Directions
Don’t make the popular “pressure cooker” or “Instant Pot” vanilla extract using vodka and vanilla beans or follow any other recipes that recommend using liquor under pressure – these recipes could result in injury and fire. Evaporating alcohol is not only flammable but it could combust unexpectedly.
This alert debunks flawed assurances that pressure cooking with liquor is safe in electric pressure cookers or with modifications (such as using jars or natural release), includes official statements from manufacturers, the UL Standards organization; and, Dr. Marco Bella, professor of Chemistry at Sapienza University of Rome, Italy.
hip info: definitions and clarifications
alcohol vs. ethanol -this alert will refer to the alcohol in liquor and wine “ethanol”. That’s because, as Dr. Bella pointed out, alcohols are a class of chemical compounds and it would be confusing to call this specific compound with such a general name.
liquor – when referring to liquor, this means distilled spirits (aka hard-liquor). This includes, but is not limited to, vodka, whiskey, tequila, rum, gin and brandy.1
But first, let’s see how this all got started.
How it all began..
Two years ago, a blogger shared her friend’s Vanilla Extract pressure cooker method which involves filling the pressure cooker with 80-proof vodka (40% ethanol) and vanilla beans, pressure cooking at high pressure. Soon after, another blogger changed the method by proposing putting the same concoction (vodka and vanilla) into a jar, screwing on the lid to “fingertip tight” and then pressure steaming the liquor-filled jars on a rack. Fast-forward to today, and a google search alone will yield over a million recipes for making vanilla extract or other concoctions using liquor in the pressure cooker – some even using 190 proof Everclear (which is 92.4% ethanol).
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But the hazards don’t stop at blogs. Unfortunately, recipe websites, magazines, apps, booklets and recipe repositories and videos created, or promoted, by pressure cooker manufacturers themselves offer pressure cooker recipes with the addition of liquor.
A manufacturer’s official Facebook group, for example, yields hundreds of results when searched for “hooch”, “moonshine”, “vodka” or “everclear”- despite the fact that each post is moderated.
Manufacturers reticent to comment
Pressure cooker manufacturers appear to be reluctant to reveal their official policy on the safety of pressure cooking with liquor. I contacted three popular pressure cooker manufacturers for their policy and only one was willing to provide a statement.
At least, Instant Pot responded with the following statement:
Regarding cooking alcohol in Instant Pot, there are many factors which could generate source of ignition of the alcohol fume. These are not part of the Instant Pot product and beyond the control of Instant Pot device. We cannot officially endorse such use given the possibility of unforeseen risks. – Robert Wang, CEO, Instant Pot
Kuhn Rikon did not want to comment on the practice, and Fagor America said that they do not recommend the use of their product outside of the UL standard. A standard that, unfortunately, doesn’t address the use of liquor to build pressure in the cooker.
UL Standard’s unclear position
A blogger promoting the practice posted the following correspondence with an employee of the UL Standards as evidence that pressure cooking with liquor is safe. The UL’s answer to this blogger is as follows (emphasis added by me):
Hi Ms. [REDACTED],
I’ve been asked to answer this question for you. I did some research, and I can’t find anything definitively that says it’s unsafe. I found a couple of cooking sites that have recipes posted for pressure cookers that appear to employ some alcohol. The UL Standard for pressure Cookers, UL136 is silent on this, as it does not state any risks in the required “Important Safeguards” that forbid the addition of alcohol. So I’m inclined to think it’s ok, but I can’t say for sure. You might want to consider consulting the manufacturer of your pressure cooker to see what they say. Hope this helps.
Best regards,
Nick [REDACTED]
Staff Engineer
So, basically, since the UL guidelines do not state that it is unsafe this employee was inclined to think it is safe to use alcohol in a pressure cooker. Keeping in mind that there not a complete list of items specifically stated in the guidelines as unsafe – for example gasoline (don’t try it) – this does not appear to be an accurate conclusion.
I contacted UL Standards directly to get clarification on their research methods, their use of omission as evidence of safety, and get their official statement on the practice of pressure cooking with liquor. In addition to a personal invitation to tour their testing facilities in Illinois at their expense, they provided the following statement for me to include in this alert…
UL develops standards and tests products for safety under normal use. UL does not evaluate pressure cookers for use with flammable liquids. If a product has been third party certified, consumers can be assured the product will operate safely if used as directed by the manufacturer. Safety instructions state “Do not use pressure cooker for other than intended use”. – Barb Guthrie, VP, UL.
So… what determines safety?
When I contacted Dr. Bella for his expertise on this issue, even before discussing the mechanics of liquor in the pressure cooker, he took issue with bloggers assuring the safety of this practice solely based on the fact that things went well for them.
Specifically, Dr. Bella wants to make it clear that warming up ethanol, which is a highly flammable liquid, should only be done in a controlled environment (a chemical laboratory or a distillery), and only by means of apparatus which has been specifically designed and tested for this specific purpose. A procedure that involves warming up any flammable liquids can be considered reasonably safe only if it was extensively tested.
“I definitively discourage anyone to warm up ethanol of other flammable liquids in pressure cookers, which are designed to warm up water and not other liquids,” said Bella.
Any cooking technique cannot be assumed to be safe even if someone posts a video describing it on the Internet, according to Bella. That poster might not have had problems, but might simply have been lucky. Making it unlikely that someone who had difficulty pressure cooking with liquor would post videos, photos or warnings on the internet or even report such an accident.
Ultimately, pressure cooking using liquor cannot be considered safe until it is proven to be safe by individuals qualified to make such assertions. Scientists in a laboratory are qualified; home cooks in a kitchen likely are not.
Pressure cooking with liquor
When liquor is pressure cooked it is technically being re-distilled; but, instead of redirecting, cooling and actually distilling the ethanol vapors a home pressure cooker releases a cloud of these combustible vapors in your kitchen.
Basically, in distillation, the differing boiling points between water and ethanol are used to separate them to make a stronger concentrate. Since ethanol boils at 173°F (79°C) and water at 212°F (100°C) – distillers capture the first vapors to evaporate and immediately condense them to ultimately concentrate into a liquor.2
But, if you pressure cook liquor the valve releases ignitable vapors over and around your pressure cooker. If a spark were to ignite the combustible vapors released from the valve of a pressure cooker, they could serve as a wick to combust the highly-concentrated alcoholic liquid and vapors that remain inside the pressure cooker.
I personally know of at least two accidents involving pressure cooking with liquor.
One I made myself as one day I absent-mindedly replaced white wine with Limoncello liquor in a chicken recipe. I smelled something burning in the kitchen and my pressure cooker was shooting flames from the valve. Thankfully, the ethanol was sufficiently diluted by the other ingredients inside the pressure cooker to avoid an explosion, but I didn’t yet know this while I crawled on my kitchen floor to turn off the cooker. Don’t try this.
A famous chef, who runs a free online pressure cooking school, was inspired to bring his cooker to pressure with Rum to further flavor his pressure cooker caramelized banana recipe. That didn’t end well. Don’t try this, either.
Is it possible to use liquor in your pressure cooker and not have any problem? Yes, it’s possible, but it is simply not worth the risk. Please, don’t do it.
If you’ve had an accident pressure cooking with liquor – we want to hear from you – please contact me privately to share your experience.
Frequently Asked Questions About Liquor and Pressure Cookers
Is it ever ok to pressure cook using liquor?
There are two exceptions when pressure cooking with liquor could be considered relatively safe.
The first is when the alcohol is burned-off (to dry) – such as when sauteing ingredients for a recipe or de-glazing a pan as all the liquids are evaporated before locking the lid onto the pressure cooker and bringing it to pressure.
The other is the use of a tablespoon or two of liquor in a cake-type recipe that is steamed. Since it will be blended with other ingredients the concentration of the ethanol will be reduced.
Why is it relatively safer to pressure cook wine and beer compared to liquor?
A bottle of wine contains on average 11% alcohol and beer 4% but liquor can contain 40-95% – the concentration of ethanol in liquor is much higher than in wine or beer. The lower the ethanol content, the higher the temperature of the solution needs to be for it to evaporate.3
According to Dr. Bella, when pressure cooking wine, even though ethanol vapors could still exit the valve, if they were to ignite, the fire would not travel into the pressure cooker and ignite the contents under pressure (as could happen with liquor) because of the lower overall concentration of ethanol inside the pressure cooker.
There’s a long history of wine being used in pressure cooker recipes with no reported accidents or official warnings. And, as mentioned earlier, the fact that there are no reported accidents is not enough to consider a practice completely safe.
While the vintage American pressure cooker booklets I consulted did not contain any recipes containing either liquor or wine – likely due to the fact that most cookers sold were aluminum (which is reactive) and as a repercussion from the 13-year prohibition on the sale of alcoholic beverages – the vintage booklet I collected from Italy uses wine quite liberally. In the 1967 fifth edition of Cucinare Bene a Meta’ Tempo (Cooking Well in Half the Time) distributed with Lagostina’s stainless steel pressure cookers 44 of the 77 meat recipes use wine as a liquid for the cooker to reach pressure. There are also six recipes that use liquor but it is either fully evaporated before pressure cooking or mixed-in afterward for flavor or flambè.
There is no history of liquor being used in a pressure cooker as the liquid for the cooker to reach pressure, as the main ingredient for a recipe, or in a jar (more on this later).
While you should still take basic precautions when pressure cooking with wine and beer (which I detail in this post) there is no historical precedent of pressure cooking liquor – and there is credible first-person evidence that it is not safe. Don’t do it.
Aren’t electric pressure cookers safer for pressure cooking with liquor?
It is a myth that just because electric pressure cookers don’t use an open flame that they cannot cause sparks. The components from which they are made, for example a relay switch, can cause sparks during normal operation4. Also, even a simple static discharge from the chef or even simply turning on a light switch could cause a spark which would ignite any nearby ethanol fumes.
Here’s a photo of Instant Pot’s relay switch, along with an industry photo with a transparent casing which shows the contacts that “click” when the heating element is being turned on and off (see graph in next section). The clicking of these metal contacts in the switch can cause an arc (electrical discharge). Instant Pot Relay Switch from “Frugal Repair” Blog – fair use Contacts in relay switch from industry image – fair use It’s worth noting that at an additional cost, a manufacturer could use solid-state or hermetically sealed switches; however, as mentioned earlier, this component change would not solve all the possible ways a spark can be generated around the pressure cooker from outside sources.
So, no. It is not any safer to pressure cook using liquor in an electric pressure cooker than it is using a stovetop pressure cooker. Don’t do it.
Why are sparks even an issue if “the pressure cooking chamber is completely sealed” and Natural Release is used?
Although it’s true that in all pressure cooker types the pressure cooking chamber is sealed during cooking – i.e. not letting any additional air in, or steam out – this can only be true as long as a constant temperature is maintained. Maintaining a constant temperature inside a pressure cooker is a problem that even third generation electric pressure cookers have not been able to solve – they actually maintain a range of pressure. For example, Instant Pot has a working of pressure from 10.1 to 11.6 psi.5 This means that at any given time, the cooker is either gaining or losing pressure – ever so slightly – and the seal from the valve is broken.
This also applies to the “Natural Release” opening method which is often touted as safe in these recipes for disaster. During this release, the temperature inside is not constant it lowering slowly so the valve is not sealed during the release.6 More importantly, the pressure cooking chamber isn’t even sealed while the cooker is building pressure – which is when a majority (but not entirety) of the ethanol is evaporating.
So, no. Using an electric pressure cooker – or even stovetop for that matter- does not “eliminate vapor release and reduce the risk of ignition” because the cooker’s seal is broken and the valve is releasing ignitable ethanol while the cooker is building, maintaining and releasing pressure. Don’t do it.
Isn’t it safer to pressure cook liquor in “hermetically” sealed jars?
First of all, it is practically impossible to “hermetically” seal a jar before pressure cooking or canning without industrial vacuum equipment.7 Canning lids, and most others are made with a small foam ring around the outer edge where the lid will come in contact with the glass jar. This compound or foam allows for air to escape the jar as its contents are heated so that a vacuum is formed inside the jar as it cools.89 If air can escape these jars during the pressure cooking process, vaporized ethanol can too.
And, as a matter of fact, the blogger that proposes the in-the-jar method of making vodka and vanilla extract notes that there will be a loss of volume in the jar after pressure cooking.
I’ve also seen advice to, instead, tightly close the lids of the jars before pressure cooking. Obviously, this does not work, either, because the air and vapors trapped inside will expand as the jar is heated and- with nowhere to go – will break or explode the glass jar.10
So, no. It is not safer to pressure cook the vanilla extract in a jar or bottle or any other tightly closed or “hermetically sealed”container. Don’t do it.
More questions?
If you have any more questions beyond what was addressed in this alert, please leave a comment, below.
To conclude..
Pressure cooking with liquor in equipment designed for home use to pressurize with water has not been tested for safety by any manufacturer, certifying or governmental organization or university. The practice of pressure cooking a highly-flammable liquid cannot be made any safer by using electric pressure cookers, jars or particular opening methods.
Hip Pressure Cooking recommends not following pressure cooker recipes from any source that require the use of un-evaporated liquor during the pressure cooking process either directly in the cooker or enclosed in some other container.
See also
All Consumer Alerts
INFOGRAPHIC: 7 Pressure Cooker Safety Tips
Images in this article are duplicated from their source under the fair use. Per the United States copyright law, limited use of copyrighted material may be used without permission from the rights holders, for use such as commentary, criticism, news reporting, research, teaching or scholarship.
references
1.
List of alcoholic drinks: Distilled Spirits. WikiPedia. https://en.wikipedia.org/wiki/List_of_alcoholic_drinks#Distilled_drinks. Published 2010.
2.
Gurstelle BW. How Distilling Works. Popular Mechanics. https://www.popularmechanics.com/home/how-to/a7569/how-distilling-works/. Published March 1, 2012.
3.
L. Waterhouse A, L. Sacks G, W. Jeffery D. Understanding Wine Chemistry. John Wiley & Sons; 2016.
4.
Understanding the sparks created when using a relay to switch a coil. OverUnity. https://overunity.com/9875/understanding-the-sparks-created-when-using-a-relay-to-switch-a-coil/. Published October 2010.
5.
Which Electric Pressure Cooker Operates at 15psi? – Instant Pot. Instant Pot. https://instantpot.com/which-electric-pressure-cooker-operates-at-15psi/. Published May 29, 2013.
6.
Pazzaglia L. Pressure Cooker Opening Methods Explained + Tips! hip pressure cooking. https://www.hippressurecooking.com/now-release-pressure/. Published December 14, 2014.
7.
How to Seal Glass Jars. wikiHow. https://www.wikihow.com/Seal-Glass-Jars. Published 2017.
8.
Peterson S. Canning Jar Lids: Everything you ever wanted to know (and why!). SimplyCanning.com . https://www.simplycanning.com/canning-jar-lids.html. Published 2017.
9.
USDA Complete Guide To Home Canning (2015 edition). National Center For Home Food Preservation. https://nchfp.uga.edu/publications/publications_usda.html. Published 2015.
10.
What the heck does fingertip tight actually mean? – Healthy Canning. Healthy Canning. https://www.healthycanning.com/what-does-fingertip-tight-actually-mean/. Published 2016.
