The purpose of vacuum packaging in plastic bags for low-temperature immersion cooking is mainly to prevent the food from losing its original juice and aroma during cooking, reduce the degree of oxidation of food, and also use the vacuum pressure to accelerate the absorption of seasonings And increase the cooking effect of food.
However, vacuum packaging is not a necessary option for Shu Simmer cooking. All Shu Simmer recipe books suggest that if ordinary households do not have a vacuum packaging machine, they can directly use common Ziploc sealable plastic bags to pack food. After squeezing out the air in the bag , and then cook in water. Of course, because there is still a small amount of air in the bag, the pressure generated by the food in the bag is limited.
Using Ziploc to package sous vide food (Source: sirenseasa.com)
A simple household vacuum packaging machine such as the common Foodsaver costs about 80 US dollars for a basic model, and Costco in Taiwan also sells it. Its principle is to seal a specially designed plastic bag on the machine, put food in it, and then Put the other end of the plastic bag into the machine to make a vacuum and seal it. I have used this machine before using Shu Wei. The main purpose is to vacuum pack and store freshly roasted coffee beans to prolong the fresh flavor of coffee beans. Of course, the north and south goods at home, such as wolfberry and longan, are also packaged by the way.
But the disadvantage of this machine is that it cannot pack liquid-containing items, because when it vacuumizes the packaging bag, it will suck out the water in the bag, such as steak gravy, etc. These juices, seasonings, etc. will be very messy If it is sprayed into the machine, the mouth of the bag will not be sealed due to moisture. Therefore, this machine is not very suitable when the simmering food contains high water content or needs to be seasoned with liquid. In addition, because Foodsaver's packaging bags require special texture designs, the cost of consumables is higher than other vacuum packaging methods.
Generally, there will be a box-shaped space inside the professional vacuum sealer (Chamber Vacuum Sealer) used by supermarkets, food industries or butchers. Vacuum the whole thing. Because the pressure inside and outside the food bag is the same, even if the bag is filled with liquid, the inside of the bag can still be sucked into a vacuum and then sealed. If the chef often uses liquids to season simmering ingredients, the vacuum tank packaging machine is the most suitable model. However, these professional machines are usually bulky, weighing more than 50 kilograms, and are also very expensive. For example, a machine from Henkelman, a well-known Dutch manufacturer commonly used in most restaurants, is priced at least $3,000 or more.
Henkelman Vacuum Slot Packing Machine (Source: henkelman.com)
A few years ago, VacMaster, a major manufacturer of vacuum tank packaging machines in the United States, finally released a household model VP112, which reduced the volume to 61x41x23 cm, reduced the weight to 24 kg, and reduced the price to $799. This machine has caused a wave of machine replacement among home users, and it has also received good reviews. Recently, VacMaster launched new home models VP115 and VP120, and the price of VP112 has been reduced to $595.
Finally, I would like to discuss with you the safety of plastic bags immersed in water for cooking. This is actually one of my worries when I hesitated to step into Shu Simmer cooking. Delicious food is one thing, but will you eat the plastic molecules dissolved in the food during the cooking process? Another well-known blogger Michelle Tam once wrote an article discussing ( link ) this issue. After reading her article and doing a few days of homework, the conclusion is that the above-mentioned Ziploc, Foodsaver and Vacmaster vacuum packaging plastic bags are all made of polyethylene that does not contain bisphenol A (BPA Free, refer to the link ) (polyethylene), the temperature at which polyethylene softens and decomposes is 90.5 degrees Celsius. Simmering cooks barely above that temperature, so it should be safe at first glance. In addition, Foodsaver's bags are said to be free of estrogenically active (EA) plasticizers, and Vacmaster's bags are said to be safe for boiling.
If you are still uneasy, there is a Spanish brand Lekue that sells reusable food bags made of silicone, which can withstand heat up to 250°C. You can also use airtight stainless steel containers for low temperature cooking, both of which sacrifice vacuum sealing pressure for absolute food safety.
I will talk about my actual cooking experience in the next article, so stay tuned.