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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. [♪ INTRO] 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, packages of food were placed  between two metal plates that had been cooled with a calcium chloride solution  to around minus 40 degrees celsius. The second method used a combination  of both temperature and pressure.

They used ammonia to cool hollow metal plates, and the food was pressurized  between the cooled plates. And that process could chill some foods down  to minus 32 degrees celsius in just 30 minutes. But the key to Birdseye’s success  wasn’t just in getting things cold.

Birdseye also developed new ways to package food, including using waterproof containers  and removing air before sealing. All of these innovations helped keep  moisture in the food, so when it was thawed it would still retain its quality, making  frozen food a much better option all around! Still, it took some time for  frozen foods to catch on.

Or rather, it took some time for the technology  to catch up with what Birdseye was selling, since in the 1930’s most people didn’t have  a freezer at home to store frozen foods in. Freezers didn’t start finding their way into  people’s homes until after World War II. And eventually, frozen foods finally  started to gain traction in American homes.

Birdseye’s innovations  matter for a lot of reasons, and not just because they gave us all  unfettered access to frozen French fries. Before Birdseye’s frozen food, lots of people  weren’t able to eat produce year-round. Instead, they ate what they  could during the growing season, and then the rest of the time  produce just wasn’t available.

Frozen food gave people access  to produce all year long. This was great for providing culinary  variety, but it was also important because it helped people maintain  healthier, more nutritious diets year-round. So that guy whose name might very well  be on your frozen peas and carrots wasn’t just the founder of a profitable  business, he was also a guy who saved us all from long winters with nothing  to eat except bread and pickles.

Who knew there was so much interesting food  history hiding behind those ice cream pints? This SciShow video is supported by Linode,  a cloud computing company from Akamai. Linode helps keep the global internet  running by providing storage space, databases, analytics and  more to you and your company.

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They do that! Need a tutorial or a 24/7 award-winning  customer support representative to help you through all these processes? They provide it all!

If you’re cloud-curious but don’t know  what I’m talking about, you can read their beginner’s guide to cloud computing  at linode.com/what-is-cloud-computing. And once you feel confident about your  decision to get started with Linode, you can click the link in the  description or head to linode.com/scishow for a $100 60-day credit on a new Linode account. Thanks to everybody who  worked on this SciShow video and thank you for watching all the way to the end! [♪ OUTRO]