Tuesday, March 12, 2013

Let's Talk About: Boiling Water Bath Canning

This is a long, boring post but it is extremely important.  Please read it before you start any BWB canning!

There are several ways that you can preserve your food:  freezing, drying, pickling, pressure canning, Boiling water bath (BWB) canning, preserving in oil, curing, and smoking.  Most of my preservation techniques center on freezing, pickling, and BWB canning.  This year my goal is to expand into drying and pressure canning.  I'm not much of a preserving in oil fan as the foods that you preserve in oil become mushy as time goes on and they really don't last that long.  Somethings preserved in oils will only be good for a month or two and if I'm going to put so much time into something, what's the point?  I don't do curing or smoking, either.  It's just way too easy to buy cured and smoked meats to put the time and effort into curing and smoking.  Today, we are going to talk about Boiling Water Bath canning.

BWB CANNING CAN ONLY BE DONE FOR HIGH ACID FOODS!

Let me repeat, BWB CANNING CAN ONLY BE DONE FOR HIGH ACID FOODS!
Ok, now that I've gotten that out of the way, let me explain why.  Overall, preserving is about prolonging the shelf life of foods by killing or neutralizing the agents that would otherwise cause them to spoil(1).  Spoilers are enzymes, molds, yeasts, and bacteria.  Bacteria is the big boogeyman of home canning, specifically salmonellae, staphylococcus, and clostridium botulinum.

BWB canning works because water boils at 212.  Enzymes die once their host gets heated past 140. Mold and yeast are destroyed from 140-190.  However, there are two classes of bacteria.   Some bacteria die at temperatures exceeding 240, which is where acid comes into play with BWB. The process of BWB kills all spoilers except clostridium botulinum, HOWEVER, this bacteria cannot thrive in a pH of 4.5 or less.  Pickling low acid foods is the only way to safely BWB can low acid foods.  Pickling is adding an acid to a food. You can add acid by using a form of vinegar and/or lemon juice (citric acid!) or fermenting the food (3).  This is why BWB is safe for foods that have a pH of 4.5 or less (2).

BWB canning also works because as the gass jars are boiling in water, the heat pushes the air out of the tissues and creates a vacuum seal.  Without oxygen, spores cannot bloom in your food.  The temperature of the boiling water will also sterilize the jars and the foods.

Once you have finished canning an item, you must make sure that the lid is vacuum sealed on. If the lid is not vacuumed sealed on and comes off easily, you must refrigerate it immediately and eat it within 2 weeks.  If the seal is strong you can place it on your shelf.  When you want to use that food item, always check the seal of that item.  If you can lift off the seal easily, you must toss the item.  For whatever reason, that item did not preserve correctly and the bacteria have been having a party in that jar.  I have been BWB canning for 3 years and have only had 1 canned item spoil on me, so if you follow the rules your chances of failure are miniscule.  If, for whatever reason, you have doubts about an item, just throw it out.  It's better to be safe than sorry!

If you are interested in preserving, I highly suggest that you do your own research.   Every canner SHOULD have Ball Blue Book Guide to Preserving and Ball Complete Book of Home Preserving.  After that, every canner should have the National Center for Home Food Preservation as a favorites link.  The National Center for Home Food Preservation stays current on the latest canning research and offers advice and tips.  If at any time you read a recipe that you are just not sure about, you can go to NCHP and look up that technique to see if the technique is valid.  I highly suggest to add Well-Preserved by Eugenia Bone, Canning for a New Generation by Liana Krissoff, and The Complete Book of Small Batch Preserving by Ellie Topp and Margaret Howard to your canning book library.  After that, there are a myriad of canning books out there that you can follow for recipes.  Finally, there is a wonderful online forum called Harvest Forum on GardenWeb.  The community is extremely knowledgeable, fun, and quick to respond.  There are other canning forums but I find that the others tend to promote unsage canning practices and tend to be not as up-to-date on modern canning practices.  Harvest Forums members' primary concern is for your safety, how can you argue with that?

Finally, BWB canning is a highly effective way of preserving food for your family.  With the state of corporate canned items being loaded with sugars, MSG, and other non-pronounceable preservatives, you will find that canning your own food items is a much healthier way.  Plus, home canned items taste so much better.  Once you start, you will wonder why you never did it!

1.       Well Preserved, Page 13, Eugenia Bone, Clarkson Potter/Publishers New York 2009.
2.       Well Preserved, Page 14, Eugenia Bone, Clarkson Potter/Publishers New York 2009.
3.      Canning for a New Generation, Page 15, Liana Krissoff, Stewart Tabori & Change New York 2010.

HAPPY CANNING!
Resources:
1.    Well Preserved, Eugenia Bone, Clarkson Potter/Publishers New York 2009.
2.   Canning for a New Generation, Liana Krissoff, Stewart Tabori & Change New York 2010
3.  Ball Blue Book, TMS Ball Corporation, Hearthmark LLC Indiana 2010

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