I recently had a conversation about dairy with a friend who is a medical practitioner. She asserted that if she were to choose to give her (as yet unborn) children milk, she would only give them whole milk because it was less processed, or in other words, more natural, than part-skimmed or totally skimmed milk.
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Just consider this proposition for a moment, doesn’t it seem logical that whole milk isn’t processed to the same extent as 1 percent, 2 percent or skimmed milk because it hasn’t had any fat stripped away? Just the word “whole” implies a lack of alteration. Sure, we understand that all milk must be heat-treated or pasteurized to kill off harmful micro-organisms (in 1987 the FDA mandated pasteurization of all milk products for human consumption). But, this small step aside, surely whole milk is as it was (minus harmful pathogens) when it left the cow’s udder, right? This got me thinking.
I asked around to gauge what other "lay" people thought. One friend, a personal trainer, thought that skimmed milk contained chemicals for preservation purposes. Others mostly agreed that the above scenario sounded about right. After all, labeling something whole implies little wiggle room. You don’t buy a whole cake and expect a tiny sliver to be missing, do you?
Perhaps you should. After all, it turns out that the word “whole” on the outside of the milk carton is more figurative, rather than literal. Milk, whole or otherwise, is more processed than we think.
Milk, as defined by the U.S. code of Federal Regulations (CFR) is:
“The lateal secretion, practically free from colostrum , obtained from the complete milking of one or more healthy cows. Milk that is in its final package form for beverage use shall have been pasteurized or ultrapasteurized, and shall contain not less than 8.25% solids and not less than 3.25% milk fat. Milk may have been adjusted by separating part of the milk fat therefrom, or by adding thereto cream, dry whole milk, skim milk, or nonfat dry milk. Milk may be homogenized.”
The composition of milk you pick up in grocery stores is standardized in the U.S. - quite different from the white stuff in its purest form. The fat content of raw milk varies with cow breed, feed, and stage of lactation among other factors. The vast majority of dairy cows in the country are Holsteins, a breed that typically produces more milk per cow than others. On average, the composition of Holstein milk is 87.7 percent water, 3.7 percent milk fat and 8.6 percent skim solids. In contrast, milk fat in Jersey cows, which are the second most prolific milk producers in the U.S., averages at 5.5 percent. But, this can fluctuate from less than 4 percent to more than 7 percent for individual Jersey cows depending on the season.
Milk fat percentage is highest during the fall and winter months, peaking in January. It declines gradually as the year warms up reaching its lowest point in July and then increases again as cold weather once again approaches. This variation depends on both climate and changes in feed. Lush spring pastures, for example, is low in fiber, and this depresses milk fat content. Conversely, in the winter, cows consume more fiber-rich, dry matter, hence richer milk.
Milk fat contributes flavor, mouth feel and texture to milk – when it varies, even by a small amount, the difference can be tasted or felt. To ensure that consumers have a consistent product day to day, month to month and year to year, producers regulate the composition of milk fat, so contents of every like carton are indistinguishable, and of course, remain true to the nutritional information on the packaging. Across the board, commercial brands of whole milk contain 8 grams of total fat, of which 5g is saturated fat.
There’s also the fact that the dairy industry is dominated by processing cooperatives that produce milk for numerous commercial retail and private label brands. This is to say that a processor might fill different cartons but the contents they churn out are the same. California Dairies Inc., for example, produces 43 percent of California’s milk or 9 percent of the milk produced in the United States.
Just how then is milk made, and just how processed is it?
Dairy cows produce milk for 10 months after they give birth to their calves, and they must be milked every 12 hours. On average a single cow produces 6.5 gallons of milk every day from two 10-minute milkings using mechanical vacuum machines that are attached to their udders. Imagine this routine taking place 9 million times every day. (There are about 9 million dairy cows in the U.S.)
While still at the dairy farm, milk is pumped along stainless steel pipes into a tank that chills the milk to 38°F or less. The fluid is constantly agitated to stop the cream from separating and to keep the temperature constant.
Every 24 to 48 hours, insulated trucks that hold up to 5,300 gallons transport milk from dairy farms to the processing plant. Once the tankers arrive at the plant, the milk has its temperature taken - if it’s above 44°F, the entire container is discarded, and another sample is tested for bacterial load. The milk is then graded, and pumped into the processing facility.
Historically, two grades of milk were established: Grade A and Grade B. The grade given depends on the milk meeting certain sanitary or quality standards. Grade A is for use in fluid milk products as well as any other dairy products, whereas Grade B which meets slightly lower standards, can only be used for manufactured dairy products, like cheese. Today, almost all the milk produced in the U.S. is Grade A.
The raw milk, regardless of what type of fluid product it’s destined to end up as, passes through a separator which spins the milk through a series of conical disks. This removes debris, sediment and some bacteria. But it also separates out the fat, splitting the contents into a cream portion that is 40 percent fat, and skim milk that is less than 0.01 percent fat.
The skim milk is drained away, then, has precise quantities of fat returned back to it, or not, depending on whether it"s going to remain as skim milk, or become 1 percent, 2 percent, or whole milk which contains between 3.25 percent and 3.4 percent milk fat based on the processor’s formula.
What happens to all the excess fat? It gets turned into butter or processed into cream or ice cream.
Once milk has been calibrated just so, it"s then pasteurized to destroy pathogens as well as spoilage bacteria and rancidity-causing enzymes that can shorten the shelf life of milk. The most common method used is the high-temperature, short-time (HTST) process in which constantly flowing milk is heated to approximately 161°F and held there for 15 seconds before being rapidly cooled.
If you thought this was the entire extent to which milk is processed, you’d be wrong. It’s then usually homogenized before being pumped into plastic jugs or cardboard cartons. This process is what stops the cream from separating again and floating to the top while milk sits on a grocery store shelf or in your fridge.
Milk naturally contains non-uniform globules of fat. It’s this lack of consistency in the size that causes the fat particles to rise to the top creating a “creamline”. To prevent this, milk is forced under extreme pressure and at high velocity to pass through tiny passages by a piston pump. This causes the fat particles to break up into countless, much smaller, identically-sized particles that are too miniscule to separate from the rest of the milk ensuring a smooth consistency for the duration of the product’s shelf life.
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I don’t mean to suggest that milk is bad or any less nutritious because it’s been processed. But, let’s be clear, it is a processed food. The white stuff that comes out of a plastic jug is undoubtedly physically changed and compositionally altered from the white stuff that flows forth from a cow’s udder. As for the question as to whether whole milk is any more “natural” than skimmed or part-skimmed milk, the answer is a definitive NO.