What are the top 3 reasons why grass fed raw milk changes in flavor and consistency? FIND OUT HERE.

Should I choose animal rennet or vegetable rennet in my natural cheese?

written by

Marie Reedell

posted on

January 23, 2025

rennet.jpg

Miller’s Bio Farm is all about giving you TMI about how your food was produced. Because, in today’s food world, you can’t just rely on labels alone. 

When you shop our A2/A2 CHEESE, you can click on each cheese and see the full product description. You can find the exact kind of rennet in the ingredient list. And, you can see any trace additives used in the cultures or rennet listed in the “Honest Disclosure” section. 

But what does that all mean, and which type should you choose? How would you know which type is used? That's what we're delving into in this blog post -- it's all about rennet!!!

What is Cheese? What is Rennet?

Legend has it that cheese was discovered by mistake, when someone used a flask made of lamb stomach to bring some nourishing milk on their travels. After walking for days in the hot sun, he found that the milk in his flask had curdled… and it was delicious! The raw milk naturally fermented, and the enzymes in the lamb stomach coagulated the curds.

Cheesemaking has come a long way since then, with specific processes and cultures needed to make different kinds of cheese. And then of course there’s regulations around food and food safety and modern expectations for consistency and affordability.

Here's an overview of how cheese is made today --- You add culture to milk and let it ferment. Then, you add rennet, which separates the milk into curds and whey. Then you press the curds and age them. Voila cheese!

Sure, you can also use vinegar or citric acid to curdle the milk for fresh cheeses like paneer, ricotta, or even mozzarella. But, for aged cheeses, you need to use rennet. It's essential.

Rennet is a complex set of enzymes that are naturally produced in the stomachs of ruminant mammals. Chymosin, its key component, is a protease enzyme. In addition to chymosin, rennet contains other enzymes, such as pepsin and a lipase.

The enzymes in rennet target casein, the main protein in milk. They cause the casein molecules to divide and re-coagulate into even larger clumps (AKA cheese curds).

curds-set-with-rennet.jpg

Above photo of how the cultured and fermented milk sets after rennet is added.

curds-and-whey.jpg

Above photo of how the curds and whey look after the curds are cut and heated a bit.

curds-after-rennet.jpg

Above photo of how the curds look after the whey is drained, before pressing the cheese. 

Types of Rennet

Veal/calf rennet: Made by grinding calf gullet/stomach and mixing it with salt. The powder is put in a solution that extracts the chymosin. It’s typically made as a liquid rennet.

Veal/calf rennet is the most natural form of rennet, since it’s the oldest form of rennet. Remember, carrying milk in a lamb stomach was likely how cheese was discovered!

Using veal/calf rennet in today’s world is not all pure and natural. Most rennets available are made from calves that are a byproduct of the conventional dairy industry. They are not likely born from happy, pasture raised cows that are 100% grass-fed. And, almost all of them contain trace additives of one kind or another. These may include sodium acetate, propylene glycol, or potassium sorbate.

Fermentation-produced chymosin (FPC): It’s a genetically modified organism! They splice genes in a mold to produce chymosin. 

I spoke with a lab tech that makes the vegetarian rennet used in our goat cheeses. They weren’t sure how they can make the claim that it’s GMO-free, but somehow the rennet and cheese companies make that happen (with a lot of * and fine print below).

Fermentation-produced chymosin is the most popular rennet for certified vegetarian” cheeses. Over 90% of all cheeses made today use this kind of rennet. It makes a good product. As it stands now, it cannot be used in "certified organic" cheeses.

The concern here is of course that it’s a bioengineered ingredient. What are the long term health consequences of consuming it? Does the GMO chymosin enzyme alter the casein proteins differently than veal rennet? Well, there’s simply not enough research done to be 100% sure.

Another concern is trace additives like sodium chloride or sodium benzoate.

Microbial rennet: Made when Rhizomucor miehei mold grows on a nutrient base that’s primarily soy. Yes, that’s right, soy. And, that means that the nutrient base is most likely GMO! 

Mold rennet is also used in “certified organic” and “certified vegetarian” cheeses. However, it’s not the best. It tends to produce undesirable bitter flavors. It also does not age very well. 

Recent research is showing that microbial rennet can have a negative impact on the gut long term. It’s definitely something to be cautious about until a lot more research is done.

Rennet Alternatives: 

You can use squares of dried salted calf stomach, which has been done for thousands of years. You can use thistle, which is traditionally used for specific cheese in Spain and Portugal and is really expensive. You can also make soft cheeses from wild rennet from plants like sorrel, cardoon, artichoke, and fig. 

However, these rennets are typically used for making cheese at home. They would not produce a cheese that’s consistent, tastes good, and holds up well. Most farmers and cheesemakers would not want to dabble with them, as they’d end up with a lot of waste and unhappy customers. 

Is GMO Vegetarian Rennet Safe?

The safety of genetically modified rennet is a topic of debate, both in the scientific world and the regulatory world. Some studies suggest that it’s completely safe, and others raise concerns about potential allergic reactions or other concerning health consequences (read more about corn and soy and allergies in this post).

Why the debate? Well, there’s limited scientific data to definitively state the long-term safety of cheeses made with GMO rennet. In my opinion, it’s likely best to wait for full safety studies before introducing a product. Sadly, that’s not how our food world works. So, now that you know, it’s your choice whether you want to stay away from "vegetarian rennet" or not!

It’s important to note that the safety and regulatory status of GMO rennet varies from country to country. While in some places, GMO rennet has been deemed safe and approved for food production, in others, it might be subject to restrictions or even prohibited altogether. Depending on local laws, cheese made with GMO rennet can be labeled as GMO-free (and that’s how it is in the US).

Labeling Requirements

With cheese, it’s required to list “rennet” or “enzymes” as an ingredient. But, the source (animal, plant, or microbial) is NOT required. For cheese companies that make cheese with vegetable rennet, the have the option of listing “vegetable rennet”. But again, the exact kind is not required on the label.

Additionally, listing the ingredients in the ingredients is also not required. For example, a cheese may say "rennet" in the ingredients list, but the sodium acetate, propylene glycol, or potassium sorbate or other additives does NOT need to be listed on the label. The same is true for basically any trace additive in food.

So, if you want to know the type of rennet or trace additives in your cheese, you need to read the product description. If it's not there, you'll need to ask. 

What’s in Our Cheese?

At Miller’s Bio Farm, we of course go above and beyond. We do everything we can to avoid the greenwashing or confusion caused by food labels. Instead, we just tell you everything we can about how the food is produced. We include an honest disclosure for each of OUR A2 CHEESES, which tells you the type of rennet and any additives in them (and not just what's listed on the Safety Data Sheet, we actually talk to the rennet and culture companies about it).

For all of our cow and goat cheeses (except mozzarella), beef rennet is used. The calf gullets used in our rennet are sourced from milk-fed veal calves mainly from New Zealand and Australia. 

Sadly, it seems impossible to find a beef/veal rennet without trace additives. We were super excited to find Walcoren brand rennet, which did not have any additives on the safety data sheet. But, when I called the company and talked to a scientist, he confirmed that the standard additives are actually in it. Since they're a Canadian company, they don't need to include them in the safety data sheet. Ugh.

As with all beef or veal rennets, our rennet contains trace amounts of sodium acetate, propylene glycol, and potassium sorbate. 

For our mozzarella cheese, a microbial vegetarian rennet is used. It's organic and simply makes a better mozzarella. It has trace amounts of sodium chloride and sodium benzoate E211.

For our cottage cheese, no rennet is used at all. It's cultured, and the curds are separated with a little heat only.

To put all of this into perspective, you only need a little bit of rennet to make a whole lot of cheese. For example, our cheesemaker uses 60ml of rennet per 1,000 pounds of milk. That’s 1.93ml per 1 gallon of milk. Then, the curds are drained and pressed and fermented. In the end, In 1 lb of finished cheese, there's about 0.00066 grams of rennet. 

Any additives would be minuscule, a trace of a trace amount. But, if a trace of a trace amount of something bad is in everything you eat, it's no longer a trace amount! 

Regardless, you deserve to know everything about your food. So, now the cheese and rennet choice is yours!

-----

*Originally posted on 7/28/23. Updated on 1/23/25.

More from the blog

Top 3 reasons why grass fed raw milk changes in flavor and consistency.

Have you ever noticed that the flavor and consistency of our raw milk varies from week to week and especially season to season? This is 100% normal! You see, when you raise animals naturally on pasture (and especially when they're 100% grass fed like our cows and buffalos), the milk changes. This is starkly different from pasteurized milk you'd find in stores, which is usually from grain fed cows in feedlots. With that level of unnatural control, the milk can be consistent (or maybe I should call it boring). Here are the top 3 reasons grass fed raw milk varies: 1- Butterfat changes with the seasons. It's highest in the colder months. From the anecdotal experience of myself and our farmers, butterfat is highest in the spring. That's when milk is the creamiest, the most yellow, and the most flavorful (after all, fat holds the color and the flavor). That's when you get a hefty creamline in your jug of milk after sitting in the fridge for a few days. But then... I found an interesting study on this. It's from 1931, before dairy farming got seriously messed up. It tracked hundreds of cows over many years. The researchers found that butterfat and outdoor temperature have an inverse relationship. And they found that it didn't really matter when the cows give birth and the age of the cow. Fascinating! In short, the higher the temp outside, the less butterfat. The lower the temp outside, the more butterfat. Check it out: Another interesting note on the graph is they found that Jersey cows produce milk with the highest butterfat. We noticed this, too, and it's why Aaron's herds are 80% Jersey and 20% Jersey crosses. That's why our milk is so darn creamy! It does make me wonder why, anecdotally, we feel butterfat is highest in spring. Maybe it's because our cows produce the most milk in the spring and least in the winter...? We feel like we're swimming in butterfat in the spring. We make sooo much butter at that time of year. 2- Flavor changes with the feed. When the forage, the weather, and the seasons change, so does the flavor. When cows are outside on pasture, eating a diversity of plants, the flavor of the milk they produce is more robust. Mostly this is a good thing. In my opinion, our pastured milk is more flavorful and tastes better than conventional grain-fed feedlot milk. But, sometimes this can kick us in the butt. For example, when a cow finds a little patch of onion grass, that can create an odd flavor in the milk. The weather affects what the cows are grazing on, too. For example, when we're in a drought, the grass doesn't grow as voraciously. It's has less moisture and protein and isn't as fully developed. That can change the flavor of the milk.  And finally, there are, of course, the seasons. When the cows are eating fresh pasture in the warmer months, the milk will have a different flavor than when they're eating dry pasture (AKA hay) in the colder months. It's hard to predict what the final flavor will be. But, I sure do love tasting the differences in milk throughout the year! 3- How long it lasts changes with cleanliness. Clean milk lasts longer! Milk safety is a top priority here at Miller's. Our strict milk safety standards go beyond what's required for a raw milk permit in Pennsylvania. We test every batch on site for general bacteria counts. Not many raw milk farmers do that, but we sure hope more hop on board! Since we test every batch, we're able to keep a close eye on how well the team is cleaning. Even a small thing like a cat licking equipment in the barn, a tiny hairline crack somewhere, or water not being hot enough can make a big difference.  Because of our constant monitoring, we're pretty confident in saying that our milk is the cleanest around. There's no manure in our milk!  And because of this, our milk lasts longer than most. It's raw milk and will sour (no way to prevent that). But, it should last at least 2 weeks after you receive it before it becomes too sour to palate. Do you value milk consistency over naturalness? Have you noticed changes in our raw milk over time? What about milk makes it "the best" for you? I'd love to hear from you. Comment below to share your thoughts with our community (no account requred). Or, contact us to keep it private 😊 PS: Did you know that we make our fresh raw cow dairy in house? That's right. Our team does it in our creamery! Our goat and buffalo farmers make their own fresh raw dairy in house, too. ----- Sources THE INFLUENCE OF ENVIRONMENTAL TEMPERA- TURE ON THE PERCENTAGE OF BUTTER FAT IN COW'S MILK*

Salt and toxic heavy metals? We swapped our salt with a cleaner one!

Are you choosy when it comes to the salt you use? Yea, Miller's is, too. On the one hand, we want natural (not highly processed) salt packed with minerals (including metals like zinc and magnesium). On the other hand, we don't want an overload of toxic heavy metals and microplastics.  So, when Jesse from Dream Salts reached out about his pink Himalayan sea salt last year, I was skeptical. I told him that I needed to see some test results before the team could even consider switching salts. Jesse pulled through, and I'm super happy with the results. Our new pink Himalayan sea salt has half the amount of lead compared to Selina Naturally's Celtic Sea Salt. It also had no microplastics detected at a low LOQ (limit of quantification).  "Normal" table salt is highly processed.  Table salt starts as something natural - salt mined from the earth. But then, it goes through some heavy processing. This removes all impurities, including all those minerals that are beneficial for us. Once it's purified, an "anti-caking agent" is typically added. This prevents the salt from caking, especially when it's humid out. In fact, that's where Morton Salt got its famous slogan - "when it rains it pours"!  Iodine is a common anti-caking agent, and it's probably the most natural one, too. Consuming a little bit of iodine is absolutely necessary for optimal health. But, as with most things, getting it naturally is best. You can get iodine naturally from seaweed, fish Greek yogurt, milk, and eggs. Plus, the iodine added to salt is typically lab produced. Other anti-caking agents might be used in table salt, too. These may include calcium silicate, sodium aluminosilicate, ferrocyanides like sodium ferrocyanide (E535), potassium ferrocyanide (E536), and calcium ferrocyanide (E538). Table salt is usually finer and dissolves more quickly. It also has a sharp flavor. Sea salt is more natural. Sea salt isn't highly processed. It's salt that was naturally occurring in the ocean, either today or a long time ago. There are 2 kinds of sea salt: From the ocean: This is when sea water is let to dry. The water evaporates, leaving the salt behind. Ever get out of the ocean and find your skin left with a whitish hue? That's salt that dried on your skin! Selina Naturally's Celtic Sea Salt is dried from today's Celtic Sea.From the land: This is from a salty body of water that dried up a long time ago. For example, Redmond Salt is from the ancient Sundance Sea in Utah. And, pink Himalayan salt is mined in Pakistan from mountains near the Himalayas. When salt is naturally occurring and not processed, it's packed with minerals which we need for optimal health. It's like a natural supplement!  On the flip side, it also can contain impurities like sand, shells, rocks, clay, and pollution (and sometimes anti-caking agents are added, too). Think about all the pollution in today's oceans. Yup, that can reside in sea salt harvested from the water! Microplastics in today's oceans can make their way into sea salt. It's no secret that our oceans are filled with plastic, slowly getting churned smaller and smaller into more and more microplastics. I read somewhere that an average human contains a credit card's worth of plastic inside them now. Wow! Microplastics are a fairly new thing, and more research is needed. But, they seem to potentially cause a host of problems including reproductive, digestive, and respiratory issues, and may even be linked to cancer. This is why I was pretty excited to see Dream Salt's test results. They tested for a range of microplastics, and none were detected at the low LOQs of 5-50 parts per billion. Love that! Minerals are good. Toxic heavy metals are bad. Sea salt is packed with minerals that we need - magnesium, iron, potassium, zinc, calcium, selenium, etc. These are good to consume. But, some of these that we commonly call "minerals" are actually metals. Some metals like magnesium and zinc are good for us (of course in moderation) but some we don't need at all and can be toxic and cause damage, even in smaller amounts. The top 4 toxic heavy metals to watch for are arsenic, cadmium, lead, and mercury. You may remember a blast of muckraking articles about sea salt last year. They specifically called out Selina Naturally's Celtic sea salt for its high levels of arsenic and lead. In fact, their lead issue is now part of a lawsuit. Yeesh! And, wow, we use their Celtic sea salt. What's going on here? To start, Miller's of course assessed its choice in sea salt. Basically, we're using sea salt for its minerals, and that comes with all kinds of metals and is in every sea salt (of course unless it's processed). We felt that, in the amount we use it, it was not harmful to anyone. Let's look at this through the lens of Mike Adams, the Health Ranger. He has a scale to rate the cleanliness of toxic metals in products. And this scale relates to the end product, not each ingredient. When it comes to salt, only a little bit is in each bite, so any level of contamination gets diluted. Selina Naturally's salt on its own rates a low B, with 489 ppb of lead (or 0.489 ppm). Our new Dream Salt also rates a B, but much closer to an A, with about half the amount of lead at 269 ppb (or 0.269 ppm).  When we have an opportunity to reduce toxins, we do it! The Actual Test Results Because you deserve to know and see everything... I'm happy to announce that we're not only selling this pink Himalayan sea salt, but we're also using it in our fresh dairy products and sausages made from this point forward. Hooray! As an FYI --- There are other foods we offer that still use Selena Naturally's Celtic sea salt. We'll be slowly working with our small scale makers to make the switch across the board. But, it will take some time! What sea salt do you choose? What's most important to you when choosing a salt? What do you think about our salt switch? I'd love to hear from you. Comment below to share your thoughts with our amazing community, or contact us to keep it private 😊 ----- Sources Sea Salt vs. Table Salt: What's the Difference?We Test Every Lot Of Celtic Sea Salt®Consumer Wellness Center Labs

Gut strengthening colostrum: What is it? Powder vs liquid? How to use it?

Colostrum is the first milk a cow produces after it gives birth. All mammals make colostrum as the "first milk". Yup, human mommies too!  Also known as "liquid gold", colostrum is a super special dairy item. It's not only important for newborn health. It also has some amazing gut healing and immune boosting properties for older mammals, too. Because of this, some people choose to take colostrum as a supplement or give it to their furry family.  But, gee, there are a bunch of colostrum options out there! And each has its own pluses and minuses and dosing recommendations. And, when it comes to raw liquid colostrum, there isn't much info out there at all.  So, I made this resource for you that answers these questions. I hope it helps you make the best choice for you when it comes to food and natural healing 🙏 Here we go! What is colostrum? Colostrum is the first liquid a mammal produces within the first 4 days after it gives birth. You can think of it like it's a super charged milk. A mammalian body produces colostrum for good reason: It's essential for optimal newborn health.  Compared to milk: Colostrum is usually thicker and more yellow.Colostrum is filled with immunoglobins to boost a baby's immune system, like 5,000%+ more. This helps protect young ones from illness. Colostrum has lots of growth factors, at least 2x more. This helps a newborn develop a strong and healthy gut.Colostrum has 2-5x as much protein. First colostrum can have up to 15% protein!Colostrum generally has more vitamins. Most notably, it has at least 47x more Vitamin E and 2x more Vitamins D and B2.Colostrum generally has more minerals, most notably it has 4x more zinc.Colostrum has more fat, at least 66% more.Colostrum at least half the amount of sugar (AKA lactose). This makes it generally easier to digest. Can see why colostrum can be called "super charged"? What's in colostrum that makes it a healing food? I could get super science-y here. But, I'll do my best to keep it simple. Antimicrobials = Enhanced Immunity and Gut Health Colostrum is packed with immunoglobins (AKA IgG antibodies) and other immune-boosting constituents like oligosaccharides, lactoperoxidase, lysozyme, and lactoferrin. Working synergistically, they help protect the body against foreign invaders like bacteria, viruses, and allergens.  Getting these via colostrum can help your body learn what to do and enhance the function of your immune system! Once your body knows what to do, it can more easily do the same thing the next time. They can also help restore balance in your gut, helping keep the numbers of "bad bacteria" in check. Did you know that humans pass this antimicrobial goodness to their babies via the placenta? Cows don't do that! And that's why cow colostrum is specifically and seriously packed with antimocrobials. Immune regulators = Help Fight Infections and Restore Balance  Colostrum contains immune regulators like cytokines and leukocytes. These can help prevent, treat, and even destroy harmful bacterias and viruses.  Gut issues are typically fraught with an overpopulation of bad microbiology and an underpopulation of the good microbiology. Removing the bad stuff can immediately reduce inflammation. And creating better balance can allow for gut healing, Growth Factors = Promote Healing and New Growth Colostrum contains so many kinds of growth factors, from the common peptides to things that can fall into categories like glutamine, nucleotides, and polyamines to super important insulin-like growth factors, too. Growth factors do exactly what they sound like they do - they encourage growth. So let's say your gut lining is damaged (or really anything in your body is damaged), colostrum can help it rebuild more quickly. What's the difference between powdered and liquid colostrum? Liquid colostrum is simply straight colostrum. It's milked from a cow and either consumed immediately or frozen for later use. It's the purest, most bioavailable, and most potent form of colostrum. All of the healing powers are intact. Powdered colostrum (and the capsules and tablets made from it) started as frozen liquid colostrum. Then, it's generally pasteurized and freeze dried. Now both of those processes can reduce, inhibit, or destroy certain healing properties of colostrum. In short, the less processing, the more healing powers. Plus, with powdered colostrum, the final product may be altered from its original composition. For example, it might have the fat removed, or maybe they put additives in there for anti-caking, preservation, etc. This can negatively affect the synergistic healing qualities of colostrum. With liquid colostrum, is there nutritional loss with freezing? The longer colostrum is frozen, the more probiotic loss. For this reason, I don't recommend freezing colostrum for more than 3-6 months. I mean, it will still have some good stuff in it. But why waste those amazing healing properties? If choosing liquid colostrum, how much should I take as a supplement? First things first, if you're new to dairy, especially raw dairy, take it slow! You definitely don't want to shock your body, especially when you're trying to heal something. Take a teaspoon, and see how you feel over the next few days. Then slowly up the dose and reduce the timing until you find a regimen that works best for you. You can't OD on colostrum. On the other hand, a little bit goes a long way. Most people taking colostrum as a supplement use about 1-2 oz per day. It's like a daily shot of liquid gold. What's the difference between first milking and second/third milking colostrum? Well, it's just like it sounds.  First milking colostrum is from the first milking after a cow gives birth. It's the most potent and contains the most healing properties. Second/third milking colostrum is from the second and third milkings after a cow gives birth. It's not as potent but still has great healing powers. You can always take more second/third colostrum to get the same benefits as first. It's also important to note that this is not an exact science. Every batch of colostrum will vary. Why? Every cow/calf combo is different. Plus, the time between birth and milking will vary. I mean, we won't know if a cow gives birth at midnight, so we can't go out there and immediately milk her on a special schedule. What about the calves? Do they get any colostrum? Of course! We know how important it is for optimal health, so the calves always get first dibs on colostrum. We take whatever is leftover, whatever they don't drink from their mom. Our colostrum inventory is always limited. This is the nature of colostrum. We can't just make more now. We need to wait for a cow to give birth. It always in and out of stock, sometimes for shorter on longer periods of time. And, if you ask when it's coming back, we may not have a direct answer. This is because we don't know the exact day cows give birth (that's nature's decision). And probably more importantly, the calf always gets first dibs. We never know how much will be left for us (sometimes there's none). The bottom line is that you've got to get our colostrum when it's available. Is colostrum part of your life? Powder or liquid? If yes, what benefits have you seen? I'd love to hear from you. Comment on the blog to share your thoughts with our amazing community, or just click reply to keep it private 😊 ----- Main Source Bovine Colostrum: Its Constituents and Uses