In this episode of The Milk Check, Ted Jacoby III welcomes Lloyd Metzger and TJ Jacoby of Valley Queen Cheese Company for a deep dive into the science, functionality and future of dairy proteins.

The conversation starts at the molecular level – the difference between casein and whey – and builds toward the real-world implications for product developers, processors and nutrition brands.

We cover:

• Why casein is built to carry calcium (and whey isn’t)


• How heat and pH change protein behavior


• Fast versus slow digestion and why both matter


• The role of whey protein in muscle maintenance, aging and GLP-1 nutrition


• What pro cream really is and why its value may be underestimated


• Why cellular agriculture is more niche than threat

If you work in dairy, food formulation or nutrition, this is a protein conversation worth digesting.

Got questions?

We’d love to hear them. Submit below, and we might answer it on the show.

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Ted Jacoby III: Hi everybody, and thank you for joining us today for this very special recording of the Milk Check Podcast. Today, our topic is: what is the future of dairy proteins? And we have two very special guests. The first is Lloyd Metzger, VP of Quality and Technical Services for Valley Queen Cheese Company, and formerly Professor of Dairy Science at South Dakota State University.

And the second, particularly special to me, is my son TJ Jacoby, Whey Technologist for Valley Queen. A South Dakota State graduate. Someone who has been interested in dairy proteins since his first biology class in high school. Guys, thank you for joining us today and welcome to The Milk Check.

Lloyd Metzger: Glad to be here.

TJ Jacoby: Good to be on, Dad.

Ted Jacoby III: It’s December 18th, 2025. Milk production in the US is up 4%. Milk production in Europe is up something similar. Milk production in New Zealand is up.

Milk production in Argentina is up. We are definitely in an [00:01:00 ] environment today where the supply of milk and dairy is overwhelming demand, at least for the moment. Cheese prices are near historical lows. Butter prices are near historical lows. Nonfat milk, skim milk powder prices are on the low end of the range.

This market is a market that feels heavy, and I think most people out there would say, it almost feels like even though we’re at lows, we may actually go lower before we go higher. And yet, on the other hand, there are whey proteins, Josh, if I’m not mistaken, whey proteins just hit historical highs.

Josh White: Maybe the highest prices we’ve ever seen for whey protein isolate and WPC 80.

Ted Jacoby III: So, we have an environment where the demand on the protein side is extremely strong, and the trends on protein consumption are extremely strong and really feel like they’re gonna be around for quite some time.

We’ve got baby boomers retiring and whether it’s because of GLP-1s or it’s just a general knowledge and understanding of what human nutritional needs are as people age, they know that they need more protein in their [00:02:00 ] diet. So, it begs the question: what is going on with dairy proteins and whey proteins and how is this going to evolve in such a unique market where demand is so strong for protein right now?

And so, I’m gonna ask the question first. What’s the difference at a molecular level between whey proteins and milk proteins? Because when we’re in an environment like we are now, where you’ve got the demand really, really high, you also have a market that’s gonna start looking for alternatives, simply because prices are so high.

What is the difference between milk proteins in general and whey protein specifically?

Lloyd Metzger: It’s important to talk about from a functional perspective how the proteins are different. I’m sure we’ll get into the nutritional differences between those proteins as well. It’s important to understand what’s driving those differences in functional characteristics. And it’s really all about calcium.

The casein system is designed to carry calcium. The whey protein system is not designed to carry calcium. That differentiates the two groups of [00:03:00 ] proteins and makes their properties very different.

TJ Jacoby: I’ll explain it like this. Milk proteins, there’s two classes of proteins, right? There’s casein and then there’s whey. The casein is used to make cheese, and then the whey protein is what comes off. So, the whey protein is everything that is not used to make cheese.

So, the reason why casein proteins works so well for cheese because those proteins like to fall together in these spheres, they like to stick to one another. They like to stick to one another ’cause they have certain groups that latch onto the calcium and then they bridge with phosphate.

When they do, they have multiple proteins, different types of casein proteins that bridge together with phosphate and then based on their repulsion forces, they stick together. Calcium and phosphates really help it stick when we make cheese. The outside of that casein, micelle, that ball, when we make cheese, that outside is stripped off, it becomes hydrophobic, and that causes those spheres to stick together. That’s a huge functional property of casein. Whey [00:04:00 ] protein is the opposite.

Whey protein is really hydrophillic. It’s very polar. So, they like to float around in solution and stay floating around in solution. And they don’t like casein. It likes to stay separate from casein. And so, when you make cheese, it readily is released into the whey stream because it likes to stick with the water.

In the same way, those kind of stick together with these sulfur groups. But when you heat it up, they unfold. And when they unfold, now there’s certain reactions that can take place. So, those are the two major differences between casein and whey. Lloyd, what did I miss?

Lloyd Metzger: I would try to simplify it a little bit. The difference between casein and whey protein is casein is what’s trapped when we make cheese. And whey protein is the soluble protein that’s left over in the water phase of cheese.

Cheese making is a dehydration process. We concentrate the fat and protein that’s in milk, the casein version of protein in milk. But you gotta look at the properties of those two [00:05:00 ] systems and the groups of protein. So, the casein protein is actually really stable to heat, but it is not stable to pH. So, casein will always coagulate at low pH. So, you lower the pH of milk, you get a yogurt-like product. That’s all the casein that’s coming out of the system. Whey proteins don’t mind a low pH, and they’ll stay soluble at a wide range of pH. But now, when you get to temperature, the complete opposite happens.

Casein can handle super high temperatures and be very stable. Whey proteins can not handle high temperature at all, they start to gel. I think it’s important to look at the two different groups. Now you get into the functional differences between those two and the very different properties you have between those.

Lloyd Metzger: That’s why you get all these products that are very different from each other. Why cheese is so much different than whey protein. And then you have these dairy products that are a combination that have the two together. So like when we make yogurt, we end up with the two products together and get this property that’s partway in between the two proteins.

Ted Jacoby III: [00:06:00 ] Based on what you’re describing, when we’re talking about milk proteins, MPC 80, for example, there’s a higher level of calcium, I take it in milk proteins than compared to whey proteins. Is that true?

Lloyd Metzger: Absolutely, but let’s remind everybody: milk protein is both casein and whey protein together at the normal ratio that’s in milk.

So, of the protein, 80% is casein, 20% is whey protein. So, when you say milk protein, you’re actually meaning 80% casein and 20% whey protein. Now, when we talk about cheese or casein, we’re basically a hundred percent casein and 0% whey protein. Now, when we talk about whey protein, we’re essentially a 100% whey protein, no casein except for one fragment of casein that actually gets solubilized, as TJ described, and now actually becomes part of whey protein.

Something that a lot of people don’t understand is that about 15% of what we call whey protein is actually a piece of casein that gets lost in the whey and now gets [00:07:00 ] captured and harvested in the whey protein manufacture process. But again, it’s important to remember milk protein is a 80 / 20 combination of casein and whey protein together.

So, when you’re talking about milk protein, you’re actually talking about whey protein and casein together.

Ted Jacoby III: It’s funny, I just learned something never really quite had my head around, and that’s that 80 / 20 ratio, that 80% of all the protein in milk is actually either alpha or beta casein. Correct?

Lloyd Metzger: There’s actually four different casein fractions that are involved that make up that 80% of the total protein.

Ted Jacoby III: Okay. The casein molecule isn’t really any bigger than most of t