1 00:00:01,920 --> 00:00:06,440 Speaker 1: Welcome to brain Stuff production of I Heart Radio. Hi 2 00:00:06,519 --> 00:00:09,680 Speaker 1: brain Stuff, I'm Lauren vogel Bomb and this this is 3 00:00:09,680 --> 00:00:13,080 Speaker 1: a classic episode from our archives. In this one, we 4 00:00:13,160 --> 00:00:15,960 Speaker 1: explore a question that's near and dear to my heart 5 00:00:16,239 --> 00:00:20,320 Speaker 1: because I love the taste of coffee. So why does 6 00:00:20,520 --> 00:00:26,439 Speaker 1: microwaved coffee taste so bad? Hey, brain Stuff, Lauren volke 7 00:00:26,520 --> 00:00:30,000 Speaker 1: Bomb Here. Hot coffee is supposed to be hot. Cold 8 00:00:30,000 --> 00:00:32,440 Speaker 1: coffee is supposed to be cold, and that's the deal. 9 00:00:32,800 --> 00:00:36,280 Speaker 1: It's pretty simple. The problem, then, with hot coffee is 10 00:00:36,320 --> 00:00:38,599 Speaker 1: that you can't drink the whole cup while it's at 11 00:00:38,600 --> 00:00:41,720 Speaker 1: the optimal temperature unless you're willing to really guzzle it. 12 00:00:42,560 --> 00:00:44,800 Speaker 1: So when it gets cold, you've got a few choices. 13 00:00:45,240 --> 00:00:48,280 Speaker 1: Drink it cold, reheat it, or just pour that cup 14 00:00:48,280 --> 00:00:50,440 Speaker 1: down the drain and start over with a fresh pot. 15 00:00:51,120 --> 00:00:53,880 Speaker 1: All three of these approaches are either perfectly fine or 16 00:00:53,960 --> 00:00:58,000 Speaker 1: completely barbaric, depending on whom you ask to Some hot 17 00:00:58,040 --> 00:01:01,480 Speaker 1: coffee that's gone cold is revolting to others. The reheating 18 00:01:01,520 --> 00:01:05,640 Speaker 1: process renders it completely undrinkable, but that doesn't stop us 19 00:01:05,680 --> 00:01:08,880 Speaker 1: from occasionally popping a cup of nine hour old office 20 00:01:08,959 --> 00:01:11,600 Speaker 1: Joe into the microwave at four pm to power through 21 00:01:11,680 --> 00:01:17,000 Speaker 1: until bedtime out of some combination of desperation and mild masochism. 22 00:01:17,319 --> 00:01:21,039 Speaker 1: Research into why reheating this humble drink is pretty much 23 00:01:21,040 --> 00:01:23,760 Speaker 1: non existent, but it most likely has to do with 24 00:01:23,800 --> 00:01:27,560 Speaker 1: our sense of smell. Humans aren't great at separating our 25 00:01:27,560 --> 00:01:31,920 Speaker 1: gusta tory that's taste and olfactory that smell responses, and 26 00:01:32,080 --> 00:01:35,200 Speaker 1: coffee has aromas and flavors that hit all five of 27 00:01:35,200 --> 00:01:37,360 Speaker 1: the tastes that can be picked up by your tongue 28 00:01:37,400 --> 00:01:42,240 Speaker 1: and other mouth and nasal passage nerves sweet, salty, bitter, sour, 29 00:01:42,400 --> 00:01:46,160 Speaker 1: and savory. So your personal sense of smell has a 30 00:01:46,200 --> 00:01:49,240 Speaker 1: lot to do with how coffee tastes to you, whatever 31 00:01:49,280 --> 00:01:53,520 Speaker 1: it's temperature, and however that temperature was achieved. That's because 32 00:01:53,560 --> 00:01:57,520 Speaker 1: the chemical makeup of coffee is astoundingly complex. Even though 33 00:01:57,520 --> 00:02:00,960 Speaker 1: its reputation relies heavily on the presence of caffeean coffee 34 00:02:00,960 --> 00:02:05,200 Speaker 1: gets its flavor from around a thousand different chemical compounds. Also, 35 00:02:05,400 --> 00:02:07,760 Speaker 1: the final flavor of the coffee you enjoyed this morning 36 00:02:08,000 --> 00:02:10,880 Speaker 1: was the product of a dizzy ng array of variables, 37 00:02:10,919 --> 00:02:14,320 Speaker 1: including the temperature and weather conditions the beans grew under. 38 00:02:14,680 --> 00:02:17,600 Speaker 1: When the beans were harvested, how they were dried, stored, 39 00:02:17,639 --> 00:02:20,920 Speaker 1: and roasted, and how they were ground and brewed. So 40 00:02:21,200 --> 00:02:24,440 Speaker 1: while the compound three methyl buttinol might make your cup 41 00:02:24,480 --> 00:02:27,600 Speaker 1: of joe taste a little caramel like and ethyl no no, 42 00:02:28,000 --> 00:02:30,560 Speaker 1: it may give it some fruity or notes. Each step 43 00:02:30,600 --> 00:02:33,760 Speaker 1: of the process either brings out or suppresses any one 44 00:02:33,800 --> 00:02:37,960 Speaker 1: of these aromatic compounds differently, which brings us to reheating. 45 00:02:38,919 --> 00:02:42,120 Speaker 1: We spoke with Christopher Hendon, a postdoctoral fellow at the 46 00:02:42,200 --> 00:02:45,280 Speaker 1: Chemistry Department at m I T and author of Water 47 00:02:45,360 --> 00:02:48,520 Speaker 1: for Coffee, a book about how coffee interacts with water. 48 00:02:49,160 --> 00:02:53,079 Speaker 1: He said reheating coffee in principle can be an absolutely 49 00:02:53,080 --> 00:02:56,800 Speaker 1: fine approach to achieving a tasty beverage. In practice, this 50 00:02:56,919 --> 00:03:00,079 Speaker 1: is not usually observed because people reheat in ways to 51 00:03:00,160 --> 00:03:04,000 Speaker 1: promote the loss of delicious volatile compounds, and so the 52 00:03:04,040 --> 00:03:07,680 Speaker 1: process of heating, cooling, and heating again drives smelling and 53 00:03:07,720 --> 00:03:12,000 Speaker 1: tasty compounds out of the cup. According to Hendon, coffee 54 00:03:12,040 --> 00:03:14,200 Speaker 1: experts seem to prefer a drink that has been brewed 55 00:03:14,280 --> 00:03:17,919 Speaker 1: within the previous five to twenty minutes. It turns out 56 00:03:18,080 --> 00:03:20,600 Speaker 1: most people prefer the coffee as it cools to around 57 00:03:20,639 --> 00:03:24,040 Speaker 1: a hundred and fifty degrees fahrenheit that's sixty five degrees celsius. 58 00:03:24,639 --> 00:03:26,800 Speaker 1: This has to do with the way our taste pathways 59 00:03:26,840 --> 00:03:30,040 Speaker 1: respond to temperature in our food. But when we put 60 00:03:30,080 --> 00:03:32,240 Speaker 1: something in our mouth that's too hot or too cold, 61 00:03:32,480 --> 00:03:34,880 Speaker 1: we can't detect all of the compounds that contribute to 62 00:03:34,880 --> 00:03:38,280 Speaker 1: its flavor. Since coffee has loads of these compounds, the 63 00:03:38,320 --> 00:03:42,200 Speaker 1: temperature of the drink can affect the taste. Brewing the 64 00:03:42,240 --> 00:03:46,040 Speaker 1: coffee brings out certain aromatic compounds, but whether the cooling 65 00:03:46,080 --> 00:03:50,040 Speaker 1: process changes the chemistry seems to be controversial. Hendon says 66 00:03:50,120 --> 00:03:53,160 Speaker 1: it is absolutely benign, while others claim it makes the 67 00:03:53,240 --> 00:03:56,040 Speaker 1: drink more acidic as the coffee is exposed to air 68 00:03:56,160 --> 00:04:00,280 Speaker 1: and oxidizes. Reheating coffee to the same temperature it was 69 00:04:00,320 --> 00:04:02,640 Speaker 1: when it was first brewed might help you reach that 70 00:04:02,720 --> 00:04:06,000 Speaker 1: sweet spot temperature wise, but it also has the potential 71 00:04:06,040 --> 00:04:09,480 Speaker 1: to cause additional chemical reactions that further alter the flavor. 72 00:04:10,200 --> 00:04:12,680 Speaker 1: And if you're reheating coffee that already has milk or 73 00:04:12,680 --> 00:04:16,599 Speaker 1: sugar in it, that's even more in the way of flavors, proteins, chemicals, 74 00:04:16,640 --> 00:04:21,360 Speaker 1: and compounds to contend with. So although many coffee connoisseurs 75 00:04:21,440 --> 00:04:23,640 Speaker 1: will tell you it's a lost cause once your coffee 76 00:04:23,640 --> 00:04:26,800 Speaker 1: goes cold. Others say it's just important to reheat your 77 00:04:26,839 --> 00:04:29,679 Speaker 1: coffee as slowly as you can in order to prevent 78 00:04:29,720 --> 00:04:34,000 Speaker 1: additional chemical reactions. But if you're reheating in the microwave, 79 00:04:34,240 --> 00:04:37,120 Speaker 1: don't worry about ghosts of past foods heated in that 80 00:04:37,200 --> 00:04:40,680 Speaker 1: microwave coming back to haunt your coffee. Hand And said, 81 00:04:41,000 --> 00:04:44,920 Speaker 1: the concentration of the volatile chemical composition of say, splattered 82 00:04:44,960 --> 00:04:47,799 Speaker 1: pasta sauce, is pretty low, so I would be surprised 83 00:04:47,839 --> 00:04:50,479 Speaker 1: if we could attribute the bad taste of microwaved coffee 84 00:04:50,480 --> 00:04:54,720 Speaker 1: to only that. Our advice crank your microwaves power down 85 00:04:54,720 --> 00:04:57,760 Speaker 1: to or lower and sap your cup of coffee in 86 00:04:57,920 --> 00:05:01,719 Speaker 1: thirty second intervals to prevent does faster. But of course 87 00:05:01,960 --> 00:05:09,880 Speaker 1: we encourage you to run your own experiments. Today's episode 88 00:05:09,920 --> 00:05:13,040 Speaker 1: is based on the article hand Signs Explain why microwave 89 00:05:13,160 --> 00:05:16,159 Speaker 1: coffee tastes so terrible on how stoffworks dot com, written 90 00:05:16,160 --> 00:05:18,720 Speaker 1: by Despolin Shields. Brain Stuff is production of I Heart 91 00:05:18,800 --> 00:05:20,880 Speaker 1: Radio and partnership with how stuff works dot Com, and 92 00:05:20,920 --> 00:05:23,880 Speaker 1: it's produced by Tyler Clang. Before more podcast It's my 93 00:05:23,920 --> 00:05:26,920 Speaker 1: heart Radio, Visit the I heart Radio app, Apple podcasts, 94 00:05:27,040 --> 00:05:28,799 Speaker 1: or wherever you listen to your favorite shows.