The Physics of Coffee & Cream

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Every Seattleite has been in this situation: On a cold, rainy December morning, you get your coffee to go from Vivace, Stumptown, or Starbucks, and then watch out the window for your bus. The bus, you know, might be a minute or two late, and you’ll have to wait a few minutes. You want to keep your coffee as hot as possible during your wait so that it’s still piping hot when you step out the door. You grab a lid for your cup, pausing at the cream. Should you add the cream to your coffee now, or will that only cool your drink faster? Maybe you should add your cream at the last minute, before you dash out the door.

The basic physics of heat provides the answer: you should go ahead and add the cream to your coffee now. Coffee with cream cools about 20% slower than black coffee, for three reasons:

  1. Black coffee is darker. Dark colors absorb heat faster than light colors (just think about wearing a black T-shirt versus a white T-shirt on a hot, sunny day). But dark colors also emit heat faster than light colors—absorption and emission are essentially two sides of the same coin. So by lightening the color of your coffee, you slow its rate of heat loss slightly.
  2. Stefan-Boltzmann says so. The Stefan-Boltzmann law says that hotter surfaces radiate heat faster—specifically, the power of emission is proportional to the temperature (in kelvin) raised to the fourth power. So let’s say you have two cups of coffee that start at the same temperature. You pour cream in cup #1 and the coffee drops in temperature immediately. But the rate at which it loses heat also drops. Meanwhile, the hotter black coffee in cup #2 cools so rapidly that within five minutes the two coffees are at about the same temperature. But you still haven’t added the cream to coffee #2! When you do, it cools even more; cup #1 is now the hotter of the two.
  3. Viscosity versus evaporation. This is the clincher. Adding cream thickens the coffee (adds viscosity), so it evaporates slower. You’d be surprised just how much heat evaporation carries away. Slow the rate of evaporation and you avoid a lot of that heat loss. (This is also one big reason that coffee stays warm longer with a lid on the cup.)

So, next time you’re caught in the rain, put the cream in your coffee right away. Your fingers will thank you.

Watch our high-speed video above of cream being poured into coffee at 2,000 frames per second.

The Microbiology of Raw Cookie Dough

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In May 2009, an outbreak of foodborne illness sickened at least 80 people across 30 states; it put 35 people in the hospital. The source of that outbreak was raw, store-bought cookie dough.

To better understand the risk of getting sick from undercooked foods, it’s important to know a little about the mechanics of foodborne illnesses. They almost always fall into one of three categories:

  • The first category is a non-invasive infection. This is when pathogens from the food get into your gut and continue living there, but without penetrating the lining. Tapeworms are typically non-invasive, as are certain kinds of bacteria, which may nevertheless secrete toxins that make you ill.
  • The second variety of foodborne illness is an invasive infection. This occurs when pathogens migrate from the gut into the blood or other organs where they can wreak havoc and secrete toxins. Some delightful examples include the parasitic trichinella worm and many strains of bacteria including Salmonella enterica and Escherichia coli.
  • The third category is food poisoning. People sometimes apply this term broadly to any kind of foodborne illness, but food poisoning actually refers specifically to the poisoning of the body by toxins that bacteria have released inside the food before you eat it. Because these toxins are already present before you start cooking, food poisoning typically sets in quickly following a contaminated meal, whereas foodborne infections take a bit of time for bacteria to reproduce inside your body. Botulism, the biggest fear of home-canners everywhere, is one well-known example of food poisoning.

E. coli, the invasive infection responsible for the May 2009 outbreak, lives in the intestinal tracts of humans and other warm-blooded animals. Like other bacteria, E. coli are tiny, being about one-thousandth of a millimeter across and only two to three times that in length. It would take 1.5 trillion of these germs to balance a small paperclip. But what E. coli lacks in size, it makes up for in notoriety. Most E. coli strains are harmless, but one in particular, E. coli O157:H7, has become infamous for its role in foodborne outbreaks, including contaminated milk, ground beef, spinach, and alfalfa.

Another common source of invasive infection is salmonella, which, although it wasn’t to blame in the 2009 cookie-dough outbreak, really is as dangerous as most people imagine. But here, too, confusion reigns over the true source of contamination. Salmonella bacteria do not live in chicken meat (muscle tissue), the source most commonly fingered as the culprit. Instead, the bacteria normally live in the intestinal tracts and feces of chickens and can contaminate the meat during slaughter and processing (except S. enterica, which can infect hen ovaries and contaminate intact eggs regardless of fecal contact). The poultry industry has made enormous strides in containing contamination, and chickens are far from alone in spreading the disease. In 2008, for instance, U.S. investigators traced a major outbreak of salmonella to tainted peanut butter and other peanut-containing foods.

Certain brands of raw cookie dough, which are labeled for raw consumption, such as cookie dough chunks in store-bought ice creams, are safe to eat raw. But even when safe handling practices are followed, eating homemade raw cookie dough, or store-bought cookie dough that is intended to be baked, will always carry some risk.

If you want to avoid a stomach ache—or worse—muster all your willpower… and wait for those cookies to emerge from the oven.

For more on the microbiology of food and food-related illness, check out our tips on Food52.com.

5 Dessert Tips from Modernist Cuisine at Home

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The last chapter in Modernist Cuisine at Home is devoted entirely to custards and pies, and is comprised of 55 recipes, including more than 40 variations. Here are some of our best tips for turning out delectable desserts every time this holiday seasons. Follow our advice to not only save but enhance your sweet creations.

  1. Give Your Eggs the Sous Vide Treatment: Just as we suggest cooking eggs for omelets and scrambles in controlled temperatures in order to achieve the perfect viscosity of this fickle ingredient, we believe that egg-based desserts need the same treatment. We fill ramekins with crème brûlée, seal them, and cook them in a water bath to a core temperature of 80 °C / 176 °F. When making a pastry cream, crème anglaise, lemon curd, or sabayon, we first cook the egg yolks sous vide (using different temperatures, depending on the dish) to fully pasteurize them, avoiding the fuss of double boilers and curdling. In Modernist Cuisine at Home, we propose eight variations of our pastry cream alone, like Amaretto, cheese, and pressure-infused coffee. Trust us, you’ll never face a boring cream pie again.
  2. Calculate Your Gelatin: Reviving the Jell-O wreath or planning a fancy panna cotta this holiday season? We use Knox gelatin in our panne cotte, firm pastry creams, apple foam, and fruit jellies because you can find it in most grocery stores. Gelatins are measured by what is called their Bloom strength (usually labeled as bronze, silver, gold, or platinum). Knox brand has a bloom strength of 225. If you are making a recipe (not just one of ours, but any recipe), be it a Jell-O wreath or a pâté, you can use a different Bloom strength than what the recipe calls for, but you’ll have to do a little math. You can convert the recipe to use whatever gelatin you have on hand if you know the weight (MA) and Bloom strength (BA). For gelatin A, you can find the equivalent weight of gelatin B (MB) with a Bloom strength of BB by using the formula MB = MA × BA ÷ BB. For example, if a recipe calls for 2.6 g of Knox gelatin, you could use 3.7 g of silver gelatin, which has a Bloom strength of 160 (2.6 × 225 ÷ 160 = 3.7). To make a vegetarian panna cotta, we substitute 0.8 g agar and 0.65 g xanthan for the 4.3 g gelatin the recipe normally calls for.
  3. Keep Your Pie Crust Flaky: You can’t have a great pie if your crust is soggy, so we tested more than 40 versions before nailing down our Flaky Pie Crust recipe. But even the best crust needs a little extra help when acting as the foundation for a pastry cream. To keep your crust crisp, let it cool and then brush a thin layer of melted cocoa butter on top of it. Let the butter solidify at room temperature before filling the pie with pastry cream. This coating of cocoa butter creates a barrier between the crust and pastry cream, which will prevent the moisture of the cream from draining into the crust, turning it to mush.
  4. Make Freeze-Dried Raspberry Powder: A great way to finish any dessert is with freeze-dried raspberry powder sprinkled on top. Pulse store-bought, freeze-dried raspberries (or any other freeze-dried fruit) in a food processor, blender, or coffee grinder until a powder forms. This powder has myriad uses. You can blend it into your pie crust, mix it with a little sugar and rim a cocktail glass with it, or sprinkle it over lemon curd, just to name a few ideas.
  5. Microwave a Cake: If you are stymied by unexpected visitors, skip our Custard and Pie chapter and thumb back to the Microwave chapter. Making individual cakes is a snap with a whipping siphon and a microwave. Siphon the batter into paper cups and microwave them for 50 seconds until thoroughly cooked. To watch Scott demonstrate this technique in a CHOW Tips video, click here.

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Nathan Demos Microwave Recipes on Rachael Ray

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Today, Rachael Ray invited Modernist Cuisine at Home author Nathan Myhrvold on her show. Using only olive oil, a little salt, and a microwave, Nathan taught Rachael how to make puffed chickpeas and kale chips. Watch the video above for the complete demonstration. To get the recipes, visit the page on RachaelRayShow.com. And for more on puffing in the microwave, watch our MDRN KTCHN video on puffy snacks.

Our Guide to Picking the Perfect Pan

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Are you looking for a new set of pans this holiday season? Scott Heimendinger, our Director of Applied Research, explains the science behind heat diffusion in stove-top cooking on MDRN KTCHN on CHOW.com. The end result: Thickness is more important than material, no matter how shiny and expensive those copper pans may be. He also gives you a few work-arounds for uneven stoves.

Top 5 Modernist Cuisine at Home Tools

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Maybe you gave someone Modernist Cuisine at Home, or perhaps you have it yourself. Now you want to know what to give with it, or what else to put on your own wish list. These are our top five suggestions.

  1. Right now, both Polyscience and SousVide Supreme have great packages.

    Digital Scale: We are very keen on precision. A digital scale allows chefs to accurately measure out Modernist ingredients, some of which can drastically alter your recipe if measured imprecisely. We recommend a scale that weighs out to a tenth of a gram because many recipes with Modernist ingredients may call for amounts as little as 0.3 g. We like the Digital Bench Scale. While our recipes in Modernist Cuisine at Home don’t call for accuracy in hundredths of a gram, you may still want to consider a scale that measures to the hundredths. If you are cutting a recipe in half, however, and it originally calls for 0.3 g, you’ll want to be able to measure out 0.15 g. For such precision, we like the Digital Pocket Scale. For something cheaper and ultraportable, try the American Weigh Signature Series.

  2. Digital Thermometer: As Nathan often says, “Why waste time being a human thermostat?” For cooking meat sous vide to precise temperatures, you’ll need a good thermometer. We like Taylor’s Professional Thermocouple and ThermoWorks’s Splash-Proof Thermapen, but if you are looking for something a bit cheaper, you may want to go with a digital oven probe.

    We make everything from carnitas to stocks to risotto in our pressure cooker.
  3. Sous Vide Setup: Sous vide cooking is becoming more and more popular, hence finding sous vide machines in stores is now easier. In making Modernist Cuisine at Home, we used the SousVide Supreme alongside various models from Polyscience. The SousVide Supreme is a little more affordable, but right now both companies have some great offers. PolyScience is offering the Sous Vide Professional (CREATIVE Series) with a copy of Modernist Cuisine at Home for just $599. SousVide Supreme is offering their model, a copy of the book, and a vacuum sealer for $599.
  4. Pressure Cooker: When shopping for a pressure cooker, you’ll want to look for one with a spring valve. This is the best choice for stocks and sauces because the valve seals the cooker before it is vented. This traps most of the aromatic volatiles before they can escape. We love our Kuhn Rikon pressure cooker, but if you are looking for something a little cheaper, try Fagor.

    Foaming is just one of many functions of a whipping siphon.
  5. Whipping Siphon: Whipping siphons are one of our favorite kitchen gadgets. We use them for everything from making foams to carbonating fruit to marinating meat. We use them interchangeably with carbon dioxide and nitrous oxide cartridges, depending on what we want to do (note that you can do this with a whipping siphon but not with a soda siphon). We prefer iSi’s Gourmet Whipping Siphon, but there are many options available. Try to find one that holds a full liter, but smaller versions work too.

 

If you are looking for more ideas, we have you covered. Check out our Gear Guide where we discuss ovens, microwaves, silicone mats, blenders, and grills, just to name a few.

Google Talks with Nathan Myhrvold

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Have you ever wondered, pound for pound, which costs more, Modernist Cuisine at Home or Parmesan cheese? Nathan does the math in the Google Talks video above, and, as it turns out, our new book is a steal. Nathan also discusses printing quality, why you shouldn’t dismiss blowtorches, how he found inspiration on eGullet, and much, much more.

For more on Google Talks, click here.

Turkey Tips

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Stop worrying over your Thanksgiving turkey! Follow our guidelines and you’ll serve up the perfect roasted bird. Place your cursor over the white circles in the photo below to learn everything you need.

If the file doesn’t display, you may download the SWF file.

Thanksgiving, the Modernist Cuisine at Home Way

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What better time than Thanksgiving to try out recipes from Modernist Cuisine at Home? To get you started, we put together a menu using recipes from our website and new book. And if you’re not hosting a Turkey-Day feast this year, we hope you’ll bring a dish or two to your friend’s or family’s house.

For tips on cooking the perfect (whole) bird, check out Nathan’s interview in Men’s Health. And for advice on cooking safely for the holidays, see our article on Food52.com. If you have any questions, or if you want to post tips of your own, check out the “Thanksgiving!” thread on our forum.

Page numbers refer to the page in the main volume of Modernist Cuisine at Home.

 

Hors d’Oeuvres

Pressure-Cooked Garlic Confit on Toast (page 126)
Carbonated Cranberries
Clams in Chowder Sauce (page 292)
Savory Cheese Pie (page 379)

Soup & Salad Course

Autumn Salad (page 166) with Modernist Vinaigrette (page 117)
Caramelized Carrot Soup (page 178)
Breadsticks (page 296)

Main Course

Sous Vide Turkey Breast (page 247)
Turkey Leg Confit (page 246)
Home Jus Gras (page 93)

Sides

Deep-Fried Brussels Sprouts
Creamed Spinach (page 199)
Pressure-Cooked Vegetables (page 185)
Potato Puree (page 230) or Dairy-Free Potato Puree
Garnet Yam Fondant with Sage Foam
Stuffing Puree

Dessert & Coffee

Pecan Gelato (page 370)
Apple Cream Pie (page 379)
Coffee Crème Brûlée

Puffy Snacks You Can Make at Home!

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Everyone loves the crunch of a tasty puffed snack, but we don’t see many of the homemade variety. In our newest video from MDRN KTCHN on CHOW.com, we bring you an easy recipe for puffed rice snacks using your microwave. Watch the video above as our Director of Applied Research, Scott Heimendinger, demonstrates the method and explains how and why it works.

For another slightly more involved recipe for puffed snacks, including tips for puffing success, take a look at our Cheese Puffs recipe in the recipe library, which can also be found in Modernist Cuisine alongside other puffed-food recipes such as crab crackers, chickpeas, and chicken feet. Our new book, Modernist Cuisine at Home includes recipes for puffed pork skin and chicken skin too!