If you grew up on a dairy farm you probably drank fresh, raw milk every day. But, these days, most consumers don’t live on or near a diary farm, so enjoying fresh from-the-udder milk isn’t an option. Raw milk is only safe when it is consumed immediately after milking a cow as bacteria that can make you sick proliferates very quickly.
Since milk needs to be packaged and delivered to a grocery store or corner market, it may be several days before it hits your glass. Pasteurization keeps milk safe and allows it to have a longer shelf life when it reaches your refrigerator.
To put it simply, pasteurization is the process of heating a substance in order to kill foodborne pathogens, such as listeria, somatic cells, and salmonella. Dairy producers pasteurize milk in order to make it safe for extended storage and human consumption. If you drink raw milk straight from a cow, without treating it, you put yourself at great risk for pathogenic bacteria.
But, there are those who argue that pasteurization makes milk harder to digest. Let’s look at the science behind pasteurization.
Ultra-pasteurization, or flash pasteurization, heats up the milk to 280 degrees for 4-5 seconds. Because the temperature of the milk exceeds 150 degrees, it is possible for the proteins to “denature,” or change from their original structure. Essentially, the heat can cause the protein compounds to breakdown. It is also argued that this process kills off some of the good bacteria that is present in the raw milk.
High-temperature pasteurization is the most commonly used pasteurization technique. This process heats up milk to 161 degrees for 15 seconds.
Like flash pasteurization, some of the micro-life present in raw milk will be killed off through HT pasteurization. But, this is a necessary evil in order to protect yourself. And despite the heat treatment, milk remains a nutrient dense food! Additionally, the proteins in high temperature treated milk may experience some denaturation—but more on that in a bit!
Low-temperature pasteurization heats raw milk to 145 degrees for 30 minutes before chilling it rapidly. Like HT and ultra pasteurization, this process can also kill off some of the probiotics present in raw milk. But, it is argued that low temp pasteurization helps to maintain the proteins that are present. And while it is true that this process does not “denature” the proteins, it can cause protein aggregation, which can actually make the proteins harder to digest. This means that rather than causing the protein compounds to break down, they actually accumulate and clump together. Aggregated protein is actually harder to digest than denatured proteins and may cause challenges for immune compromised or extremely allergic individuals.
Raw products have not been heat-treated and are at much greater risk of carrying harmful bacteria. They also have a shorter shelf life.
In summary, while heat treating raw milk will cause some of the good bacteria that is also present to be killed off, it is necessary to protect against drinking harmful bacteria. Additionally, there are some companies that re-introduce “active cultures” into their dairy products to supplement the probiotics that were affected during heat processing.
Let’s take a closer look at the “denaturation of protein”
Anti-pasteurization folks believe that the denatured proteins in pasteurized milk will inevitably cause gut inflammation because your body cannot properly break down these protein compounds.
Labels will tell you how milk has been treated.
Scientifically, the heat treatment disrupts the hydrogen bonds in a protein molecule and causes the bonds to be “disrupted.” (For reference, when you cook an egg the proteins also denature— but would you eat a raw egg?)
So, while it is true that heating raw milk can cause denaturation of protein, this has only proven to potentially affect immunocompromised patients.
Additionally, how your body digests denatured protein depends entirely on the amount of heat exposure the proteins have had. Typical high-temperature pasteurization (161 degrees Fahrenheit for 15 seconds) generates very little denatured protein.
Fairlife milk takes heat-treated milk one step further
One company that has taken proactive steps to protect your digestive system from the altered lactose content is Fairlife, owned by Coca-Cola. Fairlife milk is flash pasteurized (which prolongs shelf life) and then ultra-filtered to concentrate the protein content, sterilize the milk, and remove the lactose content from the final product. Lactose is a sugar that can disrupt your digestive system, especially if it has been heat-treated. Their cold filtration system removes any impurities in their milk and aids in the digestion of this product.
What about cheese?
Like milk, cheese is another important food when it comes to pasteurization. The U.S. Food and Drug Administration mandates that any cheese produced from raw milk must be held or aged for 60 days and kept consistently at 35-degrees Fahrenheit before it can be sold commercially. This helps ensure that foodborne pathogens are no longer present in the food, as they cannot survive in an environment after 60 days. Additionally, treating the cheese with salt and curing the rind can also protect from potentially dangerous bacteria. Like milk, pasteurized cheese can be treated at either a high temperature (174 degrees for roughly 20 seconds) or low temperature (149 degrees for 30-40 seconds).
When you think of pasteurization, you undoubtedly think of milk! Dairy products get all the heat (no pun intended) for being pasteurized. You might be surprised to learn, however, that there are many other foods that are heat treated as well. Almonds, sauerkraut, and some kinds of vinegar are pasteurized in order to sanitize the food and kill harmful bacteria. The pasteurization process keeps consumers safe!
The D2D team got their introduction to dairy farming on a visit to Evergreen Farms, run by the 2nd generation Harpster brothers in Spruce Creek, Pennsylvania.
Evergreen Farms comprises 8,000 acres of land and is one of the largest and most productive dairy farms in Pennsylvania.
They manage 7,000 animals, and milk close to 3,000 cows three times per day.
A team of 85 employees, animal nutritionists, and veterinarians care for the animals and the land they farm on.
The Beginning: A Calf is Born
The average Holstein calf is born weighing from 70-100lbs. With their familiar black and white markings, Holsteins are the most common dairy cow because they are the best producers of milk. They consume high levels of food and tend to be larger in size from other breeds.
A Jersey calf may be 40-50 pounds. Jersey cows, are tawny in color, are smaller and lighter eaters but they produce the milk which is high in butterfat and protein.
After birth, the males are either sent to a feedlot or used for breeding, while the females will stay on the dairy farm.
Newborn calves are moved to individual hutches, which are placed next to each other so the calves can begin bonding. They are bottle-fed a combination of the mother’s colostrum (for one to two days), whole milk, and a milk replacer (like Enfamil). They grow so quickly that it is imperative that they are cared for with a nutritious diet of fatty acids, proteins, vitamins, and minerals. During their stay in the hutches, the calves are de-horned as well. Yes, female cows also grow horns.
Did you know that calves…
Require passive transfer of immunity from their mother’s first milk or colostrum?
Drink two gallons of whole milk each day?
Double their birth weight in the first two months of life, from 90 to 180 pounds?
The calves will outgrow the bottle feeding after 6-8 weeks and will transition to a grain-based diet. At this point, the youngsters will be moved to larger pens or pasture, where they can roam and socialize together. Throughout this ‘growing’ phase, and up to three years old, these animals are referred to as heifers.
Cows are very social animals. They make friends in the calf pens and stay with those friends for life, even going back and forth to the milking parlor together.
Breeding the Cows
At 15 months, the heifers start ovulating and are ready to be bred. This is almost always done through artificial insemination. The average gestation period is roughly 281 days. At any given time on a farm such as Evergreen, there can be 300 or so cows preparing to calve. This phase of preparation is called “springing” for heifers and “dry period” for mature cows. During this time the cow’s nutrition, veterinary, and socializing needs are met but she is not yet a part of the milking herd. Once the calf is delivered, she produces milk and becomes an important part of daily milk production on the farm.
The average milking cow produces 65-75lbs of milk per day, which is about 130 glasses of milk. High performing dairy farms, like Evergreen farms, produce anywhere between 90 -100lbs of milk a day.
Evergreen Farms produces approximately 10 million gallons of milk per year, which means four to five times a day, a 7,000-gallon tanker truck rolls up to the milking parlor to collect the raw milk. On a smaller farm, the trucks may fill up every other day.
Roughly 100 days after delivering a calf, the cow will be impregnated again while she is still part of the milking herd. Her lactation cycle (days she produces milk) is about 310 days. She is taken out of production eight weeks prior to delivering a calf. Again, this ‘time off’ from lactating is called the “dry period.” During this dry period, she takes a break from milking and is often let out into the pasture with the heifers. Her diet is specially formulated to meet the needs of the developing calf and prepares her for her next lactation. This birthing/milking cycle continues for approximately 8 years.
Technology and the Dairy Barn
It is important to constantly monitor a cow’s health and production. The tags in their ears are unique identifiers that can be scanned to tell a farmer all of the details of her heritage, when she was last milked, and how much milk she is producing. The system also tracks her health record and at what stage she is in her lactation.
Cows have a good life. They eat about 12 times per day, are milked 2-3 times, require 16 hours of light, and rest between 11-13 hours.
Happy Cows Make More Milk
Dairy farmers take good care of their cows because happy cows make more milk.
A comfortable, quiet environment, playing music in the barns, incorporating cooling fans and sprinklers and scratching brushes, and treating them with respect are important factors for happy cows.
have a 360 degree vision – like an owl.
produce 125 pounds of saliva…a day. Saliva aids in the digestion process.
can walk upstairs, but don’t bend their knees to walk downstairs.
are colorblind. They charge at a waving blanket– not the color red, as you might think!
Feeding the Herd
Cows require a lot of food to produce milk. Their stomachs have four separate compartments, each with a specialized duty in the digestive process. They eat their food quickly, burp it up as cud, and chew it again. Digestion of feed ingredients occurs in the second compartment called the rumen. It takes about two days to process the food into milk.
Producing 100lbs of milk a day takes as much energy as running a marathon. Cows are fed a complete nutritional mix of corn silage, haylage, corn, soy, canola, high-protein, high fiber grains, vitamins, and minerals — where each bite is perfectly balanced. High milk-producing cows such as those at Evergreen Farms consume over a 100lbs of food a day.
Feed varies depending on the cow’s age— whether they are first- lactation cows or mature cows. Each dairy farm is different and requires their unique formula, adjusted as often as needed. The dairy nutritionist uses sophisticated computer models to create diets. Feed analysis takes place each week. Cows have food available 24 hours a day.
Cows need sugars in their diet. Evergreen Farms collects unsold candy from Hershey and mixes it in with the feed giving cows an added treat in their feed. (This also reduces food waste at Hershey.)
In order to feed the cows, many acres of land are needed to grow grain crops (corn and soybeans) and forage (grass and alfalfa). These crops are specific to optimize digestibility and energy and protein intake. At Evergreen Farms, 96% of the feed for the animals is home-grown or locally produced by neighbors. This is a typical sustainable model for most dairy farms.
Evergreen Farms goes through 170 tons of silage a day to feed all their animals.
What happens to the cow waste?
Manure is a resource. Farmers recycle the manure back to the crops using best management practices which include application timing and soil/crop nutrient analyses.
Barns are hosed down daily and the manure is separated into solids and liquid. Special processing equipment repackages the wastewater for irrigation use on the farm.
Manure creates a nutrient-rich, moisture-retaining soil that is essential for crop growth.
The Milking Parlor
A cow actually looks forward to the milking because her udder becomes full — and she will happily walk into the milking stall. Since they are creatures of habit and appreciate a routine, milking is scheduled at the same time each day for each group of cows. A cow is milked about every eight hours.
Today’s milking machines can milk a cow in about 7 minutes. First, the cow’s teats are cleaned with an iodine and water solution, then dried. Then rubber-lined cups are attached to the teats, and milk will flow into the milk tank. The pumping action of the cups imitates a sucking calf so it does not hurt the cow.
Milk exits a cow’s udder at a little over 100 degrees and is cooled immediately to 35 degrees by flowing through a series of stainless steel plates called a plate cooler. It is then stored in large stainless steel tanks to await the tanker truck pick up.
Milk is cooled immediately after leaving the cow to eliminate the possibility of bacterial contamination.
The milking parlors are cleaned after every milking session. With a large herd of cows, the process of moving cows to and from the milking parlor is a constant activity.
The Milk Market, Organic Milk and Antibiotic Use In Dairy Cows
Unlike most businesses that will price their products based on what it costs to make that product, and include some sort of profit, dairy producers are paid per 100lbs of milk, called a hundredweight (cwt), and are subject to prices set monthly by the U.S. Department of Agriculture. Pricing per cwt will vary according to the supply and demand for the milk and milk products in that region and will take into consideration the export market as well as any supplies of milk products waiting to be sold.
What is Raw Milk?
Raw milk is milk fresh from the cow. It is neither pasteurized nor homogenized. Both the FDA and CDC assert that raw milk can run the risk of being unsafe to drink because certain bacteria forming enzymes remain in the milk and can grow easily and quickly.
rBST & Marketing Misconception
The “rBST free” label often found on milk cartons has created a bad reputation for a growth hormone that is in reality no longer used in dairy farming.
BST is a growth hormone that is created naturally by the cows’ pituitary gland and rBST at one time was used in dairy farming to help increase the cows’ milk production. Several organizations have created fear regarding the safe use of this hormone and because of the consumer backlash, it has not been used in U.S. dairy farming since roughly 2000.
Antibiotics and Antibiotic Testing
No matter if a cow is raised on an organic or conventional farm, the use of antibiotics is accepted to treat a sick animal. In both cases, an animal treated with antibiotics is taken out of the milking parlor until all traces of the antibiotic are gone from her milk. Milking a cow not withheld for the full FDA mandated period after receiving antibiotics is a serious business. Every tanker of milk organic and non-organic milk is tested three times: by the farm, the dairy processing plant, and the USDA. If the milk tests positive for antibiotic residue the entire batch is thrown out immediately, the farmer receives no payment and is fined and put on notice by the USDA.
According to the strict guidelines in place by the USDA, organic milk must come from a cow that has not been treated with antibiotics or any type of growth hormone and has been fed at least 30 percent of its diet on pasture.
Cheese production in this country is big business and accounts for about 40 percent of the milk fat and 15 percent of skim solids from farm milk..
Mozzarella takes the greatest share of the cheese market. Cheddar is a close second. It takes 10 pounds of milk to make 1 pound of cheese. That’s good business for dairy farmers!
Processing the Milk
In order to see how raw milk is processed, the D2D team visited the Cornell Creamery, where they use milk from their local cows to create delicious ice cream, yogurt, and milk.
Raw milk is collected from the dairy storage tanks into a large, refrigerated tanker. It is re-tested for safety and then taken to a dairy processing plant. At the processing plant, the milk is retested again and then processed either into beverage milk or other dairy products. After it leaves a processing plant, it may go to a distribution center and will be delivered to the grocery store within 1-3 days.
From the udder to your cup, the U.S dairy industry follows strict government regulations to ensure that milk and milk products are safe for consumption.
Milk Safety research continues: Cornell University and IBM recently announced a joint research project that will use genetic sequencing and big-data analyses to help keep the global milk supply safe.
To make various dairy products, raw milk is spun to separate out the fat. The fat is then added back in depending on the product that is being created: skim, 2%, or whole fat milk.
Why is milk pasteurized? To make your milk safer to drink. Pasteurization kills bacteria and makes enzymes inactive so you can drink it and not get sick. It does not hurt the nutritional value. Chilled raw milk is heated by passing it between heated stainless steel plates until it reaches a temperature of at minimum 161F for a time of at least 15 seconds. It is then quickly cooled to best practice temperature of under 40F. Some milk is ultra-high temperature processed (UHT) and is heated to 280 degrees for two seconds. UHT will make a milk product more shelf-stable because it is completely sterilized. This process will also make your milk more expensive.
Why is milk homogenized? Homogenized milk is smooth with an even texture, and is more consumer-friendly — you don’t have to fuss with mixing the cream in yourself. Milk that isn’t homogenized has a layer of cream at the top.
What is the “shelf life” of milk? The shelf life of milk is based on the quality of the milk produced on the farm and the level of excellence in sanitation practices at the processing plant. Ideal storage temperatures for milk and dairy products are 34-38°F. Under these conditions, the shelf life of milk can range from 15 to 18 days. “Sell by” dates are based on the shelf life. Most pasteurized milk will remain fresh for 2-5 days after its sell-by date. When in question, the “smell test” is a good idea. Fresh milk smells, well fresh. While drinking sour milk is not necessarily harmful, it is best to not drink it. Ultra-Pasteurized milk (and products) can have a longer shelf life of 60-90 days, depending on the packaging, but only until it is opened. After opening, Ultra-Pasteurized milk should be kept well refrigerated (34-38°F) and consumed within 7-10 days for the best quality and taste.
Follow milk’s journey from farm to table in this video by Midwest Dairy:
Dirt-to-Dinner is grateful to the Harpster family for letting us into their dairy barns and educating us on all things dairy. We also thank Chris Canale and Kevin Campbell, Cargill Animal Nutrition, the Cornell Dairy Processing team and the faculty at Cornell University College of Agriculture and Life Sciences.
Unless otherwise sourced, the images in this post were taken by D2D or contributed.