Bacon: The Slice of Life — The Kitchen as Laboratory

“Whether used as a breakfast meat, a cooking ingredient, or strictly for flavoring, bacon is one of the most universally enjoyed foods in the world. It is hard to deny that bacon is an important part of our most fundamental culinary experiences.”—Timothy Knight from his chapter ‘Bacon: The Slice of Life'”

Yesterday we posted Jennifer Kimmel’s chapter The Science of Grilled Cheese from The Kitchen as Laboratory: Reflections on the Science of Food and Cooking, edited by Cesar Vega, Job Ubbink, and Erik van der Linden. Today we offer Timothy Knight’s fascinating chapter on the history, properties, and science of bacon:

Bacon is magical. It can transform an ordinary meal into an extraordinary delight. With just one bite, you get an irresistible crunch, a distinctive smoky flavor, and an unmistakable sense of deliciousness. This chapter takes you through the finely honed mandatory steps that turn a humble piece of pork into the mouth-watering slice of “meat candy” that we know and love. So hang on tight. You are about to embark on a journey behind the magical bacon curtain, where you will learn how a lowly pork belly becomes the meat that makes your life complete.

A Brief History of Bacon

For more than three thousand years, bacon was made on farms using traditional practices that involved salt curing, dry curing, and smoking pork bellies. During the 1770s, John Harris, an industrious farmer in Wiltshire, England, established himself as the first large-scale bacon manufacturer in the modern world by using so-called wet-curing methods. With the onset of the industrial era came Philip Armour’s refrigerated rail cars and the development of more advanced preservation techniques by Gustavus Swift, both of which paved the way for the development of bacon as we know it today. In 1924, Oscar Mayer took his rightful place on the smoky-salty bacon throne by introducing the first presliced bacon. However, shoppers still had to get their bacon from the in-store butcher. So, in 1948, Mayer introduced the first prepackaged bacon, a durable cellophane-wrapped slab of sliced bacon on a thin sheet of cardboard. This allowed shoppers to select packages themselves from the retail case. In 1962, with the onset of new polymer-film technologies, Oscar Mayer began vacuum packaging his bacon (and other processed meats), once again revolutionizing retail meat packaging. An airtight envelope protected the bacon against spoilage. The back-of-package window, which allowed shoppers to see exactly what they were purchasing, was embraced in 1973.

It All Starts with a Pork Belly

A pork belly does not come off a hog resembling anything like bacon. In fact, it is not actually the belly or the stomach; rather, it is the lean and fat from the side of the hog that remains after the ham, shoulder, ribs, and loin are removed. Each hog has two “bellies.” The anatomy of a pork belly is complex, having several distinct and interspersed layers of lean and fat, which can be readily identified when looking at an individual strip of bacon. These layers are not consistently proportioned or spaced throughout the length of the belly, which is why individual slices of bacon look different (­figure 18). Trimming removes sections that are too fatty to make into bacon. White bacon is made from the abdominal region of the hog and is nearly devoid of lean meat. This fatty cut is used primarily for flavoring. In some cultures, the fat from this cut is slowly melted out of the meat structure. The remaining bacon then solidifies as a crispy-crunchy “chip.”

You’ve Got Bacon Fever’ve Got the Cure

Prior to modern refrigeration, the dry curing of pork was necessary to prevent spoilage. It was accomplished by applying a salt crust to the exterior of the pork belly, where it was absorbed over time, essentially drawing moisture out of the meat and preserving it for later use. Air drying may also have contributed to preservation. Old World dry-cure mixtures typically consisted of unpurified salts and sometimes sugar. This method worked well for preservation but the quality left much to be desired; more often than not, the result was extremely salty and harsh with inconsistent salt dispersion.

Modern bacon manufacturers use a more efficient and reliable method called wet curing, or Wiltshire curing. This evolutionary method was first routinely used by John Harris and involved submerging raw pork belly in concentrated salt brine. Injection, a modern modification of this process, uses large needles to infuse brine directly into the interior of the belly instead of relying on migration of the salt from the surface over time. It provides even curing and more effective brine incorporation. Today, most bacon brines are a mixture of salt, sugar (to lessen the harshness of the salt), and a small amount of sodium nitrite for preservation purposes.

In my opinion, quality wet-cured bacon is consistently superior to the dry-cured variety because it relies on refrigeration and vacuum packaging for preservation rather than the severe conditions that preserve dry-cured products. It is also less prone to spoilage and the development of rancid flavors and aromas. This being said, there are very good dry-cured bacons of exceptionally high quality in the retail market today. All bacon lovers should experiment with and enjoy these—and not only for special-occasion meals.

The Magician’s Magic Box

The magical transformation from pork belly to bacon begins with the brine needle. After injection, the pork belly is hung to help facilitate moisture loss and prevent curling during the smoking process. As a caterpillar disappears into a chrysalis and eventually materializes as a beautiful butterfly, so too must pork belly go into its smokehouse cocoon to later emerge as delicious bacon. And as with all great magic tricks, there is a puff of smoke. In the smokehouse, pork bellies are cured, smoked, and cooked before they appear as unsliced bacon. This process can take as little as a few hours or up to a few days, depending on the manufacturer. The finished slabs are chilled, sliced, and packaged. Vacuum packing keeps destructive oxygen molecules away from the bacon, prevents the fat from becoming rancid, and helps prevent microbial spoilage. Bacon is almost always purchased refrigerated, but unopened packages can be stored frozen for months.

Up in Smoke

Smoking is a vital ingredient in the sweet science of bacon, and careful control of the delicate art of smoking is crucial to producing a quality product. Meats were originally smoked primarily for preservation, but today we are able to take advantage of smoke for much more. The smokehouse process not only partially cooks the pork but also generates the smoky flavor, aroma, and color we love and associate with bacon. In addition, this all-important step brings out the flavors in the cure and partially renders the fat. There are several methods that can be used to apply smoke to meats. The traditional and most desirable method is burning hardwood in a smokehouse. A modern method is the use of liquid smoke extracts, but it is extraordinarily difficult to reproduce the complexity and uniqueness of true hardwood-smoked meat.

When wood is heated to high temperatures, controlled oxidative combustion generates the complex mix of vapors and particulates known as smoke. Wood is made up of compounds classified into cellulose, hemicellulose, and lignin. During controlled burning, cellulose and hemicellulose break down into smaller compounds, including carbonyls and organic acids. Lignins devolve into various phenolic substances. All of these are vaporized by heat and become components of smoke. If done correctly, the combustion should result in smoke with a pleasant balance among organic acids, phenolic substances, and carbonyl compounds deposited on the pork-belly surface. The organic acids deliver a very slight tartness, but phenols provide the predominant flavor and aroma that we associate with smoke. They are fat soluble and concentrate on the exposed belly fat. Deposition of carbonyl compounds imparts a golden brown color on the lean surfaces of the bacon slab. This deposition is mostly caused by nonenzymatic browning—that is, by a Maillard reaction, in which carbonyl compounds are key .

Any bacon worth its salt should be hardwood smoked. The classification of hardwood versus softwood has nothing to do with the trees— physical hardness. It is a matter of how the trees produce their seeds. Hardwoods produce flowers and softwoods produce cones. The flavor differences between the two woods are associated with differences in the amount and types of lignins in the wood. Hardwoods are used for smoking meat because they impart desirable flavors and aromas when burned, and the smoke is sweet and clean. They include apple (slightly sweet, fruity, mild), beech, birch, cherry (sweet, fruity, mild), hickory (strong, hearty), maple (sweet), and oak (strong, earthy, robust). Softwoods produce poor-quality smoke, imparting an unpleasant flavor and smell that is described as oily, sooty, and resinous, reminiscent of the odor of cleaning.

Smoke is not the only contributor to the complex flavor of bacon, but it is one of the most predominant and important components. Poor smoking will ruin your bacon. And remember, as with most things in life, it is the quality of the smoke, not the quantity that matters. True bacon artisans work with smoke like artists with paintbrushes, having perfected their craft over time. Because it is an art as much as a science, it must be perfected with experience.

Bringing Home the Bacon

Now the transformation is complete! But there is still one final part to the magic trick before the big reveal—that perfect slab in the grocer’s freezer. Luckily, a savvy consumer who knows what to look for has a great advantage in selecting the best bacon. In Europe, shoppers are lucky enough to have a significant amount of bacon sold at traditional butchers, where it can be cut from a large side upon request. In North America, however, we all know the maddening sensation of rifling through various bacon packages, trying to decide which one to purchase. So, how do you choose the best bacon? While the answer depends mainly on usage and personal preference, you should look for a few key indicators.

Examine the strips for a good fat-to-lean ratio. The lean should be shades of reddish-pink and the fat should be white without any blemishes or discoloration. The bacon should have long streaks of evenly distributed lean that run nearly the full length of the slice. These lean streaks should be separated by snowy white fat. “Why does this matter?” you ask. Well, my scholarly shopper, research has shown that the most desirable bacon, in terms of uncooked and cooked appearance and palatability, is approximately 40 percent lean and 60 percent fat, with an even distribution of lean and fat throughout each strip. Slices with these proportions come predominantly from the middle section of the pork belly. This region is the most uniform part, possessing a large and lean musculature. Also, these slices will remain straighter and shrivel less during cooking. Consumer-preference research shows that the ideal width of a raw slice is approximately 1 inch (2.5 cm). At more than 1 1/4 (3 cm), the slice’s fat-to-lean ratio is often too high. At less than 3/4 inch (2 cm), the texture can suffer.

Next, look carefully at the color of the lean part of the bacon. During the curing process, myoglobin, the major pigment molecule in the lean portion of the meat, undergoes a series of chemical reactions that generates different-colored molecules, eventually binding with a modified form of nitrite to create the dark red pigment. This is where the pigment conversion should stop for bacon: slightly dark reddish-pink. You should see at least some lean that is this color. If the lean is entirely light pink and the red has turned to pink, it has been overly heat processed and will likely taste more like ham than bacon. You might say, “Back off, I love ham!” Well, stop your squealing! No one is saying anything bad about ham, but this is bacon, so it needs to taste like bacon, with its delicate nuances and true bacon flavor.

Once cooked, the flavor should be porky and salty, with predominantly roasted and brown top notes and a touch of sweetness, along with a clean, nonashy hardwood-smoke character. The smoke flavor should not be so powerful that it overwhelms the unique deliciousness that is generated during the curing and cooking processes. In other words, it should taste like bacon and not as though you have been slapped in the face with a slice of triple-smoked ham. If all you taste is smoke, you have been cheated out of your bacon experience. Bacon should never have undesirable off-flavors, like sourness or mustiness. It should develop a delicate crispness when cooked, and it should not have a tough or rubbery texture or seem overly greasy in the mouth.

Crispy Matters

You have brought home the bacon. You are anticipating the perfect moment when everything becomes quiet and all you hear is that unmistakable crackling (in the pan) and crunch (in your mouth) of a perfectly cooked strip. While all basketball players know that making the perfect shot is “all in the wrist,” serious bacon connoisseurs know that making the best bacon is “all in the crisp.” We all have experienced how perfectly cooked bacon can take an ordinary bacon, lettuce, and tomato sandwich and transform it into a crispy oasis of delicious goodness. Now there is scientific proof of how critical that crunch is to your lunch. The University of Leeds in England has developed an equation that demonstrates how necessary bacon crispness is to the BLT. In fact, it was determined to be the key element in the ideal sandwich. Moreover, it is the sound of the crunch that is absolutely critical to a truly desirable BLT. The researchers determined that in the best sandwich, bacon is crisply grilled and of moderate fattiness. They achieved this by cooking the bacon for 7 minutes at 480 (F) (250 (C) over a preheated oven grill.

You Brought Home the Bacon—Now Fry It Up in a Pan

The thermal treatment applied in the smokehouse is relatively mild compared with temperatures achieved on your stovetop. Bacon needs to be cooked to a typical frying temperature to allow each and every precious slice to live up to its maximum delicious potential. When a strip of bacon is prepared, there is a loss of fat and water. This serves to concentrate flavors, promote nonenzymatic browning reactions, and generate subtle flavor, aroma, and color compounds. As more and more moisture and fat are lost from the slice, it becomes crisp and crunchy, presumably because it moves into a very stable, or glassy, state (for details about the glassy state, see chapter 24). However, if you overcook bacon, all the moisture will seep out, making the structure overly dry—and after it cools, an extremely rigid microstructure of empty cells will result in a brittle and crumbly texture. Proper browning, along with curing and smoking, combine into an explosion of deliciousness when you bite into a strip. Although pan frying is the most common way to prepare bacon, it is certainly not the only method, and many people agree that oven baking is the best way to prepare it. The oven provides greater evenness of heating and produces slices with fewer convolutions and less shrinkage. Baking is easy and results in crisp, flat, and evenly cooked strips of bacon. Just line a baking sheet with a piece of aluminum foil and place a wire cooling rack on top of it. Arrange the slices perpendicular to the tines without overlapping, and bake in a preheated oven at 430 (F) (220 (C)) until the bacon reaches the desired crispness.

Trying a variety of slice thicknesses can dramatically enhance your bacon experience. If you normally use the standard thickness, let your hair down, act with reckless abandon, and pick up a pack of thin or thick strips! Thin sliced (0.8 mm) will give you a crispy strip that easily becomes brittle. Regular thickness (1.6 mm) is very popular because it is thick enough to develop crispness but not thin enough to easily overcook and turn brittle. Thick sliced (3.2 mm) is very hearty but also more difficult to crisp. It needs to be cooked over a lower heat for a longer time to achieve a crisp slice that is not tough and chewy

BYOB: Bring Your Own Bacon

Since it is complementary to so many food pairings, bacon does not have to stand alone on the breakfast plate. The salty flavor mixes well with both the sweet and savory, so let your imagination and taste buds run wild. It can be used as a main ingredient in dishes, such as the classic bacon club sandwich, quiche, or a breakfast casserole. Bacon, as well as rendered bacon fat, can heighten the flavor of any number of foods. You can add it to soups, stews, or roasts, and the rich smoky flavors especially complement bean dishes.

Rediscover bacon’s material properties. It is flexible when raw yet holds a defined shape when cooked. Try wrapping a thin slice of raw bacon around a metal rod before baking. When crisped, it can be carefully slid off to produce a delicate spiral shape. Turn a muffin pan upside down and cover the outside of the cups with bacon strips. Broil until crisp to form a bowl shape that can be filled with any number of sweet or savory treats. You can even use raw bacon to form a lattice pattern on top of a main dish and crisp it under a broiler.

Bacon complements sweet flavors very well. Bacon cured with maple or brown sugar pairs nicely with vanilla ice cream. Strips of cooked bacon can be easily candied by quickly dipping them into exotically flavored syrup sugar, at the soft-crack stage, to form a thin glassy film. For the gourmet, a delicious and easy way to make an exciting bacon treat is to paint the bacon with maple syrup during cooking, or you can liven up the bacon by sprinkling it with brown sugar and sweet spices just before oven baking. It will also balance the sweetness of an apple pie. Just crumble cooked bacon pieces and cheddar cheese shreds on top to bring out an entirely different array of flavors. I have even seen crisp strips used as swizzle sticks for tomato-based cocktails or as desserts after being covered in a thin, delicate layer of rich dark chocolate. The possibilities are practically endless with a bit of creativity thrown in for good measure.

The Slice of Life
We have seen that bacon is an extremely versatile food; however, I will argue that we do not incorporate it into cooking nearly enough. Whether used as a breakfast meat, a cooking ingredient, or strictly for flavoring, bacon is one of the most universally enjoyed foods in the world. It is hard to deny that bacon is an important part of our most fundamental culinary experiences. It is steeped in tradition and heritage, with nearly all cultures having some form of bacon in their regional cuisines. Today, we have unprecedented access to countless varieties of bacon from around the world. There is always a new style to help satisfy our most powerful bacon cravings, from the standard English rasher to the Chinese lop yuk. And to think, all of this comes from a humble cut of pork that was once considered low on the hog. Embrace the pig, and give yourself over completely to the meat that makes your life complete.