{"id":3924,"date":"2015-11-22T18:44:54","date_gmt":"2015-11-22T18:44:54","guid":{"rendered":"https:\/\/pantryparatus.com\/?p=3924"},"modified":"2015-11-25T03:59:14","modified_gmt":"2015-11-25T03:59:14","slug":"why-does-canning-jar-lid-seal","status":"publish","type":"post","link":"https:\/\/pantryparatus.com\/articles\/why-does-canning-jar-lid-seal\/","title":{"rendered":"Why Does a Canning Jar Lid Seal? Science behind the “pop”"},"content":{"rendered":"

The “pop” sound of a canning jar makes me weak in the knees. If you heart<\/em> canning, keep reading.<\/p>\n

<\/p>\n

In fact, the absence of the “pop” sound is the main complaint I hear from people about the Tattler Reusable Canning Jar Lids<\/a>–those don’t “pop.”\u00a0 They don’t actually need to, and you will know the jar is sealed if you cannot remove the lid.\u00a0 There are other reasons for using Tattler instead of Ball or Kerr, namely that they are made in America and are BPA-free with no “finishing spray” or other nasties that can leach into your foods.\u00a0 But let’s face it–most of us are addicted to the “POP!”<\/p>\n

What causes the popping of the canning jar lid?\u00a0 The answer matters because it is what protects you from food-borne illnesses.\u00a0\u00a0 There is more than one way to hear that reassuring popping sound and, sure, it’ll hold the lid tightly with several preservation methods–but that does not mean that the pop is protecting you.<\/p>\n

The Science Behind the “Pop” of the Canning Jar Lid<\/h4>\n

When you place your food into that jar and then measure the headspace,<\/a> you screw the canning jar lid onto the jar with a ring, trapping in regular, run-of-the-mill kitchen air.\u00a0 You know, the usual suspects: oxygen, carbon dioxide, nitrogen, the smell of your steaming applesauce you’re putting into the jar.\u00a0 And all gases go through a physical change when heated; most will expand if they have a place to go.\u00a0 But you tightened a ring around a lid, remember?\u00a0 You’d remember the time you didn’t.<\/p>\n

\"Canning<\/a>
Canning basket for water bath canning (click the pic to view)<\/figcaption><\/figure>\n

Since your regular, run-of-the-mill kitchen air can’t escape during it’s expansion it is going to increase in….pressure (did you guess that?).\u00a0 Sort of like that feeling in your gut when you have expanding gas you won’t let escape.\u00a0 Yup, I went there, but you know what I am talking about now, don’t you?\u00a0 This comes down to the laws of thermodynamics.<\/p>\n

Pressure, like temperature or water, likes to be even.<\/h5>\n
What happens when you put an ice cube in your hot soup?<\/h5>\n
\"Vegetable<\/a>
Vegetable & Sausage Soup from Food Storage and Autumn Garden Produce: Get the recipe by clicking the picture.<\/figcaption><\/figure>\n

The ice cube melts and the soup gets a bit cooler–it all hits a cozy equilibrium, right?\u00a0<\/strong> Pressure likes to do the same.\u00a0 The contents of the jar (your famous applesauce and the air) underwent a physical change when they hit the boiling point because of the heat.<\/p>\n

But now you move those jars to your kitchen towel on the counter, and just like your soup, the jars themselves begin to cool from the surrounding (regular, run-of-the-mill) kitchen air.\u00a0 And if it was the heat that changed the air pressure in the jar during the boiling, what will happen now?\u00a0 The air pressure decreases again.<\/p>\n

POP!<\/strong><\/h5>\n

The air pressure decreased, and it “sucks” the jar lid down because it created something of a vacuum.\u00a0 If the space inside the jar is no longer full of pressure, it will attempt to fill itself (for that equilibrium) by pulling in pressure from somewhere else.\u00a0 But the lid got in the way.<\/p>\n

You’re essentially doing this.\u00a0 In your kitchen.\u00a0 But without so much flair:<\/p>\n[youtube_sc url=”https:\/\/youtu.be\/JsoE4F2Pb20″ color=”white” theme=”light” modestbranding=”1″ rel=”0″ nocookie=”1″ showsearch=”0″]\n

The Difference Between Water-Bath Canning & Pressure Canning (or Oven Canning, even)<\/h4>\n

The heat applied to your canning process, any canning process, will kill most bacteria.<\/strong>\u00a0 It will often change the texture, flavor, or the nutritional value too, but you will live another day to tell about it because you killed the bacteria before storing the food item.\u00a0 It’s because of the change to the texture and flavor that you want to be a minimalist when you can be one; if water-bath canning will work, it just does not make sense to succumb that food to full-on pressure canning when wholly unnecessary.\u00a0 Some foods fare better to high processing than others, anyway, but for the sake of the food don’t overkill.<\/p>\n

Choose the right canning method.<\/h3>\n

 <\/p>\n

Your local county extension agency may offer classes; super idea.\u00a0 We offer a great “how to” dvd<\/a> (by Kendra from New Life on a Homestead) that will work you through proper canning procedures, too.\u00a0 You must know this–get this into your head–just because it “pops” doesn’t mean that food is safe.<\/strong>\u00a0 It does mean that no new air will get in, and that air is necessary for decomposition.\u00a0 However, not all bacteria is killed<\/strong> with a simple boiling; botulism, specifically, need to boil at an extremely high temperature and for awhile to die.\u00a0 Since botulism cannot live in highly acidic foods, the choices for killing it are either to ensure the acidity of the canned food or to switch from a water bath method over to the pressure canning method.\u00a0 Pressure Canning<\/a> is required for low acid foods.<\/strong><\/p>\n

\"Shop<\/a>
Shop Canning Supplies: click photo<\/figcaption><\/figure>\n

 <\/p>\n

What about oven-canning?<\/strong> You know, that fun little Amish banana bread recipe that got passed around as a facebook meme–you bake it in a jar, pop on the lid, and let it cool on the counter.\u00a0 That is not actually canning.\u00a0 It makes a “pop.”\u00a0 It has increased in air pressure, and then it decreased again, sucking the lid down into a vacuum.\u00a0 It is not an approved canning method–the heat of the food item is not proven safe for killing the necessary bacteria to ensure safety.<\/p>\n

The “pop” is just not enough to ensure food safety.\u00a0<\/strong><\/span> You know what is?\u00a0 Make sure you always follow the latest safety standards put out by the USDA.<\/a><\/p>\n[jigoshop_category slug=”canning” per_page=”3″ columns=”4″ pagination=”yes”]\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

The “pop” sound of a canning jar makes me weak in the knees. If you heart canning, keep reading.<\/p>\n","protected":false},"author":2,"featured_media":3931,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"footnotes":"","_jetpack_memberships_contains_paid_content":false,"jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false}}},"categories":[53,19],"tags":[458,478],"yst_prominent_words":[],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/pantryparatus.com\/wp-content\/uploads\/2015\/11\/Canning-Jar-Pop.jpg","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p9Fvks-11i","_links":{"self":[{"href":"https:\/\/pantryparatus.com\/wp-json\/wp\/v2\/posts\/3924"}],"collection":[{"href":"https:\/\/pantryparatus.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/pantryparatus.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/pantryparatus.com\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/pantryparatus.com\/wp-json\/wp\/v2\/comments?post=3924"}],"version-history":[{"count":0,"href":"https:\/\/pantryparatus.com\/wp-json\/wp\/v2\/posts\/3924\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/pantryparatus.com\/wp-json\/wp\/v2\/media\/3931"}],"wp:attachment":[{"href":"https:\/\/pantryparatus.com\/wp-json\/wp\/v2\/media?parent=3924"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/pantryparatus.com\/wp-json\/wp\/v2\/categories?post=3924"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/pantryparatus.com\/wp-json\/wp\/v2\/tags?post=3924"},{"taxonomy":"yst_prominent_words","embeddable":true,"href":"https:\/\/pantryparatus.com\/wp-json\/wp\/v2\/yst_prominent_words?post=3924"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}