Removing the Seal Under the Lid of Food Containers: Why It Matters
Diet & NutritionFood Safety

Why You Should Remove the Seal Under the Lid of a Food Container

Dairy food products often have a foil or plastic seal under the lid to help preserve freshness — but once the seal is broken, it’s actually better to remove it, according to experts. Here’s why.
Why You Should Remove the Seal Under the Lid of a Food Container
Bowonpat Sakaew/iStock
By
Annita Katee
Updated on October 29, 2025
by

Food products, especially dairy options like yogurt and sour cream, may have a plastic or foil seal under the lid. You might wonder whether you should remove this seal when you open the product or keep it in place for extra coverage.

Here’s why the foil or plastic seals on food containers exist in the first place and why removing it actually helps keep your product fresher, according to experts.

Why Do Food Containers Have These Seals?

“There are two reasons for the seal,” says Jason Tetro, a microbiologist and the author of The Germ Files and The Germ Code, who’s based in Edmonton, Alberta. “Firstly, it helps to increase shelf life — the container is usually flushed with nitrogen before sealing, which reduces the amount of oxygen inside.”

This is important because once oxygen begins to interact with the food, oxidation can occur. Oxidation is a chemical process that can negatively affect the food’s color, flavor, and nutritional value.

The second reason is to protect the contents of the container: “It helps to prevent the introduction of chemicals and microbes that could spoil the products or cause illnesses,” Tetro says.

The microbial ecologist Jack Gilbert, PhD, a professor at the University of California in San Diego, who’s based in Encinitas, California, further explains that the seal acts as a safety and quality mechanism because it creates a barrier between the product and the external environment.

This helps keep out microorganisms that could lead to bacteria, mold, or yeast forming on the food, though illness-causing pathogens can grow on food without any noticeable changes in color, look, or taste.

Lastly, the seal indicates to consumers that the product hasn’t been tampered with prior to purchase, Dr. Gilbert says.

The U.S. Food and Drug Administration (FDA) advises examining all food products before consumption to ensure the safety seal hasn’t been removed, opened, or damaged in any way.

Why You Should Remove the Seal After Opening

For several reasons, Tetro recommends removing the plastic or foil safety seal as soon as you open the product.

“Once the seal is broken, the surrounding air and oxygen can get into the product, and that will start up the microbial growth,” says Tetro. “Whether the seal is still there or not [after it’s been opened] isn’t a factor. Its sole purpose is to get [the product] from the factory to your kitchen safely.”

What’s more, keeping the seal on the open product can lead to a higher risk for contamination from continual touching, according to Tetro.

Touching food with germy hands — for example, if someone doesn’t wash their hands after using the toilet or handling raw chicken, then grabs an open yogurt container from the fridge and lifts up the unremoved safety seal — can transfer disease-causing bacteria onto the food. Those pathogens can then spread to anyone who eats the contaminated food.

It’s best to always wash your hands before handling any food products. And toss the plastic or foil safety seal on items like yogurt or cottage cheese into the trash after you first open the product, just to be safe.

The Takeaway

  • Remove the plastic or foil seal from food containers after opening, as leaving it on may increase the risk of contamination from repeated touching.
  • The seal serves to prevent microbial growth and chemical exposure only before the product is opened, not after.
  • Always inspect food safety seals before purchase to ensure they haven't been tampered with or damaged.
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
  1. How Food Spoils. University of Nebraska-Lincoln. 2024.
  2. Food Tampering, An Extra Ounce of Caution. U.S. Food and Drug Administration. March 5, 2024.
  3. 5 Common Ways Germs are Spread. Minnesota Department of Health. October 4, 2022.
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Justin Laube

Justin Laube, MD

Medical Reviewer

Justin Laube, MD, is a board-certified integrative and internal medicine physician, a teacher, and a consultant with extensive expertise in integrative health, medical education, and trauma healing.

He graduated with a bachelor's in biology from the University of Wisconsin and a medical degree from the University of Minnesota Medical School. During medical school, he completed a graduate certificate in integrative therapies and healing practices through the Earl E. Bakken Center for Spirituality & Healing. He completed his three-year residency training in internal medicine at the University of California in Los Angeles on the primary care track and a two-year fellowship in integrative East-West primary care at the UCLA Health Center for East-West Medicine.

He is currently taking a multiyear personal and professional sabbatical to explore the relationship between childhood trauma, disease, and the processes of healing. He is developing a clinical practice for patients with complex trauma, as well as for others going through significant life transitions. He is working on a book distilling the insights from his sabbatical, teaching, and leading retreats on trauma, integrative health, mindfulness, and well-being for health professionals, students, and the community.

Previously, Dr. Laube was an assistant clinical professor at the UCLA Health Center for East-West Medicine and the David Geffen School of Medicine at UCLA, where he provided primary care and integrative East-West medical consultations. As part of the faculty, he completed a medical education fellowship and received a certificate in innovation in curriculum design and evaluation. He was the fellowship director at the Center for East-West Medicine and led courses for physician fellows, residents, and medical students.

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Annita Katee

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