Posts

Replacing Your Teflon Pans?

frying-pan-skilletWhat is Teflon?
Anybody who’s spent time at the stove knows that Teflon pans were the coolest culinary invention of the time. Teflon is the trademark name for polytetrafluoroethylene (PTFE), used to create non-stick surfaces. It’s really good at what it does. Like most things in life, it has its fans and its detractors. Whichever side hollers louder gets the greater attention at a particular time, but there is science that can’t be ignored, and common sense that, apparently more often than not, is. For a product that was accidentally discovered while looking for a new refrigerant, Teflon has done pretty well since the late 1940’s. The first frying pan debuted in 1961.

Considerable controversy surrounds the base chemical from which Teflon is made—perfluorooctanoic acid (PFOA). The problem is that offgasing of fluoride derivatives is toxic to the respiratory system, as evidenced by necropsy of dead chicks that were exposed to Teflon-coated heat lamp bulbs in their hatching pens. Accounting for all possible confounders and variables, it was discovered that PFOA could be the only cause of pulmonary lesions and edema in those animals (Boucher, 2000). For the chicks to have expired from Teflon offgasing, the temperature of the heat lamps would have had to have been above 325°F and the base material of low molecular weight (Seidel, 1991). Birds have been used as indicator species in coal mines for years, where the presence of toxic gases, notably carbon monoxide and methane, or the shortage of air would cause their asphyxiation long before it affected humans. Birds are a captive audience, whether in a coop or a cage. Even if their physiology reacted adversely to an airborne toxin, they could not have vacated the space. A human could, unless lacking common sense. Even so, humans are not living under heat lamps, much less lamps with Teflon coating.

Why Teflon Has a Bad “Rap”
Some research says Teflon coated frying pans do not present serious concerns until heated to a temperature at which Teflon can break down to emit PFOA—about 600°F.  Normal sauté temperatures hover around 320°F.  Hmm, let’s see…the caramelization phenomenon called Maillard happens around 250°F (although it can happen at lower temperatures because Maillard is a reaction between amino acids and sugars, not just a response to heat). The most common cooking oils smoke far below 600°F, and that would force you out of the kitchen. One more thing…the pan should be empty to present a hazard. Considering the amount of PTFE resin on the pan, the usual frying temperatures, and the size and ventilation of a home or commercial kitchen, it’s unlikely that even abuse temperatures would cause polymer fume fever. Experiments conducted in the mid 1970’s found birds to be more sensitive to Teflon offgases than rats, but both to be more sensitive to naturally occurring frying media than to PTFE fumes. In fact, cooking oils kept at temperatures that offgas Teflon would cause flashing that would kill a bird and later cause a fire (Waritz, 1975). If you believe that the danger is in the dose, you’d probably have lots of company. But the prediction that all Teflon pans will be pulled from the stores by 2015 makes you wonder if somebody knows something the rest of us don’t.

Are there alternatives?
Cast Iron:
Almost nothing is slicker than Teflon. However, there’s a low-tech solution that’s been around for centuries…cast iron. It’s cheaper than a coated pan, it browns food better, and is almost as non-stick, once properly seasoned and cared for. In the presence of slightly acidic ingredients it adds iron to the food. That’s a good thing. Enameled cast iron may not contribute to daily mineral intake, but it does make cleanup easy and more thorough. On the other hand, it fares poorly at sticking resistance and tolerating searing heat. Chipping of the enamel and cost are issues to consider.

Aluminum: Some brands of pots and pans are now made from anodized aluminum. The process involves the formation of a hard oxide layer of the base metal on the surface of the cookware. Its name comes from the manner of electrolysis in which the aluminum becomes the anode of an electrical circuit. Such a process makes the surface harder than the base, making it non-stick, scratch-resistant and easy to clean. Because the metal is sealed, aluminum cannot leach into food. If you’re worried that aluminum could taint your food and contribute to cognitive decline, boil the pot or pan prior to cooking in order to increase the protective oxide layer (Karbouj, 2009).

Stainless Steel: Stainless steel is an option for replacing coated pans. This material contains a little more than ten percent chromium, and may also contain other metals, such as nickel and molybdenum, all of which may trickle into foods in barely detectable amounts.  Because it resists corrosion and staining, stainless steel is a favorite, but few cooks realize there are different grades. Heat conductivity is not a strong point in stainless cookware, so cladding or layering with aluminum or copper is often done to improve energy absorption and distribution. Otherwise, the part of the pan directly over the heat gets super hot, while the circumference remains cooler.

Copper: Copper cookware is favored by professionals for sauces and sautés because it excels at heat-ups and even energy distribution. Copper can leach into foods in large amounts when heated, so the pans are usually lined with tin or stainless steel. If the lining is damaged, copper toxicity may ensue and present with a host of symptoms, including tarry stools, hypotension, and GI distress, followed by liver and kidney damage over the long term. It’s expensive and pretty to look at, but copper needs special care.

The bottom line in choosing cookware concerns not only the thermal properties of diffusion and heat capacity, but also the safety and gustatory properties, the latter defining the influence of the material on the taste of the food. Aluminum and copper react with foods. Stainless steel doesn’t, but has poor thermal diffusivity. To overcome these vices, manufacturers have found ways to relieve us of heavy wallets. Combine the non-reactivity of stainless with the thermal properties of aluminum or copper.

We didn’t mention thickness of pan material. Since heat capacity is a function of mass, density is a factor. Cast iron is usually thicker than other pans. Nothing beats cast iron for consistent heat. Seasoning makes it relatively non-stick and, if done correctly, almost non-reactive except for the most acidic ingredients.  A fault is its weight. If you prefer a clad stainless, the thicker, the better, but that equals more money, and if you have nickel sensitivity, forget it. Titanium might be the latest rage, but we’ll have to see how that pans out. Smile.

References

Barrow CS, Lucia H, Stock MF, Alarie Y.
Development of methodologies to assess the relative hazards from thermal decomposition products of polymeric materials.
Am Ind Hyg Assoc J. 1979 May;40(5):408-23.

Boucher M, Ehmler TJ, Bermudez AJ.
Polytetrafluoroethylene gas intoxication in broiler chickens.
Avian Dis. 2000 Apr-Jun;44(2):449-53.

Bradley EL, Read WA, Castle L.
Investigation into the migration potential of coating materials from cookware products.
Food Addit Contam. 2007 Mar;24(3):326-35.

S.J. Genuis, D. Birkholz, M. Ralitsch, N. Thibault
Human detoxification of perfluorinated compounds
Public Health. Volume 124, Issue 7 , Pages 367-375, July 2010

Johnston CJ, Finkelstein JN, Gelein R, Baggs R, Oberdörster G.
Characterization of the early pulmonary inflammatory response associated with PTFE fume exposure.
Toxicol Appl Pharmacol. 1996 Sep;140(1):154-63.

Johnston CJ, Finkelstein JN, Mercer P, Corson N, Gelein R, Oberdörster G.
Pulmonary effects induced by ultrafine PTFE particles.
Toxicol Appl Pharmacol. 2000 Nov 1;168(3):208-15.

Karbouj R, Desloges I, Nortier P.
A simple pre-treatment of aluminium cookware to minimize aluminium transfer to food.
Food Chem Toxicol. 2009 Mar;47(3):571-7. Epub 2008 Dec 27.

Kontou N, Psaltopoulou T, Soupos N, Polychronopoulos E, Linos A, Xinopoulos D, Panagiotakos DB.
The role of number of meals, coffee intake, salt and type of cookware on colorectal cancer development in the context of the Mediterranean diet.
Public Health Nutr. 2012 Aug 8:1-8. [Epub ahead of print]

Kuligowski J, Halperin KM.
Stainless steel cookware as a significant source of nickel, chromium, and iron.
Arch Environ Contam Toxicol. 1992 Aug;23(2):211-5.

Kumar R, Srivastava PK, Srivastava SP.
Leaching of heavy metals (Cr, Fe, and Ni) from stainless steel utensils in food simulants and food materials.
Bull Environ Contam Toxicol. 1994 Aug;53(2):259-66.

Oberdörster G.
Pulmonary effects of inhaled ultrafine particles.
Int Arch Occup Environ Health. 2001 Jan;74(1):1-8.

Quintaes KD, Amaya-Farfan J, Morgano MA, Mantovani DM.
Soapstone (steatite) cookware as a source of minerals.
Food Addit Contam. 2002 Feb;19(2):134-43.

Seidel WC, Scherer KV Jr, Cline D Jr, Olson AH, Bonesteel JK, Church DF, Nuggehalli S, Pryor WA.
Chemical, physical, and toxicological characterization of fumes produced by heating tetrafluoroethene homopolymer and its copolymers with hexafluoropropene and perfluoro(propyl vinyl ether).
Chem Res Toxicol. 1991 Mar-Apr;4(2):229-36.

Shuster KA, Brock KL, Dysko RC, DiRita VJ, Bergin IL.
Polytetrafluoroethylene toxicosis in recently hatched chickens (Gallus domesticus).
Comp Med. 2012 Feb;62(1):49-52.

Waritz RS.
An industrial approach to evaluation of pyrolysis and combustion hazards.
Environ Health Perspect. 1975 Jun;11:197-202.

Wells RE, Slocombe RF, Trapp AL.
Acute toxicosis of budgerigars (Melopsittacus undulatus) caused by pyrolysis products from heated polytetrafluoroethylene: clinical study.
Am J Vet Res. 1982 Jul;43(7):1238-42.

*These statements have not been evaluated by the FDA.
These products are not intended to treat, diagnose, cure, or prevent any disease.

Microwave Safety

microwave-ovenIn the United States, food grade containers are known not to leach harmful substances into the foods they hold, whether for storage or for microwave cooking. In most homes in the country, you’ll find a range of containers in the refrigerator, from plastics of known and unknown origin to paper to glass to metals to ceramics. Although many of us probably don’t, maybe we should care whether or not a container is safe for microwave use.

How does a microwave work?  

The oscillating waves produced by a microwave oven are similar to radio waves but much faster. They act mainly by energizing the water molecules present in a food, causing them to vibrate and to make heat. Because of the speed involved, food cooks faster than with conventional means, where heat is transferred from an external source to the material, working from the outside in by way of thermal conduction. Only substances that absorb microwaves can be heated by a microwave oven, with the food itself becoming the heat source for cooking. Heating metals in a microwave produces different, and sometimes unexpected, results. Low penetration depth results in reflection of the waves, setting up high voltage between the metal and the magnetron that is the heart of the system. When this voltage surpasses a threshold, sparks fly. Powdered metal probably would react differently. But we suggest you refrain from trying this unless you work in a science laboratory.

I heard that microwaves destroy the nutrient value of food.

Yeah, we heard that, too. The fact is that any cooking method destroys some character of a food. Using too much water in a pot to cook frozen vegetables, for example, will render water-soluble nutrients to the water, which often goes down the drain. Several studies have shown that microwave cooking, if used the right way, has no more adverse effect on food nutrition than conventional heating methods. In fact, probably because of shorter cooking time, there might even be a tendency for greater nutrient retention (Lassen, 1995). If there be a fault, it would be uneven heating. Moisture loss is more noticeable (Cross, 1982) (Quan, 1985), though, and that makes sense, since all those water molecules bumping against each other create friction, and friction creates heat.

Some studies examined the effects of microwaves on human milk. Besides the usual nutrients a baby needs, breast milk contains immunity factors, such as IgA. Microwaving to temperatures between 161°F and 208°F caused a marked decrease in anti-infective factors (Quan, 1992). We have questions about this. Who heats jarred or bottled baby food or formula hotter than the human wrist can tolerate, which is far lower than the temperature of your water heater? Doesn’t milk come from mom at about 98.6°? At temperatures up to 149°F, fatty acids, most vitamins and immunoglobin are safe (Ovesen, 1996). The hydroxo- form of Vitamin B12, which predominates in foods, appears to be degraded by microwave heating as evidenced in tests on B12-dependent organisms fed a microwaved diet (Watanabe, 1998). But this is only one such test. And most of us don’t put all our eggs into one basket. Because adults cannot metabolize the vitamin B12 from food sources anyway (we lack the gastric intrinsic factor required), we mention this study as a courtesy to the young readers. To overcome poor absorption, sublingual or injectable forms of B12 are available.

So, what should not go into the microwave?

There are some things to keep in mind when using the microwave. Most containers from the takeout place, water bottles, plastic tubs from margarine, yogurt, cream cheese, mustard and mayonnaise, and whipped toppings are not safe for microwave use. Some microwavable trays, such as those from frozen dinners, are designed for one-time use. It should say that on the package. Plastic bags of any kind belong in the trash. If the plastic containers you just bought at the dollar store do not say “Microwave Safe,” don’t use them. Choosing to microwave with a plastic lacking such a declaration doesn’t necessarily mean it’s unsafe, but it is missing the assurance of safety. The symbol on the bottom of the container means nothing in this case.

Plastic wrap—saran—helps to retain moisture but it should not touch the food. The wrap itself is not heated by microwaves, but it will conduct heat from warmed food, and it could melt. The result would have to be an acquired taste that may present toxicity issues. The box of wrap will tell you if it’s microwave safe. Don’t even think about Styrofoam cups and dishware unless it says otherwise.

How about paper?

Paper coffee cups are occasionally lined with wax, and sometimes plastic. Overheating is the worry here. Learn to control the microwave. Many papers are manufactured with chemicals you don’t want in your mouth. You have to read the label. The dyes from printed paper towels can contain toxins. White paper towels are usually safe, but reading that affirmation on the package lets you know for sure. Paper grocery bags—or paper bags of any kind, for that matter—may contain unwanted metals or be recycled from who knows what. Waxed paper and parchment are safe in the microwave. Except for those coated with wax or a plastic film, paper plates should not be a problem. The wrapping will tell you. But plain paper plates are flimsy. The big-name companies have microwavable dinnerware. There is always a bottom line, right? Here it is: the preferred options are glass and ceramic. Still, the best habit to cultivate is to become a label reader. We said that already, didn’t we?

References

Anna Angela Barba, Antonella Calabretti, Matteo d’Amore, Anna Lisa Piccinelli, Luca Rastrelli
Phenolic constituents levels in cv. Agria potato under microwave processing
Food Science & Techniology. Dec 2008; 41(10): 1919-1926


Cross GA, Fung DY.
The effect of microwaves on nutrient value of foods.
Crit Rev Food Sci Nutr. 1982;16(4):355-81.

Anne Lassen, Lars Ovesen
Nutritional effects of microwave cooking
Nutrition & Food Science, 1995;  Vol. 95 Iss: 4:  pp.8 – 10


López-Berenguer C, Carvajal M, Moreno DA, García-Viguera C.
Effects of microwave cooking conditions on bioactive compounds present in broccoli inflorescences.
J Agric Food Chem. 2007 Nov 28;55(24):10001-7.


Ovesen L, Jakobsen J, Leth T, Reinholdt J.
The effect of microwave heating on vitamins B1 and E, and linoleic and linolenic acids, and immunoglobulins in human milk.
Int J Food Sci Nutr. 1996 Sep;47(5):427-36.


Quan R, Yang C, Rubinstein S, Lewiston NJ, Sunshine P, Stevenson DK, Kerner JA Jr.
Effects of microwave radiation on anti-infective factors in human milk.
Pediatrics. 1992 Apr;89(4 Pt 1):667-9.


Fumio Watanabe, Katsuo Abe, Tomoyuki Fujita, Mashahiro Goto, Miki Hiemori, and Yoshihisa Nakano
Effects of Microwave Heating on the Loss of Vitamin B12 in Foods
J. Agric. Food Chem., 1998, 46 (1), pp 206–210

*These statements have not been evaluated by the FDA.
These products are not intended to treat, diagnose, cure, or prevent any disease.

Baking With Butter (And Other Fats)

baking-with-butterDo you remember, “Nothin’ says lovin’ like somethin’ from the oven”?  Reportedly, Pillsbury says it best. How many brands of refrigerated dough can there be?  Regardless of what comes from the oven, we want it to taste good. Sometimes that means throwing discretion to the wind and eating stuff we otherwise would avoid. Yeah, right. We all know that limiting simple carbohydrates like white flour and sugar is healthful, but once in a while a splurge disrupts the routine. In that case, we crave “mouth,” the sensation of satisfaction that a food is expected to give. In the unwarranted war against fats that erupted in the last century, commercial baked goods were loaded with sugars—yes, more than one—in a feeble attempt to restore the mouth feel lost to the missing ingredient. The only real accomplishment was to increase the simple carbohydrates and practically force a person to eat several pieces of pastry in the quest for the satiety of mouth. Fat, it was discovered, was never the problem in one’s diet. Sugars were…and are. Regardless of all the emotional baggage we carry about fats, it’s a baker’s best friend, realizing that savory cooking is art, baking is science (there is a formula from which there is little room for straying).

We need to know how fat works in baking before we can appreciate its talents. When flour and water are mixed together, gluten is activated to make the dough elastic, and even stringy. In bread baking, gluten is a welcome guest because it helps the loaf to hold its shape after it rises. In cake baking, less gluten activity is desirable to prevent chewiness. Without sufficient gluten, the carbon dioxide from the addition of yeast would burst the pockets and the bread would flatten. After manipulating the water-flour mixture by kneading or stirring, and if all the gluten that could possibly develop is actually developed at this point, we would have a tough and chewy, flat baked item. This is where fat enters the scene, albeit little in breads.

In baking sweet goods, particularly, fat is almost always mixed with flour before water or any other liquid is added. The fat coats the particles of flour so that water can’t touch them. This means that not all the gluten will develop, making the final product tender. What happened is that the fat “shortened” the strings of gluten that develop. This is the origin of the term, “shortening.”  But wait, there’s more. Fat helps to trap air bubbles, especially at the point when sugar and fat are combined. This is how cakes rise. Of course, add a leavening agent and they rise even more. You see this when the height of the cake exceeds that of the batter first put into the pan.

Fat has more than one form: animal fats are usually solid, plant fats usually liquid. It’s really nature’s way of storing energy and is a more compact storage unit than carbohydrates or proteins, having twice the energy per gram. The key in baking is to choose a fat that is good for you and for the recipe.

Mistakenly labeled an enemy of the cardiovascular system, butter is a fair source of fat-soluble vitamins, especially vitamin A. It contains healthy fatty acids that support immunity, natural lecithin to help metabolize cholesterol, conjugated linoleic acid to fight disease, protects joints against degradation, and provides fatty acids essential to brain function (Lock, 2005) (Fallon, 2000). Less than two-thirds of butter is saturated fat. More than a fourth is monounsaturated, and only very little is polyunsaturated. American butter must be at least 80% fat; as much as 85% for European. It’s that 15% of water that makes a huge difference in butter’s performance in baked goods. Chocolate chip cookies baked with butter will be flatter and crisper than those baked with a less watery fat, such as canned vegetable shortening.

The taste of butter is its selling point. It can be mixed with other shortenings, too. In pie crusts, butter has to be kept cold when you work with it because it’s a more brittle fat than lard or vegetable shortening, and too much will melt into the flour, changing the texture.

What cows are fed makes a difference in the quality of the butter, which explains the inclination of some people to buy European, notably Irish, butter that comes from pasture-fed cows. European butter has more butterfat and less milk solids and water, yielding a more flavorful product. If anything, it’s the milk proteins that cause health concerns, not the fat. Some of the puzzlement about butter is caused by intrusion into the butter industry by… the government (Nuben, 1999).

Margarine is cheap, easy to make, labor-moderate and phony. Because it’s a trans-fat and has little character, we avoid it altogether.

Lard has a better lipid profile than you’d imagine. It has less saturated fat than butter, and more mono- and polyunsaturated fats. What it does for pie crust is gustatory delight. Even when cold, lard is comparatively soft, thus enveloping most of the flour particles and inhibiting the formation of gluten, resulting in the flakiest pie crust. What happens is that it separates the flour and water long enough for the steam to keep layers of lard and flour farther a part. If you’re interested, buy fresh lard and use it quickly because it isn’t a good keeper. You might not want to use lard in cakes because its large crystalline structure makes a sizeable grain, and we don’t want a flaky cake. Suet is the bovine counterpart of lard.

Oils, such as canola and olive, are good at shortening, but poor at trapping air bubbles, so they’re not recommended for all baked goods. It is possible to substitute one fat for another, and experimentation will help you decide on what you like. With pie crusts, whatever makes it tender also makes it less flaky. Covering the flour with fat will make the crust tender. That happens with overworking the dough, either from kneading by hand or flattening with a rolling pin. Leaving the clumps of flour and fat alone will separate the crust into layers that will come apart where the fat was. Getting a crust that is both tender and flaky is up to the baker. That is the art of the science.

Even the one or two percent change in fat content that American butter may have experienced over the years has made a change in the way baked goods come out of the oven. If you decide to experiment with combinations of fats, let us know the results. We never turn our noses at baked fruits.

References

Chris A. Nubern
American Butter Institute Market Situation & Outlook
Third Quarter 1999. Volume 2, Number 3
http://www.ams.usda.gov/AMSv1.0/getfile?dDocName=STELPRD3319082

Sally Fallon and Mary G. Enig, PhD
Why Butter Is Better
01 January 2000
http://www.westonaprice.org/food-features/why-butter-is-better

Haug A, Sjøgren P, Hølland N, Müller H, Kjos NP, Taugbøl O, Fjerdingby N, Biong AS, Selmer-Olsen E, Harstad OM.
Effects of butter naturally enriched with conjugated linoleic acid and vaccenic acid on blood lipids and LDL particle size in growing pigs.
Lipids Health Dis. 2008 Aug 29;7:31. doi: 10.1186/1476-511X-7-31.

Kala AL, Joshi V, Gurudutt K
Effect of heating oils and fats in containers of different materials on their trans fatty acid content.
J Sci Food Agric. 2012 Aug 30;92(11):2227-33.

Lock AL, Horne CA, Bauman DE, Salter AM.
Butter naturally enriched in conjugated linoleic acid and vaccenic acid alters tissue fatty acids and improves the plasma lipoprotein profile in cholesterol-fed hamsters.
J Nutr. 2005 Aug;135(8):1934-9.

Przybylski O, Aladedunye FA.
Formation of trans fats during food preparation.
Can J Diet Pract Res. 2012 Summer;73(2):98-101.

USDA
United States Standards for Grades of Butter
Effective August 31, 1989
http://www.ams.usda.gov/AMSv1.0/getfile?dDocName=STELDEV3004470

*These statements have not been evaluated by the FDA.
These products are not intended to treat, diagnose, cure, or prevent any disease.