Sous Vide : Popular For Taste & Nutrition. But Plastic Contamination Issues Unresolved.

Sous vide (French for “under vacuum“), refers to cooking food in a vacuum-sealed plastic bag immersed in hot water. It is favored by a diverse group of loyal adherents despite peer-reviewed research indicating that heating a plastic can accelerate the leaching of harmful environmental chemicals.

It’s important to know that peer-reviewed studies about the potential safety issues concerning plastic sous vide pouches are limited.

Some scientific tests have found the transfer of chemicals to foods prepared by sous vide. However, as a whole, the area is poorly covered in scientific journals. Please see Addendum 1 at the end of this post for more.

Both the European Union and U.S. FDA have sets of incomplete and mostly incomprehensible standards on the use of plastics in heated foods. For more on this, see Addendum 2.

Sous vide is popular among:

• Professional chefs in high-end restaurants often employ this technique to achieve precise and consistent results.
• Home cooking enthusiasts and “foodies” use it to explore new culinary horizons.
• Health-conscious individuals are drawn to the nutrient retention benefits. Busy professionals find it helpful in minimizing active cooking time.
• Food scientists and researchers employ sous vide when studying cooking processes.
• Catering businesses utilize it for large-scale, precise food preparation. Competitive barbecue teams rely on it for consistent results.
• People with dietary restrictions find it useful for the precise control it offers over ingredients and cooking methods.

Preparation:

Seasoned food is placed in a food-grade plastic bag. It should be noted that no comprehensive or complete regulatory standard exists to define “food grade,” especially at temperatures to properly and safely cook meat.

Once in the plastic bag, air is removed with a vacuum sealer or  water displacement to create an airtight seal.

Water Bath Setup:

A pot is filled with water, and a sous vide precision cooker thermometer is attached.

Cooking:

The sealed bag containing the food is submerged in the water bath. Cooking times vary widely, ranging from as short as 1 hour to as long as 72 hours, depending on the specific food item and desired outcome.

Finishing:

Once cooking is complete, the food is removed from the bag. For meats, an additional step of quickly searing in a hot pan or with a torch is often performed to develop flavor and texture via the The Maillard Reaction, a chemical processs between amino acids and reducing sugars that create melanoidins, — compounds that give browned food its distinctive flavor.

Advantages:

Sous vide cooking offers precise temperature control, ensuring consistent results every time. It allows for even cooking throughout the food and reduces the risk of overcooking.

This method excels at retaining moisture and nutrients within the food. Flavors are often enhanced as the food cooks in its own juices. Sous vide also provides the ability to prepare food in advance and offers convenience for batch cooking.

Disadvantages:

In addition to potential contamination by plastic-based chemicals, sous vide has a number of preparation issues.

There are also potential safety concerns if the technique is not executed properly, particularly regarding bacterial growth at low temperatures.

Finally,  sous vide requires longer cooking times compared to traditional methods, and the initial investment required for equipment such as a precision cooker and vacuum sealer.

Addendum 1: Environmental Chemical Transfer To Food-

Scientific Sources:

As noted in “Scientific Sources”: (below) scientists have detected the transfer of Phthalates and other chemicals in sous vide cooking.

• Identification of volatile and non-volatile migrants released during sous vide cooking by UPLC-IMS-QTOF and DI-SPME-GC-MS using a design of experiments approach
• EFFECT OF SOUS VIDE HEAT TREATMENT ON PHTHALIC ACID ESTERS CONTENT IN MEAT
• THE CONCENTRATIONS OF PHTHALIC ACID ESTERS IN A WATER BATH AT SOUS-VIDE HEAT TREATMENT.

Addendum 2: Incomplete & Incomprehensible Regulations

There are no specific or easily comprehensible standards and considerations for plastic materials used in food contact applications such as sous vide where they are intended to be warmed or heated.

This could be an important area of regulation because heat can increase the rate of migration of substances from the plastic to the food. Sadly, nothing seems to exist to help sous vide chefs know which products are safest to use.

Key points for both the EU and US

United States (US):

1. FDA regulations:
   • 21 CFR 176.170 covers “Components of paper and paperboard in contact with aqueous and fatty foods” and includes temperature considerations.
   • It specifies different food simulating solvents and test conditions based on the intended use, including heated applications.
2. Microwave applications:
   • The FDA has specific guidance for plastics intended for microwave use, as outlined in their “Guidance for Industry: Use of Recycled Plastics in Food Packaging.”
3. Temperature thresholds:
   • Generally, plastics intended for high-temperature applications (above 212°F or 100°C) require specific FDA clearance.
4. Specific polymer regulations:
   • Some polymer-specific regulations include temperature considerations. For example, 21 CFR 177.1520 for olefin polymers specifies different extraction tests based on intended use temperatures.

European Union (EU):

1. Temperature considerations:
   • Regulation (EU) No 10/2011 specifies different testing conditions based on the intended use of the material.
   • For example, materials intended for high-temperature applications are tested at 175°C (347°F).
2. Specific requirements:
   • The regulation includes a table (Table 2 in Annex V) that outlines standardized testing conditions for different temperature scenarios.
   • For instance, “Hot fill” conditions are tested at 70°C for 2 hours, followed by 40°C for 10 days.
3. Declarations of compliance:
   • Manufacturers must provide information on the maximum temperature at which the material can be safely used.
4. Dual-use additives:
   • Special attention is given to additives that are also permitted as food additives, as these might migrate more at higher temperatures.

Common considerations for both regions:

1. Migration testing:
   • Both regulations require migration testing under conditions that simulate the intended use, including temperature.
2. Overall migration limits:
   • These limits (typically 10 mg/dm² in the EU) must be met even under high-temperature conditions.
3. Specific migration limits (SMLs):
   • Individual substances may have SMLs that must be adhered to under various temperature conditions.
4. Good Manufacturing Practices (GMPs):
   • Both regions require manufacturers to follow GMPs, which include considerations for temperature resistance.
5. Reusability:
   • For materials intended for repeated use (like microwave containers), the regulations consider the cumulative effects of repeated heating cycles.

It’s important to note that these regulations are complex and can vary based on the specific type of plastic, its intended use, and the type of food it will contact.

Manufacturers should conduct extensive testing to ensure compliance for their products, especially for high-temperature applications such as sous vide. If and when that testing is performed , the results, along with procedures and the identity of the testers and their relationship too the manufacturer should be available via a web link  to prospective customers online, in ads, promotions and point of sale packaging.