Pressure cooker: 1 bar/15psi: importance and Kuhn/WMF

[Anonymous Modernist 10022]

Dear all,

a quick question regarding the pressure cookers. I am shopping for my first PC, and I have reduced my choice to two brands: Kuhn Rikon and WMF. They are both high quality brands with excellent products.

I have, however, a question regarding the pressure that develops inside these cookers.

- Only Kuhn seems to be able of reaching 15 psi/1 bar: the manual says that the maximum operating pressure is 1.2 bars. This is consistent with the MC books that cook everything on 1 bar.

- WMF offers uses two pre-set options: low-level (around 9psi) and high level (around 13psi).

If I were choosing just for me, I would go with Kuhn. But if I think of my wife, that the WMF is more gadgety/sexy. Its "ultra" model has a timer, green indicator when it can be opened and the choice of two levels is very straightforward: I am sure my wife would prefer it, as it makes cooking somehow more accessible and automated.

My question: if I choose a PC that reaches only 13 psi, will it have any influence on the cooking outcomes? Specifically;

a. would I need to add few minutes to the cooking times from the MC recepies?

b. should I expect any inferior results in the taste/outcome?

Thanx in advance,

Ivan

[MikeMac]

I own a Kuhn Rikon and love it - simple works well only two red lines to watch high temp and low temp. While I know nothing about the WWF I question how long things like a timer will last. the green indicator in terms of when safe to open can be compared to the pressure relief valve on the top of the Kuhn Rikon if its raised do not open the pressure cooker.

If you want amazing results get a induction burner for use under the pressure cooker I have one and its really simple heat the contents of the pressure cooker at full power till the ingredients just start to boil while stirring so nothing sticks put the top on leave on full power till the pressure builds up turn induction burner down to 7 it holds the pressure and leave it alone till done!

In terms of the Kuhn Rikon I bought the big one as I was worried about ingredients boiling up and clogging the valve. In retrospect maybe that was not the best thing to do but if I was buying again I would buy the same one.

Amazing quick soup!!

[Anonymous Modernist 310]

I'm also using a the Kuhn Rikon on my induction cooktop and I love it. The important thing about a pressure cooker and to have a non-venting one. The KR is of that type and I THINK the WMF is also of that type. It will take more time to cook at a lower pressure but it may also taste differently. There is some very interesting articles by Dave Arnold about that subject on Cooking Issues:

http://www.cookingissues.com/2011/08/12/voiding-your-warranty-hacking-electric-pressure-cookers/

http://www.cookingissues.com/2009/11/22/pressure-cooked-stocks-we-got-schooled/

http://www.cookingissues.com/2010/01/27/pressure-cooked-stock-2-changing-pressures-playing-with-chemistry/

For some extreme example of the change in flavor with the pressure:

http://www.cookingissues.com/2009/06/11/maillard-pipe-potatoes/

So the answer to your questions will be

a) yes

b) sometime

As for your choice I can only tell you that my wife that was quite PC adverse now has no problem with the KR.

Good luck

Louis-Frederic

[Anonymous Modernist 10022]

Thank you both!

Excellent info. Comparison of stock color is amazing and very insightful! KR should indeed be the choice.

Few things I have learned from your posts and on other online sources. In the end, I discovered something (maybe) unexpected :-).

- Valve: Indeed, the WMF valve is the same as the KH valve (non-venting). Non-venting is indeed the most important thing (as per stock clarity/color comparison picture).

- Cooking time: In terms of cooking times, there is a table that indicates that on 13 psi you should add 2 minutes per every ten minutes of cooking time (http://missvickie.com/workshop/schoolframe.html)

- FYI, I discovered that WMF operates at 14psi on the second ring and reaches 119C (as per the online manual). The regulating pressure is 19psi.

Unexpected discovery: Everyone assumes that KR develops 15psi at the second ring. In one of the articles mentioned in your replies, Dave Arnold says "I always push the valve a little past the second ring, so I probably go slightly above 15 psi."

However, the KR user manual (http://www.kuhnrikon.ch/dms/ch/PDF-de-fr-en/duromatic-ga-de-fr-en/index.html), page 61, states that the second ring indicates the pressure of 0.8 bar, which according the bar-psi chart (http://www.britishmetrics.com/pis-bar.htm) equals 12 psi.

I find it interesting that it is a common perception that the second ring = 15psi, when the KR manual says it is not. Maybe they adjust the products differently for American and European markets? Or maybe I got something wrong. Probably too much looking into psi data and numbers over the past two days :-).

Cheers again,

Ivan

[Anonymous Modernist 10142]

I wrote a detailed technical review of the Kuhn Rikon Pressure cooker (http://bit.ly/SYf5PB). They make the same model for US and Europe. You are correct, the second red ring is not 15psi. However, the rod continues to rise until the cooker's overpressure safety mechanism kicks-in at 17.4 psi. You can lower the heat and maintain pressure at any point on that bar.

In the "performance and durability" section of the review there is an illustration of what the bar should look like at 15psi - a little more than the distance between the first and second bar.

Although I do not have any WMF's in-house I have examined them on display at the Milan Housewares show. I can share my experience with Fissler - a similarly fancy featured German pressure cooker. I have used over 20 different pressure cooker models and have found that the more complex the mechanisms the more likely there is to be a defect in manufacturing or opportunity for something to go wrong. The fancier they are, the more moving parts there are to break.

I loved the Kuhn Rikon for its simplicity before reviewing it but was absolutely *enthralled* to carefully study each mechanism and discover little touches that make it truly special. For example, using the gasket's own pressure to lock the cooker closed instead of a fancy spring button mechanism. Another advantage that is not talked about much is that the Kuhn Rikon pressure regulator is COMPLETELY metal. All the parts that regulate pressure are metal - except for a piece at the end of the rod that is plastic so as not to burn the cook.

For me, this all-mental valve is important because I use the cookers really hard and have been known to accidentally set one on fire (and yes, the bake-a-lite and silicone pressure regulator on THAT one melted) - BTW don't pressure cook food with liquor on a gas burner.

Another consideration, should be replacement parts. You won't need to replace the gasket and safety valves often, but you WILL need to eventually. If you purchase the WMF pressure cooker designed for Europe get ready to order replacement parts from Germany. Kuhn Rikon has replacement parts on amazon and you can get them next-day delivery.

Finally, cooking time in the pressure cooker is really based on the DENSITY and not heat applied to the food. No matter how others have tried to make it "formulaic" they really can't. It depends on each food and cooking method used (boiling, braising or steaming). For example, I have pressure cooked the same risotto recipe for 7 minutes at 9, 11, 13 and 15 psi and it comes out nearly the same - rice is not very dense. But, instead if I pressure cook soaked chickpeas they can take 20 @ 9psi, 15 minutes @ 13psi and just 13 minutes @ 15psi.

Once you get pressure cooking you'll come to rely on the cooking times listed in YOUR pressure cooker's manual, or I recommend referring to a comprehensive pressure cooking time chart (http://bit.ly/QpPLji).

I hope to have demystified this for you enough for you to feel confident in your final pressure cooker choice.

Ciao,

L

[Anonymous Modernist 310]

Thanks for the information. I'll need to check the KR and it's manual... Seem to work correctly. It even was MC team recommended model!

Have fun with your new toy

Louis-Frederic

[Anonymous Modernist 10022]

Wow, thanx Laura -- extremely extremely valuable post -- and well maintained resource on the pressure cooking that I will certainly visit in the future! Mi piacciono le dieci ricette piu calde, sopratutto blackberry soda :-)!

Thank you all for the fast and precise feedback, it really helped.

Good cooking to everyone,

Ivan

[Anonymous Modernist 10142]

Prego!

Can't wait to read what you're going to do with your new pressure cooker!

Ciao,

L

[Anonymous Modernist 10280]

Of course the hard core MC crowd will lean towards Kuhn, but are there any success stories of someone using any of the common electric pressure cookers (Cuisinart in particular)?

I'm anticipating use mostly for stocks, meats, and beans/grains, where I _think_ precise times are less important (maybe I'm wrong?). I don't anticipate shorter cook time items like veggies, although of course this may change once I actually start using it.

Anyone on this forum able to say anything nice about electric pressure cookers, or are they truly a lost cause in the eyes of the MC crowd?

EDIT: I asked on this thread, even though it wasn't about electrics, due to the first objection to most electrics being a ~10psi maximum pressure.

[Anonymous Modernist 4954]

And, as to Kuhn-Rikon, does anyone have any experience with the differences between the older valve and the new "Top Model" valve? Here is a Modernist Cuisine link that seems to endorse the latter, in contract to the Gear links on this site: http://modernistcuisine.com/recipes/pressure-cooked-vegetable-risotto-2/

[Anonymous Modernist 10142]

Altorg, Ideas In Food actually support the use of electrics - they PREFER them to stove tops. Aki and Alex were even able to get some decent caramelized Roux from one:

http://blog.ideasinfood.com/ideas_in_food/2010/02/roux-in-a-jar.html

Ideas in Food have tons of pressure cooker recipes and techniques. Just type "pressure cooker" in their search box to start the fun.

I personally have an 11.6psi electric and am really enjoying it - but it is far from my primary cooker. Here is an article describing the benefits and drawbacks of stove top vs. electrics - psi isn't the only thing that differs: http://bit.ly/RnbKHb

Richard, I have not personally used TOP, but I can confirm that the valve in that model is the same as the other - it's a spring non-venting valve. The advantage of the "Top" over the "Duromatic" is that the normal release is a bit simpler to do. You can twist the top and release pressure automatically, instead of standing there and pushing a button in the middle of the lid for two minutes.

Ciao,

L

[Anonymous Modernist 310]

Another interesting article about the electric pressure cookers:

http://www.cookingissues.com/2011/08/12/voiding-your-warranty-hacking-electric-pressure-cookers/

[Anonymous Modernist 10280]

Thanks pazzaglia.

And I have seen that link LFMichaud, I'm just hoping not to have to break open the electric and crank it up to an untested value on something that holds 250 degree liquid at pressure.

At this point the durability of a normal stove top model has me leaning that way, as the more I read through MC, the more that browning or finishing things on the stove seem important, and the ability to use normal utensils without worrying about a nonstick surface is also appealing.

My main remaining concern is that I'll have to fiddle with the heat constantly to figure out what stove settings end up with what pressure given what contents, but nobody has really been voicing concern with that anywhere, so I'm guessing it isn't really a problem.

[Anonymous Modernist 10142]

Generally, once you find the "sweet spot" (and it is very narrow spot with the Kuhn Rikon) you'll have a feel how big the flame or what heat setting the pressure cooker needs to maintain pressure and not loose it or over-pressurize. This usually takes a few recipes to figure out - only thing I don't like about stove tops there is a steep learning curve right at the beginning and many people give up and send back the pressure cooker.

In other words, make a few easy recipes with cheap ingredients (ie. potatoes, carrots) until you figure it out. No sense in pressure cooking $50 worth of pine nuts and risk turning them into porrige because you forgot to to turn down the heat once the cooker has reached pressure.

Ciao,

L

[MikeMac]

Exactly on point "Pazzagila"

The pressure cooker at our home has not passed the wife test - she will not use it but the more I use my pressure cooker especially on the induction burner the simpler it gets. And the quality of the end product is first rate.

To me the key is size I think it would be much harder to deal with a a smaller pressure cooker with which you may have to worry a about something boiling up and clogging the valve.

Other than handling a larger device is their any technical reason not to go with a larger pressure cooker even when cooking smaller amounts?

[Anonymous Modernist 10142]

Altorg, have you seen InstantPot? It's an electric pressure cooker with a stainless steel interior - I'm testing one now and like it overall but having mixed results with some of my more advanced pressure cooker recipes (pasta cooked with sauce and risotto) and am working with the manufacturer to figure out what is going on.

Mike, I agree! Both electric and induction and electric cook-tops help in the heat regulation of a pressure cooker. All you need to figure out the right heat setting once, remember the number or wattage of the lowest-heat-possible-to-maintain-pressure and it's easily repeatable time, and time again.

To answer your question, yes an extra-large pressure cooker can affect a pressure cooker recipe two ways:

The first difference of using a larger versus a smaller cooker is the higher the minimum liquid requirement. For example, a 2.5L Kuhn Rikon may only need half a cup of liquid (125ml) to reach pressure, while a 6L needs a little less than a cup (200ml) and an 8L a little more (300ml). European manufacturers don't make pressure cookers any bigger than 10L for the home use but for comparative purposes an AllAmrican Pressure Cooker Canner with the equivalent capacity of 20L states in it's instructions that it needs at least 6 cups (or 2,500ml) of liquid to build pressure.

The minimum liquid requirement is a non-issue if you only plan to boil and steam food in the pressure cooker. But it can make a notable difference if the goal is to braise and roast.

The second difference of using a larger versus smaller cooker is the extra stainless steel that needs to be heated. More stainless steel equals more time to pressure. I measured the time to pressure between the 2.5L and 5L Kuhn Rikon on a gas burner - each with their minimum amount of liquid. On average, the larger pressure cooker took 1 1/2 minutes longer to reach pressure. As the cooker size grows, so will the time needed to reach pressure.

This is "growing" difference between pressure cooker sizes is a non-issue for long-cooking foods, roasts, legumes, ect. But remember, the food is already cooking WHILE the pressure cooker is reaching pressure. So for vegetables or any short-cooking food the extra time to pressure could throw off the timing.

I hope this answers your question about the technical differences between cooking with a smaller vs. larger pressure cooker.

Ciao,

L

[Anonymous Modernist 10142]

P.S. to Mike, you probably already noticed that pressure cooking on induction comes with a new set of "problems" - the cookers reach pressure so quickly on induction that almost none of that "cooking while coming up to pressure" is taking place. So, following a "traditional" cooking time (written for a pressure cooker on gas or electric) will result in under-cooked food.

I don't want to turn this into a link-to-me-fest. But I wrote an article about the timing adjustments that need to be made according to cook top. In brief: 2-3 minutes extra need to be added to the pressure cooking time to compensate.

[Anonymous Modernist 310]

Thanks Laura,

That probably explain why my Risotto was a little bit too "Al dente".

Louis-Frederic

[Anonymous Modernist 15362]

I know it's an old thread, but...

I was researching both KR and WMF, and I'm honestly curious where the lower psi numbers for WMF came from. The WMF manual doesn't agree with the numbers quoted in this and other threads.

See here: http://www.wmf.com/fileadmin/user_upload/wmf-uk/BAL_PerfectPlus_0711_alle_Sprachen.pdf

The WMF has an "operating pressure" of 95 kPa, or 13.8 psi.

The "regulating pressure" is 130 kPa, or 18.85 psi

The "maximum pressure" is 150 kPa, or 21.75 psi.

I'm genuinely curious why there is a common assertion that WMF has low pressure. As far as I can tell, the pressures of the WMF are the same or greater than KR.

In any case, I ordered a WMF because reviews suggest it's easier to clean, heats evenly, and a quick check of Amazon has more available parts compared to KR.

[Anonymous Modernist 11719]

The current issue of Cooks Illustrated (Jan/Feb 2013)has a good review of pressure cookers that is a worthwhile video and read:

video: http://www.cooksillustrated.com/video/default.asp?newVideo=y&docid=41668

Review: http://www.cooksillustrated.com/equipment/overview.asp?docid=41600

I have a Kuhn Rikon 5 liter and it's a little small. The bigger the better! I have also had some scorching on the corners of the bottom since the heating disc does not go to the edge as noted in the Review. It's not a major problem and may be technique related.

Tom

[Anonymous Modernist 10142]

QUOTE FROM BBUKLEY "See here: http://www.wmf.com/fileadmin/u…..rachen.pdf

The WMF has an "operating pressure" of 95 kPa, or 13.8 psi.

The "regulating pressure" is 130 kPa, or 18.85 psi

The "maximum pressure" is 150 kPa, or 21.75 psi.

I'm genuinely curious why there is a common assertion that WMF has low pressure. As far as I can tell, the pressures of the WMF are the same or greater than KR."

The number you want to look at is "operating pressure" - that is the pressure at which the WMF cooker actually cooks. The other numbers are all about when the the safety systems kick-in and the durability of the base.

I just (this week) got a WMF in-house, and even their American rep told me it cooks at 13psi. After having used it just a couple of times, I would confidently round WMF's 13.8 up to 14. I haven't done my tell-tale chickpeas, yet, but potatoes were ready in just 10 minutes - not 15 like my Euro 13psi Fissler. It will likely be the next pressure cooker I review, so stay tuned!

BTW, 15psi cookers are not really 15psi - they are 1 bar (100kpa) which is actually 14.5psi. Manufacturers round it up to 15.

Ciao,

L

[Anonymous Modernist 15362]

Thanks for both of the replies.

The Cook's Illustrated article is a great reference for temperatures, and it confirms that the pressure is not lower in the WMF. The KR topped out at 140 degrees, whereas the WMF went to 147. I wouldn't be surprised if that difference is within the normal variance between two units from the same manufacturer. The operating pressures quoted in the manuals are the same.

It's good to hear that cooking times with the WMF were shorter than the Fissler. Although in the end I'm sure they are all quality units and I'd be happy with any of them.

[Anonymous Modernist 310]

The only thing that I don't understand is the 5.6oz venting of the KR. I have no idea how they used it to get that results! I had no scorching problems at the bottom but I'm using it over induction not gas.

[Anonymous Modernist 10142]

Having measured the KuhnRikon evaporation myself using a gas range, I am certain that Cooks Illustrated measured it while it was in over-pressure. This cooker needs VERY LITTLE heat compared to say.. a Fagor. So I imagine they used the same heat setting causing it to continuously vent (thusly evaporating).

I would take the temperature readings with a grain of salt. It's obvious that the testers didn't know how to operate the pressure cookers. The Magefesa, for example is photographed with the valve in the incorrect position (which would explain why it "couldn't" maintain pressure) so taking measurements in conditions that are not ideal would give you junk results.

I have used 5 of the 8 cookers listed - 6 if you count the Euro Vitaquick (which appears to be re-disgned for US) and thoroughly reviewed 2 of them.

Can't say that I agree with ANY America's Test kitchen's pressure cooker review conclusions. Here are more of my thoughts on their review previously posted in another forum...

"Unlike the ATK reviewers, I haven't had any issues with "bulging cookers". I absolutely love the "beer belly" on the Fagor Futuro which accommodates larger cuts of meat without having to go to the expense of getting a pressure braiser (though those are REALLY nice, and REALLY wide!) - no scorching, though I haven't made a crepe in it like ATK testers.

I had the most trouble with their "highly recommended" model - the Fagor Duo. It works great, but it's tricky to lock the lid shut and to tell when it has really reached pressure - it's prone to false positives which in turn alerts the cook to turn down the heat too soon.

Unfortunately, I cannot comment on their highly recommended model Vitaquick - I only have their Euro model and could never get it to work properly. I reviewed the big- sister the Vitavit and it broke during the review process (it was great while it lasted - except for the laser-beam three-directional pressure release). On the bright side, the US Vitaquick appears to have substantial changes from the Euro model - and if it's anything like the US Blue point (their previous US model) then I expect that it performed quite well."

Ciao,

L

[Anonymous Modernist 10142]

P.S. I'm not the first to say this, and probably won't be the last, but something about those reviews just doesn't "smell" right.