Holly asked me a question that is much deeper and puzzling than it looks at first. I'll try to cut through some of the confusion.
I recently had the ALCAT test done and it shows I have no reaction to casein and a severe reaction to whey. This surprized me because I have never had a noticeable reaction to dairy. I was told that it doesn't mean that I'm lactose intolerant - just whey intolerant. My question is: hasn't the whey been cooked out of evaporated milk, condensed milk, caramel, cream cheese, and most cheeses? I would think so but I can't find an answer anywhere.
Milk is like every other food we eat, a mixture of chemicals that we group into three basic families: the fats, the carbohydrates, and the proteins. That's not even including the pure minerals, notably calcium, potassium, and phosphorus, that make milk so healthy. Or the micronutrients like vitamins. All of these float in a vast sea of water. A full 88% of a glass of whole cow's milk is water. Carbohydrates - our old friend lactose - make up 4.66%, fats, 3.34%, and proteins 3.29% That tiny fraction of a percent of discrepancy is referred to as ash, and contains all the minerals and anything else that doesn't fall neatly into one of the big three categories.
The proteins, though comprising the smallest bulk of the three majors, has the most complex set of subfractions. For our purposes, all we need to concentrate on are the two main families of proteins, the caseins and the wheys. A table at an Ohio State website breaks down the families into five types each.
Having five types of casein is confusing enough. The wheys are worse. There are at least two immunoglobulins and several minor proteins.
And I'm not even going to talk about the Proteose-Peptone Fraction, which is defined as whatever is "not precipitated at pH 4.6 from skim milk previously heated to 95-100° C for 30 minutes." (I quoted that from the National Dairy Council. That Ohio State site gives slightly different numbers. Don't you love it when experts disagree on basics?) Those are at least four proteins that have some relationship to both the caseins and the wheys and I don't understand them at all. Everybody else ignores them, however, and so shall I.
In liquid milk, all the proteins, like the fats and the carbohydrates, are in a colloidal suspension. "A colloid is a substance microscopically dispersed evenly throughout another substance." You can't, therefore, go through milk and pick out the proteins very easily. It takes high-technology techniques like the membrane process of ultrafiltration, some called "very specific enzyme precipitation," or the ion-exchange processes.
Or cheesemaking. Rennet, produced in the stomachs of most mammals, is an enzyme that coagulates casein, clumping the individual molecules into larger lumps that can be much more easily separated from the rest of the liquid.
Why then do food processors and scientists need such high-tech procedures to do what villagers and nomads have done for thousands of years? Purity. Those curds of soft cheese that are formed are mostly casein protein. But they also contain some lactose and some fat and some water. And some whey. As long as there is water present, some whey will be there as well. The aging process also hardens the cheese, which is done by almost literally squeezing out the remaining water. Additional heating of cheese can harden it even further. Most of the lactose is removed with the water, which is why true milk cheeses can be sold as lactose-free. Most of the whey goes with the water as well. I can't guarantee that all of the whey goes, though. A few micrograms of remaining lactose is meaningless for anyone who is lactose intolerant. A few micrograms of remaining whey protein could trigger a reaction.
And that's where we come back to Holly's question. Processed dairy products may be low in whey, even negligible in whey for practical purposes. Allergies are impractical. They can affect people in doses too tiny to be otherwise noticed. That's exactly why those with severe dairy protein allergies are advised never to eat any dairy product. Removing every last molecule of protein is a task for a scientific lab, not a food processor. This difference is the main reason for the vast gulf between lactose intolerance and a milk allergy. You can take chances with lactose. Allergies require extreme caution and care. Some people, like Holly apparently, have mild symptoms to no symptoms at all. For others, the symptoms are frequent and severe. For those people allergies are serious and must be treated that way. And the more you know about food, its composition, and its processing, the better off you are.