Cooking For Geeks Part 7

To a kitchen newbie, working with combinations of heat might be frustrating, but as you get experience with different heat sources and come to understand how they differ, you'll be able to switch methods in the middle of cooking to adjust how a food item is heating up. For example, if you like your lasagna like I do-toasty warm in the middle and with a delicious browned top-the middle needs to get hot enough to melt the cheese and allow the flavors to meld, while the top needs to be hot enough to brown. Baking alone won't generate much of a toasted top, and broiling won't produce a warm center. However, baking until it's almost done and then switching to the broiler achieves both results.

NoteThe convenience food industry cooks with combinations of heat, too, cooking some foods in a hot oven while simultaneously hitting them with microwaves and infrared radiation to cook them quickly.

When cooking, if something isn't coming out as you expect-too hot in one part, too cold in another-check to see whether switching to a different cooking technique can get you the results you want.

If you're an experienced cook, try changing heat sources as a way of creating a challenge for yourself: adapt a recipe to use a different source of heat. In some cases, the adaptation is already common-pancake batter, when deep-fat fried, is a lot like funnel cakes. But try pus.h.i.+ng things further. Eggs cooked on top of rice in a rice cooker? Chocolate cookies cooked in a waffle iron? Fish cooked in a dishwasher? (See Nathan Myhrvold on Modernist Cuisine Nathan Myhrvold on Modernist Cuisine.) Why not?

It might be unconventional, but heat is heat. Sure, different sources of heat transfer energy at different rates, and some are better suited to transitioning the starting thermal gradient (edge to center) of the food to the target thermal gradient. But there are invariably similar enough heat sources worth trying. And you can push it pretty far: fry an egg on your CPU, or cook your beans and sausage on an engine block like some long-haul truck drivers do! As a way of getting unstuck-or just playing around-it's fun to try.

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Cooking methods plotted by rate of heat transfer. This plot shows the amount of time it took to heat the center of uniformly sized pieces of tofu from 40F / 4C to 140F / 60C for each cooking method. Pan material (cast iron, stainless steel, aluminum) and baking pan material (gla.s.s, ceramic) had only minor impact on total time for this experiment and are not individually listed.

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Foodborne Illness and Staying Safe[2]

The American food supply is one of the most interconnected and interdependent ones in the world. As I write this, I'm eating my morning bowl of cereal, yogurt, bananas, and almonds. The muesli cereal is from Switzerland, the yogurt local to New England, the bananas from Costa Rica, and the almonds from California. The only direction from which food hasn't come 3,000 miles is north, and that's probably only because not much grows at the North Pole!

As our food system has become more interconnected, the number of people that can be affected by a mistake in handling food has also increased. Today, a single bad batch of water sprayed onto a field of spinach can sicken hundreds of American consumers because that crop can be transported thousands of miles and make its way into so many dishes before the contamination is noticed.

Handling food carefully-taking note of what has been washed in the case of produce and cooked in the case of meats, and being careful to avoid cross-contamination-is among the easier ways of keeping yourself healthy.

Bacteria related to common foodborne illnesses begin to multiply above 40F / 4.4C. The standard food safety rule provided by the FDA for mitigating foodborne illnesses from bacteria states that food should not be held between the temperatures of 40F / 4.4C and 140F / 60C for more than two hours food should not be held between the temperatures of 40F / 4.4C and 140F / 60C for more than two hours. Below 40F / 4.4C, the bacteria remain viable but won't have a chance to multiply to a sufficient quant.i.ty to bother us. Above 140F / 60C, the bacteria won't be able to survive long. (Bacterial spores, however, can.) This is called the "danger zone rule," and as you'd probably imagine, a vast simplification of what's really going on in the bacterial world. Still, as an easy safety rule there's really no reason to violate it, because there are few dishes that I can think of that actually need to violate it to be made.

NoteFor those recipes that say to marinate meat at room temperature: don't! Let it marinate in the fridge.

Keep in mind that it's c.u.mulative time here that matters. Say you buy a chicken at the store, and that it was kept chilled the entire time before you picked it up. Between the time you put it in the cart and when you stick it in your fridge, it'll be in a warmer environment, and any time it spends above the temperature at which bacteria begin to multiply will increase the bacterial count in the meat.

While cooking food kills off most of the bacteria, a minor (yet safe) number can survive even post-cooking. Given the right temperature range, they can reproduce back up into unsafe quant.i.ties. When cooking, stick any leftovers in the fridge right away, as opposed to letting them sit around until post-meal cleanup. The bacterial level is all about exposure-the amount of time and rate of multiplication at a given temperature.

NoteThis is why you should defrost large pieces of meat in the fridge overnight. Letting it thaw, even under cold running water, can take too long to be safe-unless your cold water happens to be below 40F / 4.4C!

One detail this rule glosses over is that some bacteria can reproduce at lower temperatures. Luckily, most bacteria related to foodborne illness don't multiply very quickly at near-freezing temperatures, but other types of bacteria do. Spoilage-related bacteria, for example, are happy breeding down to freezing temperatures. These are the ones that cause milk to go bad even below 40F / 4.4C and break down the flesh in things like raw chicken, causing uncooked meats to go bad after a few days. The danger zone rule addresses only the common pathological bacteria, which don't reproduce very quickly at the temperature of your fridge.

Another area that the danger zone rule glosses over is the different rates of reproduction at different temperatures. Salmonella, for example, is happiest breeding around 100F / 37.8C. It's not like the bacteria go from zero multiplication at 40F / 4.4C to full-on party mode at 41F / 5C; it's a gradual ramp up to an ideal breeding temperature. The two-hour window is given for the worst-case scenario: that the food is being held at the ideal breeding temperature for the most aggressive of the common bacteria, Bacillus cereus Bacillus cereus.

Since food safety codes are currently adopted on a state-by-state level, some states still use a danger zone rule of "40 to 140 for four hours," on the basis that B. cereus B. cereus accounts for only a minor amount of foodborne illness and that a four-hour exposure isn't likely to produce much risk. If you're getting the impression that food safety is a probability game, you're right. The rules reduce the odds to an acceptable level. Still, that lunch you took to work and forgot to toss in the fridge is probably safe, given that the total amount of bacterial multiplication is likely to be well below the level necessary to trigger any sort of foodborne illness. accounts for only a minor amount of foodborne illness and that a four-hour exposure isn't likely to produce much risk. If you're getting the impression that food safety is a probability game, you're right. The rules reduce the odds to an acceptable level. Still, that lunch you took to work and forgot to toss in the fridge is probably safe, given that the total amount of bacterial multiplication is likely to be well below the level necessary to trigger any sort of foodborne illness.

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The danger zone rule suggests that bacteria multiply right up until 140F / 60C, whereas the real multiplication rates of foodborne illness-related bacteria follow a curve with an ideal breeding range in the middle. Of the foodborne pathogens listed in the FDA's "Bad Bug Book," Bacillus cereus Bacillus cereus has the highest survival temperature, at 131F / 55C. has the highest survival temperature, at 131F / 55C.

"But wait," you might be saying. "What about all that food in the pantry? Why doesn't it go 'bad'?" There are other factors that bacteria need in order to multiply. The acronym FAT TOM is commonly used to describe the six factors necessary for multiplication: - F = Food - Bacteria need proteins and carbohydrates to multiply. No food, no multiplication.

- A = Acidity - Bacteria can only survive in certain pH ranges. Too acidic or basic, and the proteins in the bacteria denature.

- T = Temperature - Too cold, and the bacteria effectively sleep. Too hot, and they die.

- T = Time - Bacteria have to have enough time to multiply to a sufficient quant.i.ty to overwhelm our bodies.

- O = Oxygen - As with pH levels, bacteria will reproduce only if sufficient oxygen is present, or, for anaerobic bacteria (e.g., Clostridium botulinum Clostridium botulinum), if no oxygen is present. Keep in mind that vacuum-packed bags are not necessarily devoid of oxygen.

- M = Moisture - Bacteria need water to reproduce. Food scientists use a scale called water activity water activity, which is a measure of the freely available water in a material (from 0 to 1). Bacteria need a water activity value of 0.85 or greater to multiply.

The reason so many pantry goods are "shelf stable" is either low moisture content (crackers, dry goods like beans and grains, oils, even jams and jellies in which the sugar is hygroscopic and "holds on to" the water) or acidity (pickled items, vinegars). Given these six variables, you can see why some foods don't need refrigeration. When in doubt, though, stick it in the fridge, which you should keep on the chilly side (3436F / 12C).

NoteKeep basic physics in mind. Placing a large pot of hot soup into the fridge will warm up all the contents of the fridge until the evaporator has a chance to transfer the heat back out. Refrigerators are made to keep things cool, not to chill things, so when you're storing a large quant.i.ty of hot food, place it in an ice bath first to chill it and then transfer it to the fridge once it's cooled down.

There's one variable that deserves special mention, because of the potentially fatal consequences, and that's the oxygen level needed for bacterial growth. Specifically, anaerobic environments-ones without without oxygen-are necessary for some types of bacteria to multiply. Oil creates an anaerobic environment, but by itself doesn't provide any moisture for bacteria to grow. But with the addition of something like a raw clove of garlic, an anaerobic environment is created, and the garlic provides the food and moisture necessary for anaerobic bacteria to thrive when given sufficient time at the right temperatures. oxygen-are necessary for some types of bacteria to multiply. Oil creates an anaerobic environment, but by itself doesn't provide any moisture for bacteria to grow. But with the addition of something like a raw clove of garlic, an anaerobic environment is created, and the garlic provides the food and moisture necessary for anaerobic bacteria to thrive when given sufficient time at the right temperatures.

NoteOil, even though a liquid, is technically dry because there is no water present.

A garlic clove stored in oil can become the perfect breeding ground for botulism, the illness caused by Clostridium botulinum Clostridium botulinum. And since C. botulinum C. botulinum doesn't produce any noticeable odor, there's little to tip you off that the food is teeming with bacteria and their toxins. The toxins generated by doesn't produce any noticeable odor, there's little to tip you off that the food is teeming with bacteria and their toxins. The toxins generated by C. botulinum C. botulinum are much more heat stable than the bacteria themselves and might remain active through the cooking process. And now to scare you senseless, the botulinum toxin is the most acutely toxic substance known: a dose as small as ~250 nanograms-1/120,000th the weight of a grain of rice-will do you in. are much more heat stable than the bacteria themselves and might remain active through the cooking process. And now to scare you senseless, the botulinum toxin is the most acutely toxic substance known: a dose as small as ~250 nanograms-1/120,000th the weight of a grain of rice-will do you in.

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If you're going to make something like duck confit or homemade jam the traditional way-cooking it and then sealing it for storage at room temperature-make darn sure you get the food hot enough to sterilize it and that you avoid recontaminating it after it's cooked and before it's sealed. To be safe, stick it in the fridge and treat it as perishable. Note that sterilization means completely eradicating any bacteria, as opposed to pasteurization, which reduces bacteria to "safe" levels for near-term consumption. Sterilized milk can be left at room temperature indefinitely; pasteurized milk cannot.

There's one last aspect I should mention in this brief primer on food safety, and that's the risk/consequences equation. While following food safety rules reduces the risk of illness, it doesn't completely eliminate risk. For most of us, the consequence of contracting most foodborne illnesses is gastrointestinal distress gastrointestinal distress-diarrhea, vomiting, muscle spasms, and the like. However, for those who are in an at-risk group at-risk group-anyone for whom having foodborne illness can lead to further complications-the consequences of a bout of foodborne illness can be much, much greater, so the acceptable risks are accordingly much lower. If you are cooking for someone who is elderly, extremely young, pregnant, or immunocompromised, be extra vigilant with regard to food safety issues and skip dishes that have higher risks (e.g., raw egg in Caesar salads, unpasteurized cheeses, suspect meats that might be past their expiration dates).

For additional information on food safety and bacteria, check out the FDA's "Bad Bug Book," available online at http://www.fda.gov/Food/FoodSafety/FoodborneIllness/. Also, Texas A&M University's Department of Horticultural Sciences maintains a good overview page at http://aggie-horticulture.tamu.edu/extension/poison.html.

While bacteria are the most common and easiest-to-manage cause of foodborne illnesses, they're not alone: viruses, molds, toxins, and contaminants are also of concern. Toxins and contaminants are primarily issues for producers of foods, so as a consumer you're (mostly) off the hook for those. (If you grow your own veggies, test your soil for contaminants.) [image]

Besides proper cooking, the best way to combat bacteria, mold, and viruses is good was.h.i.+ng and avoiding cross-contamination: - Wash your hands! And don't double-dip with the same spoon when tasting a dish.

- Nuke your sponges (rinse them and give them two minutes on high) or run them through the dishwasher weekly. Better yet, use towels and allow them to dry completely between uses.

- When working with raw meats, be careful not to use the same towel for wiping your hands that you then use to wipe with post-cooking.

- Wash can lids before opening them. Wash the can opener, too. The blade picks up food while cutting through the lid.

How to Prevent Foodborne Illness Caused by Bacteria Salmonella: it's the poster child of foodborne illness. And for good reason. Salmonella accounts for a full 30% of the roughly 1,800 deaths due to foodborne illnesses per year in the U.S.-more than any other cause in this category. Salmonella's ideal breeding temperature? Around 100F / 38C-close to body temperature. Clearly it likes us. And according to some reports, the most likely food that'll harbor the bacteria in our modern food supply isn't chicken or meats, but produce. Wash your veggies!

The odds of dying from foodborne illness are actually surprisingly low, especially considering the media attention given to it. But the media attention isn't unmerited: 1 in 8 of us will contract illnesses from foods in any given year, and about 1% of those cases will require hospitalization, according to the U.S. Centers for Disease Control and Prevention (CDC).

Contracting a foodborne illness is a game of probabilities: a single bacterium of salmonella isn't likely to cause a problem, but given a few dozen cells, the odds change. E. coli E. coli is similar: only a few bacteria are necessary for the possibility of infection. A few strains are decidedly nasty, O157:H7 being the most talked about. is similar: only a few bacteria are necessary for the possibility of infection. A few strains are decidedly nasty, O157:H7 being the most talked about.

It's not always "just a handful" of cells, though. Contracting listeriosis requires ingesting somewhere around 1,000 organisms of Listeria monocytogenes Listeria monocytogenes, which tends to be present in animal products and multiplies at temperatures as low as 34F / 1C. Luckily, listeriosis isn't an issue for many of us, but it can cause complications for at-risk groups-especially pregnant women, where the baby is at risk. This is why pregnant women are told to avoid foods such as soft and surface-ripened cheeses, deli salads, raw milk, hot dogs, and shrimp; to ensure that chicken is thoroughly cooked; and to be careful with previously cooked ready-to-eat foods.

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Bacteria can be grouped into three broad categories, based on the temperature at which they are most active. There are bacteria that remain active in food above 122F / 50C, but these are only beneficial (e.g., Bacillus coagulans) Bacillus coagulans) or spoilage bacteria, and not related to foodborne illness. From a taste perspective, we're extremely lucky that no thermophilic bacteria cause foodborne illness; otherwise, we'd have to cook foods to higher temperatures to kill them. or spoilage bacteria, and not related to foodborne illness. From a taste perspective, we're extremely lucky that no thermophilic bacteria cause foodborne illness; otherwise, we'd have to cook foods to higher temperatures to kill them.

GRAPH BASED ON E. ANDERSEN, M. JUL, AND H. RIEMANN (1965), "INDUSTRIEL LEVNEDSMIDDEL-KONSERVERING," COL. 2, KULDEKONSERVERING, COPENHAGEN: TEKNISK FORLAG).

Salmonella gets most of the limelight in the media for a couple of reasons, though: it's hardy-that is, able to survive in the environment for longer periods of time and at temperatures above what most other common-to-food bacteria can tolerate-and it's surprisingly prevalent, affecting 1.4 million Americans a year on average.

Caliciviruses-a family of viruses, norovirus being the best known-are also getting more attention these days, and deservedly so; these are typically spread by a sick individual preparing food for others. If you've spent a night "praying to the porcelain G.o.d"-diarrhea, vomiting, chills, headache-you can probably thank salmonella or norovirus for the experience.

NoteIf you're sick, don't cook for others. If you're around someone sick, wash your hands. Often.

Now, pay attention, because this is important. Salmonella is killed at 136F / 58C Salmonella is killed at 136F / 58C only when held for a sufficient length of time only when held for a sufficient length of time. Seeing your thermometer register an even hotter temperature-say, 140F / 60C-does not guarantee that the food will be free of salmonella. Think of it like being in a hot desert: you can survive 136F / 58C heat for a while, but if you're exposed to it for too long, eventually you will die. The same is true for bacteria like salmonella: given a short amount of time at a particular temperature, the bacteria might survive, but given a longer exposure, they will eventually die.

Salmonella actually lives in a temperature range of 35117F / 247C according to the FDA's "Bad Bug Book." The 136F / 58C temperature is based on what the FDA Food Code gives as the lower bound for pasteurization.

Back to the desert a.n.a.logy. Let's say an average human can survive for four hours in 136F / 58C heat. Given 100 people in a desert, though, this doesn't mean all 100 people will be alive at 3 hours, 59 minutes and all suddenly drop dead one minute later. The same is true for bacteria that might be hitching a ride on that chicken you're about to cook: the proteins in the bacteria don't all spontaneously denature at a specific temperature. It's a probability thing: as the temperature goes up, the probability of the molecular structure of each kind of protein denaturing increases. There's not an exact temperature at which this occurs, like there is when a solid melts into a liquid.

NoteWhen talking about reducing the number of bacteria in food, scientists use the term log log10 reductions reductions. A single log10 reduction is simply the reduction of the number of bacteria present by a factor of 10; a 7 log reduction is simply the reduction of the number of bacteria present by a factor of 10; a 7 log10 reduction is a 10,000,000-fold reduction. The USDA's Food Safety and Inspection Service (FSIS) division is responsible for providing guidelines relating to the number of log reductions necessary to achieve an acceptable quant.i.ty of bacteria. Given that different kinds of meats have different properties-different amounts of fats, water, etc.-the number of log reductions necessary to reduce the bacterial count from a potential starting amount to an acceptable number differs. Hold time for sufficient pasteurization is also affected by variables such as how smooth the surface of the food is and its chemical composition (e.g., nitrite levels). reduction is a 10,000,000-fold reduction. The USDA's Food Safety and Inspection Service (FSIS) division is responsible for providing guidelines relating to the number of log reductions necessary to achieve an acceptable quant.i.ty of bacteria. Given that different kinds of meats have different properties-different amounts of fats, water, etc.-the number of log reductions necessary to reduce the bacterial count from a potential starting amount to an acceptable number differs. Hold time for sufficient pasteurization is also affected by variables such as how smooth the surface of the food is and its chemical composition (e.g., nitrite levels).

One important caveat about pasteurization: sometimes it's not the bacteria themselves that are the issue, but the toxins they produce. While appropriate cooking might safely reduce the bacterial count, the toxins themselves, such as those produced by B. cereus B. cereus, can be heat-stable. Refrigeration of meats is therefore critical to prevent the multiplication of bacteria in the meat tissue. Remember the simple food safety rule mentioned earlier: avoid holding foods at temperatures between 40F / 4C and 140F / 60C for more than two hours. This includes the amount of time it takes to bring the food from fridge temperature to a safe hot temperature! While it is true that the 40-to-140F / 4-to-60C rule for two hours is a vast simplification of the real multiplication rates of bacteria, it's a simple rule accepted by the food industry, and rarely is there any need to skirt it.

NoteWho said scientists don't have a sense of humor? Try saying B. cereus B. cereus out loud. out loud.

At 140F / 60C, a hold time of 35 minutes is necessary for chicken with 12% fat to achieve a 7-log10 reduction. The time drops in leaner chickens; chicken meat with 1% fat requires 25.2 minutes at 140F / 60C. Longer hold times are okay; these times are reduction. The time drops in leaner chickens; chicken meat with 1% fat requires 25.2 minutes at 140F / 60C. Longer hold times are okay; these times are minimum minimum times. Chicken meats can be infected with salmonella throughout the tissue. While sick birds are supposed to be culled, it's still possible for them to go unnoticed. (Data from times. Chicken meats can be infected with salmonella throughout the tissue. While sick birds are supposed to be culled, it's still possible for them to go unnoticed. (Data from http://www.fsis.usda.gov/OPPDE/rdad/FSISNotices/RTE_Poultry_Tables.pdf.) [image]

Minimum amount of time in minutes required to cook chicken safely (a.s.suming 7-log10 reduction in chicken with 12% fat). reduction in chicken with 12% fat).

"Why then," I bet you're thinking, "do 'they' say to cook chicken to a temperature of 165F / 74C?" "They" happen to be the fine folks at the CDC, and what they say specifically is: All poultry should be cooked to reach a minimum internal temperature of 165F [74C].

--http://www.cdc.gov/nczved/divisions/dfbmd/diseases/campylobacter/

Why 165F / 74C? One reason is that this is the temperature at which salmonella dies a quick death. From a "keeping it simple" perspective, seeing 165F / 74C on the thermometer is an easy guideline. Even if your thermometer is miscalibrated or you misprobe the meat and it's only reached a temperature of 155F / 68C, the pasteurization time for chicken at this temperature is less than a minute, which you're likely to exceed. The 165F / 74C guideline effectively removes the variable of time, making it an easier to follow (harder to screw up) rule.

Since none of the bacteria related to foodborne illness can survive, let alone reproduce, at moderate temperatures, holding food above 140F / 60C indefinitely is safe. This is why the soup at your local lunch counter can be kept hot all day long in a heat-controlled container and why hot buffets use steam baths to keep the foods warm. While you might be perplexed by the idea of storing foods hot, from a bacterial control perspective, it's actually safer than storing them in the fridge: bacteria are unable to survive in the hot environment, while storing them in the fridge generally only slows their reproduction.

Note[image]The serving spoons, by the way, are supposed to stay in the food, so that they too stay above 140F / 60C. Otherwise, that mashed potato clinging to the serving spoon at room temperature will be a potential hangout spot for bacteria.

In the U.S., the FSIS and the FDA run testing programs to monitor the food supply. Both agencies have the ability to hold foods at processing plants, to request voluntary recalls, and to outright seize product through court order if it comes to that. Still, there's a lot of food going through the system, and lapses in protocol happen (probably more than we want to know about). A lot of work is done in identifying hazard points in the food system (HACCP-Hazard a.n.a.lysis & Critical Control Points), but still, errors happen. What's a nervous food geek to do?

The most common vector for foodborne illness is surface contamination, either from contaminated water sprayed on vegetables during farming or from fecal contamination in meats during slaughter and processing. How does this affect you when cooking? Since it's the surface of most products that becomes contaminated, it's the surface that needs to be pasteurized. Pan searing a steak heats the outer portion well beyond any temperature that bacteria can survive. Likewise, steaming vegetables thoroughly heats their surface.

NoteWhen cooking vegetables in the microwave, use a container with the lid mostly closed and with a small amount of water inside: the microwave will boil the water, and the container will keep the steam in contact with the vegetables.

What about hamburgers? Well, they're all outside, in the sense that surface contamination will have been ground throughout the meat. Industry calls things like steak whole-muscle intact whole-muscle intact meat, as opposed to ground meat. When looking at consumer cooking guidelines, the temperatures given are lower for whole-muscle intact than ground meats, presumably because the outside of a whole muscle cut will be well beyond pasteurized by the time the middle comes to temperature. meat, as opposed to ground meat. When looking at consumer cooking guidelines, the temperatures given are lower for whole-muscle intact than ground meats, presumably because the outside of a whole muscle cut will be well beyond pasteurized by the time the middle comes to temperature.

Simple CheeseburgerIn a clean bowl, work together using your fingers: - 1 pound (500g) ground beef or hamburger - 1 teaspoon (6g) Worcesters.h.i.+re sauce (optional) - 1 teaspoon (5g) salt - teaspoon (1g) ground pepper (fresh, not preground) Form into three or four patties. Using either a grill (radiant heat from below) or broiler (radiant heat from above), cook on each side for about 5 minutes, until the internal temperature registers at 160F / 71C.If grilling, add cheese (try mild cheddar or Provolone) after flipping the first time. If broiling, add the cheese after reaching temperature and return to broiler for half a minute or so, until the cheese has melted.[image]Notes - Yes, you can haz cheezburger. Just cook it properly. Use a digital thermometer and make sure the internal temperature reaches 160F / 71C. You can pull it off the grill when it is a few degrees lower, because carryover will take it up to temperature.

- Fun fact: "hamburger" can have beef fat added to it; "ground beef" cannot.

NoteFor a little light reading, pull up the FDA's 2009 Food Code (http://www.fda.gov/Food/FoodSafety/RetailFoodProtection/FoodCode/) and look at section 3-401.11: Raw Animal Foods.

When cooking a hamburger, the USDA says to heat the meat to 160F / 71.1C-high enough to kill any common bacteria but also high enough that both actin and myosin proteins will denature, leading to a drier burger. Since fats help mask dryness in meat, using ground beef that has more fat in it will lead to a juicer burger. Alternatively, if you have a way of cooking your burger to a lower temperature and then holding it at temperature long enough to pasteurize it, you could avoid denaturing the actin proteins while still pasteurizing the meat. Take a look at the section on sous vide cooking in Sous Vide Cooking Sous Vide Cooking of of Chapter7 Chapter7 for more on this. for more on this.

Note that change in color is not an accurate indicator of doneness. Myoglobin, oxymyoglobin, and metmyoglobin can begin to turn grey starting around 140F / 60C, and they can also remain pink at 160F / 71C if the pH is at or about 6.0. Use a thermometer when cooking ground meats and poultry!

How to Prevent Foodborne Illness Caused by Parasites Not long ago, I overheard the fishmonger at one of my local grocery stores (which shall remain nameless to protect the guilty) tell a customer that it was okay to use the salmon he was selling for making sus.h.i.+. Given that the fish wasn't labeled as "previously frozen" and that it was in direct contact with other fish in the case, there wasn't any real guarantee that it was free from harmful parasites or bacteria, two of the biggest concerns that consumers need to manage for food safety. What's a shopper to do in response to the disappearance of the true fishmonger?

For one, start by understanding where the risks actually are. Not all fish and meats share the same set of risks for foodborne pathogens. Salmonella, for example, tends to show up in land animals and improperly handled vegetables, while bacteria such as Vibrio vulnificus Vibrio vulnificus show up in fish that are exposed to the brackish waters of tidal estuaries, such as salmon. Deep-water fish, such as tuna, are of less concern. Because of these differences, you should consider the source of your ingredients when thinking about food safety, focusing on the issues that are present in the particular food at hand. show up in fish that are exposed to the brackish waters of tidal estuaries, such as salmon. Deep-water fish, such as tuna, are of less concern. Because of these differences, you should consider the source of your ingredients when thinking about food safety, focusing on the issues that are present in the particular food at hand.

With uncooked and undercooked fish, one concern is parasites. Parasites are to fish as bugs are to veggies: really common (if you've eaten fish, you've eaten worms). But on the plus side, most parasites in seafood don't infect humans. However, there are those that do, Anisakis simplex Anisakis simplex and tapeworms ( and tapeworms (cestodes) being the two parasites of general concern. A. simplex A. simplex will give you abdominal pains, will possibly cause you to vomit and generally feel like c.r.a.p, and will possibly take your doc a while to figure out. It's not appendicitis, Crohn's disease, nor a gastric ulcer, and with only around 10 cases diagnosed per year in the United States, chances are your doc won't have encountered it before. On the plus side, humans are a dead-end host for will give you abdominal pains, will possibly cause you to vomit and generally feel like c.r.a.p, and will possibly take your doc a while to figure out. It's not appendicitis, Crohn's disease, nor a gastric ulcer, and with only around 10 cases diagnosed per year in the United States, chances are your doc won't have encountered it before. On the plus side, humans are a dead-end host for A. simplex A. simplex. The bacteria will die after about 10 days, at which point you'll go back to feeling normal. (Unless you have an extreme infection, in which case, it's off to surgery to remove 'em.) That leaves tapeworms as the major parasitic concern in fish.

For cooked dishes-internal temperature of 140F / 60C-there is little risk from these parasites directly. Cooking the fish also cooks the parasite, and while the thought of eating a worm might be unappetizing, if it's dead there's little to worry about other than the mental factor. (Just think of it as extra protein.) Of course, raw and undercooked seafood is another matter entirely. Cod, halibut, salmon? Fish cooked rare or medium rare? Ceviche, sas.h.i.+mi, cold-smoked fish? All potential hosts for roundworm, tapeworms, and flukes. Fortunately, like most animals, few parasites can survive freezing.

NoteSome parasites do survive freezing. Trich.o.m.onas Trich.o.m.onas-parasitic microorganisms that infect vertebrates-can survive temperatures as cold as liquid nitrogen. Yikes!

For the FDA to consider raw or undercooked fish safe to eat, it must be frozen for a period of time to kill any parasites that might be present: FDA 2005 Food Code, Section 3-402.11: "[B]efore service or sale in ready-to-eat form, raw, raw-marinated, partially cooked, or marinated-partially cooked fish shall be: (1) Frozen and stored at a temperature of 20C (4F) or below for a minimum of 168 hours (7 days) in a freezer; [or] (2) Frozen at 35C (31F) or below until solid and stored at 35C (31F) or below for a minimum of 15 hours..." "[B]efore service or sale in ready-to-eat form, raw, raw-marinated, partially cooked, or marinated-partially cooked fish shall be: (1) Frozen and stored at a temperature of 20C (4F) or below for a minimum of 168 hours (7 days) in a freezer; [or] (2) Frozen at 35C (31F) or below until solid and stored at 35C (31F) or below for a minimum of 15 hours..."

The second concern with undercooked fish is bacteria. While freezing kills parasites, it does not kill bacteria; it just puts them "on ice." Researchers store bacterial samples at 94F / 70C to preserve them for future study, so even super-chilling food does not destroy bacteria. Luckily, most bacteria in fish can be traced to surface contamination due to improper handling-that is, cross-contamination from surfaces previously exposed to contaminated items.

NoteDon't put cooked fish or meat on the same plate as the raw food! In addition to being potentially dangerous, that's just gross.

If your grocery store sells both raw and "sas.h.i.+mi-grade" fish, the difference between the two will be in the handling and care related to the chances of surface contamination, and in most cases the sas.h.i.+mi-grade fish should have been previously frozen. The FDA doesn't actually define what "sas.h.i.+mi grade" or "sus.h.i.+ grade" means, but it does explicitly state that fish not intended to be completely cooked before serving must be frozen before being served.

If you don't have access to a good fish market or find the frozen fish available at your local grocery store unappealing, and you plan on serving undercooked fish, you can kill any parasites present in the fish by freezing: check that your freezer is at least as cold as 4F / 20C, and follow the FDA rule of keeping the fish frozen for a week. If you happen to have a supply of liquid nitrogen around-you know, just by chance-you can also flash-freeze the fish, which should result in better texture and cut the hold time down to less than a day.

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Luckily for oyster lovers, the FDA excludes molluscan sh.e.l.lfish, as well as some types of tuna and some farm-raised fish (those that are fed only food pellets that wouldn't contain live parasites) from the freezing requirement.

Doug Powell on Food Safety[image]PHOTOS USED BY PERMISSION OF DOUG POWELLDoug Powell is an a.s.sociate professor at Kansas State University's Department of Diagnostic Medicine and Pathobiology. His blog, "barfblog: musings about food safety and things that make you barf," is at http://www.barfblog.com.Is there a tension between safety and quality in cooking, and if so, are there methods to achieve both?Safety and quality are two very different things. Quality is something that people love talking about, whether it's wine, or organic food, or how it was grown, and people can talk themselves to death about all that. My job is to make sure they don't barf.[image]For somebody cooking at home, it's easy for them to see a difference in quality. It's very hard for them to see a difference in safety until they get sick, I imagine?There are tremendous nutritional benefits to having a year-round supply of fresh fruits and vegetables. At the same time, the diet rich in fruits and vegetables is the leading cause of food-borne illness in North America because they're fresh, and anything that touches them has the potential to contaminate. So how do you balance the potential for risk against the potential benefits? Be aware of the risks and put in place safety programs, beginning on the farm.If you look at cancer trends in the 1920s, the most predominant cancers were stomach cancers. All everyone ate during the winter were pickles and vinegar and salt. Now that's almost completely eradicated because of fresh food. But now you have to prevent contamination from the farm to the kitchen, because more food is eaten fresh. There are tradeoffs in all of these things. In preparing hamburger and chicken, there is an issue with cooking it thoroughly and validating that with a thermometer, but most of the risk is actually a.s.sociated with cross-contamination. Potatoes are grown in dirt, and birds c.r.a.p all over them, and bird c.r.a.p is loaded with salmonella and campylobacter. When you bring a potato into a kitchen or a food service operation, it's just loaded with bacteria that get all over the place.What's the normal time between ingestion and symptoms?It's around one to two days for salmonella and E. coli. E. coli. For things like listeria, it can be up to two months. Hepat.i.tis A is a month. You probably can't remember what you had yesterday or the day before, so how can you remember what you ate a month ago? The fact that any outbreak actually gets tracked to the source I find miraculous. In the past, if a hundred people went to a wedding or a funeral, they all had the same meal. They all showed up at emergency two days later, and they would have a common menu that investigators would look at to piece it together. Nowadays, through DNA fingerprinting, it's easier. If a person in Tennessee and a person in Michigan and a person in New York have gotten sick from something, they take samples and check against DNA fingerprints. There are computers working 24/7 along with humans looking to make these matches. And they can say these people from all across the country, they actually have the same bug, so they ate the same food. For things like listeria, it can be up to two months. Hepat.i.tis A is a month. You probably can't remember what you had yesterday or the day before, so how can you remember what you ate a month ago? The fact that any outbreak actually gets tracked to the source I find miraculous. In the past, if a hundred people went to a wedding or a funeral, they all had the same meal. They all showed up at emergency two days later, and they would have a common menu that investigators would look at to piece it together. Nowadays, through DNA fingerprinting, it's easier. If a person in Tennessee and a person in Michigan and a person in New York have gotten sick from something, they take samples and check against DNA fingerprints. There are computers working 24/7 along with humans looking to make these matches. And they can say these people from all across the country, they actually have the same bug, so they ate the same food.Think of spinach contamination in 2006. There were 200 people sick, but it was all across the country. How did they put those together? Because they had the same DNA fingerprint and they were able to find the same DNA fingerprint in E. coli E. coli in a bag of spinach from someone's kitchen. Then they were able to find the same DNA fingerprint from a cow next to the spinach farm. It was one of the best cases with the most conclusive evidence. Normally, you don't have that much evidence. in a bag of spinach from someone's kitchen. Then they were able to find the same DNA fingerprint from a cow next to the spinach farm. It was one of the best cases with the most conclusive evidence. Normally, you don't have that much evidence.What to do about it isn't very clear-cut, but when you look at most outbreaks, they're usually not acts of G.o.d. They're usually such gross violations of sanitation that you wonder why people didn't get sicker earlier. With a lot of fresh produce outbreaks, the irrigation water has either human or animal waste in it, and they're using that water to grow crops. These bugs exist naturally. We can take some regulatory precautions, but what are we going to do, kill all the birds? But we can minimize the impact.When farmers harvest crops, they can wash them in a chlorinated water system that will reduce the bacterial loads. We know that cows and pigs and other animals carry these bacteria and they're going to get contaminated during slaughter. So we take other steps to reduce the risk as much as possible, because by the time you get it home and go to make those hamburgers, we know you're going to make mistakes. I've got a PhD, and I'm going to make mistakes. I want the number of bacteria as low as possible so that I don't make my one-year-old sick.Is there a particular count of bacteria that is required to overwhelm the system?It depends on the microorganism. With something like salmonella or campylobacter, we don't know the proper dose response curves. We work backward when there is an outbreak. If it's something like a frozen food, where they might have a good sample because it's in someone's freezer, we can find out more. With something like salmonella or campylobacter, it looks like you need a million cells to trigger an infection. With something like E. coli E. coli O157, you need about five. O157, you need about five.You have to take into account the lethality of the bug. For 10% of the victims, E. coli E. coli O157 is going to blow out their kidneys and some are going to die. With listeria, 30% are going to die. Salmonella and campylobacter tend not to kill, but it's not fun. So all of these things factor into it. A pregnant woman is 20 times more susceptible to listeria. That's why they are warned to not eat deli meat, smoked salmon, and refrigerated, ready-to-eat foods. Listeria grows in the refrigerator and they're 20 times more susceptible and it can kill their babies. Most people don't know that either. O157 is going to blow out their kidneys and some are going to die. With listeria, 30% are going to die. Salmonella and campylobacter tend not to kill, but it's not fun. So all of these things factor into it. A pregnant woman is 20 times more susceptible to listeria. That's why they are warned to not eat deli meat, smoked salmon, and refrigerated, ready-to-eat foods. Listeria grows in the refrigerator and they're 20 times more susceptible and it can kill their babies. Most people don't know that either.Are there any particular major messages that you would want to get to consumers about food safety?It's no different than anything else, like drunk driving or whatever other campaign: be careful. The main message about food in our culture today is dominated by food p.o.r.nography. Turn on the TV and there are endless cooking shows, and all these people going on about all these foods. None of that has anything to do with safety. You go to the supermarket today, you can buy 40 different kinds of milk and 100 different kinds of vegetables grown in different ways, but none of it says it's E. coli E. colifree. Retailers are very reluctant to market on food safety, because then people will think, "Oh my G.o.d, all food is dangerous!" All they have to do is read a newspaper, and they'll know that food is dangerous.A lot of the guidelines I see talk about the danger zone of 40140F / 460C.A lot of those guidelines are just complete nonsense. The danger zone is nice and it's important not to leave food in the danger zone, but at the same time it doesn't really get into any details. People learn by telling stories. Just telling people "Don't do this with your food" doesn't work; they say, "Yeah, okay, why?" I can tell you lots of stories of why or why not. The guidelines aren't changing what people do and that's why we do research on human behavior, how to actually get people to do what they're supposed to do. As Jon Stewart said in 2002, if you think those signs in the bathrooms ("Employees must wash hands") are keeping the p.i.s.s out of your food, you're wrong! What we want to do is come up with signs that work.I'm wondering what your signs look like?We have some good ones! Our favorite picture is the skull in the bed of lettuce! The dead person from carrot juice is pretty good, too.[image]A Final Note on Food SafetyThe safest way of preventing bacterial and parasitic infections from seafood and meats is with proper cooking. The USDA recommends cooking fish to a minimum internal temperature of 145F / 63C, ground beef to a minimum internal temperature of 160F / 71C, and poultry to 165F / 74C.If you enjoy your fish cooked only to a rare point or even raw in the middle and you're concerned about parasites, give frozen fish a chance. I've found distinct differences in the quality of frozen fish. Some stores sell frozen product that's downright bad-mushy, bland, uninspiring-but this isn't because because the fish was frozen. Some of the best sus.h.i.+ chefs in j.a.pan are finding that quick-frozen tuna is exceptionally good. Frozen at sea right after it's caught (in a slurry of liquid nitrogen and dry ice), the tuna doesn't have much time to break down and so maintains its quality during transportation. the fish was frozen. Some of the best sus.h.i.+ chefs in j.a.pan are finding that quick-frozen tuna is exceptionally good. Frozen at sea right after it's caught (in a slurry of liquid nitrogen and dry ice), the tuna doesn't have much time to break down and so maintains its quality during transportation.[image]One last comment on keeping yourself safe in the kitchen: the biggest issue isn't contaminated food from the store, but cross-contamination while preparing it at home. Avoid cross-contamination by was.h.i.+ng your hands often, especially both before and after working with raw meat. Use hot water and soap, and wash for a good 20 seconds.

[2] Well, safer-there's no such thing as 100% safe. Well, safer-there's no such thing as 100% safe.

Key Temperatures in Cooking Most discussions of cooking are structured around the different heat transfer methods listed at the beginning of this chapter. Instead of looking at sources of heat, the rest of this chapter is going to take a different approach and talk about what reactions happen when each of the critical temperatures in the following table is reached, briefly touching on cooking techniques that relate to each temperature as they come up.

Temperature What happens 104F / 40C and 122F / 50C Proteins in fish and meat begin to denature 144F / 62C.

Eggs begin to set 154F / 68C.

Collagen denatures (Bovine Type I) 158F / 70C.