1 00:00:00,520 --> 00:00:03,840 Speaker 1: Welcome to Brainstuff from house stuff works dot com where 2 00:00:03,840 --> 00:00:15,160 Speaker 1: smart happens. I am Marshal Brain with today's question, why 3 00:00:15,200 --> 00:00:19,120 Speaker 1: do eggs turn hard when you boil them? Eggs are 4 00:00:19,239 --> 00:00:23,360 Speaker 1: rich in protein, especially the egg whites. It's this protein 5 00:00:23,440 --> 00:00:26,720 Speaker 1: that causes eggs to become hard when you boil them. 6 00:00:26,720 --> 00:00:30,480 Speaker 1: Here's how it works. Protein is a chain of amino acids. 7 00:00:30,960 --> 00:00:35,159 Speaker 1: These amino acid strings fold back of themselves, and the 8 00:00:35,200 --> 00:00:40,160 Speaker 1: way the strings fold determines the proteins chemical and biological properties. 9 00:00:40,720 --> 00:00:44,640 Speaker 1: The proteins are held in place by weak bonds, that is, 10 00:00:44,840 --> 00:00:49,839 Speaker 1: non covalent bonds between different parts of the amino acid string. 11 00:00:50,520 --> 00:00:54,360 Speaker 1: When you break those strings by various methods, you are 12 00:00:54,440 --> 00:00:59,160 Speaker 1: doing what's called denaturing the protein. You can do nature 13 00:00:59,320 --> 00:01:03,160 Speaker 1: a proteinen in several different ways. Here are two ways 14 00:01:03,240 --> 00:01:06,560 Speaker 1: to do it with eggs. The first is heat. When 15 00:01:06,600 --> 00:01:10,520 Speaker 1: you heat an egg, the proteins gain energy and literally 16 00:01:10,680 --> 00:01:13,880 Speaker 1: shake apart the bonds between the parts of the amino 17 00:01:13,920 --> 00:01:19,520 Speaker 1: acid strings, causing the proteins to unfold. As the temperature increases, 18 00:01:19,800 --> 00:01:23,640 Speaker 1: the proteins gain enough energy to form new, stronger bonds, 19 00:01:23,680 --> 00:01:28,440 Speaker 1: in this case covalent bonds with other protein molecules. When 20 00:01:28,440 --> 00:01:32,400 Speaker 1: you boil an egg, the heat first breaks or unfolds 21 00:01:32,400 --> 00:01:36,360 Speaker 1: the proteins and then allows the proteins to link back 22 00:01:36,360 --> 00:01:40,280 Speaker 1: together with other proteins, so the egg white turns from 23 00:01:40,280 --> 00:01:43,440 Speaker 1: this kind of liquid e mass into something that's much 24 00:01:43,440 --> 00:01:47,360 Speaker 1: more like plastic. The second way to do nature proteins 25 00:01:47,520 --> 00:01:50,760 Speaker 1: is to use chemicals. You can break the weak bonds 26 00:01:50,800 --> 00:01:54,240 Speaker 1: between protein molecules with chemicals, and then they can link 27 00:01:54,280 --> 00:01:57,320 Speaker 1: back together in the same way. Heat causes this to happen. 28 00:01:57,800 --> 00:02:01,640 Speaker 1: According to an experiment done by the bat BC Science Shack, 29 00:02:02,160 --> 00:02:05,320 Speaker 1: if you put vodka on an egg white, the alcohol 30 00:02:05,440 --> 00:02:09,040 Speaker 1: in it breaks weak hydrogen bonds in the protein. If 31 00:02:09,040 --> 00:02:11,679 Speaker 1: you put vinegar on an egg white, the acid in 32 00:02:11,880 --> 00:02:15,440 Speaker 1: it breaks ionic bonds. If you mix the two, the 33 00:02:15,520 --> 00:02:19,160 Speaker 1: vodka and the vinegar together, you break both types of 34 00:02:19,200 --> 00:02:23,440 Speaker 1: bonds and quite effectively de nature the protein. You do 35 00:02:23,560 --> 00:02:28,080 Speaker 1: something similar when you whisk egg whites. By exerting mechanical 36 00:02:28,200 --> 00:02:32,040 Speaker 1: energy in the whisking process, you cause the protein bonds 37 00:02:32,080 --> 00:02:36,360 Speaker 1: to break and subsequently to reconnect. Once these new strong 38 00:02:36,440 --> 00:02:39,840 Speaker 1: bonds are formed, the eggs stays in that state. The 39 00:02:39,919 --> 00:02:44,200 Speaker 1: proteins have formed a network of strong, permanent cross links. 40 00:02:44,240 --> 00:02:47,720 Speaker 1: A cooked, chemically altered, or well beaten egg will never 41 00:02:47,800 --> 00:02:51,720 Speaker 1: go back to its original state. When cooking eggs, use 42 00:02:51,919 --> 00:02:55,400 Speaker 1: moderate heat. High heat causes the protein and eggs to 43 00:02:55,480 --> 00:02:59,640 Speaker 1: become tough and rubbery. Be sure to check out our 44 00:02:59,720 --> 00:03:03,120 Speaker 1: navd you podcast, Stuff from the Future. Join how Staff 45 00:03:03,120 --> 00:03:06,040 Speaker 1: Work Staff as we explore the most promising and perplexing 46 00:03:06,120 --> 00:03:11,040 Speaker 1: possibilities of tomorrow. The hou Stuffork's iPhone app has arrived. 47 00:03:11,160 --> 00:03:13,080 Speaker 1: Download it today on iTunes.