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Showing posts with label Cooking. Show all posts
Showing posts with label Cooking. Show all posts

Craftsy.com Thai Cooking Essentials Lesson Giveaway

11:49 AM Posted by Rhoda , , , ,

I am partnering with Craftsy.com to give away Thai Cooking Essentials with Robert Danhi. There will be three (3) winners whom will receive one (1) Thai Cooking Essentials with Robert Danhi. The suggested retail price of the Thai Cooking Essentials with Robert Danhi is US$39.99.

Discover how to recreate Thai cuisine’s signature blend of spicy, sweet, sour and savory in 10 favorite dishes. Guided by Thai food expert Robert Danhi, learn essential techniques like how to use a mortar and pestle to turn chili peppers, fish sauce and tamarind into three homemade chili sauces — plus, make two fun, flavor-packed appetizers. Perfect the popular green papaya salad and cook a rich and flavorful tom yum goong soup with stock made from shrimp shells. Prepare a classic red curry paste to simmer with chicken, coconut milk and lime, and easily create the international phenomenon pad Thai. Learn the techniques to bring the incredible flavors of Thailand home any time you desire!

Eligibility: Worldwide. No purchase necessary and subject to this official giveaway rules. Closing Date: April 13, 2014, 11:59 pm PST. Winners will be randomly selected and contacted via email on April 15, 2014. The prize is proudly sponsored by Craftsy.com. To enter, please follow the steps below.



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Sous Vide: Sous Vide Cooking at Home Setup Guide

11:37 PM Posted by Rhoda , ,
Have an analytical mind? Like to cook? This is the site to read!

This article covers a variety of different ways to put together a sous vide cooking station at home. For some people, all the equipment they need for some of the simpler configurations will be in their homes already enabling them to try out sous vide cooking at little or no additional cost. For others, one or two extra components will be all that is needed to get started. My hope is that, through this article, I'll provide enough information to both lower the barrier to entry for sous vide cooking at home and to provide reasonable upgrade paths for those wishing to increase the precision and flexibility of their sous vide setup.

To make this guide easier to read and digest, I've divided the components needed for sous vide cooking into two main sections. The first I'll cover is the temperature controlled water bath. The second is the vacuum sealer. As described in the Introduction to Sous Vide article, sealing ingredients in plastic bags with minimal air and cooking the food-filled bags in temperature controlled water is a relatively new, but versatile cooking technique. Like all cooking techniques, it is not the perfect cooking method for all types of foods, but, when used in the correct situations, produces food with taste and texture superior to more traditional techniques, can be very convenient, and can make food safer to consume for the immune compromised (depending on how sous vide cooking is employed).

A future article will cover more information on food safety when cooking sous vide, but I'll make a few notes here and there in this article where appropriate.

My Favorite Setups for the Home
Before I begin, I'll describe my two favorite sous vide setups for the home. For bagging, I either vacuum seal the ingredients with a FoodSaver or, for meats of uniform shape cooked a relatively short time (such as one hour to two hours), a quart or gallon sized Ziploc-brand Freezer bag (which random people on the internet claim is safe for use up to 90.5°C (195°F); a few calls to S.C. Johnson & Son, Inc. did not shed any light on the situation - more at the bottom of the article on this). In most cases, you only need the plastic bag to hug the food tightly so the water bath can have maximum contact with the surface it is trying to heat, so the vacuum is not as important. Odd shaped items (like chicken wings) benefit greatly from the shrink wrap effect of vacuum sealing, so for those foods (as well as foods that need to be cooked at 82-85°C (180-185°F) such as root vegetables) I recommend using a vacuum sealer with simmer proof bags. For my water baths, I use a Panasonic SR-42HZP 23-cup (46-cup cooked) rice cooker with an Auber Instruments PID Controller and thermocouple. When cooking a large quantity of food, I use a PolyScience Sous Vide Professional Immersion Circulator in a 25 L polycarbonate tub with a couple of 1/4 hotel pan lids to reduce water loss from evaporation. For small quantities of food, I have not found the lack of circulation to be a problem given a volume of water much greater than the food being heated. (The natural convection currents seem to be enough to keep an even temperature in most cooking vessels so long as the bag of food does not cover the entire area of a cross-section, thus dividing the volume into two separate portions.) In addition to these components, I keep a Thermapen on hand to double check water temperature in case of thermocouple failure or miscalibrated temperature controllers. (Many thermometers can be off by a couple degrees, so I strongly recommend a highly accurate thermometer that is factory calibrated to a standard and can be recalibrated later if necessary. The difference between a few C° might not be noticeable on some ingredients, but on others, like eggs, can have drastic effects to texture.)

Temperature Controlled Water Bath
Of the two main components, the water bath is the more complicated (and has the most options... or the most opportunities to be creative), so I'll cover it first.

I tried to break the various ways to put together a temperature controlled water bath into a few "categories" which I then attempted to rank starting from potentially lowest cost to highest cost. More or less, this also roughly translated to least effective to most effective systems. For these categories I tried to price out a complete "lowest cost" solution as well as a "mid-cost" solution. I left out "high cost" since the sky is pretty much the limit (for example, the categories involving a pot could use a $500 copper cauldron if you wanted). All prices quoted are for new components, rounded for readability, and current at the time of the initial publication of this article. Used equipment may be available at lower cost, but remember that anything not intended or not previously used for food preparation should be thoroughly sterilized. (For example, used laboratory equipment like an immersion circulator might not be clean and may have been used in research that may prove dangerous to the health. Boiling is often not enough to sterilize in such cases and a full regimen of water boiling, vinegar bath, bleach solution bath, alcohol bath, and second water boiling should probably be employed.)

I also left out any sous vide setups that required disassembling components or involved any steps that required technical expertise significantly outside the scope of this article (like soldering, cutting wires, or even sawing). One could argue that this decision makes this guide less than complete, but given the number of options and length of this guide, I believe most readers will forgive me.

In many of the earlier examples, I include the cost of a $20 probe thermometer such as the Polder 362-90, but if you already have a thermometer (even a non-probe model) that works in the range of 49-88°C (120-190°F), then you can use that to check the temperature of the water bath instead.

I also include the use of a $12 silicone steamer such as the Chef'n Sleekstor VeggiSteam which can be used to keep the plastic bags from resting on the bottom of the pot or cooking device. This silicone steamer measures 215 mm (8-1/2 in) in diameter and fits most pots nicely, but any steamer insert or rack that fits the pot or device and elevates the bags of food should work well. In many cooking applications, leaving out the steamer insert does not make a noticable difference so long as the temperature of the water is well controlled (such as in the rice cooker with PID controller setup).

Large Pot in Warm Oven
Heat Source (during cooking): Oven
Heat Adjustment: Manual
Lowest cost: $33
Mid-cost: $60

Method: The key elements in this method is the size of the pot (amount of water), the thickness of the pot (a big heavy cast iron pot would be ideal because it heats up and cools down slowly due to its mass), and how low the temperature controls of your oven go down to.

Preheat the oven to the lowest temperature above the target temperature which will be the lowest temperature setting in most cases (the lowest setting on my oven is 77°C (170°F)). Fill the 3/4 of your pot with hot water and warm it on the stove to the target temperature. Clip the probe (I use a binder clip for this purpose) of the probe thermometer to the side of the pot with the probe tip submerged in the water. Be careful not to get the junction between the cable and the probe wet (most low cost probe thermometers do not have sealed junctions between the probe and the cable and getting them wet is the most common way of damaging them). Place the food in the water, cover the pot as best as you can (the thermometer probe may get in the way a little), and put the whole thing in the oven on a rack set near the bottom. Over time, the water temperature should rise above the target temperature due to the oven being warmer than the target. At that point, turn off the oven and wait until the temperature drops back to the target temperature. Turn the oven back on at this point and repeat for the duration of the cooking time.

Having a probe thermometer is very useful in this scenario since it allows the temperature to be checked without opening the oven which can drop the temperature considerably. If the oven door is never opened, temperature changes are relatively slow, so be aware that even after you turn off the oven, the water will continue to warm up (although slower and slower) until the oven temperature drops below the water temperature. If you take this into account and turn off the oven a little early and turn it on a little early, you can get a relatively stable (within 1-2 C°) water bath with human intervention only every 5 to 15 minutes depending on the volume of water (the more water the slower the temperature changes) and the oven.

Ice Chest with Hot Water
Heat Source (during cooking): None
Heat Adjustment: Manual
Lowest cost: $40
Mid-cost: $70

Method: The ice chest is first filled with hot water a couple C° above the target temperature (for example, 60°C/140°F). This isn't as easy as it sounds since the volume of water can be quite immense. The easiest way is to first fill a large pot full of water and pour it into the ice chest. Then, boil a large pot full of water and pour it into the chest. Close the lid of the chest to slow down the heat loss (mainly due to evaporation), and repeat until you have enough water. You'll need more hot water than room temperature water due to the heat loss from the ice chest as you wait for the water to heat up. After stirring briefly, measure the temperature of the water and adjust by adding more hot water or cold water until the desired temperature has been reached (a couple degrees above your target temperature). Place the probe of the probe thermometer into the water while being careful that the junction between the probe and the cable does not get wet (that's the number one reason why the probes die). One way to help prevent water from getting into the probe is to place it in a large waterproof bag while taking care that the opening of the bag is outside of the cooler (try taping the opening to the side of the cooler so it doesn't slip in when you open or close the lid). Program the thermometer to sound an alarm once the water temperature drops below the target temperature. Place the bagged food into the chest and close the lid. It's probably a good idea to heat some more water so it will be ready when the water temperature drops below the target temperature. Add hot water as necessary throughout the entire cooking time.

Because of the nature this particular technique, I don't recommend foods that require long cooking times (certainly not 24-72 hour long recipes!).

Stovetop with Thermometer
Heat Source: Range
Heat Adjustment: Manual
Lowest cost: $45
Mid-cost: $72

Method: A large, heavy (or heavy bottom) pot on a burner with a thermometer clipped to the side can work effectively for many sous vide applications. The two options that I have listed above are inexpensive starting points, but, if you already have a large, heavy pot (such as a Dutch oven), then that will probably work better than the two entry-level examples shown. Simply take your large stock pot or Dutch oven, place the silicone steamer insert on the bottom, and fill it 3/4 full of water and bring it up to the target temperature over a burner. If you overshoot, you can bring the water temperature back down by adding small amounts of cold water from a cup. Some patience will be needed to adjust the burner's magnitude to maintain an even water temperature (chances are you will not succeed, but you should be able to keep the temperature somewhat stable and be able to walk away for a few minutes at a time). If you clip the probe of the probe thermometer to the side of the pot (I do this by running the probe through the tabs of a large binder clip), you can program the thermometer to alert you when the temperature rises outside of the desired range as well as below the desired range. Once the water temperature is stable, place the bagged food into the water to begin heating.

One variation of this method is to use a portable induction cooktop that has the ability to keep water at a warm temperature. The induction cooktops that I've used have rather coarse granularity (15-30 F° increments) and do not result in exactly consistent water temperatures (both consistent over time and consistent with the digital setting). If you attempt to use the cooktop's temperature setting, I recommend testing the temperature with a thermometer over a thirty minute period to get a feel for the water temperature at a given setting. Different pots and different settings will result in different water temperatures, so it may be possible to get the water temperature in a range that is useful for sous vide cooking.

Putting a lid on the pot is a personal choice, just remember that if you stabilized the temperature without a lid, then placing a lid on will increase the temperature (and vice versa). So, be consistent - if you use the lid, use it all the time; if not, keep it off.

Rice Cooker or Slow Cooker or Food Warmer without External Controller
Heat Source: Built-in
Heat Adjustment: None
Lowest cost: $52
Mid-cost: $182

Method: This option takes a little luck to get working and is less flexible than the previous two because the temperature of the water bath can't be altered because no external control source is available (unless you sit there and toggle it on and off). If it does work in your situation, it does allow the operator to walk away and not have to "tend the fire".

Before attempting this, fill your cooking device with water and set it on the "keep warm" setting and walk away for a few hours. Measure the temperature to determine the equilibrium temperature of your device. Each device will be a little different. For example, my small rice cooker settles at 64°C (147°F) while my industrial rice cooker settles at 85°C (185°F). For this technique to work, we're at the mercy of whatever the "keep warm" temperature is for your device and are limited to the cooking applications for that temperature. Here's a rough guide ("unpasteurized" is noted where the water bath temperature is not high enough to kill the most common pathogens over time; these food items should be heated to the desired temperature and consumed within four hours total cooking and eating time by the non-immune compromised):
38-43°C (100-109°F): very rare to rare tuna (unpasteurized)
39-49°C (101-120°F): very rare to medium-rare salmon (unpasteurized)
49-55°C (120-130°F): medium-rare to medium fin fish and shellfish (unpasteurized)
55-60°C (131-140°F): beef
57°C (135°F): pasteurizing eggs (but keeping them uncooked)
60°C (140°F): pork and chicken (pink but pasteurized)
63-65°C (145-149°F): poached eggs
70-80°C (158-176°F): rendering fat (lard, tallow, etc.)
80°C (176°F): duck confit
82-85°C (180-185°F): root vegetables

You can also try to alter the settling temperature by removing the lid to the device thus providing two possible cooking temperatures.

Once you've determined the temperature your device "keeps warm" at, you can simply run the device at full power to that temperature and then switch it to "keep warm". Wait a few minutes for the temperature to settle (check with a thermometer) and insert your food.

Pot with bucket heater and PID Controller
Heat Source: Bucket heater
Heat Adjustment: External PID Controller
Lowest cost: $170
Mid-cost: $230

Method: This is the lowest cost solution involving a type of controller called a PID controller. Essentially, the controller turns on and off the device plugged into it at a rate dictated by a feedback loop algorithm. You can think of it as turning the device on full power when the temperature is much lower than the target, then reducing the power level as it gets closer, then turning off the device as the temperature overshoots, and then gently controlling the power level to maintain the temperature. In reality, external heating devices are usually only on-off devices, so the PID controller approximates variable power by pulsing the power on and off. The longer the pulses, the higher the power; the shorter the bursts, the less power is provided. Since heating elements take time to cool off and warm up, this does a good job of approximating the range from 0-100% power. The PID controller in this section and the ones below can be programmed to better match the cool down and heating rates of your cooking device (in this case, a bucket heater, and, in the case below, a rice cooker). The PID controllers listed here are all rated to handle 1800 W which should be sufficient for most heating devices. If you are using a different PID controller, please check the maximum power rating as a fire hazard can present itself if the heating element used draws more power than the controller is designed for.

These PID controllers also come with thermocouples (used to measure temperature). The thermocouple probes are sealed and watertight, so unlike the Polder probe thermometer, there is little fear that water will destroy your thermocouple (unless the seals fail).

Fill a large container with water. This can be a large stock pot, Dutch oven, ice chest, or any other large container. Insert the bucket heater (following the directions according to the heater - many need to be fully submerged to work properly) into the water being careful to position it so the heating element does not touch the container directly if high heat can damage the material of the container (such as the plastic in an ice chest) - you can use a block of wood or something heat resistant as a barrier is needed. Plug the bucket heater into the output of the PID controller. Place the thermocouple connected to the PID controller into the water (preferably away from the heating element). It is important that the thermocouple be in the water when using the PID controller. Otherwise, the PID controller's feedback loop will have the wrong temperature feedback (probably in the air on the counter next to your cooking vessel) and try to run your heating device nonstop in an attempt to raise the temperature. This can be a dangerous (fire warning) situation. (Boiling off all the water in your cooking vessel is not going to end well.) Plug the PID controller into the wall socket, turn it on, and program it for the desired temperature. If the water volume is too large, the bucket heater may not be able to bring the temperature up in a reasonable amount of time. In this case, you'll need to either use less water or a more powerful bucket heater.

Once the water has reached the desired temperature, place the bag of food into the water, preferably away from the heating element.

Please note that PID controllers can be off by a few degrees (even though it may be precise (that is, it keeps the temperature within a degree), the accuracy could be off and 55°C might be 53°C in reality), so double check the reported water temperature with a measurement of the actual water temperature using a calibrated thermometer. (Again, I really like the Thermapen.)

Rice cooker / slow cooker / food warmer with PID Controller
Heat Source: Built-inHeat Adjustment: External controllerLowest cost: $182
Mid-cost: $312

Method: This setup requires an electric rice cooker, slow cooker, or food warmer (an electric device that is designed to keep a food pan or hotel pan hot for service) with a simple mechanical switch or dial that turns the device on. Advanced electronic versions of these appliances will not work because the PID controller will attempt to turn the device on and off rapidly to control the heating elements. In electronic rice cookers, for example, turning the power off and then on does not cause the device to start cooking, but, instead, puts the device into a "wait" state where it waits for user input to program it or start it. Luckily, mechanical switch controlled devices are still readily available, and, as an added bonus, most are cheaper than their electronic counterparts.

In the rice cooker example, fill the interior vessel with water and place in the rice cooker. Most rice cookers automatically turn the mechanical switch off when the vessel is removed, so depress the switch once the filled vessel is back in place. Insert the thermocouple of the PID controller into the water along with the silicone steamer insert (to protect the food from the heating elements at the bottom of the rice cooker). (I actually don't run my rice cookers with the steamer insert normally because, once the water is at the target temperature, the bottom of the rice cooker does not get much hotter than the surrounding water so long as the water is free to circulate around the food pouch.) Place the lid on the rice cooker and turn on the PID controller. Program the controller to the desired target temperature. Once the water bath has settled at the target temperature, place the food bag into the rice cooker.

Using a device with a lid saves power and water. Because the water isn't evaporating directly into the environment, water loss is prevented and heat loss is reduced which causes the PID controller to turn on the cooking device for less time. In fact, the rice cooker with PID controller is the most efficient (in terms of water and power consumption) sous vide setup I have tested. (The average measured power draw to sustain a temperature of 55°C (131°F) in my large rice cooker with the Auber PID controller is about 8 W!)

Auber Instruments has suggested that a rice cooker is superior to a slow cooker because the heating elements in a rice cooker are at the base while the slow cooker heats from the sides. Apparently, heating from the bottom causes natural convection currents to circulate more effectively than heating from the sides. I have not done any testing to confirm or refute this theory.

Another reason I like rice cookers is that the interior vessel can be removed and carried over to the sink to be poured out and washed. Many slow cookers also have this feature.

Pot with Air Bubbling Heating Element and PID Controller
Heat Source: Submerged heating element
Heat Adjustment: External controller
Cost: $300
Method: Fresh Meals Solutions sells these kits that enable you to use their heating element along with an air bubbler (that agitates the water) in a water bath (either the large polycarbonate container in their kit or a pot or vessel you already own). Treat this system as you would the previous method: fill the vessel with water, insert the heating element and thermocouple (and bubbler), turn on and program the PID controller to the target temperature, and insert food when stabilized.

Stand Alone Water Bath Appliance
Heat Source: Built-in
Heat Adjustment: Built-in
Lowest cost: $300
Mid-cost: $400

Method: For many readers, this will be the best solution. The three products listed here are complete standalone appliances. They are essentially a vessel for holding water, a heating element, and a PID controller all built into one device. (There's no thermocouple to forget to put into the water and minimal fire hazard since all the devices have auto-shutoff in case the water fully evaporates, etc.)

The smallest of these is the new Sous Vide Supreme Demi which has a 9 L water bath vessel. It's 20% smaller than the bigger and 50% more expensive Sous Vide Supreme (11.2 L). Neither of the Sous Vide Supreme models come with removable interior vessels (a slight cleaning problem if a bag bursts, but not insurmountable).

The Sous Vide Magic Water Oven is the largest of these at 14 L and has air bubbling for circulation/agitation as well as a removable interior pot for easy clean up.

Usage is simple - just fill to the specified water level, program the target temperature, and insert the food when the device beeps telling you it has stabilized.

Costco.com is currently running a great Sous Vide Supreme Demi deal which includes the appliance along with a vacuum sealer, two boxes of bags, and Douglas Baldwin's excellent book, Sous Vide for the Home Cook, all for $350.

Immersion Circulator
Heat Source: Built-in
Heat Adjustment: Built-in
Cost: $800
Method: Immersion Circulators are generally considered the gold standard for controlling the temperature of water baths both in the kitchen (for sous vide cooking) and in the laboratory. Just place the device into a vessel filled with water (a large pot, large and deep hotel/food service pan, ice chest, even the kitchen sink), set it for the desired temperature and watch it rapidly heat the water by taking in water, heating it, and pushing the warm water out to circulate quickly. Due to the constant water movement, the temperature is extremely stable (I measured 0.1 C° drifts on both PolyScience units with the cheaper Sous Vide Professional about 0.4 C° off the target temperature of 55°C and 0.1 C° difference from actual on the PolyScience 7306 where each was running in a 25 L open air polycarbonate vessel.), but that constant motion also contributes to a larger amount of water loss. (Luckily, adding more water does not drop the temperature for too long due to how quickly the unit heats water.) Covering the open areas of the water bath with lids or plastic wrap helps reduce water loss.

Due to the even temperature control in very large volumes of water, an immersion circulator allows cooking large quantities of food sous vide without issue. One thing to keep in mind, though, is to match the cooking vessel to the quantity of food being prepared. A large cooking vessel with only a few eggs could result in broken eggs as the circulator pushes water around the vessel causing eggs to slam into the walls and each other. When the vessel is filled (or mostly filled) with a layer of eggs, this is no longer an issue. Likewise, a single bag of short ribs will likely be picked up by the current and "swim" around the vessel as it cooks (which is not really a problem and somewhat entertaining to watch).

These devices typically mount to a cooking vessel by screwing a clamp onto the side. You can also build a platform for the laboratory models to rest on top of the vessel. (The PolyScience Sous Vide Professional model is shrouded by a sealed plastic container making it possibly easier to clean but also unable to be mounted with standard platform brackets.) Platform brackets or mounts that span the water bath and allow the secure positioning of the immersion circulator in the middle of the bath are available from PolyScience as well (for a price).

The $800 PolyScience Sous Vide Professional from Williams-Sonoma comes with a 63-page introduction and recipe book by Thomas Keller (and until March 21, 2011, also comes with a free 20 qt pot and 25 L polycarbonate container).

Other common brands of immersion circulators include Techne, Grant, Roner, and Fischer Scientific.

Bags and Vacuum Sealers
Before putting the food into a temperature controlled water bath, the food needs to be protected from the water (or we will be simmering or poaching instead) by something that will also enable the heat from the water to easily transmit itself into the food. Heat-safe (to simmering temperatures at least) plastic bags are used for this purpose. Using a vacuum pump to remove the air and seal the bag causes a shrink wrap effect which presses the plastic closely against the ingredients allowing for maximum heat transfer and prevents air bubbles which may lift the bag out of the water. (This may still occur if steam forms in the bag - just put a plate on top of the food to weigh it down in these cases.)

A vacuum seal isn't always needed for good results, however. The use of a Ziploc-brand Freezer bag is adequate for most sous vide applications. (I did speak to a few representatives at S. C. Johnson & Son, Inc., the makers of Ziploc-brand bags, where they repeated said their bags had not been tested at temperatures where most sous vide cooking takes place. The medical and public health representative I spoke to said that the information they had was more concerned about the risk of burning if the bags lost integrity due to high heat and burst, and there did not seem to be an ingestion concern. Ziploc-brand Freezer bags are made of thick polyethylene which melts at 230°F, said another customer service representative, and they recommend staying away from boiling temperatures. Only use Ziploc-brand Freezer bags for sous vide applications if you feel comfortable to do so in light of the company's request for people not to use the bags in untested ways.) For higher temperature (vegetables, rendering fat, confit) and longer duration (three day short ribs, 36 hour skirt steak) recipes, I prefer the sturdier plastic and seal of a vacuum sealed bag. Another benefit of the vacuum sealed bag is that after cooking food such that it is pasteurized, properly handling the food (rapidly cooling and storing in the refrigerator or freezer) can allow the food to remain safe to eat for extended periods of time (up to 30 days if the food is kept in a refrigerator at 3.3°C (38°F); longer at lower temperatures).

Not all bags used with vacuum sealers are appropriate. Specifically, refrigerator bags are not usually simmer proof and the bags used in conjunction with the FoodSaver FreshSaver handheld vacuum pump (the zip top bags with a port for the vacuum pump) are not compatible with sous vide cooking. Use freezer bags or bags whose boxes are specifically marked as appropriate for simmering.

Countertop Vacuum Sealers
Low Cost: $55 Rival Seal-A-Meal Vacuum Sealer
Mid-Cost: $150 FoodSaver V2440 Vacuum Sealer

Countertop vacuum sealers often are equipped with just enough power to create a minimal vacuum. They are normally incapable of creating the strong vacuums used for some interesting new food preparation techniques such as compression (as in "compressed cucumber" or "compressed watermelon") and vacuum pickling. To do this, one must defeat the pump shut off in the countertop vacuum sealer (a procedure described on page 358 of Jeff Potter's Cooking For Geeks; while you're looking at that book, take a look at pages 262-263 as well) or acquire a chamber vacuum sealer (which also works much better with foods that contain liquids). (Trying to vacuum seal foods heavy with liquids can be a challenge without a chamber vacuum sealer. Hanging the bag off the edge of the counter while sealing and manually starting the seal as soon as the liquid is about to reach the clamp works most of the time as does freezing the liquid before vacuum sealing in a bag.)

Chamber Vacuum Sealer
Low Cost: $1800 MiniPack MVS 31

Published on January 19, 2011 at 12:11 PM


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Sous Vide: An Introduction to Sous Vide Cooking

8:58 PM Posted by Rhoda ,
Have an analytical mind? Like to cook? This is the site to read!

Sous vide (pronounced SOO-VEED) cooking is the preparation of food by submerging ingredients in a temperature controlled water bath (often while the ingredients are enclosed within a vacuum sealed plastic bag). Until recently, this method of cooking has been limited to restaurants and industrial food service, but it is becoming increasingly easy to prepare sous vide food at home. Like all methods of cooking, there are benefits and disadvantageous to sous vide cooking which we'll also discuss below. In most cases, cooking sous vide simply involves two steps: the sealing of foods in plastic bags and submerging the bags into hot water baths for a period of time to heat through. The water is typically regulated at the desired final temperature of the food or just above. The food is held in the water bath until it reaches the same temperature as the water (and then held at that temperature until service or a final cooking step takes place such as searing). In many ways, this is similar to simmering (such as in a poached fish recipe), except the sous vide water is usually at a lower temperature and food is kept from making direct contact with the water by a barrier (such as a plastic bag or eggshell in the case of sous vide eggs, thus minimizing flavor and nutrient loss of the ingredients to the cooking liquid).

Let's walk through what happens to the food while in the water bath with a concrete example. I'll use the example of a rib eye steak which I intend to cook to medium-rare. For the purposes of this example, I've vacuum sealed the steak after lightly seasoning with salt and pepper. The bagged steak is then deposited into a water bath set to 55°C (131°F). Its temperature starts off at refrigerated temperature of 5°C (40°F) and slowly rises over time as the heat from the water transfers through the bag and into the steak. Eventually, the entire steak will reach equilibrium at 55°C (131°F) - the exact time depends on the thickness of the steak. For most large rib eye steaks, one hour is sufficient for the entire steak to be at 55°C. At 55°C, the proteins we consider to be tough in raw beef have denatured (unraveled). (Raw beef is chewy because these proteins, called myosin, are intact. By cooking at temperatures higher than 50°C/122°F, myosin begins to break down making the beef more palatable.) There are other proteins in beef which, when denatured, are tough to chew. These proteins (actin), when denatured, also squeeze out a lot of water which causes the steak to become dry. At 55°C, the actin are more or less intact, thus preserving the tenderness of the beefsteak. At this point, the steak is "cooked" since it's reached the desired temperature and texture, but not necessarily safe to eat. Holding the steak at 55°C for an hour pasteurizes it making it safe to eat. (This pasteurization process kills most Listeria pathogens; however, at this temperature and time, salmonella can still be alive, but salmonella is not common in beef steaks. Salmonella can be an issue with ground beef which should be cooked longer to fully pasteurize. Had we set the water bath to 60°C (140°F), pasteurization time would have been only a few minutes - so sous vide cooking meats to higher levels of doneness takes less time than lower levels of doneness due to food safety concerns.)

At this point, the entire steak is at our desired final temperature - from edge to center to edge. Unlike other cooking techniques, there is no noticeable temperature gradient. When you grill a steak, the meat is placed over an extremely hot heat source and the outside layer of meat reaches temperatures in excess of 175°C (350°F). Under that layer is a layer of extremely well-done beef (much greater than 70°C/160°F which looks like grayish colored beef and is dry and chewy) which gradually becomes well-done, medium-well, then medium, and, finally (if the steak was flipped at the right time and pulled from the grill at the right time), a center which is medium-rare. If you like your steak medium-rare, then grilling a steak over high heat really doesn't produce much medium-rare beef. So, many techniques have been created to solve this problem - the two that work the best for me is to sear the outside of the steak (since the brown exterior is very flavorful and desirable) and move it onto a cooler (but still warm) part of the grill or placing the steak into an oven (even though the temperature of the oven is relatively high compared to the target temperature, air is a really inefficient conductor so heat transfers slowly into the meat providing more even cooking than a hot grill would have). This minimizes the amount of well-done beef in the medium-rare steak. Sous vide gives us an easy alternative to the oven, because, since we set the temperature of the water bath to the final internal temperature of the steak, it is impossible for the steak to overcook to medium-well or well-done. In fact, we can leave the steak at 55°C (131°F) for hours without being able to detect a difference in taste, texture, or flavor.

The only problem with sous vide steak is that the temperature never goes above our water bath temperature, so no surface browning can occur. That brown crust is one of the joys of eating a steak, so a quick sear on the hottest burner possible is all that is needed to finish the steak. This can be achieved with a very hot charcoal grill, a searing burner on a gas grill, infrared searing burner, a pan (people generally prefer cast iron) that has been superheated on the range, or a blowtorch (the medium sized ones from hardware store work much better than the small expensive kitchen torches). The hotter the heat source, the faster the steak can be browned, the more abrupt the temperature gradient you'll have in the steak. It should look something like: browned, medium-rare, browned with almost no discernable areas of well-done or even medium.
Sous vide cooking can be used to cook all types of proteins: fish, fowl, lamb, beef, etc. However, each type of meat has some differences in the proteins and denaturing temperatures. For example, in most fish, myosin begins to denature at around 40°C (104°F), while in mammals (beef, lamb, etc.) myosin doesn't denature until 50°C (122?F). The difference in protein denaturing temperatures in fish from other animals is one of the reasons why the tenderest fish is cooked at lower temperatures than beef or chicken. In fact, there are protein denaturing differences between types of fish - if we cooked salmon to 60°C (140°F), its proteins would have unraveled and tightened up so much that it would taste dry and perhaps even a little grainy. However, Mediterranean sea bass (also called branzino or dace) can be cooked to that same temperature without producing unsavory textures. In some meats with lots of connective tissue (such as beef ribs), long cooking times can be used to break down collagen into gelatin without bringing the meat up to the relatively high temperatures of 77°C (170°F) and above used when smoking ribs or braising short ribs. I'll cover the specifics of cooking various types of foods, the health concerns (which pathogens or parasites need to be considered or dealt with), and which proteins we're aiming at denaturing and which ones we want to avoid overheating in future articles.

Eggs are of particular interest in sous vide cooking due to their complex composition of different proteins which denature at distinct temperatures. They can be cooked in their shells, so it's one of the easiest foods to experiment with once a temperature controlled water bath is set up. Just drop (well, place them gently so the shells don't break) them into the heated bath and wait one hour. Each one C° temperature change can alter the consistency of the egg white and egg yolk. My personal favorite is 65°C (149°F) where the yolk has thickened into a gel and the whites have taken on a custard-like consistency.

Vegetables can also be prepared sous vide, but the goal is the breakdown of starches. In general, this occurs around 85°C (185°F). For the most part, steaming, blanching, or sautéing vegetables produces almost the same result as sous vide. Because of this, I don't often bother to sous vide vegetables except for carrots, beets, and potatoes. When those vegetables are sliced or cubed, bagged, and cooked sous vide, you can get consistent texture through the entire piece without any liquid or nutrient loss to boiling water.

Disadvantages of Sous Vide Cooking
Expense. Cooking sous vide requires a temperature controlled water bath. This can be approximated on the least expensive end with either a large ice chest filled with hot water (measured with an accurate thermometer) or a large pot with a thermometer attached and a diligent cook adjusting the flame / heat source (potentially $0 cost if you already own a thermometer). On the expensive side, you can get what the professionals use - a piece of scientific laboratory equipment called an immersion circulator which regulates the water temperature and keeps it circulating to maintain a precise temperature within 0.1C° (these run at about $1000 and up). There is now a consumer water bath appliance on the market called the Sous Vide Supreme that runs about $450. In a future article, I'll discuss all the options from the $0 to the immersion circulator.

In addition to the water bath, a vacuum sealer is needed (although using Ziploc brand bags should work when starting out - they are supposedly safe up to about 76°C/170°F). FoodSaver is the most popular brand and has offerings starting just under $100 to about $200. Chamber vacuum sealers are often used in restaurants and generally start at around $2000.

Time. It takes a lot of time to cook sous vide. Because heat transfers gradually from the surroundings into the ingredients, cooking always occurs at a faster rate when there is a large delta between the cooking environment and the food and slows down as the two temperatures get closer together. For example, placing a steak on a pan heated to over 500°F will transfer a large amount of heat (assuming the pan doesn't cool down too fast) into the steak rapidly. It only takes a few minutes to cook with such a heat differential. The same steak takes longer in the oven for two reasons: the temperature in the oven is usually lower and air is a poor conductor (when compared to metal cooking pans or water). Luckily, cooking sous vide is not as slow as the equivalent process in an oven (if both were set to the same temperature) because water is excellent at holding heat and imparting it (that's why we can stick our hand in a preheated oven at 175°C (350°F) for a while before feeling extremee discomfort while a few seconds at 85°C (185°F) in simmering water would give us severe burns). Unfortunately, the low temperature delta between food and heat source leads to long cooking times. In addition, since the food is often cooked at a lower temperature than flash pasteurization temperatures, once the food has reached its target temperature it should be held there for a period of time to ensure the destruction of pathogens, thus extending the total cooking time. (For foods cooked sous vide for short amounts of time with fresh ingredients, it is not necessary to pasteurize before eating by healthy adults.) For foods where connective tissue breakdown is desired, the cooking time could be days. (Of course, for some of these foods there are no alternative cooking methods that yield the same results.)

Temperature Limitations. You can't sous vide cook near the boiling temperature of water, so all cooking has to take place significantly below the temperatures needed to brown foods (Maillard reactions and caramelization all occur well above 150°C (300°F).) Also, no significant temperature gradients (which can be an advantage as previously mentioned) are present in the cooked food, so pan-seared salmon where the skin is crispy and textures range from well-done to rare are not possible. Another example where gradients are preferred is when soft boiling an egg such that the whites are solid and the yolk is running or gelled. Eggs cooked sous vide results in a uniform temperature and at 65°C the yolk has gelled and conalbumin (one of the major proteins in the whites) has denatured, but ovomucoid has not denatured which results in partially runny layers of whites. This can be solved with two water baths - one set to 75°C (high enough to denature ovomucoid but not ovaalbumin which causes whites to become rubbery) and another at 65°C. Setting the eggs in the first bath for just long enough to set the whites and then transferring them to the 65°C to be held for service.Another limitation related to temperature is that for any particular water bath, you can only have one uniform temperature. So, if you need to cook two things at the same time at different temperatures, you'll need multiple water baths. With some planning though, you can cook the hotter items first and lower the temperature and cook the lower temperature items while keeping the high temperature items warm at the lower temperature. For short periods of time (a few hours) this is usually not a problem.


Advantages of Sous Vide Cooking
Time. I previously mentioned that the amount of time it takes to cook sous vide was a disadvantage, but the type of time it uses can be seen as an advantage. For most of the cooking time, the cook is not active. You bag the food, heat the water bath, stick the bag in, and walk away for an hour (go to the gym, chat with guests, etc.) or a day or two (live your life normally - go to work, sleep, etc.). The food is safe and ready when you are to eat. With sous vide there is a large amount of flexibility. Eggs hold for a couple hours as do steaks. If the meat is done early, but you're not ready to eat - leave it in the water bath (unless it is fish or shellfish which contain enzymes which will work to soften the texture until it becomes mushy). If it's food that is cooked across multiple days, holding it another half day probably won't have any noticeable effect. If you changed your mind (or are working with fish or shellfish), shock the food down and refrigerate to be reheated in the same bag (properly shocked down and refrigerated most sous vide foods can be stored for a month in the refrigerator - indefinitely, in the freezer).

Temperature Control. Being able to target a specific temperature allows the cook to handpick which proteins should denature and which should not. This allows incredible control over texture. This control allows for the ability to cook foods in a way that are not possible through other means - gelatin rich medium doneness short ribs or medium doneness chicken breast. Another benefit of a temperature controlled water bath is the ability to pasteurize eggs in the shell at 57°C (135°F) and use them in place of raw eggs in recipes for the immune compromised (homemade mayonnaise, buttercream frosting, or even raw cookie dough).

Temperature Gradient. The slow cooking process and 0 difference between heat source temperature and desired food temperature means there is essentially no temperature gradient within the food maximizing the quantity of food at the desired temperature (and therefore the desired texture). No temperature gradient also means there is no carryover cooking and less of a need for food to rest.

Quantity Cooking. With an immersion circulator and a large water vessel, you can sous vide cook a LOT of food at once. Large bags of beaten eggs can be heated in a water bath to make scrambled eggs (a technique often employed at emergency shelter facilities). Chicken or turkey breasts can be vacuum sealed and cooked to produce large quantities of tender meat for use in salads or to be sliced with a rotary slicer (many industrial poultry breasts prepared for use by delis are cooked sous vide in the very bag they are sold to the deli or supermarket in).

Reduced product loss. Due to the vacuum sealing and a lower cooking temperature than most other cooking techniques, there is usually significant reduction in water and fat loss to the environment when cooking sous vide. Chicken, when cooked at 60°C (140°F) loses less than 20% of its weight (while frying, roasting, or grilling typically results in water loss of about 30%) resulting in more juicy chicken. The liquid isn't really lost either since it's captured in the bag and can be used for the basis of a sauce or gravy. In fact, it is rumored that the origins of sous vide cooking in restaurants began in France during the 1970's where George Pralus pursued this technique as a way to reduce product loss when preparing foie gras.


In future articles, I'll discuss the particulars of how to sous vide cook different ingredients as well as how to put together your own sous vide setup at home. Published on December 01, 2010 at 04:57 AM


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