# Canning Butter the *Right* Way



## NotAGrasshopper (Oct 25, 2010)

In every task we undertake, there are one or more right ways and many, many wrong ways to go about our efforts. Canning butter is no exception. I have read numerous articles here and on other forums, blogs, etc. that advocate canning butter in a water bath. The instructions on the interwebs leave out critical information such as: It is *very* unsafe to can unsalted butter in a water bath. Even salted butter is iffy, because you have no way to determine if there is enough salt in the butter to prevent C. botulinum from growing.

Here I am going to walk through the steps of safely canning butter, but first need to clear up some items that seem to be confusing to even the most respected bloggers.

Clostridium botulinum is a bacterium that is primarily found in soil, but as a practical matter, exists everywhere. It's on your kitchen counters, on your food, etc. It exists in two forms: As vegetative (actively growing) cells, which produce a potent neurotoxin and as dormant spores, which basically do nothing but sit there.

The vegetative cells are obligate anaerobes, meaning that oxygen will kill them. Just like all other bacteria, they cannot tolerate temperatures above about 165 degrees. They thrive in a middle-range pH environment and cannot tolerate low pH (i.e., they don't like acid).

The spores can survive in the presence or absence of oxygen and can tolerate a *much* higher temperature - up to about 240 degrees or so. They can tolerate a somewhat acidic environment but cannot "hatch" there. DO NOT believe anyone who tries to tell you that processing at any temperature less than 240 degrees will kill the spores, regardless of the amount of time used for processing. You can boil the spores for hours before they die.

When the spores are in a favorable environment (high Water Activity[sup]*[/sup] (Aw), neutral pH, moderate temperature) they hatch into vegetative cells. These cells multiply and produce one of the most potent neurotoxins found in nature. 75 nanograms (75 billionths of a gram!) can kill you. Fortunately, this toxin is denatured (rendered harmless) at about 180 degrees, so boiling canned food immediately before consuming it can prevent botulism in the event the food was contaminated. Since we don't typically heat butter right before eating it, it is very important that butter not contain any botulinum toxin!

It is important to understand the difference between the spores and the toxin: The toxin can be neutralized by boiling - the spores are NOT!

Here is what happens when you can a high Aw food improperly (i.e., in a boiling water bath):

1. Food is loaded into jars, along with C. botulinum spores.
2. As the temperature rises past 165 degrees, all bacteria are killed. There probably aren't any vegetative botulinum cells in there because up til now it's been an aerobic environment.
3. Processing continues at 212 degrees, insufficient to kill botulinum spores.
4. Food is cooled.
5. Environment is now anaerobic, moderate pH, high Aw, moderate temperature.
6. Spores hatch, begin growing and producing toxin.
7. If you eat it without boiling it first, you spend the next six weeks in an iron lung, assuming the S hasn't HTF and one is available.

You MUST can low acid foods with a pressure canner. Using a water bath is dangerous and idiotic, and guess what that says about someone who tells you it's okay? This is not some big conspiracy between the FDA, the USDA and food manufacturers. It is based on sound microbiological science.

Summary:
165 degrees - vegetative cells die
180 degrees - toxin is denatured
240 degrees - spores die

[sup]*[/sup]Water Activity

Water Activity (Aw) is a measure of how much water in a food is available to support the growth of bacteria and fungi. Pure distilled water has an Aw of 1.0, meaning that 100% of the water is free to support growth. A number of things can "bind up" water such that it isn't available for the bacteria: Sugars, salts and acids are the most useful for the home canner.

It is not how "wet" a food is that determines whether bacteria can grow - it is Aw. Look at pickles, for example. They are very "wet" but most bacteria, including C. botulinum, can't grow in them. Same with jelly and honey - the sugars in them reduce Aw to a point where bacteria can't grow. Dried foods have a low Aw just because they are dry.

C. Botulinum cannot grow in an environment where Aw is lower than about 0.97. Unsalted butter is made up of about 15% water mixed with proteins and sugars and that aqueous portion has an Aw of very nearly 1.0. Homemade butter typically contains much more water - up to 30%. The aqueous portion of either type of butter is an ideal environment for C. botulinum.

Now... Given all of the above, why can't we just use a pressure canner to can our butter and not worry about Aw? The primary reason is that fat is a very effective insulator. We simply don't know how much processing time will be required to ensure that *all* of the contents of our can/jar have reached the required 240 degrees. If we could reliably determine that it had reached that temperature, it would be okay to home-can *anything*. But making such determinations is expensive and difficult and for one reason or another, nobody has done this for butter.

So what about salted butter? As I said above, you have no reliable way to know how much salt is in your store-bought butter. Yes, you could look at the nutrition panel for the butter and using the sodium content, calculate how much salt is in there. But then you are relying on the manufacturer's word and hoping this isn't a slightly "off" batch of butter. It is much safer to start with unsalted butter and add your own salt to guarantee an Aw of less than 0.97. Consulting a chart derived from the FDA's "Bad Bug Book", we know that a 7% salt solution has an Aw of 0.96. I am going to build in a 100% margin for safety and bring the salt content to 14%, resulting in an Aw of below 0.92.

The bottom line is that lowering the Aw to a point where C. botulinum can't grow provides a safety net in case our pressure canning fails to kill all of the botulinum spores present in the butter.

So to get started...










Ingredients & Equipment: Butter, salt, 8 oz cans and lids, a gram scale (borrowed from my reloading supplies - does grains or grams), gravy separator, graduated (in milliliters) measuring cup.










Microwave 3 sticks of butter (enough for two cans) in the gravy separator.










Decant aqueous portion of the butter into graduated measure. We have 70 ml of non-butterfat liquid comprised of water and some protein and sugars.


















Water weighs 1gm/ml. To make a 14% salt solution here, we need to add 9.8 grams of salt to this amount of butter, or 4.9 grams per can. Doing the math, this will result in a total salt content of about 2.9% in the butter. This is about as salty as the saltiest commercial butter.










Place all cans on a baking sheet and add 4.9 grams of salt to each can. Add the salt *first* so you don't accidentally miss a can!










Add butter and heat to 170 degrees in the oven. This is a step that is necessary for canning in metal cans. If you are using jars you can skip it. The three cans on the left contain mozzarella, sharp cheddar and Velveeta. Since I'm firing up the canner I want to experiment with cheese and see how canning affects its taste and texture.










Attach can lids and seal.










Process at 10 psi for 90 minutes. This is a long time for such small containers but I'm being very cautious here.










Canned butter! The cans should be shaken vigorously as they cool to mix the water and proteins back into the butterfat.

Due to a small mistake in my arithmetic, the actual salt concentration is more like 12 point something percent. That's why we build in safety margins!


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## partdeux (Aug 3, 2011)

I appreciate all the effort you put into the write up... but can you make it a bit more simple for me?

How much salt (volume) per pound of butter?


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## NotAGrasshopper (Oct 25, 2010)

partdeux said:


> I appreciate all the effort you put into the write up... but can you make it a bit more simple for me?
> 
> How much salt (volume) per pound of butter?


I'm afraid the answer isn't that simple. To determine how much salt you need to add, you must first determine how much water is in your butter.

My butter contained 70 ml of water per 355 ml of butter - about 19% water and 81% milkfat - just over the minimum required butterfat content.

A higher grade of butter might contain less water and thus need less salt. Homemade butter can contain lots of water and will need more salt.

Assuming you are using USDA graded butter (which will not contain more than 20% water), you can use 13 grams of salt per pound of butter. Remember, this is *unsalted* butter you start with. If you added that much salt to already-salted butter it would be too salty.


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## partdeux (Aug 3, 2011)

13 grams using canning salt, is how many teaspoons?


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## NotAGrasshopper (Oct 25, 2010)

partdeux said:


> 13 grams using canning salt, is how many teaspoons?


I have no idea - you need to weigh it!


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## The_Blob (Dec 24, 2008)

13 grams is almost 1/2 oz (28 grams = 1 oz)


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## The_Blob (Dec 24, 2008)

removed, not worth getting banned over effing SALT


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## partdeux (Aug 3, 2011)

I have another silly question,

If you're already running it through the high temperature canning, why do you also need salt? Wouldn't you need one or the other?


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## lazydaisy67 (Nov 24, 2011)

Extremely informative and thanks for your time in explaining. I'm not sure for me personally it would be worth it to go to so much trouble just to have butter on hand when other fats can be used for cooking. I can and have made butter from my goat milk, so I'm pretty happy with that, but in the event that my goats are either taken away from me and/or die, I guess I think I'd be ok with using other spreads for bread and fat in other forms for cooking.


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## PrepN4Good (Dec 23, 2011)

Think I'll stick with my Red Feather and/or dehydrated butter powder from Provident Pantry...!


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## Davarm (Oct 22, 2011)

lazydaisy67 said:


> Extremely informative and thanks for your time in explaining. I'm not sure for me personally it would be worth it to go to so much trouble just to have butter on hand when other fats can be used for cooking. I can and have made butter from my goat milk, so I'm pretty happy with that, but in the event that my goats are either taken away from me and/or die, I guess I think I'd be ok with using other spreads for bread and fat in other forms for cooking.


I have heard that butter can be made from goat milk and have even copied directions from an old magazine article which seemed pretty far out in left field. We had a dairy goat years ago but never tried to make it from her milk.

Question: 
Being that you are the only person that I have access to who has actually made goat butter, how do you do it. Have quite a bit of experience with cows milk but none with goat milk.


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## *Andi (Nov 8, 2009)

Davarm said:


> I have heard that butter can be made from goat milk and have even copied directions from an old magazine article which seemed pretty far out in left field. We had a dairy goat years ago but never tried to make it from her milk.
> 
> Question:
> Being that you are the only person that I have access to who has actually made goat butter, how do you do it. Have quite a bit of experience with cows milk but none with goat milk.


Making butter with goat milk is the same as with milk from the cow ... The only real difference is the amount of milk you get and the goat milk takes a little longer for the cream to come to the top.

But yes, it can and has been done.


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