Thanks to Linode for supporting this SciShow video! That link gives you a $100 60-day credit on a new Linode account. You might not think about the food in your freezer much, except when trying to find room between the bags of peas and carrots for one more bag of French fries. But those frozen fries — and everything else in your freezer — are surprisingly worthy of pondering, given that they’re the end result of a pretty clever innovation. As it turns out, getting things from where they were grown or harvested into your freezer is harder than you would think, and doing it wrong leaves you with food that’s basically ruined. The technique that keeps your frozen broccoli green and your dumplings fresh helped solve major problems with nutrition in the 20th century. And it all started with a guy going fishing. We know that things like meat and produce can spoil quickly. In warm temperatures, organic matter becomes an ideal breeding place for decomposers and pathogenic bacteria. Those microbes can make you sick, or at the very least, make your food look and taste bad. So preventing foods from spoiling has been an important thing for us for an extremely long time. One particular concern is Staphylococcus, which is the kind of food poisoning you are most likely most familiar with. It causes sudden onset of nausea and vomiting that usually lasts around a day. I had it earlier this year…meatballs! Staphylococcus thrives when food is kept at temperatures between 4 and 60 degrees Celsius for more than two hours, so inconsistently cold temperatures are somewhat risky. There’s also another food illness classic, E.coli. E.coli can even survive in dried meat, so lots of food storage methods that work on a lot of things still can’t beat it. Fermenting and canning might be tricky, too. If you don’t do it right, you could end up accidentally making the perfect breeding ground for the bacteria that causes botulism. Botulism is an especially dangerous kind of food poisoning that affects the nervous system and may even lead to paralysis and death. The only method of food storage that prevents your food from wilting and keeps you from getting sick is freezing it. So you’d think that once we had the technology to keep stuff cold, we’d be freezing our food all the time, right? Well, not so much. It turns out that freezing food is harder than you’d think. At least, it’s difficult if you want that food to still taste good at the end. Early efforts at bringing frozen foods to the masses turned once-delicious veggies into a soggy, tasteless mess when they thawed. When food freezes slowly, the water can form large ice crystals that puncture the cell membranes of whatever’s being frozen, causing those changes in texture and quality. This is especially noticeable in things like frozen produce, because the plants’ cell walls get broken apart by the ice crystals and they lose all their structure, leading to gross, mushy veggies. Plus, when these foods thaw they release a lot of water, and with it, a lot of their flavor. So frozen food wasn’t exactly appealing to most consumers, and there just wasn’t demand for it. But then, along came Clarence Birdseye. And you may have heard that name before. It might even be on one or two packages of frozen veggies in your freezer right now. While living in northeast Canada, he noticed that when he went ice fishing with some Inuit people, their fish that they caught would freeze almost immediately after it got tossed onto the ice. And, those fish tasted perfectly fresh when they were thawed out and cooked, even for months after being caught. Birdseye realized that fast-freezing leads to smaller ice crystals, which cause less damage to the food and results in a better product. So beginning in the 1920’s, he used that knowledge to develop two novel ways to freeze food quickly. In the first method, packages of food were placed between two metal plates cooled with a calcium chloride solution to around -40°C. The second method used a combination of temperature and pressure to cool the food to -32°C in 30 minutes using ammonia and hollow metal plates. However, it was not just the cooling process that made Birdseye’s frozen food successful; they also developed new ways to package food, such as using waterproof containers and removing air before sealing. This helped keep moisture in the food, making frozen food a much better option. Despite this, it took some time for frozen foods to become popular as most people did not have a freezer at home until after World War II.
Birdseye’s innovations had a great impact as it gave people access to produce year-round, providing culinary variety and healthier, more nutritious diets.
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