (Food Chemistry, 2012; 131(3):915-926). Two of these aldehydes, 4-oxo-[E]-2-decenal and 4-oxo-[E]-2-undecenal, have been linked to some neurodegenerative diseases and certain cancers.
McNeill points out that using and abusing the wrong oils are likely pre-forming toxic substances in the fryer. Iit goes into the foods and its been shown to be bioavailable. It does get absorbed into the body. We dont know what the effects are right now because it will take years before it would express itself."
Monounsaturated fats, like peanut oil, canola oil and sunflower oil, are slightly more stable. The breakdown of monounsaturated fats is not as bad as you get from polys, but you do get more breakdown than you get from saturates," says McNeill.
To minimize the degradation process, attendees at the 6th International Symposium on Deep-Frying - Errors and Myths of Industrial and Catering Frying, held May 2011 in Hagen, Germany, recommend avoiding fats with trans fatty acids and using fats with less than 15% saturated fatty acid. Oils rich in linolenic acid, such as soybean oil, should not be used in kitchens with poor exhaust systems. At deep-frying temperatures, linolenic acid decomposes to acroleine, a volatile carcinogenic compound.
Mono-acid-rich oils form oxidized monomeric triglycerides, a degradation product of oleic acid. Studies from the University of Vienna show that "oxidized monomeric triglycerides, as a degradation product of oleic acid, are absorbed in the human stomach and intestinal tract," according to the recommendations.. These degradation products have been linked to cardiovascular disease and type 2 diabetes. Mono-oxidized products are predominately formed in high oleic oils, whereas the dimerisation is the preferred route of degradation in oils rich in polyunsaturates."
Three fatty acids are of particular interest when discussing frying oils. Linolenic acid oxidizes faster than oleic acid or linoleic.
Improving the stability of the oil is very important," adds Tiffany. High-oleic, low-linolenic soybean oil and high-oleic, low-linolenic canola are receiving considerable attention today as these oils offer stability and flavor along with 0 grams trans fat per serving and saturates below 13% of their total composition."
Unlike traditional soybean or canola oils, these oils are the product of plants selectively bred to contain higher amounts of the fatty acid oleic acid and lower levels of linolenic acid.
Susan Knowlton, senior research manager, DuPont Pioneer, Wilmington, DE, says: High-oleic soybean oil is addressing the trend for healthier frying oils. Its a healthier alternative to traditional frying oils, with health benefits and functionality benefits for the restaurant and food manufacturer." Their product has 0 grams trans fat and is 20% lower in saturated fats. It has 3% or less linolenic acid, as opposed to 8% in traditional soybeans. It has more than 75% oleic content, compared to traditional soybeans 22%, which makes it very similar to olive oil," she says.
Compared to typical commodity soybean oil, Knowlton says this high-oleic soybean oil lasts two to three times longer in the fryer, leading to fewer oil changes and less clean-up time. It also has increased shelf life for manufactured products," she says. "Because there is less polymer build-up, there is decreased equipment maintenance, which also saves time and money."
Food manufacturers and restaurants, Knowlton notes, are typically looking for three things from their frying oil: cost, taste and functionality. With new, enhanced oils, such as high-oleic soybean oil, they can get all necessary requirements from a single source."
According to Michelle Peitz, technical sales representative, ADM, Industrial, foodservice and quick-service operations take availability, nutrition, stability and price into consideration when selecting a frying medium. Each segment will prioritize the four options in a different order."
Tiffany points out that oils such as corn oil; cottonseed oil; peanut oil; mid-oleic sunflower oil; high-oleic, low-linolenic soybean oil; and high-oleic, low-linolenic canola; or blends thereof, offer industrial, foodservice and quick-service industries many opportunities to select an oil to meet their needs. For example, corn, cotton and peanut oils have characteristic flavors that benefit some applications, whereas mid-oleic sunflower, high-oleic, low-linolenic soybean oil, and high-oleic, low-linolenic canola have more-bland flavor profiles that some developers might find valuable," he says.
Depending on the food product application, different oils may be needed. Oils that do not contain solid fat can be used in cooking french fries or chicken. Frying mediums used for doughnuts need a solid-fat profile," says Peitz. The solids slow oil migration that can interfere with sugar and glaze adhesions. Solid fat is also needed to minimize the staining of packaging materials."
One option, recommended by Knowlton, is to blend naturally stable, liquid oil, like high-oleic soybean oil, with a source of more-solid fat. The benefits of new oils is the blending capabilities, so a restaurant or food manufacturer can work with their processing partner to determine the right oil for their needs," he says. "Oils such as high-oleic soybean oil can work in all applications, and be blended as needed."
Solid fats need not contain trans fats. When oil is fully hydrogenated, trans are not produced as there are no double bonds to create a trans (or cis) conformation.. Standard partial-hydrogenation techniques, on the other hand, produce a plethora of unhealthy trans bonds.
Fractionation is another method used to create solid fats. During heating and cooling, crystals of different melting points are isolated. These fractions will have different functional properties. In palm oil, palm stearine may be isolated. This is a hard solid with a melting point of 55°C.
Palm oil is semisolid at room temperature and is often blended with soybean oil. Palm oil is a mixture of mono and saturated fat. It contains linoleic acid and no linolenic acid. It also contains natural antioxidants, called tocotrienols, that add another layer of protection. Its most resistant to oxidation," says McNeill. It hardly breaks down."
Cost is another advantage of palm oil. He foresees higher yields with the farming of new varieties of palm.
Trends in coatings
Its no surprise that trends leading the food industry are impacting batter and breading formulations. Consumers are increasingly looking beyond processed foods," says Callen Sistrunk, team leader, batters and breadings, Ingredion, Inc., Westchester, IL. There is demand for cleaner labels with minimal ingredients." Likewise, straightforward claims are preferred, like 100% natural ingredients. He also sees unbreaded products coming into vogue. These products are simply coated with a flavoring glaze.
The gluten-free trend is also making its way into batters and breadings. "Using a combination of starches and flours, such as tapioca and rice flour, it is possible to put together gluten-free breadings," Sistrunk says. "There are differences in browning and texture. Because of the type of modification or the inhibition of starches or flours that we process, we can create products that give you something thats more similar to a standard wheat formula."When preparing any fried breaded product, there are four key drivers to success: bind moisture into the substrate, adhere the breading to the substrate, manage water, and add a texturizing agent. Perhaps most important of all, make sure you bind moisture inside your substrate," advises Sistrunk. This is especially critical for chicken because excess moisture can lead to sogginess. He suggests using a binding starch in the marinade. Ingredion offers a chemically modified starch for that purpose, but also has a natural version that is labeled simply as potato starch. We have clean-label versions of a majority of our ingredient solutions," he says.
Film-forming is an important step. Moisture loss during frying applications results in increased product porosity, which in turn allows for increased fat or oil absorption," explains Jenette Lee, technical documentation specialist, Gum Technology Corporation, Tucson, AZ. "It contributes to reduction in product texture quality, such as product hardening or coating inflexibility. Moisture loss also reduces product volume, resulting in shrinkage.
Excessive moisture retention, on the other hand, can result in a soft or mushy center to the product, migration of moisture from the center of the product to the outer layers or coating, resulting in reduced adhesion or blow-off, and loss of color development," Lee continues. Either extreme will reduce the quality and appeal of the product to prospective customers. In order to maintain the balance between moisture retention and oil absorption, many manufacturers are turning to the utilization of hydrocolloids. With their water-binding capabilities, film-forming and thermal gelation properties, and ability to provide viscosity, as well as contribute to freeze/thaw stability, hydrocolloids provide manufacturers with a flexible toolkit to tailor their product development and manufacturing processes to produce a product that will entice their customers."
Sistrunk recommends using high-amylose starch in batter formulations. High-amylose starch will form a film, which will hold in moisture while enhancing crispiness during baking and frying," he says.
Breadings are meaningless if they dont adhere to the substrate. We would typically recommend high-adhesion starch," Sistrunk says. This starch would be applied as a pre-dust and/or as part of the batter system." Theres also a technique to enhance crispness. Wheat flour breadings will impart crunchiness. If you want added crispness, the addition of dextrin is recommended," he says.
As consumers and health professionals focus a lens on the nutritional impact of fried foods, fat comes clearly into view. While the type of fat used can improve the healthfulness of the fatty-acid profile, it is less likely to affect the caloric value. Fats contribute 9 calories per gram, as opposed to 4 calories per gram of carbohydrates or protein.
A sure way to limit fats contribution to a fried foods total calorie load is to reduce fat absorption. However, the challenge is to not affect quality, texture, flavor and overall customer acceptance of the product.
There exists a delicate balancing act between reducing fat absorption during frying applications and maintaining the very sensory qualities of the product that make it so appealing," Lee says. "Moisture is at the core of this issue."
A major tool in the effort to minimize oil penetration into fried products is hydroxypropylmethylcellulose (HPMC). HPMC is a hydrocolloid that forms a barrier against moisture loss and oil absorption upon heating," Lee explains. "The thermal gelation properties of HPMC not only provide barrier functionality but can also contribute to strengthening the batter of the product and aid in gas retention during the frying process."
While HPMC and other thermal-gelling hydrocolloids utilize barrier-forming properties to reduce fat absorption and increase moisture retention, there is another strategy that manufacturers can employincreased batter viscosity," Lee says. "Hydrocolloids such as xanthan gum can be readily dispersed to provide increased viscosity and consistency to batters and aid in controlling moisture migration throughout the product." Using such gums can produce higher-quality batters with increased flexibility and reduce coating or breading blow-off and flaking.
Due to the unique properties of various hydrocolloids, manufacturers can create custom solutions to produce the perfect fried product. For example, a moist, tender, fried chicken breast can be ensured by utilizing the thermal gelation properties of hydrocolloids in the pre-dusting stage of manufacturing," Lee says. HPMC and cellulose derivatives function well in fried meat applications, while blends containing HPMC, xanthan, konjac and some starches work well in maintaining the moisture/oil penetration balance in fried cheese applications, and prevent blow-out. Viscosifiers and texture enhancers can be utilized in the batter to ensure flexibility and increase gas retention during frying. For vegetarian or nonmeat products, citrus fiber or a carboxymethylcellulose (CMC) and taragum blend works to increase moisture retention and control moisture migration while at the same time aiding in batter flexibility and gas retention to produce a crisp outer coating to products. In the world of hydrocolloids the options are manyand the benefits are profound."
Cindy Hazen, a 20-year veteran of the food industry, is a freelance writer based in Memphis, TN. She can be reached at [email protected].
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