FREQUENTLY ASKED QUESTIONS on Sous Vide ... - PolyScience

<strong>FREQUENTLY</strong> <strong>ASKED</strong> <strong>QUESTIONS</strong> on
Sous Vide Cooking
Sous Vide Professional
CONTENT
1. GENERAL <strong>QUESTIONS</strong>
2. HOW TO COOK SOUS VIDE
3. VACUUM SEALING
4. TIME, TEMPERATURE & PROBING
5. STORING & REHEATING
6. FOOD SAFETY & CLEANING
PolyScience is a leading global producer of laboratory equipment for customers
worldwide. Founded in 1963, PolyScience’s core competence is designing and
manufacturing extremely precise temperature control solutions. This expertise presented
company president Philip Preston, a passionate home chef, with the opportunity to
support the first wave of creative chefs re-examining sous vide cooking.
Over this time, PolyScience has developed great relationships with many of the world’s
best chefs. Next to their creativity, the best ingredients and knowing what customers
enjoy, PolyScience culinary technology has become one important element in their
kitchens.

1. GENERAL <strong>QUESTIONS</strong>
WHAT IS SOUS VIDE?
Sous Vide is a cooking method in which food is vacuum sealed in a plastic pouch and then
cooked at a gentle temperature in a precisely controlled water bath. Compared to other cooking
methods, it provides more control and allows for perfect, repeatable results every time. It is easy
to learn and takes the stress out of cooking, because food can be held at a perfect level of
doneness for a much longer time than usual methods allow.
Who should invest in a Sous Vide Professional?
Anyone that likes to take advantage of a cooking system that allows:
- Repeatable, perfectly cooked food every time
- The stress to be taken out of cooking by eliminating short windows of time for perfect doneness
- Meals to be prepared ahead of time and still taste delicious even days later
- The production of the most moist and tender texture
- Financial savings by making tougher cuts of meat taste like tenderloin
- One to cook like chefs in the world’s best restaurants
What are the nutritional benefits of sous vide cooking compared to traditional methods?
Food cooked sous vide retains as much of the integrity and important nutrients as possible. Since
they will not be lost to cooking liquid and the temperature is lower than with usual techniques,
more nutrients remain in the food. Fats in meats and fish, which can be easily damaged at high
temperatures in the presence of oxygen, remain un-oxidized, intact, and more healthful.
What are the convenience benefits of a Sous Vide Professional for a home chef?
This technique eliminates all stress, time crunch and worries of overcooking because this
technique offers a much greater window of time. Practically one can’t overcook.
It takes out the guesswork! The perfect control guarantees that results turn out perfect every time.
That gives even a less experienced cook a chance to cook a perfect medium-rare steak or
delicate fish filet.
The Sous Vide Professional also allows preparing meals in advance and enjoying home
cooked meals, without compromising quality, even on busy days.
What is the difference between a Sous Vide Professional and a slow cooker?
The Sous Vide Professional can be used as a slow cooker, but is outperforming any slow
cooker in the following areas:
o Level of control and temperature precision - food cooks exact and repeatable every
time
o Flexibility – cook for 2 or for 50 people. The Sous Vide Professional clamps to any
size of vessel.
o Ease of storage and cleaning – the Sous Vide Professional is slightly larger than a
stick blender and can be stowed in a drawer. To clean the cooking vessel, simply put it in
the dish washer.
To set up a Sous Vide Professional as slow cooker simply insert a stainless steel pan or
ceramic container into the water bath that is controlled by the Sous Vide Professional.

2. HOW TO COOK SOUS VIDE
What are the basic steps to cooking sous vide?
1. Vacuum seal food in food-grade plastic pouches certified as suitable for cooking.
2. Place pouch in water bath that has reached desired temperature and is precisely controlled by
a Sous Vide Professional.
3. Let food cook for minimum time. Compared to traditional techniques, food can generally stay
longer in water bath without overcooking.
4. Remove and serve! Some foods require a quick sear in a hot pan or on a grill to create a
browned surface and impart a caramelized flavor.
What kind of foods can you cook sous vide?
- Any type of delicate or tougher cuts of meats—such as beef, pork, lamb, game, or poultry. A
beef tenderloin will turn out perfectly cooked every time. Spare ribs will be so tender and juicy like
you’ve never had them before.
- Excellent for delicate fish and seafood, ensuring that these delicate foods are not dried out or
overcooked.
- Almost any vegetable except for greens (broccoli, green beans). Root vegetables and potatoes
benefit very much in flavor and consistency with sous vide cooking
- Eggs can only be cooked very precise in a sous vide circulating bath. See our temperature
reference guide which illustrates the dramatic changes at each degree. Obviously eggs do not
have to be vacuum packaged.
- Fruits, in particular delicate ones like peaches, apples and pears do not only turn out with the
right mouth feel, but taste wonderful when cooked with flavor infusions.
- Cook custard-style ice cream base, béarnaise sauce, crème anglaise and custards without
worrying about curdles. The Sous Vide Professional water bath is excellent to hold these
custards and sauces at serving temperature. (see iSi Whip Canister Holder)
How do you season food to be cooked?
Because food is packaged in food-safe bags and cooks in its own natural flavors, it does not give
up aroma and moisture to surrounding liquid or the air. Seasoning will be more efficient and
requires less than usual. With herbs we recommend to use only 30% of what you usually would
use. Salt and pepper would not be applied much differently than with other methods. It is
important to evenly distribute the seasoning in the bag or on the food. Otherwise there will be
parts that have more seasoning than others. As an example: if you cook carrots in cumin butter,
simply melt the butter and mix in the cumin powder before introducing it into the bag.
One big difference to traditional methods is the use of garlic. Garlic added to foods like steak,
chicken or fish does not cook in the cooking pouch at these temperatures. The result is a
unattractive flavor. To avoid that, we recommend adding garlic after it is sautéed or roasted.
Alcohol in wine, beer, liqueurs, or distilled spirits will not evaporate as it does on the stovetop or in
the oven and can develop a harsh, unpleasant flavor. We recommend to pre-cook any alcoholbased
liquids that are added as flavor when cooking sous vide.

How much food can you cook with a Sous Vide Professional?
One of the big advantages to a Sous Vide Professional is that it clamps to any size container,
pot or vessel, from a small stock pot that holds food for 2-4 people, up to the maximum volume
with 7.4 gallons (28 Liter). This allows you to cook for more than 50 people, or cook several items
at the same time for over 25 people.
When you fill the water bath with food, there should always be enough space to allow for
circulation of the water!
Make sure that you cover the bath with our custom-lids or plastic-wrap for better heat efficiency
and avoidance of evaporation. This matters especially with higher temperatures like 185°F/85°C
when cooking vegetables.
Can you cook an entire meal in a Sous Vide Professional?
Yes, there are two ways to cook an entire meal:
Foods with different foods cook at different temperatures
1. Since food doesn’t overcook when holding at a lower temperature, one simply organizes
the sequence from high to low temperatures. For example, first cook carrots and potatoes
at 185°F/85°F for 45 minutes, then lower the temperature to 138°F/59°C for medium-rare
beef tenderloin. Adding ice cubes helps to speed up the cool-down process.
2. Pre-cook different foods, chill in an ice-bath and store in the refrigerator. Later re-heat all
foods at the temperature that you’ve used for the food with the lowest temperature, which
would be at 138°F/59°C for example when serving medium-rare meats.
One-pot meals and stews
3. A Sous Vide Professional can be used like a slow cooker. Simply vacuum seal your
stew into a bag or fill into a container that sits in the water bath and will be cooked by the
surrounding temperature-controlled liquid.
Visit our website for recipes or share any of your recipes via Facebook!

3. VACUUM SEALING
What different methods of vacuum sealing exist?
External vacuum sealer
A vacuum pump device is clamped to the outside of a bag, pulls out as much air as possible and
seals the plastic. While these machines are less costly, light and small, and often accomplish a
basic result, the performance is not able to remove as much air as a chamber vacuum sealer.
They also present a challenge when liquids are in the bag, since the pump will pull any content
from the bag that isn’t heavier than the pump can pull.
Chamber vacuum sealer
A chamber vacuum sealer is a device that creates a low pressure within a chamber before
sealing the bag. Equipped with a powerful pump, it can pull up to 99.9% of air from the bag.
It is important to understand two additional considerations when working with a vacuum sealer:
When using an external vacuum sealer, how can I vacuum seal bags that contain foods
with larger amounts of liquid?
- Simply put all the ingredients into a large (1 gallon/3.8 liter) sized zip closure freezer bag,
remove as much air as possible from the bag and either zip close or use vacuum sealer to seal
only without removing air to guarantee a great seal.
- Elevate vacuum sealer to a level that makes it hard for the pump to pull up the liquid. This slows
the process of rising liquid and allows you to press the seal button before it reaches the seal area.
What should you do if a pouch floats?
Ideally there is nothing but the thin plastic between the food and the water. That allows for
efficient heat transfer and even cooking. Having little air in the bag can be solved by putting some
weight on it, like a porcelain plate.
If the bag was properly vacuum sealed and did not float at the beginning of the cooking process
and all the sudden developed air inside the bag, you should thoroughly check if that food was not
contaminated with bacteria and thus has developed into a food safety risk. If the cooking water
has taken on color or food aroma, it is an indicator that the bag is not properly sealed and you
should discard it.
Compression & Infusions
Depending on the vacuum level, the food may be compressed and change texture from the
compact packaging. When adding liquids, the vacuum sealing process creates a rapid infusion—
especially with more porous foods. This can add benefits to flavor and texture, but may not
always be a desired result. For example, a delicate fish filet or chicken breast may become very
dense in texture. Therefore, the PolyScience ® Chamber Vacuum Sealer features customizable
vacuum levels.

4. TIME, TEMPERATURE & PROBING
Where can I find times and temperatures?
PolyScience provides a sous vide cook book with the Sous Vide Professional that lists several
recipes and a table with time/temperature guidelines for the most commonly sous vide cooked
foods. Find a downloadable version on www.sousvideprofessional.com
For what time do you cook foods sous vide?
With sous vide one has a much greater window of time for the perfect doneness. Time is much
less critical since food is not overexposed to heat and thus cannot really overcook in a traditional
sense.
Cooking times depend on thickness and tenderness of the food. It can range from as little as 20
to 30 minutes (lean fish, foie gras, scrambled eggs) to as long as 72 hours (spare ribs, tough
meats).
Thickness:
How long it takes a given portion of food to come to temperature depends on the
thickness of the portion, not the total weight. Cooking time increases exponential to
thickness. A 4 inch thick steak needs at least 3 times of cooking time than a 2 inch thick
steak
Tenderness:
Tender or delicate foods (fish, shellfish, foie gras, beef or pork tenderloin, lamb chops)
need only to be brought to the desired serving temperature to be delicious and ready to
eat. Extended cooking times can result in their becoming overly tender to the point of
mushiness. Portioned chicken breasts and tender steaks typically take a minimum of one
or two hours, depending on thickness.
Tougher foods (roasts, grass fed cuts, game, spare ribs) will be brought to temperature
based on the thickness of the portion, but then benefit from slow low cooking for hours to
tenderize them. Skirt steaks and top round roasts typically take a minimum of six hours
and a maximum of twelve hours. Ribs and briskets cook for twenty-four to forty-eight
hours.
Tables for time and temperature are available in the PolyScience Sous Vide cook book or the
Temperature Reference Guide. (For recipes and downloads visit www.sousvideprofessional.com.)
Can you cook steaks to different levels of doneness at the same time?
You would not cook them at the same time, but there are simple tricks to prepare different levels
of doneness.
Method 1: Cook all steaks in the water bath to medium-rare, then, when finishing the steaks in the
skillet or on the grill, simply leave the medium steak on for a bit longer. Method 2: Cook the two
steaks sequentially – the medium steak in a 140°F/60°C a day or one hour beforehand, then
lower the temperature to 138°F/59°C and add the medium rare steak for another hour. Both cook
to perfection. The medium steak will not overcook since it is only being held until ready to serve.
After the medium-rare steak is cooked to perfection, sear them quickly for flavor and appearance
in a hot skillet or on a grill.
Is there a way to measure internal temperature of meat as it cooks?
Yes. It can be done if you don’t have the PolyScience recipes handy or want to develop your own
recipes. The best way is to cut the bag open on the top, measure the temperature and reseal the
bag if necessary. Other ways are to apply foam tape on the bag, poke a temperature needle
through the bag and measure that way. However, this method cannot be considered as food safe,
because it is breaking the seal and very likely leaks water into the bag. We recommend this
method only for recipe development but not for food that’s served for consumption.

At what temperature do you cook foods sous vide?
Using the sous vide method, a food is cooked precisely and gently at its desired serving
temperature. Sous vide cooking temperatures are generally in the range of 115-190F degrees,
and always below boiling.
The key to successful sous vide cooking is maintaining a consistent water temperature
throughout the cooking period. A difference of as little as one degree can change appearance,
flavor and texture of some foods.
This level of control allows you to repeat over and over the exact same results of your steak,
chicken, scallops, or eggs.
Quick reference for cooking temperatures of common foods:
Meat –120°F/49°C(rare); 134°F/56°C(medium-rare); 140°F/60°C (medium); 150°F/65°C (medium
well)
Poultry - white meat – 140°F/60°C to 146°F/63°C up to 160°F/71°C as desired
Poultry – dark meat – 176°F/80°C
Fish – 116°F/47°C (rare); 126°F/52°C (medium-rare); 140°F/60°C (medium)
Shellfish – 135°F/56°C to 140°F/60°C
Vegetables –185°F/85°C
Eggs – 147°F/64°C (soft boiled) to 167°F/75°C (hard boiled)
Cakes – 190°F/88°C
Custard – 170°F/76.5°C
Tables for time and temperature are available in the PolyScience Sous Vide cook book or the
Temperature Reference Guide. (For recipes and downloads visit www.sousvideprofessional.com.)
Can I cook slow cooker recipes with the Sous Vide Professional?
Yes, every slow cooker recipe will work and turn out even more delicious and cooked perfectly
according to your set temperature.
For well done foods, simply cook all ingredients together at 185°F/ 85°C.
For medium-rare or medium foods, lightly sauté or steam vegetables in the skillet and then add
them to the meat and spices and cook in vessel or food-safe pouch.
How do I set up the Sous Vide Professional as a slow cooker?
To cook the recipe in a Sous Vide Professional, you can:
1. Use food-grade zip closure pouches: Remove air and zip closed
2. Vacuum seal food
3. Fill food into stainless steel or ceramic cooking vessel that will fit into the water bath,
controlled by the Sous Vide Professional.

5. FOOD SAFETY & CLEANING
Food Safety: Is cooking in plastic bags safe?
The chief concerns raised about cooking in plastic bags involve the leaching of potentially harmful
chemicals, such as BPA (bisphenol-A) and phthalates, or toxic metals, such as lead, from the bag
into the food. Food grade plastic bags, certified as suitable for cooking by their manufacturer, are
safe to use.
Vacuum & Food Safety
Vacuum-packaging creates an anaerobic or low-oxygen environment that can encourage the
growth of bacteria such as salmonella and botulism when food is handled improperly. Safe food
handling and hygiene standards should always be maintained.
Food Safety: What clean up is involved when cooking with the Sous Vide Professional?
Clean up couldn’t be easier. Since the food is sealed in cooking pouches, the water and bath stay
clean. Simply recycle the cooking pouch. As to cleaning the vessel after cooking, turn off and
unplug the Sous Vide Professional, detach it from vessel, wipe dry with a towel and store in a
safe place. Clean out vessel in dish washer or sink.
Occasionally or when a cooking pouch may have leaked, simply replace the water with a
vinegar/water solution and run unit at 160°F for 25 minutes to remove any residuals or lime. After
the cleaning process, turn off and unplug the Sous Vide Professional, detach it from vessel,
wipe dry with a towel and store in a safe place. Clean out vessel in dish washer or sink.
Food Safety: Is cooking at low temperatures safe?
Reducing the risk of food-borne illness by cooking food depends not just on temperature, but also
on time. The lower the temperature, the longer the time. For instance, Salmonella, a common
type of food-borne bacteria, will be killed in 30 seconds at 150°F/65.5°C but it will take 15 minutes
to do so at 130°F/54.5°C.
Almost all potentially harmful organisms will be killed at 130°F/54.5°C given sufficient time to heat
the food completely to that temperature. Since most sous vide cooking is done between
130°F/54.5°C and 195°F/95°C, the food will be safe. The most common exception is fish, which
some people prefer to eat rare or medium rare (116°F/46.5°C to 126°F/52°C). In this case, it is
important to only buy fish you would be willing to eat raw—in other words, sushi grade ocean fish.
Important warning: Individuals who are immuno-compromised for any reason should not eat rare
or raw food; they should only eat food cooked at or above 140°F/60°C for a sufficient amount of
time to ensure the food is pasteurized.
What are important food safety considerations with sous vide cooking?
When handling food, whether cooking sous vide or using more traditional techniques, all cooks
should familiarize themselves with basic food safety practices:
• Only work with fresh food that is thoroughly cleaned
• Prevent cross contamination by using separate cutting boards, washing your hands and use
separate and clean storage units
• Observe recommended cooking temperature and times to avoid bacteria growth
• Serve food right away or chill properly in an ice-bath and store immediately in the refrigerator.
Find additional food safety and handling tips in the PolyScience cook book or visit
http://www.fda.gov/food/foodsafety/default.htm.

6. STORING & REHEATING
How long can you keep sous vide cooked foods in the refrigerator safely?
Any fresh food that is cooked properly and quick chilled can be kept safely in its pouch in the
refrigerator for up to 48 hours. After 48 hours, it depends on what type of food it is. Delicate
proteins like fish and seafood should be consumed or frozen after that period. Vegetables and
meats that have been cooked for longer than 6 hours at 140°F/60°C can be held for 1 week
before they have to be consumed.
How do you quick chill sous vide cooked foods?
Completely submerge food in its pouch in an ice bath (50/50 ice cubes and water) to allow the
temperature to drop quickly through the danger zone (40°F/4°C to 130°F/54°C). How long the
food should stay submerged in the ice water should mirror the minimum cooking time for that
food, in most cases 30 minutes to 1 hour.
Do not place the hot or warm pouches in the refrigerator. They will not cool down quickly enough
and will heat up your refrigerator and other foods in it.
Is it possible to reheat or cook frozen foods?
Yes. This is very practical for two situations:
When cooking with raw frozen ingredients, the cooking time needs to be extended for the time it
needs to thaw. That is usually double or longer of the regular cooking time.
When reheating previously sous vide cooked and frozen foods, the time in the Sous Vide
Professional water bath depends only on how quickly the serving temperature is reached.
What should not be cooked sous vide?
Whole chicken, duck or game hen in one piece. The issue with that for any method is that white
and dark meats require different cooking times. For sous vide specifically a whole bird cannot be
vacuum sealed without remaining a cavity, resulting in uneven cooking. We recommend to break
down the parts and cook legs and thighs separate from breasts.
Green vegetables, such as green asparagus, broccoli and spinach. Based on our experience and
the feedback of the best chefs in the world, green vegetables don’t benefit from longer and low
temperature cooking times. Traditional methods like blanching or sautéing achieve much better
results.
Hamburgers or any ground meats or fish. From a food safety perspective, we don’t recommend
cooking hamburger patties sous vide. Bacteria grow on the surface of ground meats due to its
increased surface at a much higher risk for bacterial contamination than portioned meat cuts –
unless they are cooked at higher temperatures and for extended time. In that case we’d rather
use a traditional grill.
How long can I hold foods in the Sous Vide Professional?
With the Sous Vide Professional, food can be held at the desired cooking temperature for much
longer than with traditional cooking techniques. However, at some point food will become mushy
and overcooked in its texture. To ensure perfect results we recommend the following rules of
thumb:
- For the best results don’t hold foods longer at cooking temperature for double of their minimum
cooking time (see PolyScience temperature reference guide for time and temperatures).
- Maximum cooking time is 72 hours.