Early Blowing and Cheesemaking

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Sometimes you just know something is wrong. That is what happened to me this week. I pulled some neglected cheeses out of the press after 18ish hours of being forgotten. I had made them the day prior and after putting the curds in the press, I had done a mic drop and gone to the garden.

Forgotten, never redressed, left to their own devices; when I pulled them from the press, I knew I had done wrong. 

One was dried and stuck to the cloth, peeling it off left pieces behind and my cheesecloth was ruined. The other had been improperly pressed, I could feel that it was squishy, too high in moisture, and riddled with mechanical holes. 

I dry salted them, put them on the drying rack and resolved to do better next time. This was in the morning. 

Later that night, children tucked in bed, I went downstairs to make myself a warm cup of milk. Standing in my kitchen I looked at those badly pressed cheeses. There was something wrong.

They had become slightly swollen. Occasionally you see slight swelling from salting, but I had a bad feeling about it. They felt spongy. 

Early Blowing is characterized by excessive gas formation in cheeses within the first day or two of making. It can be caused by either yeast contamination or bacterial contamination in cheeses. The contaminant feeds on nutrients in the cheese, the byproduct CO2 and H2, which form gas bubbles within the cheese. These gas bubbles pop, leaving behind shiny, usually perfectly round, holes. Gas holes can be distinguished from mechanical holes by not only their shiny interior and round shape, but also by their uniformity throughout the cheese. 

I had seen early blowing once before. A few months back, I had a batch of cheese contaminated with yeast. Post brine salting, both cheeses from the same batch ballooned up and had a notable yeasty smell. Upon cutting them open, I found that the interior was riddled with gas holes. 

These cheeses were reminding me of that day. 

As my milk heated on the stove for my late night drink, I grabbed a knife and cut the largest one in half. It was the cheese that I had thought was heavy in moisture and I expected to find mechanical holes in its interior. Opening it up proved that it had indeed been contaminated. Not only were there mechanical holes, but the interior had turned to what can only be described as the look and feel of a sponge.

This case of contamination was different from the one I had had earlier in the year. The batch of cheese that had been contaminated with yeast a few months prior, had smelled notably yeasty. I had been confident to say that it was a yeast contamination.

This cheese did not smell yeasty. I wasn’t confident to say what the contaminant could have been. I cut open the second cheese; the same spongy interior. 

Coliform contamination in cheese

What Causes Early Blowing?

When hunting for the cause of early blowing, the first thing you need to consider is your milk. Good quality, fresh raw milk is what I use to make cheese. I characterize good quality raw milk, as milk that has come from a good source, a trusted source. Milk that was milked out in a very clean way, milk that was handled quickly and efficiently, that was not left to sit unattended, milk that is coming from a healthy cow; Milk that you would feel comfortable feeding to your family. 

Raw milk is the perfect host for growing bacteria. That’s why it makes such good cheese, but that is also why we as cheesemakers, need to use excellent milk handling practices to prevent contamination risk. 

Raw milk will naturally have contaminants introduced into it during the milking process and during transport from the barn to the cheese pot. It is pretty safe to say that most raw milk probably has coliform bacteria in it. Coliform comes from cow poop, and is probably the most dreaded culprit of early blowing. Cow’s Poop. It’s life! The best you can do is use very clean milking techniques, use safe milk handling, and know that raw milk is a living ecology. Even if a microscopic amount of coliform gets into your milk, it does not guarantee coliform contamination. Raw milk is a living ecology that houses many different bacterias and fungus that can protect your milk. However, if a lot of coliform lands in your milk, or your milk is not handled safely, coliform is a likely candidate for early blowing. Watch this video on how I keep my raw milk good for cheesemaking.

When considering whether or not a case of early blowing is caused by coliform, ask yourself, “Did I use excellent Milk handling practices?”. If the answer is yes, then coliform is most likely not the culprit. 

If you know that your milk handling practices have been stringent, it is probably not a coliform contamination. 

Yeast contamination is a common cause of early blowing, especially in a homesteaders kitchen. We have bread baking, sourdough starter on the counter, kombucha bubbling. Yeast is common in the homestead kitchen, and yeast loves milk!

To limit yeast contamination risk during cheesemaking, it is recommended to not bake bread, to not keep a sourdough starter, to not keep ferments on the counter. As a homesteader, who has a lot of other things going on and needs to have these things taking up the same space as cheese, there are things we can do to prevent yeast contamination in our cheeses. 

First off, if you have a contamination and you suspect yeast, clean everything. Take a bucket of hot soapy water, with a tiny bit of bleach and go to town scrubbing all of your equipment, counters and surfaces. Toss out your salt brine (because yeast can live in there). Keep your ferments, and starters on one side of the kitchen and your cheesemaking supplies on the other. If you touch your ferments, wash your hands. By taking precautions to prevent cross contamination, you will have a lot lower risk of contaminating your cheese. 

Can you bake bread while making cheese?

I do. 

But I am also writing a blog post about how I have had yeast contamination before, so use your discretion. For me as a homesteader, when I am in the kitchen, I need to be doing other things, Am I going to spend 4 hours in the kitchen only making cheese, when I also need to bake bread for the week? No, the answer is No.

I understand the risks, I understand that this opens my cheese up to contamination, but I make a lot of cheese and the odd contamination makes the optimized use of kitchen time worth it.

The breads baked, the cheese is made, the homestead is happy. 

Ways that I limit the yeast contamination risk. 

If you are planning on baking bread at the same time you make cheese, try to only do so after your milk has been cultured and has had a chance to ripen for a little while. Think of your culture as the goalie. If the goalie is in the net, it is a lot harder for the yeast to score.  

If you have a lot of yeasty ferments in your kitchen, and you are consistently struggling with contamination, try adding your freeze dried culture to your milk before even warming your milk. In doing this, you allow your freeze dried culture the chance to start feeding and multiplying as soon as the temperature is in an adequate range. This way you are making sure that yeast always has competition. 

Raw milk already contains yeast. In fact some yeasts are actually really beneficial to cheesemaking. Yeast contamination does not necessarily have to come from your kitchen, it can come from the yeast already present in the milk, it can come from other aspects of the environment. As a cheesemaker, you want to give your added bacteria a chance to take hold of the milk, and gain the majority vote. As soon as your milk is well cultured with good bacteria, it is at a much lower risk of contamination. 

Contamination happens. It is a fact of life, an obstacle that even the most experienced cheesemakers face sometimes. Don’t get discouraged. Arm yourself with a bucket of hot soapy water, scrub your kitchen, and try again. 

Happy Cheesemaking!

Robyn 

Want to learn more? Check out my Homestead Cheesemaking 101 Course. 

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