1 00:00:02,120 --> 00:00:09,399 Speaker 1: Welcome to brain stuff from how stuff works. Hey, I'm 2 00:00:09,480 --> 00:00:12,080 Speaker 1: Christian Seger, and this is brain stuff. You know when 3 00:00:12,080 --> 00:00:14,320 Speaker 1: you reach inside the fridge and your loaf of bread 4 00:00:14,360 --> 00:00:17,439 Speaker 1: has turned green and it's covered with white wisps of mold, 5 00:00:17,880 --> 00:00:20,599 Speaker 1: or when your tomatoes look like a deflated balloon and 6 00:00:20,640 --> 00:00:23,520 Speaker 1: they have spores growing out the top. It's even worse 7 00:00:23,560 --> 00:00:26,400 Speaker 1: when those spores start turning black and wrinkly and they 8 00:00:26,440 --> 00:00:30,280 Speaker 1: bore into your food and spread out their fungal roots. Obviously, 9 00:00:30,520 --> 00:00:33,239 Speaker 1: we're all disgusted by this kind of imagery, as if 10 00:00:33,280 --> 00:00:36,000 Speaker 1: we've got some kind of natural revulsion despoiled food, and 11 00:00:36,000 --> 00:00:38,720 Speaker 1: we all scream that's gross and probably dangerous. Do not 12 00:00:38,840 --> 00:00:42,680 Speaker 1: put it in your mouth. Well, luckily we have refrigerators 13 00:00:42,680 --> 00:00:46,360 Speaker 1: which slow the growth of bacteria on our food. Freezers 14 00:00:46,360 --> 00:00:49,640 Speaker 1: will do you one better by stopping bacteria completely by 15 00:00:49,640 --> 00:00:53,559 Speaker 1: freezing them solid. But we can't freeze everything. Some foods, 16 00:00:53,640 --> 00:00:57,480 Speaker 1: like let us, milk or eggs are less than appetizing 17 00:00:57,560 --> 00:01:01,080 Speaker 1: after you freeze them, And imagined trying to thaw orange 18 00:01:01,160 --> 00:01:04,080 Speaker 1: juice every morning. There's got to be some middle ground 19 00:01:04,160 --> 00:01:07,679 Speaker 1: between freezing your food rock solid and leaving it out 20 00:01:07,720 --> 00:01:11,800 Speaker 1: to rot. So what's the best temperature to set the 21 00:01:11,800 --> 00:01:14,840 Speaker 1: inside of your fridge at? Well, before I answer that, 22 00:01:14,959 --> 00:01:21,240 Speaker 1: let's understand spoilage a little bit better. Basically, microscopic organisms 23 00:01:21,280 --> 00:01:26,240 Speaker 1: are constantly feasting on our unattended food items. Spoilage bacteria 24 00:01:26,319 --> 00:01:31,120 Speaker 1: are fast and inevitable. They're constantly consuming tiny portions of 25 00:01:31,120 --> 00:01:33,959 Speaker 1: our food and then spreading their waste all over it. 26 00:01:34,240 --> 00:01:37,679 Speaker 1: M M. That's what makes rotten food smell foul and 27 00:01:37,720 --> 00:01:42,720 Speaker 1: appear spoiled. And bacteria multiply, sometimes rapidly. As long as 28 00:01:42,840 --> 00:01:46,840 Speaker 1: nutrition and water are present, bacteria be making babies. While 29 00:01:46,840 --> 00:01:50,240 Speaker 1: there are many methods to detect bacteria, most take several 30 00:01:50,240 --> 00:01:53,600 Speaker 1: hours unless you've got an infrared light handy to trace 31 00:01:53,840 --> 00:01:57,840 Speaker 1: their biochemical footprints. Even if you can find them, not 32 00:01:58,120 --> 00:02:02,520 Speaker 1: all bacteria are necessarily bad. For instance, a certain degree 33 00:02:02,520 --> 00:02:06,720 Speaker 1: of bacteria are necessary to prevent illness. Others are used 34 00:02:06,720 --> 00:02:10,160 Speaker 1: by food manufacturers to enhance the taste or texture of 35 00:02:10,200 --> 00:02:14,440 Speaker 1: their products. Bacteria in beer can control its calorie content. 36 00:02:14,800 --> 00:02:18,520 Speaker 1: The holes in Swiss cheese occur when bacteria use lactic 37 00:02:18,560 --> 00:02:22,679 Speaker 1: acid to produce bubbles of carbon dioxide gas that leave 38 00:02:22,760 --> 00:02:26,520 Speaker 1: holes behind. And of course, there's yogurt that stuff has 39 00:02:26,560 --> 00:02:32,200 Speaker 1: bacteria a plenty, containing probiotic enzymes that produce vitamins, enhanced digestion, 40 00:02:32,600 --> 00:02:37,160 Speaker 1: and aid our absorption of nutrients. But for the most part, 41 00:02:37,400 --> 00:02:40,639 Speaker 1: visible bacteria and mold is a sign that food is 42 00:02:40,800 --> 00:02:45,760 Speaker 1: not suitable to eat. Some can even be lethal, like salmonella, E. 43 00:02:45,880 --> 00:02:50,240 Speaker 1: Coli and listeria. So what's our best solution? Using our 44 00:02:50,320 --> 00:02:55,079 Speaker 1: cold refrigerators to slow bacteria's growth without also freezing our food. 45 00:02:55,600 --> 00:02:59,040 Speaker 1: The US Food and Drug Administration recommends that you keep 46 00:02:59,080 --> 00:03:04,040 Speaker 1: your refrigerator at or below forty degrees fahrenheit or four 47 00:03:04,080 --> 00:03:08,760 Speaker 1: degrees celsius. Anything higher and the food will spoil too quickly. 48 00:03:09,240 --> 00:03:11,680 Speaker 1: For the food that you can freeze, you'll want the 49 00:03:11,720 --> 00:03:16,880 Speaker 1: temperature to be zero degrees fahrenheit or negative eighteen degrees celsius. 50 00:03:17,280 --> 00:03:21,080 Speaker 1: Check both of these periodically with a digital appliance thermometer. 51 00:03:21,160 --> 00:03:24,040 Speaker 1: And you want another tip, don't jam your fridge full 52 00:03:24,120 --> 00:03:27,360 Speaker 1: of stuff. This prevents the proper air circulation needed and 53 00:03:27,440 --> 00:03:31,160 Speaker 1: can hasten spoilage in the freezer. However, feel free to 54 00:03:31,320 --> 00:03:35,480 Speaker 1: fill her up. A full freezer actually cools more efficiently. 55 00:03:40,240 --> 00:03:42,480 Speaker 1: Check out the Brainstuff channel on YouTube and for more 56 00:03:42,520 --> 00:03:45,040 Speaker 1: on this and thousands of other topics. Visit how stuff 57 00:03:45,080 --> 00:03:59,840 Speaker 1: works dot com.