PedroG

Greisinger GTH 175/Pt - WPT2 Model: GTH 175/Pt - WPT2 Manufacturer: Greisinger electronic GmbH, Germany URL: www.greisinger.de/index.php?language=en&task=2&wg=27&artikel=543#107785 Price ca. USD: 158 Resolution: 0.1° Accuracy: ±0.1°C at 55°C Probe type: Pt1000 insertion, fixed cable Min/max function: yes Comments: The same as Greisinger GTH 175/Pt, but with certified 2-point calibration 0°C/70°C. So far best price tag for ±0.1°C accuracy with calibration certificate. Beware not to destroy calibration by turning the trim-pot!!

A triple layer of bubble wrap will do the job to insulate the bottom and sides of a pot, see a post on FreshMealsSolutions' customer forum. Equally important is an adequate cover to avoid evaporation, see my post in the old SV topic. During a 48h-cooking without a cover you may easily evaporate 5 liters. Ping pong balls or styrofoam spheres would theoretically cover pi/(6*tg(30°))= 91% of the water surface, if they were exactly half immersed, but in practice they float higher. An alternative is a styrofoam cover fitting exactly into the pot and floating on the water, but in my experience it gets thinner and thinner with time (maybe due to the temperature changes expanding and contracting the included air), so I let the styrofoam cover ride on ping pong balls to separate it from the water. Whenever possible it is best to use the snugly fitting original lid of your pot, eventually cutting out a thumb-thick notch to accommodate the stem of the FMM. Be aware that perfect PID tuning of a very well insulated pot may be trickier as there is less heat loss counteracting overshoot.

I agree. If you like the egg white rubbery, reheat in boiling water, if you prefer a firm gel, keep water temperature below 84.5°C/184°F to prevent ovalbumin from denaturing.

Herr Newton beneathen der tree bin gesprawlen mit watchen ein smallisher appel gefallen. Ach himmel! Herr Newton been overexciten and soonish abouten der appel bin writen. Der lesson: Meinself is not thinken der fallen surprisen comparen mit iffen der appel bin risen. By Dave Morrah, Saturday Evening Post The article Culinary Biophysics: on the Nature of the 6X°C Egg is very interesting. I am not so much surprised that time does matter, as temperature describes the average kinetic energy level of the molecules, so even at a temperature below the threshold energy level of a reaction, there is a percentage of molecules at a higher kinetic energy level exceeding the threshold and thus undergoing the reaction. This is in accordance with the experience that a steak cooked sous vide to medium rare may be held at the final temperature for some time, but if holding time is extended too much, texture will change noticeably and liquid loss will increase. The problem of the egg white not setting at temperatures yielding a soft egg yolk is not satisfactorily addressed in the Khymos articles, but has been solved by Douglas Baldwin in his post Science: Cooking Eggs in Their Shells, continued in a later post. Later he posted a new egg heating time table which is my preferred reference now (direct link to In-Shell Egg Heating Times in a 75°C Water Bath Using Circumference). Cooking a perfect "perfect egg" in a quarter of an hour at 75°C to me is definitely more practical than cooking for a much longer time at 6X°C and then setting the egg white by a short dip in a hotter bath. See also the section on cooking eggs in the sous vide page in wikiGullet.

Greisinger GTH 175/Pt - K Model: GTH 175/Pt - K Manufacturer: Greisinger electronic GmbH, Germany URL: www.greisinger.de/index.php?language=en&task=2&wg=27&artikel=39#100410 Price ca. USD: 93 Resolution: 0.1° Accuracy: ±0.25°C at 55°C Probe type: Pt1000 insertion, fixed cable and handle heat resistant up to 250°C/480°F. Min/max function: yes Comments: The same as Greisinger GTH 175/Pt, but with Teflon handle and Teflon cable which are both temperature resistant up to 250°C/480°F, and the probe is insertable, allowing e.g. core temperature measurement in an oven or in a BBQ grill/smoker. Greisinger is delivering worldwide (except crisis regions like Iran, Irak, Libya etc.). To see price info on the Greisinger website, registration/login is necessary.

This may work, but for repeated visualization you have to add another few drops of ink again and again until the water gets too dark. I tried various corpuscles to continuously visualize convection currents: plastic snippets, short threads of cotton or Nylon, grains and seeds, all were either too heavy or too light; finally, with ground quinoa I succeeded, although it was not floating in perfect equilibrium. I used my FreshMealsMagic (2000W) in its transparent polycarbonate container without bubbling. While heating at full power, natural convection current was easily visible, but during steady state at 55°C (heating at about 110W), no significant convection current was visible. I turned the bubbler on for a few seconds to show the quinoa corpuscles moving; after stopping the bubbler movement subsided. My suspicion is that if 110W does not induce significant convection current, in a well insulated rice cooker or stock pot with a heat loss of less than 50W, there will be even less, i.e. practically no convection current. The videos are now on Youtube (in my earlier post of 10 July 2010 they were on www.mydrive.ch which requested login). On the other hand, steady-state heating will require much less fluid velocity in order to maintain the "same" uniformity. Yes, for a water bath without adding cold food. Forced circulation does make a difference in surface heat transfer coefficient, as Douglas Baldwin posted upthread. And poor circulation increases thermal inertia of the system, which would call for different PID settings. My SVM/FMM usually is stable ±0.04°C during LTLT cooking. One day stability had deteriorated to ±0.1°C or even worse, until I noticed that the silicon tube of the bubbler was kinked (at first I did not notice the missing bubbling, as the bubble wrap insulating the polycarbonate container obstructs vision).

Visualizing convection currents This may work, but for repeated visualization you have to add another few drops of ink again and again until the water gets too dark. I tried various corpuscles to continuously visualize convection currents: plastic snippets, short threads of cotton or Nylon, grains and seeds, all were either too heavy or too light; finally, with ground quinoa I succeeded, although it was not floating in perfect equilibrium. I used my FreshMealsMagic (2000W) in its transparent polycarbonate container without bubbling. While heating at full power, natural convection current was easily visible, but during steady state at 55°C (heating at about 110W), no significant convection current was visible. I turned the bubbler on for a few seconds to show the quinoa corpuscles moving; after stopping the bubbler movement subsided. My suspicion is that if 110W does not induce significant convection current, in a well insulated rice cooker or stock pot with a heat loss of less than 50W, there will be even less, i.e. practically no convection current. The videos are now on Youtube (in my earlier post of 10 July 2010 they were on www.mydrive.ch which requested login).

Greisinger GTH 175Pt Model: GTH 175Pt Manufacturer: Greisinger electronic GmbH, Germany URL: /www.greisinger.de/index.php?language=en&task=2&wg=27&artikel=37#100390 Price ca. USD: 77 Resolution: 0.1° Accuracy: ±0.25°C at 55°C Probe type: Pt1000 immersion, fixed cable Min/max function: yes Comments: This would have been my reference thermometer if I had not decided to opt for the GMH 3710 with 0.01°C resolution allowing more sophisticated PID-tuning experiments. Calibration can be adjusted with trim-pot.

Here is a template for convenience: click the quote button, then delete the (quote) including this line and the end (/quote). Title Model: Manufacturer: URL: Price ca. USD: Resolution: Accuracy: ± Probe type: Min/max function: yes/no Comments:

Cyclotest Lady Digital thermometer for cycle control Model: ®Cyclotest Lady Manufacturer: UEBE Medical GmbH, Germany URL: www.cyclotest.de/fileadmin/downloads/7_0620_001_A_01.pdf Price ca.: from € 9 to CHF 30 (may eventually not be easily available in the Fahrenheit world) Resolution: 0.01°C Accuracy: ±0.10°C between 35.50°C and 42.00°C Probe type: maximum thermometer Min/max function: no Comments: This was my first reference thermometer before I bought the Greisinger GMH 3710 high precision thermometer. Calibration against the GMH 3710 gave the following results: offset at 33.11°C -0.06°C, at 36.02°C -0.03°C, at 38.72°C -0.02°C, at 41.88°C +0.01°C, i.e. accuracy well within specification. Inexpensive digital fever thermometers are not automatically inaccurate, but extrapolation from calibration at 37°C to 55°C may be inaccurate, as I have pointed out in my Wikia article on thermometer calibration. A digital fever thermometer with 0.01°C resolution may be a backup: calibrate against your reference thermometer, and check e.g. every two months. Should there be change of 0.1°C or more, recalibration of the reference thermometer may be due.

Loose whites are a problem when cooking eggs at target temperature. See the scientific background in Douglas Baldwin's post. The solution is Delta-T-cooking, see the sous vide page in wikiGullet and the topic "all about sous vide eggs". Be aware that an unnoticed crack in an egg can mess up your SV rig, so I would not recommend cooking eggs in a FreshMealsMagic or an immersion circulator, but rather in a PID-controlled rice cooker or stock pot or in a SVS, all of which are easier to clean.

If you do not plan long time cooking, you may well start sous vide with a water pot in the oven, see post #3540 and #3541 in the old sous vide topic. The larger the water volume, the easier to keep temperature stable. If heating hot tap water to 85°C takes too long, preheat on the stove top or with a bucket heater.

Greisinger GMH 3710 high precision thermometer Model: GMH 3710 Manufacturer: Greisinger electronic GmbH, Germany URL: http://www.greisinger.de/index.php?language=en&task=2&wg=26&artikel=653#112100 Price ca. USD: 370 (incl. GTF 401 1/10 DIN Immersion probe Pt100 for gases and liquids and and 2-point-calibration 0°C/70°C) Resolution: 0.01°C/F Accuracy: ±0.03°C Probe type: Pt100 1/10 DIN Immersion probe with cable and handle Comments: my GMH 3710 has been in the water for over two years without any problem. Initial calibration stated deviation -0.05°C at -18.00°C, +0.01°C at 5.01°C and +0.05°C at 65.08°C. Recalibration after one year stated +0.004°C at 5.06°C and +0.017°C at 65.15°C. (Calibration was not done at the factory, but at the testo™ calibration lab located near my home). If I had known there was the GMH 3750 with data logging capability, I would have ordered this one, but www.conrad.ch did not offer it.

I started a new topic Reference thermometers and thermometer calibration methods for sous vide for presentation and discussion of reference thermometers to be included in the wikiGullet market overview Reference thermometer. Please contribute your recommendation and experience! As it would be best to have a calibrated reference thermometer instead of trying to calibrate at 0°C/37°C/100°C, I started compiling a market overview of precision thermometers in wikiGullet. Please contribute your experiences and criticisms and ideas.

Here is the place to present your reference thermometer you use to calibrate your sous vide equipment. Your description should include model and manufacturer, URL to the manufacturer's website (if possible, deep link to the model), price in USD (ca.), resolution, accuracy, probe type, your comments and experiences (e.g. result of repeat calibrations, cost of recalibration). After eventual discussion ("peer review"), the thermometer model may be included in the market overview in the wikiGullet article Reference thermometer.

If you do that once-in-a-life-time bathtub long duration sous vide, how about pouring vegetable oil on the water to prevent evaporation? You can recover all the oil later. dcarch I'm thinking it'll still bubble through. How about covering the surface with plastic film (not wrap)? Bubble wrap would float and insulate to some degree and avoid evaporation.

Steady state consumption in the bath tub at 55°C was about 1060W, with Frank's 120L SS pot steady state consumption at 85°C (!) was only about 125W according to heating slope and cooling slope data Frank reported. Insulation and prevention of evaporation are the key. Who will report the data with a 100-quart cooler?

Hi Kerry, when you pull the real big things out of your freezer, you might need a 100-quart cooler, or you can even heat your bath tub with your FMM. Have fun!

When you use a bubbler, use the airstone as a weight only and cut a lateral hole in the silicone tube. This produces larger bubbles that rise faster resulting in more vigorous circulation, and thanks to the reduced surface relative to volume they carry away less heat and water vapor. In my experience a bubbler works equally well as a pump, and it can be used at temperatures above 58°C where many pumps fail. No forced circulation at all definitely results in poor temperature stability. Natural convection occurs during ramping up at full power but becomes almost nul at steady state, see http://egullet.org/p1750074 .

Thermometer calibration As it would be best to have a calibrated reference thermometer instead of trying to calibrate at 0°C/37°C/100°C, I started compiling a market overview of precision thermometers in wikiGullet. Please contribute your experiences and criticisms and ideas.

I don't generally store water in the tank when it's not in use, so changing the water wouldn't help. The tap water here is very hard (25 gpg or ~430 ppm), but softened with an ion exchange unit. If this is galvanic corrosion then wouldn't the stainless food rack be involved? It's been my impression that the worst spots on the grill are from where it is in contact with the rack, but it could be my imagination. Does your ion exchange unit exchange only cations (Na+ for Ca++ and Mg++) or also anions? In the latter case, chloride ions may cause corrosion of aluminium.

Follow-up: I recently calibrated the sensor using boiling water (I figure, as a standard, it's closer to cooking temps than ice water is), and my sensor was under-reading by about 2.3F. Huge deal? Maybe. I'll have to do more to see. Inaccuracy of 2.3°F/1.3°C is not quite what we desire. If you do not have an ISO- or NIST-calibrated reference thermometer, you might calibrate your sensor or thermometer in ice-water (no need for distilled water, tap water will do, molecular freezing point depression in tap water is neglectable for our purposes) and in boiling water (taking into account altitude above sea level and barometric pressure; a difference of 40 mBar makes a 1°C difference) and against an ovulation thermometer at 100°F/37.8°C. With temperature stability of ±0.1°C in a PID-controlled water bath (SousVideMagic or immersion circulator) inaccuracy of more than 0.2°C is absurd. See the Wikia article Importance of temperature control on pasteurizing times (0.5°C inaccuracy makes a significant difference in pasteurizing times) and the Wikia article on thermometer calibration: sensors and thermometers are not guaranteed to be linear and equally accurate over the whole range from 0°C to 100°C; 50k thermistors (SVM 1500C and 1500D) are better than 5k thermistors (SVM or Auber 1500A and 1500B). See also the sous vide page in wikiGullet (the sum of accuracy and stability should be ±0.25°C or better for long-time cooking and pasteurizing).

See Harold McGee, On Food and Cooking, p. 152: at 145-155°F (Medium-well) "Pink fades to gray-brown". Nathan Myhrvold in Modernist Cuisine, p. 3•86 and 3•234, recommends 52-56°C (126-133°F) for hamburgers. How accurate (accuracy, not resolution of the display!) is your temperature control? Is your reference thermometer NIST-calibrated? Some SV-rigs have been reported to be several degrees off ex factory. How long was your SV-cooking time? Post-searing method/temperature/time?

When you convert a traditional stew to sous vide, the sauce will lack the taste that comes from searing the meat. A workaround is sacrificing a small portion of the meat to give flavor to the sauce by grinding and searing, the rest of the meat may be cooked sous vide LTLT. I did this method with Ossobuco sous vide.

By "Sous Vide Mini" did you mean "SousVideMagic" (SVM) mentioned upthread?