Milk (15 page)

EXERCISE
2 Let the milk sit in the refrigerator, covered, until a well-defined layer collects at the top. Layering will start within hours, but it may take from
twelve hours to two days before the “top milk,” as people used to call it, is really well separated.

Why such wide variation? Take this as the first concrete illustration of what you just read about the non-uniformity of milk in a state of nature—something you should get used to if you plan to work much with milk in your own kitchen. If your sample came from
Jersey cows, it will separate faster and more distinctly than
Holstein-Friesian milk. Goats’ milk would take several days for a somewhat incomplete separation, while
water buffaloes’ milk would separate quite clearly in much less time than cows’ milk.

Use your skimmer to remove the top layer to a smaller nonreactive container such as a small glass bowl or measuring cup. You won’t be able to get all of it without a little remixing of top and bottom. Another lesson: The two layers can’t be fully separated by
hand (it takes a mechanical
centrifuge). But you have now performed your first feat of applied dairy chemistry. You have used gravity to isolate (though incompletely) the emulsified phase from the other two milk phases.

Of course you know that the thicker liquid in the smaller container is cream. It rose, or “creamed,” because it is lighter than the rest of the milk. (“Heavy cream” is a misnomer as regards specific gravity.) It contains nearly all the milkfat, still emulsified in a small amount of the original water-based solution; traces of the suspended micelles also remain. The reason for differences in creaming time is variation in the size of milkfat globules; larger ones, like those in buffaloes’ milk, rise faster than the much smaller ones in goats’ milk. With cows’ milk there are well-known differences among breeds.

When cream separates more promptly there’s also more of it. A gallon of good rich Jersey milk may give you as much as two or three cups of cream. But don’t be surprised if your sample yields less than half that amount—again pointing to the unpredictability of mothers in comparison with machines. Taste it. Maybe if it were shocking pink or moss-green, one wouldn’t have the same reaction, but its ivory sheen and caressing smoothness suggest some stunning union of virginal and carnal. Put it back in the refrigerator for the nonce.

EXERCISE
3 Your original container of milk is now a container of “
skim milk,” which means the solution and suspension parts of the three-phase system that you started out with. Stir any vestiges of cream back into the whole, pour out a small amount, and taste it. It will be very slightly sweeter than the milk you sampled before. (The cream will be sweet, too, but the two kinds of sweetness are indefinably different.) Notice how much richer and finer this feels on the palate than any commercial skim milk, even or especially the kind
enriched with intrusive-tasting milk solids. In hand-skimmed milk the residual trace of cream creates an effect you wouldn’t guess from its minuscule volume.

If you weren’t able to obtain unhomogenized milk, proceed with a gallon or half a gallon of skim milk. In any case, pour half of the milk into a saucepan, half into a nonreactive bowl or wide-mouthed jar. Stir a little cultured “
buttermilk” into the second half—we’ll come later to the reason for the quotation marks. Plain
yogurt is not as suitable because yogurt cultures really require special cosseting. But it will work as a second choice. Whichever you use, the label should unmistakably say that it contains active cultures.

Relative amounts aren’t terribly important, since different samples will vary with the strength of the culture. Half a cup of “buttermilk” or plain yogurt should be more than enough for two quarts of skim milk. What you are doing is “inoculating” the milk with microorganisms that will convert some of the lactose into
lactic
acid. Cover the container and let it sit undisturbed at room temperature until it is slightly
soured. This happens faster in a warm room, but timing will be unpredictable no matter what—eight hours, twelve, sixteen. You will get a thriving colony sooner or later and shouldn’t worry if it’s later. (The only reason for complete failure would be antibiotic contamination of the milk—illegal and rare, but not absolutely unheard of.)

Keep tasting the milk at intervals until it has a perceptible sourness and a bit of body. Now pour yourself a little and drink it. You are tasting something that most of the world’s milk users are far more familiar with than fresh sweet milk. Plain soured milk brings history to life, or more accurately, prehistory. It harks back to the earliest chapters of human culinary discovery—the knowledge of how to change one flavor into another.

EXERCISE
4 While the inoculated batch is souring, turn your attention to the remaining skim milk. For each quart of milk you will need about 2 tablespoons of freshly squeezed lemon juice or 1 to 1½ tablespoons of distilled white vinegar (please, no fancy vinegars here!).

Quickly bring the milk to a boil. Turn off the heat, stir in the lemon juice or vinegar, and take the pan off the stove. The milk will quickly separate into a soft fluffy-looking (the technical term is “flocculent”) substance and a thin greenish-white liquid. If the separation is not fairly distinct, add more lemon juice or vinegar (about 1 tablespoon per quart of milk).

Dampen a piece of tight-woven cheesecloth (
not
the gauzy stuff) or a large cotton handkerchief, wring it out, and use it to line a colander set over a deep bowl. Pour and scrape the contents of the pan into the colander, then gather up the corners of the cloth and tie them together securely to make a bag. After a few minutes’ draining, lift up the bag and put it somewhere to drain more
completely. I usually suspend it on a long wooden spoon placed across the top of a pail or deep stockpot. Leave it until the liquid stops dripping, which may be anywhere from four to more than eight hours.

Meanwhile, taste some of the greenish liquid that drained into the bowl. You probably know that this is “
whey” and the solider white stuff is “curd,” or “curds.” The flavor of whey depends on the method used for
separating it from the curd. This batch may be almost imperceptibly sour from the lemon juice or vinegar, but there will still be something definitely milky about it—though without the body of whole or skim milk. Set it aside, at room temperature or in the refrigerator. When the curd is drained, transfer it to any convenient container and taste a spoonful. It will be quite bland and delicate, a little like a closer-grained ricotta cheese (which is based on a similar idea).

You have now removed the
suspended
phase of the milk from the aqueous
solution
that it was suspended in. The solution is no longer white and opaque because it has lost the components—milkfat globules and still more importantly
casein—that make milk milky-looking by refracting light off their surfaces. Line up the whey, curd, and previously separated cream, and you will see the three phases of milk side by side, as well isolated from one another as they can be by low-tech home methods developed thousands of years ago.

There are really several possible means of separating curd and whey. The one given here happens to be the simplest for American home cooks. It is a classic method in northern
India, where Western-style cheese is unknown. Like all other ways of producing curd, it persuades the tiny casein micelles to come together in large enough clusters to literally fall—chemists say “precipitate”—out of the whey by the force of gravity. What you did was to combine the action of heat and an acidulant, which join forces to precipitate curd faster than any other method.

You can eat the curd as is, or perhaps turn it into a spread with a dash of salt and some minced scallion and/or green chile. It is the
chhenna described more fully on
this page
and used in several of my Indian recipes (see
Vegetarian Malai Kofta
, and
Saag Panir
).

EXERCISE
5 You can easily see that your efforts have produced more whey than anything else. In earlier and thriftier dairying eras, all the whey drained from curd got used. Today millions of pounds are literally thrown down the drain—except where prohibited by local environmental regulations—because the amount that can be put to any halfway profitable purpose is only a fraction of the volumes produced in commercial cheesemaking. But if you seriously love making the dairy foods that yield whey as a by-product, you will eventually want to try finding a good use for it.

Whey comes in two basic forms. You have just tasted one of them, “sweet”
(i.e., unfermented) whey. This is very bland, because the acidulant that you used to curdle the milk was too mild to impart much of an acid taste. The alternative is “sour” whey. To make it, inoculate the bowl of whey with live-culture “
buttermilk” or plain
yogurt by stirring in anything from ¼ to ½ cup per quart just as you did with the first batch of skim milk; leave it to culture in exactly the same way, tasting it occasionally to follow the souring process.

You may already be familiar with another excellent version of sour whey, the liquid that separates from
drained yogurt. For more about forms of whey and their uses, see “Fresh Cheeses.” But for a first experiment I suggest either mixing sweet whey with enough sugar and lemon juice to jazz it up a bit or seasoning sour whey with a vigorous pinch each of salt and dried mint. Both versions are extremely refreshing poured over ice cubes.

EXERCISE
6 The cream obtained in Exercise 2 has one more trick to play, if you haven’t already put it on strawberries. For those who couldn’t get unhomogenized milk and are working with “boughten” cream, the general idea is the same. In both cases you are going to get two results—very small in quantity, but thought-provoking for any real cook—from one batch of cream.

I suggest doing or at least trying to do this by hand. It’s laborious, but enables you to track critical stages of change more closely than any other method. People who have had to settle for ultrapasteurized cream may need to use a handheld immersion blender, but I recommend first seeing how far you can get without it.

Have the previously skimmed cream or half a pint of commercial heavy cream in a small glass bowl or measuring cup. Both cream and container should be very cold when you begin, because the amount is small enough to easily become overwarmed through simple friction. Start rapidly agitating it with a small wire whisk. Large bubbles will appear, then stop appearing. The whole consistency will gradually become heavier. (This will take longer with ultrapasteurized cream.) Keep plying the whisk until you recognize the beginnings of whipped cream.

In technical terms, you have incorporated air into the mass while partly knocking apart the remarkably constructed membrane that surrounds each milkfat globule. Some dislodged components of the membrane now form walls around the air bubbles. Whipped cream is not your present goal, so go on
beating the cream stiffer and stiffer until the whisk will scarcely move through it. Keep watching the pace of change. After a longer or shorter interval (once more depending on variables beyond your control) you will see a bit of liquid seeping from the stiff, heavy foam. Keep on whisking, and the whipped cream will resolve itself into a grainy yellow-white substance and a thin, cloudy whitish liquid.

Scrape the wires of the whisk as clean as you can, and beat the half-separated components with a small wooden spoon to separate them further. Drain the liquid into a small cup; work the yellow stuff with the spoon to force out any more residue, and drain that off, too.

You have now produced butter and true
buttermilk by wrestling your way through a phenomenon known as
phase inversion.
The cream at the start of the proceedings still consisted of
milkfat globules emulsified in the underlying solution, which held the fat globules as a fabric may hold tiny beads or sequins. The solution—not too far removed from the
whey you saw in the curd experiment—at that time formed what is known as a
continuous phase,
with the milkfat globules sprinkled throughout as a
dispersed phase.
(The suspended
casein micelles that later came together as curd were a whole different dispersed phase; you may now be starting to see why food chemists never tire of pointing out that milk is an incredibly complex substance.) Agitating the system forcefully enough eventually causes the separate globules of fat to unite in a coherent mass, squeezing out most of the original wheylike solution. Most of this liquid will drain from the mass as you work it, but not quite all.

In a switch of roles, the previously dispersed milkfat has become the continuous phase: butter. The tiny amount of the original solution/suspension that hasn’t drained off now remains scattered through the mass in minuscule droplets of true buttermilk as the dispersed phase of a suddenly inverted emulsion.

Examine the buttermilk. Its main difference from the whey that you obtained before is that it retains whatever casein was in the original cream. (This is why it looks whiter.) Taste it. In spite of starting with a gallon of milk, you unfortunately don’t have enough to do anything more with, but at least you can recognize it as a pleasant cousin of both sweet whey and milk. If you had cultured the cream before churning it, the buttermilk—the liquid residue of the phase-inversion process—would be more like soured milk. (What is sold in today’s America as “buttermilk” is really a kind of soured milk similar to the version you tasted in Exercise 3.) In dairying parlance, the culturing of cream for butter often is called “ripening.”

If you ever make ripened butter by the directions in “Butter and True Buttermilk” and sample the resulting buttermilk, probably you will scratch your head in puzzlement at the complete unavailability of real ripened buttermilk in any part of this country.

The small amount of cream used here yields only a little butter—but oh, what celestial stuff! Put it in the refrigerator to chill briefly. (Butter most emphatically is
not
among the foods that reveal their ultimate perfections when left to bask in the warmth of an American kitchen.) Dig out a bit on a spoon and eat it, trying to concentrate on every microsecond of its delicate passage
from solid to melted. Spread some on a plain cracker or piece of sturdy bread and eat it. If there is enough left, scrape it out onto a helping of piping hot cooked vegetables or noodles. It is like the Platonic essence of the cream you tasted earlier, containing tiny, elusive vestiges of the original fresh skim milk together with the suave, luscious, ineffable newly churned butter. It is not as wonderful in consistency as butter made by very good professionals who know the ideal temperature for different batches of cream. But the flavor ought to make any butter lover wonder how manufacturers have the nerve to call some of their wares “butter.”