Can you boil food in a Ziploc bag? (5 Tips)

In this brief guide, we will answer the question, can you boil food in a Ziploc bag? We will discuss some reasons to refrain from boiling food in a Ziploc bag and some alternative bags that you can use to boil food in. 

Can you boil food in a Ziploc bag?

You cannot boil food in a Ziploc bag. Ziploc Bags are made of plastic, hence cannot stand high temperatures. A high temperature that exceeds even 149 Fahrenheits would make the plastic melt. In the case of the plastics that compose Ziploc bags, the melting temperature is of circa 230°F or 110°C (2).

According to the manufacturers website, the materials used to produce Ziploc bags are Polyethylene-Low Density, also known as LDPE,commonly used in rigid plastic containers and Polyethylene-Linear Low Density, also known as LLDPE, which is commonly used in packaging, containers and wraps such as bubble wraps. Both are approved for use in products that come into direct contact with food. Polyethylene-Low Density can withstand both heat and freezing and meet the safety requirements of the U.S. Food and Drug Administration (FDA) for temperatures associated with defrosting and reheating food in microwave ovens, as well as room, refrigerator, and freezer temperatures.

It is estimated that the share of the so-called advanced packaging represents approximately 5% of the total value of the packaging market, of which 35% belongs to active systems (1).

Is Ziploc safe?

Ziploc is made of polyethylene, a few other plastics, and dyes. Luckily, Ziploc claims to be free of the chemical Bisphenol-A. However, there are studies to prove otherwise and if you use Ziploc for cooking, you need to stick to a safe temperature. 

However, some other additives commonly used, slip additives to prevent films from sticking together, such as oleamides, stearamide, erucamide, stearyl erucamide, and oleyl palmitamide, are able to migrate into food during storage. In a study, the highest migration of such additives occurred from polyolefins LDPE to olive oil (2).

Why is it discouraged to boil food in a Ziploc bag?

While Ziploc is manufactured to minimize the negative impact on health by eliminating BPA, dioxins, and chlorine, using it to boil in water is a risky business. 

However, the Zip n Steam bag was purposefully designed to be used in the microwave, and characteristics such as temperature and heat medium have an impact on how food interacts with the Ziploc bag. 

Presence of additives such as antioxidants, plasticizers, heat and light stabilizers, lubricants, UV printing inks components or slip additives etc. in the polymer matrix allows the modification or improvement of the polymer properties and performance. However, the migration of such additives to food causes adverse health effects on the human body such as elevated cholesterol level, reproductive problems like low infant birth weights, some immunological problems such as lowering of immune functions, liver and kidney damage, thyroid functions, and cancer in some cases (4).

You can reheat food in the microwave if it is in a Ziploc bag. The Ziploc freezer bag is meant to be stored in the freezer but it can be put in the microwave. 

The microwave produces energy called microwaves which affect the food only and does not have an impact on the Ziploc bag. If any other source of energy such as heat would be applied, the bag might not do well to serve its purpose. 

Ziploc brand bags have a softening point of 195 degrees, which means they would melt at boiling point, 212 degrees (3).

When the temperature of Polyethylene exceeds 149 Fahrenheit, the substance starts to break down. Studies show that at even lower temperatures (104°F), additives migrated from the LDPE material to the food during storage (2). As Ziploc softens, it releases its residues which can easily make their way into your stomach. If you are adamant about boiling food in a bag, you can opt for the ones that are specifically designed to handle the high temperature. Serious health risks may arise when the amount of unreacted monomers or low-molecular-weight substances in food reaches to a specified limit and thus absorbed by the human body (2).

If you exceed the temperature of the water that you are boiling your food in; the Ziploc it is secured in makes it rip open the seal and expose your food to water. Hence, if you plan on attaining a temperature that is greater than 158 Fahrenheit, use two Ziplocs, one over the other, to make it secure. 

Which bags do I use for sous-vide-style cooking?

Sous-vide Style cooking requires a heat-resistant bag to put your food in and let it cook. Boiling eggs in bags is also gaining acceptance as a way of making bag-omelet. People who are always on the go or looking for convenient ways to cook, benefit the most from such techniques. 

Sous vide is French for ‘‘under vacuum’’ and sous vide cooking is defined as ‘‘raw materials or raw materials with intermediate foods that are cooked under controlled conditions of temperature and time inside heat-stable vacuumized pouches”. Sous vide cooking differs from traditional cooking methods in two fundamental ways: the raw food is vacuum-sealed in heat-stable, food-grade plastic pouches and the food is cooked using precisely controlled heating (5).

 For sous-vide Style cooking, the kind of bag recommended is either a Vacuum-style bag or a reusable silicone bag. The bags that are designed to withstand high temperatures would stay safe and provide you with the assurance that your health is not at stake. 

There is a lack of data on the chemicals leaching specifically from sous vide bags. The Environmental Epidemiology Program at the Utah Department of Health recommends the use of appropriate plastic bags for sous vide that follow current FDA guidelines and are free of BPA and phthalates. Bags and pouches used in sous vide should be made of food grade plastics such as high density polyethylene, low density polyethylene, and polypropylene (6).

The official advice from Sous vide manufacturer is to use food-grade vacuum sealing bags. Vacuum bags are BPA-free and made of polyethylene which makes them safe for use as a boiling medium. 

Some tips to keep safe if you plan to heat a Ziploc bag:

The heating of food directly in the ziploc bag is not safe and it must be avoided. 

However, if you do it, do not exceed the temperature of 195°F.

• Do not use a plastic bag that you suspect contains BPA; while never heat a plastic bag that has Polyvinyl Chloride (PVC) or polycarbonate plastic as a constituent. Bisphenol is a carcinogenic compound and has estrogen-mimicking properties. 
• Look for instructions and adhere to the usage guidelines provided. Check the minimum and maximum temperature that you are allowed to expose the plastic to and be wary of them. 
• When you heat the bag, make sure to leave a small opening to allow the gas to escape. The build-up of gas could make the bag explode, thus wasting your food and creating a mess. 
• To seal food securely inside a Ziploc bag, submerge the bag in a bowl of water. Before you submerge the Ziploc, make sure there is a slight space near the seam. 
• Do not seal the Ziploc all the way through as you drop the bag in the water; the zipper area should be exposed to air. The pressure in water will assist you in removing air and making the Ziploc airtight. 

In this brief guide, we answered the question, can you boil food in a Ziploc bag? We discussed some reasons to refrain from boiling food in a Ziploc bag and some alternative bags that you can use to boil food in. 

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