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How exact are Cvap ovens?


Rasmus
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actually they might do reasonably well. 

a fluctuation of +/-5C in _air_ would produce a steady state internal temp of whatever is being held.

 

given the the mass of water typically used in sous vide, to "fluctuate" +/-5C over a short term/cycle like an air oven does requires a high capacity heat/cool apparatus.  water conducts heat much better than air.

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7 hours ago, AlaMoi said:

actually they might do reasonably well. 

a fluctuation of +/-5C in _air_ would produce a steady state internal temp of whatever is being held.

 

given the the mass of water typically used in sous vide, to "fluctuate" +/-5C over a short term/cycle like an air oven does requires a high capacity heat/cool apparatus.  water conducts heat much better than air.

Wouldn't +/- 5C mean that you can't reliably cook say a ribeye medium rare (~54C)? It seems like it could end up being rare or medium instead, whereas sous vide would always be exact...

 

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1 hour ago, JoNorvelleWalker said:

I'm waiting to see the specs on the anova oven.

 

Do you think they will let you steam at low temperatures (i.e. below 100C) for sous vide? I think Electrolux had an oven like that before, but I don't know how well it worked.

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5 minutes ago, Rasmus said:

Do you think they will let you steam at low temperatures (i.e. below 100C) for sous vide? I think Electrolux had an oven like that before, but I don't know how well it worked.

 

Hope springs eternal.  We should know in another month or two.  As it is the CSO (Cuisinart Steam Oven), which many of us know and love,  works as low as 100F/38C.

 

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Just now, JoNorvelleWalker said:

 

Hope springs eternal.  We should know in another month or two.  As it is the CSO (Cuisinart Steam Oven), which many of us know and love,  works as low as 100F/38C.

 

How precise is the Cuisinart? Can you use it instead of sous vide, for say meat?

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58 minutes ago, Rasmus said:

How precise is the Cuisinart? Can you use it instead of sous vide, for say meat?

 

You might, but considering I have an anova circulator, I don't.  I've not tried to measure the temperature inside the CSO because the door gasket forms a tight seal and I've not yet been able to afford the requisite temperature measuring technology.

 

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2 minutes ago, JoNorvelleWalker said:

 

You might, but considering I have an anova circulator, I don't.  I've not tried to measure the temperature inside the CSO because the door gasket forms a tight seal and I've not yet been able to afford the requisite temperature measuring technology.

 

Did you manage to slow cook food in it though? E.g. can you cook a steak to medium rare?

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2 minutes ago, Rasmus said:

Did you manage to slow cook food in it though? E.g. can you cook a steak to medium rare?

 

Sorry, I never tried.  Though I just cooked a lovely dry aged ribeye to rare/medium rare on my Philips grill.  My mouth tastes so good I'd like to eat my tongue.

 

Hang on and wait for a month to see what the anova steam oven has to offer.

 

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1 hour ago, JoNorvelleWalker said:

 

Sorry, I never tried.  Though I just cooked a lovely dry aged ribeye to rare/medium rare on my Philips grill.  My mouth tastes so good I'd like to eat my tongue.

 

Hang on and wait for a month to see what the anova steam oven has to offer.

 

Ok, thanks... My company is developing a precision steamer, so that's why I am curious what else is out there. It's a bit challenging but not THAT hard so I wonder why the current steamers aren't better.

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10 hours ago, Rasmus said:

Wouldn't +/- 5C mean that you can't reliably cook say a ribeye medium rare (~54C)? It seems like it could end up being rare or medium instead, whereas sous vide would always be exact...

 

that's the air temperature.  all ovens fluctuate like that - and the fluctuation is a fairly rapid cycle.  with the result that the meat - except for the 0.01mm top surface - sees an "average" temperature.

the real question is whether the oven thermostat (a) is really accurate - most are not and (b) will hold that +/-5C' at low temps.

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10 hours ago, Rasmus said:

Ok, thanks... My company is developing a precision steamer, so that's why I am curious what else is out there. It's a bit challenging but not THAT hard so I wonder why the current steamers aren't better.

 

If your product is for home use, two thoughts:  make the chamber wide and deep enough to accommodate at least a quarter sheet pan; make the chamber high enough to accommodate baking at least a kg boule.

 

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It depends on the means of control.

A thermostat (bi metal strip or capillary type) will have a hysteresis so it turns on at one temperature (usually the set temperature) then turns off a few degrees higher. This turns the full heating element on fully. That is why they typically specify them at +-5 degrees

A thermistor type with electronic control will use a PID controller and the controller "creeps up" on the set temperature, reducing the heating as it approaches the set temperature. The PID part usually learns the characteristics of the appliance and will maintain the temperature very closely to its set temperate. (+- 0.1 degrees)

 

Having said that, air is not a good conductor of heat so it would be better to heat a finned block of metal or ceramic and blow air across it. The PID controller would be able to perform better, particularly if the set temperature was for the air but from that the temperature of the block is set by some sort of lookup table or learned behavior.

 

I imagine you could use the device like a SV but bear in mind the heat transfer to the food is MUCH better in water than air (even in the vacuum bag) and you would still need to bag it to prevent drying out.

 

At temperature below boiling point you could generate steam continuously but it would condense on the food and so the food would probably need to be bagged so the steam advantage (to keep moist) is negated)

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11 hours ago, JoNorvelleWalker said:

 

If your product is for home use, two thoughts:  make the chamber wide and deep enough to accommodate at least a quarter sheet pan; make the chamber high enough to accommodate baking at least a kg boule.

 

We currently base the width and depth on the Gastronome standard, specifically GN 1/2. It's fairly shallow, but the main reason is to serve small households, and the small size means faster and better control. The height shouldn't be a problem though.

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3 hours ago, gfweb said:

Can you really steam at less than 100C? Wouldn't it just condense?

It works. The product my company works with blows in short clouds of steam. The temperature peaks briefly, but it's pretty accurate. The lab tests has the temperature vary around 2C.

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1 hour ago, Rasmus said:

We currently base the width and depth on the Gastronome standard, specifically GN 1/2. It's fairly shallow, but the main reason is to serve small households, and the small size means faster and better control. The height shouldn't be a problem though.

 

Google didn't help me with GN 1/2.  I strongly suggest you fit at least a quarter sheet pan if you want to interest folks here.  Or unless the price is significantly less than the price of the CSO.

 

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38 minutes ago, JoNorvelleWalker said:

 

Google didn't help me with GN 1/2.  I strongly suggest you fit at least a quarter sheet pan if you want to interest folks here.  Or unless the price is significantly less than the price of the CSO.

 

GN 1/2 is 325 × 265 mm, whereas quarter pan is 460x330, so it's smaller. But the target customer are small households where this machine replaces their microwave. But in the future we may make a version of the home chef.

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5 minutes ago, Rasmus said:

GN 1/2 is 325 × 265 mm, whereas quarter pan is 460x330, so it's smaller. But the target customer are small households where this machine replaces their microwave. But in the future we may make a version of the home chef.

 

According to Wikipedia a quarter sheet pan is 9 by 13 inches, 23 by 33 cm.

https://en.wikipedia.org/wiki/Sheet_pan

 

Not everyone has a microwave.

 

 

 

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Oh, then it's large enough.

The machine we build is for people who don't have time to cook, so they either order in or use a microwave to heat up food. But microwaves are of course terrible for almost all types of cooking. With precise steam, functioning at low temperatures, we hope that people even with limited cooking skills can succeed with cooking protein, e.g. a steak. Sous vide is way too much of a hassle for this group.

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11 hours ago, Bernie said:

It depends on the means of control.

A thermostat (bi metal strip or capillary type) will have a hysteresis so it turns on at one temperature (usually the set temperature) then turns off a few degrees higher. This turns the full heating element on fully. That is why they typically specify them at +-5 degrees

A thermistor type with electronic control will use a PID controller and the controller "creeps up" on the set temperature, reducing the heating as it approaches the set temperature. The PID part usually learns the characteristics of the appliance and will maintain the temperature very closely to its set temperate. (+- 0.1 degrees)

 

Having said that, air is not a good conductor of heat so it would be better to heat a finned block of metal or ceramic and blow air across it. The PID controller would be able to perform better, particularly if the set temperature was for the air but from that the temperature of the block is set by some sort of lookup table or learned behavior.

 

I imagine you could use the device like a SV but bear in mind the heat transfer to the food is MUCH better in water than air (even in the vacuum bag) and you would still need to bag it to prevent drying out.

 

At temperature below boiling point you could generate steam continuously but it would condense on the food and so the food would probably need to be bagged so the steam advantage (to keep moist) is negated)

Right, but I meant that Cvap specifically which keeps 100% humidity throughout the cooking cycle, but manages to do so at a lower temperature. The question then is how it can be used for slow cooking say a steak when it isn't more precise than +/-5C... It seems to not be precise enough. Even if the average temperature would be say 54C, it still will spend a good deal of time at 57-58C, which seems like it would make the steak medium instead of medium rare...

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50 minutes ago, Rasmus said:

Right, but I meant that Cvap specifically which keeps 100% humidity throughout the cooking cycle, but manages to do so at a lower temperature. The question then is how it can be used for slow cooking say a steak when it isn't more precise than +/-5C... It seems to not be precise enough. Even if the average temperature would be say 54C, it still will spend a good deal of time at 57-58C, which seems like it would make the steak medium instead of medium rare...

 

True, but compared to how your target customer cooks a steak, this 2 degree variance is probably an improvement.

 

I question whether the microwave addict would see  the need for this unit.  They are almost the definition of a non-cook, contentedly unaware of all that goes into cooking. The Instant Pot hit that demographic; I'm not sure that this does. Perhaps with serious marketing.

 

Does your company have an opinion on why Cuisinart seems to be backing away from the steam oven?

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Yes, 2C should be fine, but 5 seems like it would mean a different cooked steak.

The microwave crowd typically order in food, so we here think that a well working and automated oven can help them succeed with cooking themselves.

I didn't know about Cuisinart backing away from steam ovens. It seems a bit strange, given how much the Asian market is growing and it is a popular appliance there. It's typically a combo oven with steam and microwave, so this is where we want to compete.

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11 minutes ago, Rasmus said:

 

I didn't know about Cuisinart backing away from steam ovens. 

That’s been the conjecture here. Their website has listed it as discontinued. Perhaps they are planning one with a microwave that will fit a 1/4 sheet pan!

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