US 4,641,005 · Granted 1987-02-03

The Microwave Container That Actually Browns Food

You know how microwave food often comes out pale and sad-looking? This patent solves that by coating the inside of disposable food containers with a super-thin metal layer that heats up in the microwave and browns the food's exterior, just like a conventional oven would. It's basically hiding a tiny heating element in your takeout container.

Curated and verified by the IsItPatented Editorial team

The plain-English version

What it protects

The claim covers a disposable food receptacle with a thin, electrically conductive material (like metal) bonded to the food-contact surfaces via vacuum vapor deposition. What's protected here is the specific combination of the conductive coating layer, its application method, and its integration into a disposable food container designed to heat and brown food during microwave cooking.

Why it matters

Before this patent, microwave cooking had a major weakness: food looked unappetizing because microwaves don't brown. This invention lets manufacturers—especially food companies selling prepared meals—offer microwave-ready products that actually look appetizing straight from the microwave. The technology became the foundation for the browning sleeves and susceptor films now common in frozen food packaging, transforming how millions of people heat their meals.

Real-world use

You've encountered this technology every time you've microwaved a frozen pizza, burger, or fried chicken—those shiny, metallic-looking films inside the packaging are descendants of this patent, designed to crisp and brown the food.

Original USPTO abstract

A disposable food receptacle for use in microwave cooking is disclosed which includes a provision to brown the exterior of the food in the receptacle. A thin layer of an electrically conductive material, such as an elemental metal is incorporated into the receptacle on the food contacting surfaces thereof, so that the conductive layer will become heated by the microwave radiation and will, in turn, brown the exterior of the food in the receptacle. The conductive layer is formed as an extremely thin film deposited on a substrate protective layer by a process of a vacuum vapor deposition.

Patent details

Publication number: US 4,641,005
Filing date: 1986-01-21
Grant date: 1987-02-03
Assignee: James River Corporation
Inventor(s): SEIFERTH; OSCAR E.
CPC class: B65D81/34

View original record on Google Patents →

Want to file your own patent?

If you're thinking about designing a kitchen gadget or food product innovation, check our free patentability scanner to see what's already locked down in food preparation and packaging.

Free patentability scan