Clarence Birdseye Watched Inuit Fishermen Pull Fish From a Hole in the Ice and Worked Out Why Frozen Food Tasted Bad

US1773079 was filed by Clarence Birdseye on June 18, 1927, under the title Method of Preparing Food Products. It is one of a large group of patents he filed through the 1920s, and together they created the frozen food industry.

The thing worth understanding is that Birdseye did not invent freezing food. People had been doing that for as long as there had been cold places. He worked out why the results were usually terrible.

Labrador

Birdseye spent time in Labrador in the 1910s working as a fur trader and naturalist. The winters there run far below zero, and he watched local Inuit fishermen pull fish up through holes cut in the ice.

What he noticed is that the fish froze almost the instant they hit the air, which at those temperatures could be forty below. And when those fish were thawed and cooked weeks or months later, they tasted like fresh fish. Not acceptable fish. Fresh.

This did not match what he knew about frozen food back home, which was widely regarded as a last resort. Commercially frozen fish in the United States at the time was mushy, watery, and unpleasant, to the point that frozen goods carried a genuine stigma and sold at a discount.

Same fish. Same freezing. Completely different result.

The size of the crystals

The explanation is the entire patent, and it is a nice piece of physics.

When water freezes slowly, the ice organizes itself into large crystals. Inside a piece of meat or fish, that water is held within cells and between muscle fibers, and large crystals growing in that space act like blades. They puncture cell walls and tear the fiber structure apart.

The damage is invisible while the food stays frozen. It shows up on thawing, when the ruptured cells cannot hold their liquid any more. The moisture runs out, taking flavor compounds with it, and what is left is the limp, dry, watery texture that gave frozen food its bad name. The food was not spoiled. It was structurally destroyed.

When water freezes very fast, there is no time for large crystals to form. You get a great many very small crystals instead, small enough that they sit within the tissue without slicing it open. The cell walls survive. On thawing, the food holds its own moisture, and it behaves like fresh food because structurally it still is.

Slow freezing and fast freezing are not different degrees of the same process. They produce physically different material.

Turning that into a machine

Knowing this does not get you a product. The engineering problem is removing heat from food fast enough, in industrial quantities, on a factory floor.

Birdseye's approach was to package the food first, in flat, relatively thin cartons, and then press those packages between metal plates chilled to well below freezing. Metal conducts heat far better than air does, contact on both faces halves the distance heat has to travel, and a thin flat package has very little interior that is far from a cold surface.

That combination is what makes the freeze fast enough. The system is usually described as the multiplate quick freeze machine, and the principle is still how commercial freezing works.

The flat rectangular package that frozen food still comes in is not a merchandising choice. It is a consequence of the physics.

What he sold, and for how much

Birdseye founded a company, struggled with it, and in 1929 sold the business and patents to Postum Company and Goldman Sachs for $22 million, which was an enormous sum. The buyer became General Foods, and the brand kept his name, respaced as Birds Eye.

He had to solve one more problem that was not technical. Almost nobody owned a freezer. Grocery stores had no way to hold frozen goods and no reason to want them. The company ended up leasing freezer display cases to retailers cheaply, because the product could not exist without a distribution chain that had never been built.

Birdseye held close to 300 patents when he died. The frozen food aisle exists because a fur trader paid attention to how fast a fish stopped moving.

See the original

The full text and figures of US1773079 are on Google Patents.