“Tea and Coffee,” on Food and Cooking

ON FOOD AND COOKING

The Science and Lore of the Kitchen

COMPLETELY REVISED AND UPDATED

Harold McGee

Illustrations by Patricia Dorfman,Justin Greene, and Ann McGee

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ISBN-13 978-0-684-80001-1 ISBN-10 0-684-80001-2

Page 884 constitutes a continuation of the copyright p::ige . TEA AND COFFEE --1-33 cooking with Vanilla VanilJa is used served by minimal heat and drying. Coffee inly in sweet food . Almost hall of rhe and tea thus offer two very different expe nlllnilla flavormg· consume d m· t he Umre · d riences of botanical inventiveness and Sva tes goes ·mto ·ice cream, and rnuc h o f human art. ;: r.esr into soft drink and chocolate. Bur . also works savory hes: lobster and in di CAFFEINE ttork are popular examples. Added with a f. hr touch, vani lla can contribute a sense of Caffeine is the most wiJely consumed J:prh, warmth roundness, and persistence behavior-modifying chemical in the wodd. co al.most any food. It is an alkaloid (p. 23 8) that interferes The flavor of the whole vanilla bean with a particular signaling system used by t:esides in two. different p~rts. of th~ bean: many different cells, and therefore has sev the ticky, reslDOUS matenaJ lil wlitcb the eral different effects on the human body. ciny seeds are embedded and the fibrou Above all, caffeine stimulates the central pod waJI. The :first is easily scraped out of nervous system, relieves drowsiness and the bean and dispersed in a preparation, fatigue, and quickens reaction times. It also while the pod itself muse be soaked for increases energy production in muscles and some time in order to extract its flavor. so their capacity for work. It's said to Bec:iuse the volatiles are generally more improve mood and mental performance, soluble in fat than in water, the cook can though recent studies suggest that these cxtr:ict more flavor if the extraction liquid may be the result of relieving the initial includes either alcohol or fat. Prepared symptoms of overnight caffeine with v:inilb extracts can be dispersed through drawal! Less desirably, in high doses it out :i dish instantly, and are usually best causes restlessness, nervousness, and insom

3 dded toward the end of cooking; any nia. It has complex effects on the heart and period of time spent at a high temperature arteries, and can produce an abnormally c:iuses aroma loss. fast heartbeat. There is some evidence that caffeine speeds the loss of calcium from bone, so habitual consumption may con TEA AND COFFEE tribute to osteoporosis. Caffeine reaches its maximum levels in Tea and coffee are the most widely con the blood between 15 minutes and two sumed drinks in the world, and their pop hours after consumption, and its levels are ularity stems from the same source as that reduced by half with111 three to seven of herbs and spices: the plant materials hours. Its effects are more noticeable in they're made from are crammed with people who don't normally consume it. chemical defenses that we have learned to Withdrawal symptoms can be unpleasant, dilute, modify, and love. Tea leaves and but usually disappear within three days of coffee beans have one defense in common, abstaining. and that's caffeine, a bitter alkaloid that has A chemical relative of caffeine called significant effects on our bodies. And they theophylline is found in tea and is in some both contain large doses of phenolic com respects more potent than caffeine, but tea pounds. However, they're very different contains only trace amounts. Though cof materials. Coffee begins as a seed, a store fee beans arc 1-2 % caffeine and tea leaves house of protein, carbohydrate, and oil, 2-3%, brewed coffee contains more caf and is the creation of high heat a robust feine than brewed tea because a larger epitome of roasted foods and flavors. Tea weight of coffee is extracted per cup (8-10 begins as a new, actively growing leaf, rich grams, vs. 2-5 grams for tea). in enzymes, and is the delicate creation of those enzymes, carefully captured and pre- 434 FLAVORINGS FROM PLANTS

TEA, COFFEE, AND HEALTH WATER FOR MAKING TEA AND COFFEE Not so many years ago, both coffee and tea were suspected of contributing to various Brewed rea and coffee are --98 % water diseases, including cancers, so they were so their quality is strongly influenced by th~ among the many pleasures to feel guilty quality of the water u ed to make then:i about. No longer! Coffee is now recog The off-flavors and di in£ectant chlorio,~ nized as the major source of antioxidant compounds of most tap waters are large!¥ compounds in the American diet (medium driven off by boiling. Very hard water, high roasts have the highest antioxidant activ in calcium and magnesium carbonates, has ity). Black and especially green teas are several undesirable effects: in coffee, these also rich in antioxidant and other protective minerals slow flavor extraction, cloud the phenolic compounds that appear to reduce brew, clog the pipes in espresso machines damage to arteries and cancer risk. and reduce the fine espresso foam; in tea Certain kinds of brewed coffee do turn they cause the formation of a surface scu~ out to have an undesirable effect on blood made up of precipitated calcium carbonate cholesterol levels. Two lipid (fat-like) sub and phenolic aggregates. Softened water stances, cafestol and kahweol, raise those overextracts both coffee and tea and gives levels, though they only get into the coffee a salty flavor. And very pure distilled water when the brewing technique doesn't filter gives a brew best described as flat, with a them out. Boiled, plunger-pot, and espresso missing dimension of flavor. coffees contain them. The significance of The ideal water has a moderate mineral this effect isn't known and may well be content, and a pH that is close to neutral, so small, since the cholesterol raisers are that the final brew will have a moderately accompanied by a large dose of substances acid pH of around 5, just right to support that protect the cholesterol from oxidation and balance the other flavors. Some bottled and causing damage (p. 255). spring waters are suitable (Volvic is used in Hong Kong). Many municipal tap waters

Caffc-i!le Numbers

I Daily caffeine consumption in milligrams per capita, J 990s Norway, Netherlands, Denm:irk 400 Germany, Austria 300 Fr,1ncc 240 Brit,1i11 200 I

United States .I 70 I

Caffeine content, milligrams per serving Brewed coffee 65-175 Espresso 80-115 Tea 50 Cola 40-50 Cocoa 15 TEA AND COFFEE 435

e iarentiona!Jy made alkaline to reduce aroma and color when they're allowed to 11-: e corrosion, and this can reduce the acid wilt or are pressed before being dried. It was piP and liveliness o-f botb tea and dark around this time th::it China began to trade ~~asted coffee (l!ghc roasts_contribute plenty extensively with Europe and Russia, and the f cheir own acid). AlkaJme tap water can new, more complex style of tea conquered ~e corrected by adding tiny pinches of England, where consumption rose from cream oI tartar-tartaric acid-until it just 20,000 pounds in 1700 to 20 million in begins tO have a slightly tan taste. 1800. The strong "black" tea that's most familiar in the West today is a relatively recent invention, the result of intensive press TEA ing; the Chinese developed it in the 1840s Though it has lent its name to many other specifically for export to the West. infusions, tea-from the Chinese word c!J,1-is a drink prepared from the green The Spread of Tea Production Until the leaves of a kind of camellia. Young tea late 19th century, all tea in world trade leaves turn out to be as packed with inter w::is China teJ. But when China began to esting defensive chemicals as any spice. resist Britain's practice of paying for its Beginning in southwest China around expensive tea habit with opium, the British 2 000 years ago, people learned how to intensified tea production in their own use physical pressure, mild heat, and time colonies, particularly India. For warm to coax a number of different flavors and regions they cultivated ::in indigenous vari colors from the tea leaf. Tea became a sta ety, Camcllic1 si11e11sis var. ass,mzica, or ple of the Chinese diet around 1000 CE. In Assam tea, which has more phenolic com 12th-century Japan, Buddhist monks who pounds and caffeine than China tea and valued tea as an aid to long hours of study produces a stronger, darker black tea. They found that tea itself was worthy of their planted the hardier China types in the contemplation. They developed the formal Himalayan foothills of Darjeeling and at teJ ceremony, which remains remarkable high elevations in the south. India is now for the attention it pays to the simplest of the world's largest tea producer. prep:1rations, an infusion of leaves in water. Today about three-quarters of the tea produced in the world is black tea. China The History of Tea and Japan still produce and drink more green tea than black. Tea in China The tea tree, Canzclli,1 si11e11sis, is native to Southeast Asia and southern The Tea Leaf and Its Transformation A Chim, and its caffeine-rich, tender young fresh tea leaf tastes bitter and astringent, leaves were probably chewed raw long and not much else. This is a reflection of the before recorded history. The preparation of fact that its major chemical component, tea leaves for infusion in water evolved even more abundant than its structural slowly. There's evidence that by the 3rd cen materials, is a host of bitter and astringent tury CE the leaves were boiled and then dried phenolic substances whose purpose is to for later use, and that by cl1e 8th century make the leaf unattractive to animals. And they were also stir-fried before drying. These its aromatic molecules are locked up in techniques would give green or yellow-green nonvolatile combinations with sugar mol leaves and infusions, and mild but bitter and ecules. Green tea retains many of the qual astringent flavor. More strongly flavored and ities of the fresh leaf. But the key to making orange-red teas like modern oolongs were oolong and black teas is encour:1ging the developed around the 17th century, proba leaf's own enzymes to transform these aus bly beginning with the accidental observa tere defensive materials into very different, tion that the leaves develop a distinctive delightful molecules. FLAVORINGS FROM PLANTS

How Tea Enzymes Create Flavo1; Colo,; lea f s browning enzyme, pol_yphenolo:ll'i and Body The period of enzyme activity da e, uses ox-ygen from the rur to joi11 th during tea-making has traditionally been mall phenolic molecules together ii,t e 0 called "fermentation," but it doesn't involve larger complexes (p. 269). A combinatio any significant microbial activity. In tea of two phenoli give a kind of molecu.i'1 making, "fermentation" means enzymatic (theaflav.in) that's ye llow to light copper i e transformation. It occurs when the tea color: less bitter bu.t srill astringent. Con:i~ maker presses the leaves to break open their plexes of £ram three to ten of the original cells, and then allows the leaves to sit for _phenolic are orange-red and les asrriit some time while the enzymes do their work. gent (thcarubigens). Even larger complexes There are two general kinds of enzy are brown and not astringent at all. 'fhe matic transformation in making tea. One is more the tea leaves are pressed, and the the liberation of a large range of aroma longer they're allowed to sit before the compounds, which in the intact leaf arc enzy mes are killed by heating, the less bitter bound up with sugars and so can't escape and astringent and the mo.re colored they into the air. When the cells are crushed, become. In oolong teas, about half of the enzymes break the aroma-sugar complex small phenolics have been transformed; in apart. This liberation makes the aroma of black teas, about 85%. oolong and black teas fuller and richer than The red and brown phenolic com the aroma of green teas. plexes-and another complex, between The second transformation builds large double-ring molecules of caffeine an d the molecules from small ones, and thereby thcafla vins-lend bodv to brewed tea modifies flavor, color, and body. The small because they're large e1;ough to obstruc; molecules are the tea leaf's abundant supply e:tch other and slow the movement of the of three-ring phenolic compounds, which water. are astringe nt, bitter, and colorless. The

hitter 1•en, bitta less bitter not 1stri11gcnt ,llld ,;stringc11t ,md ,1stri11gcnt The evolution of tea taste. The {res/; tea leaf contains rich stores of simple phe110 /ic com· 110 1111ds (catechi11, left) that are colorless md bitter b11t not astringent. When the tea leaf Is bruised or rolled leaf enzymes md oxygen combine the simple compounds into larger ones with different colors and tastes. Brief enzyme actio11 produces a yellowish compo1md (theaflavin, ceI)ter) that is both 1 ety bitter and ,tstringcnt. More extensii •e cm;wne action pro duces a compo1md (t/}(:aflm•in digallate, right) that is 111odcr,1tely bitter ,md rstringent. Ast/Jc phmolic 11lOicwles get forge;; they get progressiucly d,zrl~er ,md 111ilder. TEA AND COFFEE 437

their enzymes and stop the enzymatic J\1aking Tea production of flavor and color. High dry heat will also generate flavor. '{be Tea Plant and Its Leaves The best tea • The leaves arc heated to dry them out insde from rhe plant's small young and preserve them for long keeping. ~toors and unopened leaf buds, which are • The dry leaves are sieved ;:ind graded 1e most tender and vuJnerabl and con by piece size, which ranges from tlin rhe highest concentration of chemical whole leaves to "dust." The smaller defenses and related enzymes. The choice the piece, the faster the extraction of Juck " is the terminal bud and two adja- color and flavor. !'nt leaves. Most tea is now harvested by :iachine, and therefore contains a large Major Tea Styles The Chinese developed proporrion of Ider and less flavorful a half-dozen different styles of tea. Three [caves. of them account for most of the tea con sumed in the world. Tea Manufacturing The production of tea involves several diffrrent steps, some stan Green Tea Green tea preserves some of the dard and some optional. original qualities of the fresh leaf, while heightening them and rounding them out. • The newly harvested leaves may be It's made by cooking the fresh or briefly allowed to "wither," or sit and wilr withered leaves to inactivate their enzymes, for minutes or hours. Withering then pressing them to release their moisture, c;:iuses them to shift their metabolism and drying them in hot air or on J hot pan. in ways that change their flavor, and In China, the cooking is done on a hot pan, to become physically more fragile. and this "pan-firing" produces aroma mol The longer the withering, the deeper ecules characteristic of roasted foods the flavor and color of the leaves and (pyrazines, pyrroles) ;:ind a yellow-green the brew they make. infusion. In Japan, the cooking is done with • The leaves are almost always "rolled," steam, which preserves more of the grassy or pressed to break down the tissue flavor and green color in both leaf and tea. structure and release the cell fluids. If the leaves are rolled while they're still Oolong Tea Oolong tea is made by allow raw, this allows the leaf enzymes and ing some modest enzyme transformation oxygen to transform the cell fluids of leaf juices. The le;:ives are withered until and generate additional flavor, color, they become significantly wilted and weak and body. ened. Then they are lightly agitated to • The leaves may be heated to inactivate bruise the leaf edges, allowed to rest for a

Tc,1. The choicest pluck consists of the bud tip ,ind two vo1mgcst lcm'cs of c.1ch branch of the tc,1 bush. FLAVORINGS FR OM PLANTS

Making Green, Oolong, and Black Teas

Tea leaves -----~ ---. lwithcrl · wirhi.: r 20 mi n wirhl' 1.. huu 1·$

ro ll ligh tl i· bru ise roll l/2-J hour

I (-_ ''4 1 i I .. h.TlllLIH • 1r I I '------~ - t t

lp,rn -lird ( pan-tire 'l '--~--,------/ I cp I I V I roll

I t q:::J i Chinese gree n tea J apanese green tea Oolong tea Black tea

yL·ll c1w: g rcl'll: j1 ,1Jc Ol"d ll ).!. !,.': 1·<..-"d -O ~ lll~l·:

lllL~ lf )~. fk, wci.-- y. J.!r.1:,;:,.y, ha~~. tlc, wcr~t. dried ro,~. hll ~1• ~11 i1.·r. SL';l\VCcd. toa~ty, fruit s- m o h:~,. woqd ~,. llnwcr}", ;1ni m:1l -.· h,J1.: ol :ll l'" TEA AND COFFEE 439

•few bours until enzyme action has tu.med different sources. Tea is mildly acid and rhe bruised edge red pan-fued at a high bitter and contains traces of salt. It's also cemperarnre, rolled, and finally dried gen rich in a unique amino acid, theanine, cly, at temperatures jusr bel~w 212"F/ which is itself sweet and savory, and partly 100°c. Ooloug tea brews t0 a light am ber breaks down during manufacturing to <;o lor with a di tinctive fruity arnma. savory glutamic acid. Chinese green teas also contain synergizers of savoriness (GMP 13Jack Tea Black tea is made by allowing a and IMP, p. 342). Finally, bitter caffeine profound ·enzyma-cic transformanon of the and astringent phenolics bond to and take leaf fluids. The leaves arc withered for the edge off each other and produce the hours, rolled repeatedly for as much as an impression of a stimulating but not harsh hour, then are allowed to rest for between body. This effect is especially important to one and four hours, during which enzyme the taste of black teas, in which it's called action turns them a coppery brown and "briskness." causes them to emit the aroma of apples. The aromas of different teas are strik finally, the leaves are air-dried at tempera ingly different. In green teas, early applica tures around 100°C, and become quite tion of heat prevents much enzyme activity dark. in the leaves. Steam heat gives grassy and seaweed, shellfish notes to Japanese green Tea Flavor The taste of tea, a lively, teas (the sea notes from dimethyl sulfide), mouthfilling quality, comes from several while pan-firing and drying produce more

Some Prized and Uuusml Tc;is

Herc are a nu111ber. of teas 111ade in unusual ways, with unusual qu,1lities:

• \Xihite tea: a Chinese green tea made ,1lmost exclusivel y From buds whose hai1·s 111ake the111 look white, withered for two to three days, sometimes steamed, then dried without rolling. • Pu-erh: a Chinese green tea that is made in the usual w,ff, then moistened and fermented in heaps for some ti111e by a variet)• of microbes. A.II of its phcm) lic contents are converted into nonastringent thearnbigens and brown com plexes, and it develops a complex, spicy, clove aroma. • l.apsang souchong: a Chinese black tea, dried over smokv pine fires. • Scented teas: Chinese teas of various types, scented b); being held for 8- 1. 2 hours in the same container with Aowers, including jasmine, cassia bud, rnsc', orchid, ,rnd g;_irdenia. The packaged tea may include ·1-2'½, flower petals. • C vokura and kabcsucha: Japanese green teas made from shoots that h,n:e been covered with bamboo boxes and almost completelv shaded fni· the two weeks before harvest. They develop a higher con.trnt <;f carotenoid pig ments that contribute \' i<)lct notes to the unique "covered ar<)n1,1." • Hoji-cha: Japanese green tea of standard grade that is roasted at high temper atures (360"F/1 SO"C), which triples the ·olatile content and so ho<, ,ts fbv<)r.

OPPOSITE: Making green, oolo11g, and bh1ck teas. Vari,ztio11s in processing produce uerv dif ferent colors and fLw ors from the same fresh bwes. 440 FLAVORINGS FROM PLANTS savory, toasted notes in Chinese green teas. extracted, more than three quarters of th In oolong and black teas, enzyme activity total in_the first 30 econds, while the large: liberates floral and fruity aroma molecules phenolic complexes come out much rnoi:e from their odorless storage forms, and pro slowly. duces a much richer, stronger aroma (more than 600 volatiles have been identified in Serving Tea Once tea is properly brewed black tea). the liquid should be separated from th; Cooks exploit tea flavor in a number of leaves .immediately; otherwi e ext.ractio 11 different preparations: marinades and continues and the tea gets harsh. AU kinds cooking liquids, ices and ice creams, in of tea are best drunk fresh· a they ·rand steamed foods, and as a source of aromatic their aroma dissipates, and their phenoli~ smoke (e.g., Chinese tea-smoked duck). components react with dissolved oxygen and each other, changing the color and Keeping and Brewing Tea Well-made taste. tea is fairly stable and can be stored for Tea is sometimes mixed with milk. several months in an airtight container that When it is, the phenolic compounds imme is kept cool and dark. Tea quality does diately bind to the milk proteins, become eventually deteriorate thanks to the effects unavailable to bind to our mouth surfaces of o ·ygen and some re idual enzyme activ and salivary proteins, and the taste becomes ity; aroma and briskness are lost, and the much less astringent. It's best to add hot tea color of black tea infusions becomes less to warm milk, rather than vice versa; that orange-red, more dull brown. way the milk is heated gradually and to a Teas are brewed in various ways in dif moderate temperature, so it's less likely to ferent parts of the world. In the West, a rel curdle. atively small quantity of black tea leaves-a Lemon juice is sometimes added to tea teaspoon per 6-oz cup/2-5 gm per 180 to bolster its tartness and add the fresh cit ml-is brewed once, for several minutes, rus note to its aroma. It also lightens the then discarded. In Asia, a larger quantity of color of brewed black tea by altering the leaves of any tea-as much as a third the structure of the red phenolic complexes volume of the pot-is first rinsed with hot (the complexes are weak acids themselves, water, then infused briefly several times, and take up hydrogen ions from the lemon with the second and third infusions offering juice). Alkaline brewing water, conversely, more delicate, subtle flavor balances. The tends to produce blood-red infusions from infusion time ranges from 15 seconds to 5 black tea, and can even make green tea minutes, and depends on two factors. One red. is leaf size; small particles and their great surface area require less time for their con Iced Tea Iced tea is the most popular form tents to be extracted. The other is water of tea in the United States; it first caught on temperature, which in tum varies depend at the 1904 World's Fair in steamy St. ing on the kind of tea being brewed. Both Louis. It's made by brewing tea with about oolong and black teas are infused in water half-again as much dry tea per cup, to com close to the boil, and relatively briefly. pensate for rbe later dilution by melting Green tea is infused longer in much cooler ice. The addition of ice to normally brewed water, 160-110°F/70-45°C, which limits tea tends to make the tea cloudy, due to the extraction of its still abundant bitter and formation of particles of a complex astringent phenolics, and minimizes dam between caffeine and theaflavin. The way to age to its chlorophyll pigment. avoid chis is to brew the initial tea auoom In a typical 3-5 minute infusion of black or refrigerator temperature over evcral tea, about 40% of the leaf solids are hours. This technique extracts less caffeine extracted into the water. Caffeine is rapidly and theaflavin than brewing in hot wate1; so TEA AND COFFEE 441

che caf.feine-~heaflavin complexes don't drunk right away or the sediment will form in uffi~1ent quantities to become vis increase the already considerable bitterness. ible in the c.h11led tea. French Refinements The first Western mod ifications of coffee brewing date from COFFEE around 1700, when French cooks isolated Coffee trees ar native to east Africa, and the solid beans within the liquid by enclos were probably first valued for their sweet ing the grounds in a cloth bag, and thus cherry-like fruit and for their leaves, which produced a clearer, less gritty brew. Around could be made into a kind of tea. Even 1750, the French came up with the most roday an infusion of the dried fruit pulp is important advance before espresso: the drip enjoyed in Yemen, where the seeds or pot, in which hot water was poured onto a "beans" were apparently first roasted, bed of grounds and allowed to pass ground, and infused in the 14th cenrury. through into a separate chamber. This Our word cotfee comes from the Arabic invention did three things: it kept the tem qahtvtzh, whose own origin is unclear. The perature of the extracting water below the coffee tree was taken to south India around boil, it limited the contact time between J600 , from India to Java around 1700, water and ground coffee to a matter of a and from Java (via Amsterdam and Paris) few minutes, and it produced a sedimenrless to the French Caribbean shortly thereafter. brew that would keep for a while without Today Brazil, Vietnam, and Colombia are getting stronger. The limits on brewmg tem the largest exporters of coffee; African perature and time meant a !t::ss complete countries contribute about a fifth of world extraction of the coffee. This reduced the production. bitterness and astringency, and allowed the other elements of coffee fla vor more promi The History of Coffee Brewing The nence, the tartness and aroma that were original version of brewed roasted coffee more appealing to European tastes. beans is the Arab version, which still thrives in the Middle East, Turkey, and Greece. Machine-Age Espresso The 19th century The finely powdered beans are combined brought the invention of several new brew with water and sugar in an open pot, the ing methods. There was percolation, or mixture boiled until the pot foams, then allowing boiling water to rise in a central settled and boiled to a foam once or twice tube and irrigate a bed of ground coffee. more, and finally decanted into small cups. There were plunger pots, which allowed This is the coffee that found its way to the coffee brewer to steep the grounds, then Europe around 1600; it's concentrated, push the grounds to the bottom with the includes some sediment, and has to be plunger and pour the beverage off. But the

Coffee berries ,md seeds. Each red bcrrv con t,1ins tuu; seeds. 442 FLAVORINGS FROM PLANTS biggest innovation in coffee brewing made liquefied by a day or nvo of fermentation its debut at the Paris Exhibition of 1855. by mi.crobes. The seeds are then washed i That was Italian espresso, a word which copious water, cL·ied to about 10% moj ~ means something made at the moment it's ture, and the adherent inner ' parchrncn ordered, rapidly, and for one customer. The shell' removed by machine. Some sugar: way to make coffee fast is to force water and minerals are leached our of wee. through the grounds with high pressure. processed beans, so rhey tend to produc In the process, the pressure extracts a sub coffee with less body and more acidity th~ stantial amount of the coffee bean's oil, dry-processed beans. However they often and emulsifies it into tiny droplets that cre have more aroma, and tend to be of mort1 ate a velvety texture and lingering flavor in uniform quality. the drink. Espresso is an expression of the power of the machine to force the most Roasting Raw green coffee beans are as and the best from a traditional 111gredient hard as unpopped popcorn, and about as and make it into something new. casry. Roasting transforms chem into fragile easily opened packages of flavor. Most peo'. Coffee Beans ple let the professionals take care of roast ing, but it's a fas inating (and smoky) Arabica and Robusta Coffees Coffee beans experience to roast coffee at home, as cooks are the seeds of two species of a tropical in many countries have long done and still rehtivc of the gardenia. Coffea nmbica, a do with equipment ranging from frying pans 15 ft/5 m tree that is native to the cool to popcorn poppers to special roasters. highlands of Ethiopia and the Sudan, pro Coffee beans are roasted to tempera duces what are known as "arabica" beans; tures between 375 and 425°F/190-220"C; and Coffca c mcti/Jom, a larger tree native the process usually tahs between 90 sec to hotter, more humid West Africa, pro onds and 15 minutes. As the bean temper duces "robusta" be;rns. About two-thirds ature approaches the boiling point of water, of the beans in international trade are ara the small amounts of moisture inside the bicas, which develop a more complex and cells turn into steam and puff the bean up balanced flavor than the robustas. They to half again its original volume. Then at contain less caffeine (less than 1.5 % by progressively higher temperatures, the pro weight of the dry bean, vs. 2.5% for robus teins, sugars, phenolic materials, and other t as), less phenolic material ( 6. 5 % vs. constituents begin to break into molecular 10%), and more oil (16% vs. 10% ) and fragments and react with each other, and sugar (7% vs. 3.5%). Robusta varieties develop the brown pigments and roasted didn't become prominent until the end of aromas typical of the Maillard reactions the 19th century, when their disease resist (p. 778). At around 310°F/l60"C, the creac ance became important in Indonesia and tions become self-sustaining, like a candle elsewhere. flame, and extreme molecular bre:tkdown generates m.o.re water vapor and carbon D1y and Wet Processing To prepare coffee dioxide gas whose production rises sharply beans, the ripe coffee berries are picked at 400"F/200°C. If the roasting continues, from the trees, and the seeds cleaned of oil begins to escape from the damaged cells the fruit pulp by one of two basic methods. to the bean udace, where it provides :i In the dry method, the berries are left in the visible gloss. sun co dry, or first piled to ferment for a few When the beans ha vc reached the days, then spread out in the sun. The fruit is desired degree of roast, the roaster cools th~ then removed by machine. In the wet beans immediately with cold air or a water method, most of the pulp is rubbed from spray to quench the molecular breakd0wn. the seeds by machine, then the remainder is The result is a brown brittle, s_poogelike TEA AND COFFEE 4+3 bc:1D, with the holes in the sponge filled roasting, so does the brew·s fullness of body: with carbon d1ox1de. there's less there to stimulate our tongue. Medium roasts give the fullest body. y/Je Develo~ment of Coffee Flav~r The hot rer the bean ts roasted, the darker it gets, and Storing Coffee Once roasted, whole coffee itS color is a good indicator of flavo.r ba1- beans keep reasonably well for a couple 110ce. Io the early stages of roasting, ugars of weeks at room temperature, or a couple are broken down into vru.ious acid (formic, of months in the freezer, before becoming acetic, lactic), which together with their own noticeably stale. One reason that whole organic acids (citric, malic) give light-brown beans keep as long as they do is that they're beans a pronounced tartness. As roasting filled with carbon dioxide, which helps proceeds, both the acids and astringent phe exclude oxygen from the porous interior. nolic materials (chlorogenic acid) are Once the beans have been ground, room dcsrroyed, so acidity and astringency temperature shelf life is only a few days. decline. Howt:ver, bitterness increases because some of the browning-reaction Grinding Coffee The key to proper cof products are bitter. And as the bean's color fee grinding is obtaining a fairly consistent becomes darker than medium brown, the p:uticle size that's appi:opriate to the brew distinctive aromas characteristic of prized ing method. The smaller the particle size, beans become overwhelmed by more generic the greater the surface area of bean exposed ro::istcd flavors-or, conversely, the flavor to the water, and the faster its contents arc deficiencies of second-rate beans become less extracted. Too great a range of particle obvious. Finally, as acids and tannins and sizes makes it hard to control the extraction soluble carbohydrates dt:cline with dark during brewing. Small particles may be

Th~. Effects of Ro:1sting 011 Cot.Yee 13 e:u1s

Weight Loss of Roasted Coff.ee Beans Degree of Roast Weight Loss, % C:innan1\)ll (.175'' F/ I 'JO ''C ) 12, mostly moisru 1·e iV)c'diurn 13 Ci tv 15 Full cin• 16, h:1lf moisture and h,11f be,rn so lid s French ' 1.7 luli ,111 (425"F/220~C) 18-20, mostly bc:111 sc lid,

Composition of Raw and Roasted Coffee Beans, Percent b~, Weight Raw Roasted \Vate1· 12 4 Prnn:i11 10 7 Carbohydr,1tc 47 .34 Oil 14 J 6 Phcnolics 6 J ') - l.:irgc com pie:-; :1ggreg,1tcs that provide color, bod)' () _ .) 444 FLAVORINGS FROM PLANTS

Coffc·e Fbvor, frl)lll the l)e:lll inro the Cup

This chart shows the rclatinnships between coffee flal'

Percent coffee sol ids in brewed cup 2

(,,II, /,i11a. l11/a11ud .1st1·/11gc11l aei,I /lawr avor /lmJ

Pcrcellt coffee solids extracted from gr

"e,rex:tracced and large o □ es underex espresso the strongest. The initial propor ~racted, and rhe resulting brew can be borh tion of coffee to water is 1:15 for American, bitter and weak . The co=on propeJl,or 1 :5 for cspresso. One clear lesson from the dnder smashes all-tlte bean pieces lIIltil the chart is that it's always best to use too much ~achine is stopped, no matter ?OW ~all coffee rather than too little: a strong but the pieces get, so coarse and medium gnnds balanced cup can be diluted with hot water end up containing some fine powder. .More and remain balanced, but a weak cup can't expet1sjve burr grinders allow sm all pieces be improved. This principle can help avoid cG escape through grooves in the grinrung problems caused by the fact that cup and surfaces and give a more even particle size. coffec scoop measures vary, and that scoops themselves are a very approximate measure Brewing Coffee Brewing is the extrac (one 2-tablespoon/30-ml scoop may deliver tion into water of dcsirable substances from anywhere from 8 to 12 gm coffee, depend the coffee bean, in amounts that produce a ing on grind and packing). b::ilanced, pleasing drink. These substances Each brewing method has its draw include many aroma and taste compounds, backs. Percolators operate at the boil and as well as browning pigmcnts that provide tend to overextract ..Many automatic drip color (almost a third of the total extract) brewers aren't able to deliver near-boiling and cell-wall carbohydrates that provide water, so they brew for a long time to com body (also almost a third). The flavor, color, pensate, lose aroma, and extract some bit ::ind body of the finished drink are deter terness. Manual drip cones give little mined by how much ground coffcc is used control ovcr extraction time. The plunger for a given volume of water, and by what pot leaves tiny suspended particles in the proportion of that coffee is exrracted into brew that keep releasing bitterness. The the warer. Inadequate extraction and a Italian stovetop moka pot operates above watery, acid brew are caused by grinding the boil, at around 230°F/l l0°C (and 1.5 the beans too coarsely, so that flavor is left atmospheres of pressure), and produces a inside the particles, by too brief a contact somewhat harsh brew. Overnight extrac time betwcen coffee and water, or by too tion in cold water doesn't obtain as many low a brewing temperaturc. Overextrac aromatic compounds from the ground cof tion and a harsh, bitter brew result from an fee as the hot-water methods. excessively fine grind, or long contact time, or high brewing temperature. Espresso True espresso is made very The ideal brewing temperature for any quickly, in about 30 seconds. A piston or style of coffee is 190-200°F/85-93°C; any sprmg or electrical pump drives thing higher extracts bitter compounds too 200°F/93°C water through finely ground quickly. For a standard cup of American coffee at 9 atmospheres of pressure. (Inex coffee, the usual brewing time ranges from pensive household machines rely on exces 1 to 3 minutes for a fine grind, to 6 to 8 sively hot steam, develop far less pressure, minutes for a coarse grind. and take longer to brew, so the result is rel atively thin and harsh.) The proportion of Brewing Methods There are a number of ground coffee is three to four times the different methods for brewing coffee. Most amount used in unpressurized brewing, of them extract between 20 and 25% of and deposits three to four times the con the bean's substance, and produce a cup centration of coffee materials in the brew, containing somewhere between 1.3 % and creating a substantial, velvety body and 5.5% bean soli ds by weight. The faci ng intense flavor. These extracted materials chart places some of the major styles in include a relatively large amount of coffee relation to each other. Standard American oils, which the high pressure forces from filter-drip coffee is the lightest, and Italian the bean particles to form a creamy emu!- Mt·thods ot- BrL·wi11g Coffee

This charr summarizes the imporrant fr:1tures of so1nc common Wfl\'S of brewing coffee, :111cl the kinds of brew they produce. Thc sr,1bi lir v of a hrew is determined h)• how 111:1ny coffee particles re111;1in in it; the more particles, the more bitterness and astringency cnntinue ro be e:,;tractcd in the cup m put.

Middle Eastern/ Mediterranean, Machine Manual Plunger Pot "Espresso" Espresso Boiled Filter Filter Percolator (French Press) Moka (Steam) (Pump)

Coffee grind Very fine Coarse ivledium Coarse Coarse iV!cdium Fine Fine (0.1111111) (I 111111) (0.5 111111) (I 111111) (lmm) (0.5111111) (0.3 111111) (0.3 mm)

Brew temperature To 2.Ll"F/ 1"80-185"F/ I 90-200"F/ 2'12"F/ l 90-l 95"F/ 230"F/ 2 !2''F/ 200"F/ I00"C: 82-85"C 87-93"C I00"C 87-90"C 1·1o"C I00"C 93"C

B(ew time ·10-12 min 5-12 min 1-4 min 3-5 min 4-6 min ·t-2 min l-2 min 0.3-0.5 min

Extraction 1 l( +) I(+) "1.5 1(+) 9 pressure, atmospheres

Flavor Full hur Light, Full Full, Full Full hut Full but Very full bitter often often bitter bitter (sweetened) bitter bitter

~ Body Full 1..ight Light Light I J'vkdium Full Full Very full

Stability Poor Good Cood Good Poor Fai1· Poor Po(.Jr once brewed TEA AND COFFEE 447

•on of tiny droplets, and wl1ich contribute a characteristic smoky, tarry aroma th::it is 1 che low prolonged release of coffee fla valued in dark roasts (they are also dis ':r iJJ the mouth, long afte.r the last sip. tinctly less ::icidic than :uabicas). Milk and Aoorber UDique feature of espresso is the cream reduce the astringency of coffee by crema the remarkably stable, creamy foam providing proteins that bind to the tannic d,at develops from the brew q.Ild covers its phenolic compounds, but these liquids ::ilso surface. It the p_roduct of carbon dioxide bind aroma molecules and weaken the gas still trapped m the grmmd coffee, and overall coffee flavor. die mixture of dissolved and suspended carbohydrates proteins phenolic materials Decaffeinated Coffee Decaffeinated cof 90p large pigment aggregates, all of which fee was invented in Germany around 1908. bond in one way or anothei; to each other It's made by soaking green coffee beans and hold the bubble walls together. (For the with water to dissolve the caffeine, extract milk foams often served with coffee, see ing the caffeine from the beans with a sol p. 26.) vent (methylene chloride, ethyl acetate}, and steaming the beans to evaporate off Serving and Holding Coffee Freshly any remaining solvent. In the "Swiss" or brewed coffee is best enjoyed immedi "water" process, water is the only solvent ately-its flavor is evanescent. The ideal used, the caffeine removed from the water drinking temperature is around 140°F/ by charcoal filters, and the other water GO"C, where a sip won't scald the mouth, solubles arc then added back to the beans. and the coffee's full aroma comes out. Some of the organic solvents used in other Because it cools in the cup, coffee is usually processes have been suspected of being held in the pot just below the brewing tem health hazards even in the tiny traces left in perarure. High heat acceler,ates chemical the beans (around 1 pai:t per million). The reactions and the escape of volatile mole commonest, methylene chloride, is now cules, so coffee flavor changes noticeably thought to be safe. More recently, highly after less than an hour in the pot; it pressurized ("supercritical") and nontoxic becomes more acid and less aromatic. Cof carbon dioxide has been used. Where ordi fee is best kept hot by retaining its original nary brewed coffee may contain 60-180 heat in a preheated, insulated, closed con milligrams caffeine per cup, decaffeinated tainer, not on a hot plate that constantly coffee will contain 2-5 mg. supplies excessive heat from below while heat and aroma escape above. Instant Coffee Instant coffee became com mercially practical in Switzerland just Coffee Flavor Coffee has one of the most before World War IL Ir's made by brewing complex ilavors of all our foods. Ar its ground coffee near the boil to obtain base is a mouth-filling balance of acidity, aroma, then a second rime at 340°F/170°C bitterness, and astringency. A third or less and high press'ure to maximize the extrac of the bitterness is due to easily extracted tion of pigments and body-producing car caffeine, the rest to more slowly extracted bohydrates. Water is removed from the two phenolic compounds and bi:owning pig extracts by hot spray-drying or by freeze ments. More than 800 aroma compounds drying, which retains more of the volatile have been identified, and they supply notes aroma compounds and produces a fuller that are described as nutty, earthy, flowery, flavor. The two are then blended together fruity, buttery, chocolate-like, cinnamon, and supplemented with aromas captured tt:a, honeyed, caramel, bready, roasty, spicy, during the drying stage. Instant coffee crys even winey and gamy. Robusta coffees, tals contain about 5% moisture, 20% With their substantially higher content of brown pigments, 10% minerals, 7% com phenolic substances th:rn arabicas, develop plex carbohydrate, 8 % sug::irs, 6% acids, FLAVORINGS FROM PLANTS and 4% caffeine. As an essentially dry con wood is well-known for its high-tempe, _ centrate, instant coffee is a valuable fla rure fire which it owes to it 64% lign~ voring for baked goods, confections, and content (hickory a common hardwood 1 ice creams. 18% Lignin). Most wood al o comain; ! small amount ~f pr,otei~, enough to sup port the browning reacaon that generate WOOD SMOKE typical roasted flavors (p. 778) at moder-s AND CHARRED WOOD ately hot temperatures. Evergreens such as pine, fir, and spruce also contain significant Neither wood nor the smoke it gives off is amounts of resin, a mixture of compounds an herb or a spice, strictly speaking. Yet related to fats that produce a harsh soot cooks and makers of alcoholic liquids when burned. often use burned or burning wood as fla voring agents-in barbecuing meats, in How Burning Transforms Wood into barrel-aging wines and spirits-and some Flavor Burning temperatures transform of the flavors they supply arc identical to each of the wood components into a char spice flavors: vanilla's vanillin, for exam acteristic group of compounds (see box, p. ple, and clove's eugenol. That's because 449). The sugars in cellulose and hemicel wood is strengthened with masses of inter lulose break apart into many of the same linked phenolic units, and high heat breaks molecules found in caramel, with sweet these masses apart into smaller volatile fruity, flowery, bready aromas. And th~ phenolics (p. 390). interlocked phenolic rings of lignin break apart from each other into a host of smaller, volatile phenolics and other frag THE CHEMISTRY ments, which have the specific aromas of OF BURNING WOOD vanilla and clove as well as a generic spici Charred wood and smoke are products of ness, sweetness, and pungency. Cooks get the incomplete combustion of organic these volatiles into solid foods, usually materds in the presence of limited oxygen meats and fish, by exposing the foods to the and at the relatively low temperatures of smoky vapors emitted by burning wood. ordinary burning (below l,800°F/1,000°C). Makers of wine and spirits store them 111 Complete combustion would produce only wood barrels whose interiors have been odorless water and carbon dioxide. charred; the volatiles are trapped in and just below the barrels' inner surface, and The Nature of Wood Wood consists of are slowly extracted by the liquid (p. T 21). three primary materials: cellulose and The flavor that wood smoke imparts to hemicellulose, which form the framework food is determined by several factors. and the filler of all plant cell walls, and lig Above all there's the wood. Oak, hickory, nin, a reinforcing material that gives wood and the fruit-tree woods (cherry, apple, its strength. Cellulose and hemicellulose are pear) produce characteristic and pleasing both aggregates of sugar molecules flavors thanks to their moderate, balanced (pp. 265,266). Lignin is made of intricately quantities of the wood components. A sec interlocked phenolic molecules-essen ond important factor is the combustion ti:dly rings of carbon atoms with various temperature, which is partly determined additional chemical groups attached-and by the wood and its moisture content. is one of the most complex natural sub .Maximum flavor production takes place stances known. The higher the lignin con at relatively low, smoldering temperatures, tent of a wood, the harder it is and the between 570 and 750°F/300-400°C; at hotter it burns; its combustion releases higher temperatures, the flavor molecules 50% more heat than cellulose. Mesquite are themselves broken down into simpler