1 00:00:04,040 --> 00:00:08,040 How often do you stop and really think about your food? 2 00:00:08,040 --> 00:00:11,840 Look at all this lovely fat and sugar. Yummy. 3 00:00:13,000 --> 00:00:17,040 Do you ever wonder why you eat what you eat, 4 00:00:17,040 --> 00:00:20,040 what cooking does to food... 5 00:00:20,040 --> 00:00:21,480 Delicious. 6 00:00:21,480 --> 00:00:24,160 ..or what effect it has on your body? 7 00:00:24,160 --> 00:00:26,120 I trained as a medical doctor 8 00:00:26,120 --> 00:00:28,600 and I'm absolutely obsessed by nutrition 9 00:00:28,600 --> 00:00:30,520 and the hidden chemistry of food. 10 00:00:30,520 --> 00:00:34,520 So, I've teamed up with botanist James Wong to explore food, 11 00:00:34,520 --> 00:00:37,360 each of us coming from very different perspectives. 12 00:00:37,360 --> 00:00:39,160 Truly delicious. 13 00:00:39,160 --> 00:00:41,040 Together, we have taken over 14 00:00:41,040 --> 00:00:43,720 the country's leading food science lab... 15 00:00:45,320 --> 00:00:48,480 ..to deconstruct some of our favourite foods... 16 00:00:48,480 --> 00:00:50,560 It's all sunk to the bottom. 17 00:00:50,560 --> 00:00:53,760 ..and to reveal some truly remarkable secrets. 18 00:00:53,760 --> 00:00:58,480 I want to find out what effect food has on us and our biology, 19 00:00:58,480 --> 00:01:00,920 right down to the molecular level. 20 00:01:02,360 --> 00:01:04,760 As a botanist, I am fascinated 21 00:01:04,760 --> 00:01:08,480 by the massive diversity of edible plants on our planet. 22 00:01:08,480 --> 00:01:10,600 I'm going to put them under the microscope 23 00:01:10,600 --> 00:01:15,000 to discover exactly how their biology interacts with our own. 24 00:01:17,000 --> 00:01:19,400 So, join us, as we seek out 25 00:01:19,400 --> 00:01:22,920 the most remarkable food stories on the planet 26 00:01:22,920 --> 00:01:26,120 and reveal the hidden science of our food. 27 00:01:37,600 --> 00:01:41,080 Flavour makes our food delicious. 28 00:01:44,600 --> 00:01:49,800 Each flavour is a potent combination of aroma and taste molecules. 29 00:01:52,480 --> 00:01:56,440 Get that combination right and food tastes heavenly. 30 00:01:58,600 --> 00:02:00,560 But what is taste? 31 00:02:02,040 --> 00:02:04,240 Thai cuisine is particularly good 32 00:02:04,240 --> 00:02:07,440 at exciting our full range of taste receptors... 33 00:02:08,600 --> 00:02:10,320 ..on one plate. 34 00:02:11,360 --> 00:02:15,880 So, this is a Thai stir-fry and I'm very fond of Thai. 35 00:02:15,880 --> 00:02:17,640 There is... 36 00:02:19,840 --> 00:02:23,040 ..a bit of fried chicken, lemon, garlic, 37 00:02:23,040 --> 00:02:27,440 onion - a real sort of explosion of taste. 38 00:02:27,440 --> 00:02:31,400 And it's really strange to think that all these sensations 39 00:02:31,400 --> 00:02:34,240 which are going on in my mouth at the moment 40 00:02:34,240 --> 00:02:37,240 are generated by five simple tastes. 41 00:02:37,240 --> 00:02:40,920 'In front of me, I've got liquids containing chemicals 42 00:02:40,920 --> 00:02:42,960 'that will trigger these different tastes. 43 00:02:42,960 --> 00:02:44,960 'I have no idea which is which.' 44 00:02:46,040 --> 00:02:47,760 Salty. That's definitely salty. 45 00:02:49,400 --> 00:02:50,960 Sweet. 46 00:02:55,120 --> 00:02:59,400 That is sort of bitter, a bit like coffee. And this... 47 00:03:01,000 --> 00:03:03,960 ..is similar but more lemony and makes your mouth pucker up. 48 00:03:03,960 --> 00:03:05,400 This is sour. 49 00:03:08,880 --> 00:03:11,680 And this one is really hard to describe. 50 00:03:11,680 --> 00:03:15,280 This is the taste that has been most recently discovered. 51 00:03:15,280 --> 00:03:17,600 This is umami. 52 00:03:17,600 --> 00:03:20,320 The word "umami" is a derivation 53 00:03:20,320 --> 00:03:24,760 of the Japanese for "a pleasant, savoury taste". 54 00:03:24,760 --> 00:03:29,080 And it is very, very strange to think that every taste sensation 55 00:03:29,080 --> 00:03:33,600 you ever have will consist of one or more of these tastes. 56 00:03:36,080 --> 00:03:40,640 The sensations happen here, on the surface of the tongue. 57 00:03:42,520 --> 00:03:45,880 Our tongue holds around 4,000 taste buds. 58 00:03:45,880 --> 00:03:49,480 Inside them are the five taste receptors. 59 00:03:51,520 --> 00:03:55,120 In humans, this is where the taste begins 60 00:03:55,120 --> 00:03:58,560 and in this programme, we'll show you how the food we eat 61 00:03:58,560 --> 00:04:00,800 dazzles each of these receptors. 62 00:04:02,800 --> 00:04:04,760 But why these five tastes? 63 00:04:04,760 --> 00:04:08,200 And why is it that some combinations taste vile 64 00:04:08,200 --> 00:04:10,800 and some taste utterly delicious? 65 00:04:12,520 --> 00:04:15,760 'We're going to travel the globe, in search of the foods 66 00:04:15,760 --> 00:04:18,960 'that are particularly good at stimulating each taste...' 67 00:04:18,960 --> 00:04:20,840 JAMES LAUGHS 68 00:04:20,840 --> 00:04:22,440 ..and in the process, 69 00:04:22,440 --> 00:04:27,240 uncover how evolution underpins our relationship with food. 70 00:04:39,200 --> 00:04:42,360 To learn about the most unusual taste, 71 00:04:42,360 --> 00:04:44,840 I've come to an extraordinary celebration 72 00:04:44,840 --> 00:04:49,400 of our most popular fruit, which is rich in umami. 73 00:04:49,400 --> 00:04:51,600 CROWD HUBBUB 74 00:04:51,600 --> 00:04:53,480 I'm here, in southern Spain, 75 00:04:53,480 --> 00:04:58,520 with about 20,000 other people to celebrate the tomato. 76 00:04:58,520 --> 00:05:01,120 CROWD HUBBUB 77 00:05:01,120 --> 00:05:04,000 THEY CHANT IN SPANISH 78 00:05:11,920 --> 00:05:16,760 Welcome to La Tomatina and the world's biggest food fight. 79 00:05:18,320 --> 00:05:20,480 It's been running for over 70 years 80 00:05:20,480 --> 00:05:23,760 and it's thought it started with a street fight. 81 00:05:23,760 --> 00:05:25,080 It was so much fun, 82 00:05:25,080 --> 00:05:29,360 the locals decided to do it again the next year and the next. 83 00:05:29,360 --> 00:05:32,520 As well as making a perfect food missile, 84 00:05:32,520 --> 00:05:35,920 tomatoes carry a heavy punch of umami. 85 00:05:35,920 --> 00:05:39,280 The trouble with being at the back is you get hit a lot. 86 00:05:41,000 --> 00:05:43,560 But what exactly is umami 87 00:05:43,560 --> 00:05:47,640 and why does it have such a powerful hold over us? 88 00:05:49,480 --> 00:05:52,240 The answer lies inside the tomatoes. 89 00:05:53,960 --> 00:05:57,320 'To get at the umami, I'm going to blitz them, 90 00:05:57,320 --> 00:06:01,320 'then spin them at high speed in a centrifuge, 91 00:06:01,320 --> 00:06:06,480 'filter, then finally stir and simmer to concentrate the taste.' 92 00:06:08,400 --> 00:06:11,600 After all that boiling down, this is all that's left 93 00:06:11,600 --> 00:06:14,120 and it no longer smells tomatoey at all 94 00:06:14,120 --> 00:06:17,560 because those volatile flavours have been boiled off. 95 00:06:17,560 --> 00:06:19,800 And this stuff... 96 00:06:22,040 --> 00:06:24,520 ..doesn't taste tomatoey either. 97 00:06:24,520 --> 00:06:28,960 It tastes salty, earthy, meaty. 98 00:06:30,400 --> 00:06:33,800 What my tongue is sensing is a chemical known as glutamate. 99 00:06:33,800 --> 00:06:35,480 It's an amino acid, 100 00:06:35,480 --> 00:06:39,680 a type of molecule derived from protein in the tomato. 101 00:06:39,680 --> 00:06:43,280 Whenever you get a glutamate molecule in food, 102 00:06:43,280 --> 00:06:45,800 it triggers that umami taste, 103 00:06:45,800 --> 00:06:49,560 fuelling a desire for more umami-rich food. 104 00:06:50,920 --> 00:06:53,040 It's our love of the glutamate in tomatoes 105 00:06:53,040 --> 00:06:56,920 that has made them such an important crop for this region. 106 00:07:06,960 --> 00:07:10,480 HORN BLARES 107 00:07:10,480 --> 00:07:13,720 BELL TOLLS 108 00:07:16,800 --> 00:07:20,680 It's found here, in the ancient oak forests of south-west Spain... 109 00:07:22,680 --> 00:07:26,840 ..home of the chunky local pig known as the "pata negra". 110 00:07:31,400 --> 00:07:35,320 These pigs roam freely, foraging whatever they can find. 111 00:07:35,320 --> 00:07:38,360 But their favourite treats are the acorns 112 00:07:38,360 --> 00:07:41,120 that fall from the oaks every winter. 113 00:07:43,000 --> 00:07:47,680 And it turns out that pigs and acorns are a match made in heaven. 114 00:07:48,680 --> 00:07:53,200 Together, they make the most delicious and most expensive 115 00:07:53,200 --> 00:07:57,760 umami-packed ham in the world - Iberico ham. 116 00:08:01,680 --> 00:08:04,400 HEN CLUCKS 117 00:08:04,400 --> 00:08:06,360 It's early morning in January. 118 00:08:08,080 --> 00:08:12,160 Acorn season is coming to an end and Juana Marquez is preparing 119 00:08:12,160 --> 00:08:15,480 for one of the most important events of her year. 120 00:08:18,240 --> 00:08:23,440 In this part of Spain, the annual killing of a pig is a major event. 121 00:08:23,440 --> 00:08:25,360 It is known as a "matanza", 122 00:08:25,360 --> 00:08:28,560 and it involves the gathering of an entire family. 123 00:08:28,560 --> 00:08:33,160 THEY SPEAK IN SPANISH 124 00:08:44,040 --> 00:08:46,760 PIG SQUEALS 125 00:08:50,200 --> 00:08:54,360 For Juana's pig, it's as respectful a death as you could hope for. 126 00:08:55,920 --> 00:09:00,720 It will take the family the entire day to turn 150 kilos of pig 127 00:09:00,720 --> 00:09:03,840 into enough meat to keep them going all the year. 128 00:09:06,040 --> 00:09:09,480 But butchering is only the prelude to transforming this meat 129 00:09:09,480 --> 00:09:14,040 into an incredibly powerful umami-tasting explosion. 130 00:09:17,480 --> 00:09:20,880 The secret to the intense umami taste begins 131 00:09:20,880 --> 00:09:23,760 with the extraordinarily thick layer of fat... 132 00:09:25,680 --> 00:09:29,200 ..which comes from the acorns the pigs enjoyed in life. 133 00:09:33,760 --> 00:09:38,280 The acorn fat from the local oak trees is rich in oleic acid, 134 00:09:38,280 --> 00:09:41,480 the same fatty acid that's found in olives. 135 00:09:44,600 --> 00:09:48,440 That's why the locals refer to the pigs as "olives with legs". 136 00:09:51,120 --> 00:09:55,760 Walking olives that can eat up to ten kilos of acorns a day. 137 00:10:03,240 --> 00:10:07,600 Most hams end up here, in the darkness of an Iberian cellar. 138 00:10:08,840 --> 00:10:14,400 This is where biochemistry kicks in and the exquisite umami taste forms. 139 00:10:15,920 --> 00:10:18,960 The surface of the ham is under constant attack. 140 00:10:18,960 --> 00:10:22,760 Microbes and oxygen in the air react with the fat on the outside, 141 00:10:22,760 --> 00:10:24,960 making it yellow and rancid. 142 00:10:26,080 --> 00:10:28,240 But the meat within is protected. 143 00:10:29,720 --> 00:10:34,600 The acorn-fed fat layer is so thick it can keep the meat air-free 144 00:10:34,600 --> 00:10:39,080 for up to three years, much longer than any other ham. 145 00:10:40,480 --> 00:10:44,840 This allows the natural chemistry locked inside the flesh to unfold. 146 00:10:49,800 --> 00:10:51,960 The meat starts to cure. 147 00:10:53,440 --> 00:10:56,200 Over the years, naturally occurring enzymes 148 00:10:56,200 --> 00:10:58,680 break the proteins in the meat down 149 00:10:58,680 --> 00:11:01,680 into their basic building blocks - amino acids. 150 00:11:03,240 --> 00:11:05,800 One of these is the all-important glutamate, 151 00:11:05,800 --> 00:11:09,320 the molecule responsible for the taste of umami. 152 00:11:11,080 --> 00:11:14,800 The longer meat cures, the greater the build-up of the glutamate 153 00:11:14,800 --> 00:11:17,440 and the stronger the taste will become. 154 00:11:19,720 --> 00:11:25,120 And time is exactly what its thick, fatty case provides each ham. 155 00:11:25,120 --> 00:11:27,440 By the end, these hams have 50 times 156 00:11:27,440 --> 00:11:31,160 the glutamate levels of fresh meat... 157 00:11:31,160 --> 00:11:34,040 HE PLAYS GUITAR 158 00:11:34,040 --> 00:11:37,800 ..making them the world's finest, meatiest, 159 00:11:37,800 --> 00:11:41,520 most delicious umami-tasting hams. 160 00:11:48,600 --> 00:11:52,640 It's a taste prized by charcuterie connoisseurs the world over. 161 00:11:52,640 --> 00:11:55,880 But there's a biological reason 162 00:11:55,880 --> 00:12:00,160 why we are drawn to the umami flavour of glutamate. 163 00:12:03,240 --> 00:12:05,440 So, the reason... Mm! 164 00:12:05,440 --> 00:12:07,560 ..why this ham is so delicious 165 00:12:07,560 --> 00:12:12,000 is because glutamate is one of the building blocks of protein. 166 00:12:12,000 --> 00:12:14,680 And protein is essential to the building 167 00:12:14,680 --> 00:12:17,720 and running of every cell in our bodies. 168 00:12:17,720 --> 00:12:21,440 THEY SING IN SPANISH 169 00:12:26,160 --> 00:12:29,520 So, what the ham is really saying to me is, 170 00:12:29,520 --> 00:12:33,560 "Eat me because I will make you big and strong." 171 00:12:33,560 --> 00:12:36,920 THEY SING IN SPANISH 172 00:12:41,040 --> 00:12:45,080 And the way it sends that message is, of course, via my taste buds. 173 00:12:49,800 --> 00:12:52,520 As food enters the mouth, it meets the tongue, 174 00:12:52,520 --> 00:12:57,520 a seething landscape of muscle, covered by spiky papillae. 175 00:12:57,520 --> 00:13:01,040 These help move each mouthful of food around. 176 00:13:03,480 --> 00:13:07,400 As it swirls across the tongue, the food comes across larger, 177 00:13:07,400 --> 00:13:11,160 dome-shape papillae, and here, we find the taste buds. 178 00:13:13,200 --> 00:13:15,040 The glutamate enters each bud, 179 00:13:15,040 --> 00:13:17,880 where it encounters the five taste receptors. 180 00:13:19,600 --> 00:13:22,720 But the glutamate molecule has a distinctive shape 181 00:13:22,720 --> 00:13:26,120 that can only activate the umami receptor... 182 00:13:27,920 --> 00:13:30,600 ..sending a signal to the brain that tells us, 183 00:13:30,600 --> 00:13:34,960 "Mm, that mouthful of food is rather delicious." 184 00:13:36,320 --> 00:13:39,120 We're hardwired to enjoy the taste of umami 185 00:13:39,120 --> 00:13:42,760 because it signals the protein we need to build our bodies. 186 00:13:44,000 --> 00:13:46,520 But we can't survive on protein alone. 187 00:13:54,200 --> 00:13:58,000 We would grind to a halt without a ready supply of energy. 188 00:13:59,320 --> 00:14:01,200 So, we have another taste receptor 189 00:14:01,200 --> 00:14:03,960 that fires off whenever it encounters the chemicals 190 00:14:03,960 --> 00:14:06,760 that give us a quick energy hit. 191 00:14:08,080 --> 00:14:09,400 Yum! 192 00:14:09,400 --> 00:14:11,040 When you bite into a strawberry, 193 00:14:11,040 --> 00:14:14,320 if you had to pick one word to describe its taste, 194 00:14:14,320 --> 00:14:16,440 you would probably pick "sweet", 195 00:14:16,440 --> 00:14:20,640 and that's how our bodies detect the amount of sugar that's in fruit. 196 00:14:20,640 --> 00:14:24,200 'But sugar and nature seldom comes on its own. 197 00:14:24,200 --> 00:14:27,840 'It's usually balanced out by another taste - 198 00:14:27,840 --> 00:14:30,480 'the taste of acid.' 199 00:14:30,480 --> 00:14:32,600 I'm going to show you that, 200 00:14:32,600 --> 00:14:35,720 with a fantastically geeky piece of kit here. 201 00:14:35,720 --> 00:14:42,080 This is a pH meter and it detects how acid solutions are. 202 00:14:42,080 --> 00:14:46,680 Now, I've got some distilled water here. 203 00:14:48,320 --> 00:14:49,520 OK. 204 00:14:50,920 --> 00:14:53,840 And pretty much instantly, bam. 205 00:14:53,840 --> 00:14:56,080 As I was hoping for, pH 7. 206 00:14:57,120 --> 00:14:58,880 Perfectly neutral. 207 00:14:58,880 --> 00:15:00,880 On the other end of the scale, 208 00:15:00,880 --> 00:15:05,640 I've got this stuff over here - some hydrochloric acid. 209 00:15:06,920 --> 00:15:09,760 Exactly what I was hoping for. This is pH 1. 210 00:15:09,760 --> 00:15:12,360 You've got pure water on one end, which is 7, 211 00:15:12,360 --> 00:15:16,280 and hydrochloric acid as 1, about as acidic as it gets. 212 00:15:16,280 --> 00:15:18,600 'So, let's test a range of fruit...' 213 00:15:18,600 --> 00:15:20,520 Let's get some of that juice out. 214 00:15:20,520 --> 00:15:25,480 '..to find out where they fit on the scale, starting with a strawberry.' 215 00:15:26,880 --> 00:15:28,400 Yeah, it's going down. 216 00:15:28,400 --> 00:15:30,480 For something most people describe as sweet, 217 00:15:30,480 --> 00:15:32,120 this is pretty acidic stuff. 218 00:15:33,240 --> 00:15:35,880 Look at that. 3.5. 219 00:15:38,320 --> 00:15:40,000 Right there. 220 00:15:40,000 --> 00:15:41,880 'The pH meter is measuring 221 00:15:41,880 --> 00:15:44,800 'the number of hydrogen ions in the fruit, 222 00:15:44,800 --> 00:15:48,560 'which defines the acidity of each sample. 223 00:15:48,560 --> 00:15:50,640 'Take a watermelon.' 224 00:15:50,640 --> 00:15:55,000 Watermelon juice is relatively non-acidic. 225 00:15:55,000 --> 00:15:57,040 5.5, over there. 226 00:15:58,200 --> 00:16:01,080 'These hydrogen ions trigger our sour receptors, 227 00:16:01,080 --> 00:16:03,720 'so the sour, let's say, in orange, 228 00:16:03,720 --> 00:16:05,840 'is actually the taste of acid.' 229 00:16:05,840 --> 00:16:07,840 Unexpected. 230 00:16:07,840 --> 00:16:10,240 3.5 again. 231 00:16:10,240 --> 00:16:12,360 'Last up, grapefruit.' 232 00:16:13,440 --> 00:16:15,840 Huh, 3.52. 233 00:16:17,320 --> 00:16:19,520 So, this is quite odd. 234 00:16:19,520 --> 00:16:21,920 All this fruit is the same pH, 235 00:16:21,920 --> 00:16:27,000 yet people describe strawberries as tasting sweet, 236 00:16:27,000 --> 00:16:29,880 despite having a similar amount of acid. 237 00:16:29,880 --> 00:16:34,160 Strawberries have a cunning ability to hide their acidity, 238 00:16:34,160 --> 00:16:37,800 which begs the question, why produce it in the first place? 239 00:16:48,400 --> 00:16:52,800 The reason is actually down to a beautiful bit of evolution. 240 00:17:02,640 --> 00:17:05,320 Strawberry plants have specifically evolved 241 00:17:05,320 --> 00:17:10,840 this sweet, succulent fruit here to encourage animals to eat them. 242 00:17:10,840 --> 00:17:12,720 And that's because, 243 00:17:12,720 --> 00:17:16,760 when these seeds pass through the digestive tract of an animal, 244 00:17:16,760 --> 00:17:20,360 they're deposited, with a bit of fertiliser, far and wide, 245 00:17:20,360 --> 00:17:22,880 helping the strawberries' empire grow. 246 00:17:24,080 --> 00:17:27,640 The thing is, that only works when the seed is fully mature 247 00:17:27,640 --> 00:17:31,400 and ready to sprout. Until that point, they're not sweet at all. 248 00:17:31,400 --> 00:17:35,600 In fact, they're packed full of acid, making them taste sour. 249 00:17:35,600 --> 00:17:37,360 It's an animal deterrent. 250 00:17:42,200 --> 00:17:45,240 The mild acidic solution from the unripened fruit 251 00:17:45,240 --> 00:17:49,360 washes over the tongue, stimulating the sour receptors. 252 00:17:57,120 --> 00:17:59,880 The brain interprets this taste as unpleasant 253 00:17:59,880 --> 00:18:03,720 and a sign that the food could be spoiled or unfit to eat. 254 00:18:05,840 --> 00:18:10,320 It's a biological reaction that plants use to their own ends. 255 00:18:12,000 --> 00:18:16,240 A taste strong and repellent enough to put most animals off. 256 00:18:17,600 --> 00:18:19,160 'But just at the right moment,' 257 00:18:19,160 --> 00:18:22,080 when the seeds have matured and are ready to grow, 258 00:18:22,080 --> 00:18:25,240 it needs to mask this acidity to make it more palatable. 259 00:18:27,680 --> 00:18:29,480 All the acid is still there, 260 00:18:29,480 --> 00:18:32,080 but the fruit becomes flooded with sugar, 261 00:18:32,080 --> 00:18:34,400 produced when hormones from the seeds announce 262 00:18:34,400 --> 00:18:36,440 they're ready to be eaten. 263 00:18:36,440 --> 00:18:39,520 The sugars react with other plant molecules 264 00:18:39,520 --> 00:18:43,480 and make attractive red pigments that say, "Eat me." 265 00:18:45,120 --> 00:18:47,640 I know you're not supposed to eat them till you've paid, but... 266 00:18:48,760 --> 00:18:52,000 ..that's the point. They are irresistible. 267 00:18:56,280 --> 00:18:57,960 So, everyone's happy. 268 00:18:57,960 --> 00:19:01,800 The plant, having sacrificed some sugar, gets its seeds spread... 269 00:19:05,320 --> 00:19:09,000 ..and, in return, the diner gets a sugar reward. 270 00:19:14,280 --> 00:19:16,600 But the strawberry is sneaky, 271 00:19:16,600 --> 00:19:20,160 because we may not be getting as much sweet sugar as we think. 272 00:19:23,000 --> 00:19:27,000 I love strawberries and I also love blueberries. 273 00:19:27,000 --> 00:19:32,240 But which has more sugar in it? Well, going on taste alone... 274 00:19:35,320 --> 00:19:38,520 ..I'd have said it's the strawberry. But am I right? 275 00:19:38,520 --> 00:19:43,480 What I'm going to do is squeeze a few of these, 276 00:19:43,480 --> 00:19:46,080 get a few drops of juice out. 277 00:19:48,440 --> 00:19:52,440 That's the blueberry done. Now to do a strawberry. 278 00:19:56,840 --> 00:20:00,040 Now I'm going to use this thing, which is called a refractometer. 279 00:20:00,040 --> 00:20:03,880 What happens when light passes through any liquid is it gets bent, 280 00:20:03,880 --> 00:20:07,480 and the more sugar there is in that liquid, the more it gets bent. 281 00:20:10,040 --> 00:20:13,160 First to be tested for sugar is the blueberry juice. 282 00:20:15,560 --> 00:20:21,760 And then I can look at the light and I can see a number. 283 00:20:24,840 --> 00:20:29,920 This gives me the number 13. So, that's 13 for the blueberries. 284 00:20:29,920 --> 00:20:32,120 Let's do it again with the strawberry. 285 00:20:38,560 --> 00:20:40,640 Wow, that's surprising! 286 00:20:40,640 --> 00:20:43,240 Er, that is about 8, 287 00:20:43,240 --> 00:20:47,920 which means it's nearly half as much sugar per gram 288 00:20:47,920 --> 00:20:51,680 as there is in the blueberries. I am genuinely surprised by that. 289 00:20:51,680 --> 00:20:55,200 So, why is it that a strawberry tastes so sweet 290 00:20:55,200 --> 00:20:57,760 but it doesn't actually contain that much sugar? 291 00:20:57,760 --> 00:21:00,560 Well, part of the secret of its success... 292 00:21:00,560 --> 00:21:02,840 HE INHALES ..is its smell. 293 00:21:05,520 --> 00:21:08,960 Surprisingly, strawberries have altered the way they taste 294 00:21:08,960 --> 00:21:10,960 using the power of smell. 295 00:21:12,680 --> 00:21:14,520 Because, alongside the molecules 296 00:21:14,520 --> 00:21:17,960 that give strawberries their characteristic aroma, 297 00:21:17,960 --> 00:21:21,440 there lurk other smells with a more crafty purpose. 298 00:21:23,080 --> 00:21:28,400 36 molecules that seem to boost our taste sensation around sweetness. 299 00:21:28,400 --> 00:21:31,160 The aroma deceives our brain into thinking 300 00:21:31,160 --> 00:21:34,520 we're getting a lot more sugar than we actually are. 301 00:21:37,040 --> 00:21:40,720 Despite the fact that I now know that an awful lot of the sweetness 302 00:21:40,720 --> 00:21:43,760 I think I'm experiencing in my mouth is actually coming from stuff 303 00:21:43,760 --> 00:21:48,200 that's going in nose, it hasn't diminished my pleasure at all. 304 00:21:48,200 --> 00:21:51,040 I still find strawberries deliciously sweet. 305 00:21:54,640 --> 00:21:56,320 It's a clever trick. 306 00:21:56,320 --> 00:21:59,360 By boosting how sweet its fruit seems to be, 307 00:21:59,360 --> 00:22:01,720 the plant needs to give away less sugar, 308 00:22:01,720 --> 00:22:04,600 while still encouraging us to spread its seeds. 309 00:22:06,480 --> 00:22:09,320 Food scientists are really interested in discovering 310 00:22:09,320 --> 00:22:12,000 just how strawberries do what they do, 311 00:22:12,000 --> 00:22:15,400 because if they could replicate that trick with other foods... 312 00:22:17,080 --> 00:22:20,360 ..then they could produce stuff which tastes satisfyingly sweet, 313 00:22:20,360 --> 00:22:23,240 but which has far less added sugar. 314 00:22:39,000 --> 00:22:41,800 Our sense of taste is not just about attracting us 315 00:22:41,800 --> 00:22:43,600 to what's good to eat and when. 316 00:22:48,080 --> 00:22:52,160 It's also evolved ways to help us avoid foods that can kill us. 317 00:22:58,320 --> 00:23:00,440 Take the seeds in fruit. 318 00:23:00,440 --> 00:23:04,560 Even a few crushed cherry or plum stones can produce 319 00:23:04,560 --> 00:23:09,560 enough cyanide in the gut to cause paralysis, liver and kidney damage. 320 00:23:12,440 --> 00:23:17,000 Rhubarb leaves contain the same chemical used to make bleach. 321 00:23:20,160 --> 00:23:23,720 And uncooked, just five raw kidney beans 322 00:23:23,720 --> 00:23:26,520 contain enough phytohaemagglutinin 323 00:23:26,520 --> 00:23:30,160 to bring on vomiting, nausea and diarrhoea. 324 00:23:36,160 --> 00:23:37,960 Here, in Peru, 325 00:23:37,960 --> 00:23:41,880 there's an everyday food you might not expect to be a threat. 326 00:23:46,320 --> 00:23:49,360 Eating is a dangerous business. 327 00:23:51,120 --> 00:23:53,280 The world is full of things 328 00:23:53,280 --> 00:23:56,240 that look like they could be interesting to eat. 329 00:23:58,120 --> 00:24:00,920 But some things might not be such a good idea. 330 00:24:06,160 --> 00:24:11,360 Take the potato, for instance. Is it friend or foe? 331 00:24:14,400 --> 00:24:18,080 'The potato plant originated in South America, 332 00:24:18,080 --> 00:24:22,200 'but most of these wild potatoes would have been left well alone 333 00:24:22,200 --> 00:24:25,920 'because of their intensely sharp, bitter taste.' 334 00:24:25,920 --> 00:24:30,760 Potatoes belong to the deadly nightshade family, 335 00:24:30,760 --> 00:24:34,800 which is packed full of species that are super, super toxic. 336 00:24:34,800 --> 00:24:38,560 And a toxin that's found in potatoes is called solanine. 337 00:24:38,560 --> 00:24:42,360 It tastes incredibly bitter. Bad idea to do what I'm doing but... 338 00:24:45,400 --> 00:24:48,600 I barely punctured this with my teeth 339 00:24:48,600 --> 00:24:52,240 and already a bitter bloom is going throughout my mouth 340 00:24:52,240 --> 00:24:54,480 that makes me want to spit it out instantly. 341 00:24:54,480 --> 00:24:57,520 That's my sense of taste telling me instantly, 342 00:24:57,520 --> 00:24:59,800 "This is not good for you. Get rid of it." 343 00:25:02,920 --> 00:25:08,880 Bitter has a crucial role to play in our survival. It's a warning sign. 344 00:25:11,280 --> 00:25:14,360 Your sense of taste is really a complex chemical detector 345 00:25:14,360 --> 00:25:18,640 that allows healthy good-for-you foods in and keeps toxic things out. 346 00:25:21,280 --> 00:25:25,480 The potato plant uses this to protect itself from being eaten. 347 00:25:27,200 --> 00:25:30,520 See all this green blush over the surface? 348 00:25:30,520 --> 00:25:33,800 That's evidence it's started to grow and produce solanine. 349 00:25:33,800 --> 00:25:36,640 They generally are packed in young growing tips 350 00:25:36,640 --> 00:25:38,640 to help protect the plant even more. 351 00:25:38,640 --> 00:25:42,560 So, I'm going to try this sprouted potato and it should be even worse. 352 00:25:45,240 --> 00:25:47,200 Oh, it's... Why did I do that? 353 00:25:50,200 --> 00:25:53,880 Because the consequences of eating a poison can be so deadly, 354 00:25:53,880 --> 00:25:58,920 we have 25 types of bitter receptor, all on the lookout for toxins - 355 00:25:58,920 --> 00:26:01,960 about 20 more than we have for sweet. 356 00:26:03,000 --> 00:26:07,080 Cos sweet is nice, but bitter can be deadly. 357 00:26:08,360 --> 00:26:10,160 Can I spit this out? Sorry. 358 00:26:13,360 --> 00:26:16,040 So, if the original potatoes were poisonous, 359 00:26:16,040 --> 00:26:20,320 how come the humble spud has become such an important part of our diet? 360 00:26:22,200 --> 00:26:25,360 Surprisingly, we have the Inca to thank. 361 00:26:29,840 --> 00:26:32,120 It was in places like here, 362 00:26:32,120 --> 00:26:34,920 in the mountains of the sacred Incan valley, 363 00:26:34,920 --> 00:26:38,080 where the poisonous solanine was gradually bred out. 364 00:26:40,520 --> 00:26:43,640 You know, when people talk about the Inca, 365 00:26:43,640 --> 00:26:49,160 they tend to mention lost cities and temples and gold, 366 00:26:49,160 --> 00:26:56,520 but all of this has nothing to do with power or status. 367 00:26:56,520 --> 00:27:01,400 Everything you see here only exists to grow crops. 368 00:27:01,400 --> 00:27:04,720 And king amongst them? The potato. 369 00:27:13,720 --> 00:27:17,560 But for some people who live on the very edge of existence, 370 00:27:17,560 --> 00:27:21,920 the battle to tame the poisonous spud is still being fought. 371 00:27:24,720 --> 00:27:29,040 Martin Calisaya and his family live here in this village, 372 00:27:29,040 --> 00:27:31,320 4,000 metres high in the Andes. 373 00:27:32,800 --> 00:27:35,480 Their lives depend on the potato. 374 00:27:35,480 --> 00:27:38,760 Almost nothing else will grow at this altitude, 375 00:27:38,760 --> 00:27:41,560 so spuds provide virtually all their nutrition 376 00:27:41,560 --> 00:27:45,560 and they grow a huge variety to survive in this harsh environment. 377 00:27:54,600 --> 00:27:57,160 But even with 100 different varieties, 378 00:27:57,160 --> 00:27:59,720 a hard frost could spell disaster. 379 00:28:03,800 --> 00:28:07,920 As a precaution, they grow the hardiest known potato in the world, 380 00:28:07,920 --> 00:28:10,680 one that can survive even the toughest winter. 381 00:28:12,800 --> 00:28:14,240 The only downside? 382 00:28:14,240 --> 00:28:18,640 They're bitter, poisonous and inedible, 383 00:28:18,640 --> 00:28:21,160 packed full of deadly solanine. 384 00:28:22,720 --> 00:28:26,920 The incredible thing is, the people from the Andes have developed 385 00:28:26,920 --> 00:28:31,400 an ingenious technology that turns poison into dinner. 386 00:28:36,320 --> 00:28:38,480 The trick is to freeze-dry the potatoes 387 00:28:38,480 --> 00:28:42,080 to remove the toxins and so they can be stored for years. 388 00:28:44,280 --> 00:28:48,840 In order to get maximum freeze factor, the Quechua need to find 389 00:28:48,840 --> 00:28:53,560 the very coldest spot and that means going right up there. 390 00:29:03,120 --> 00:29:07,760 Once a year, the Calisaya family haul their crop 391 00:29:07,760 --> 00:29:10,200 of inedible, bitter potatoes to a site 392 00:29:10,200 --> 00:29:14,120 that's 300 metres higher than their village, 393 00:29:14,120 --> 00:29:17,680 ready to begin a food processing technique 394 00:29:17,680 --> 00:29:20,960 that dates back around 2,000 years. 395 00:29:28,960 --> 00:29:30,840 HORSE WHINNIES 396 00:29:33,760 --> 00:29:38,920 At 4,300 metres, we reach the corral, 397 00:29:38,920 --> 00:29:41,120 where the potatoes will be processed. 398 00:29:47,360 --> 00:29:50,760 - BREATHLESSLY: - Growing potatoes the traditional way 399 00:29:50,760 --> 00:29:53,040 is incredibly labour-intensive. 400 00:29:53,040 --> 00:29:56,720 But here, you've got to haul this stuff up a mountain 401 00:29:56,720 --> 00:30:01,200 and, in this thin air, even just the act of spacing them apart, 402 00:30:01,200 --> 00:30:04,080 so frost gets to them, is killing me. 403 00:30:10,440 --> 00:30:13,200 At night, the temperature plummets. 404 00:30:17,720 --> 00:30:22,040 Ice crystals form throughout the potato, rupturing the cell walls. 405 00:30:25,640 --> 00:30:29,280 This allows the poisonous solanine to leach out. 406 00:30:35,160 --> 00:30:39,160 After a night out in sub-zero temperatures, 407 00:30:39,160 --> 00:30:42,000 these guys are frozen solid. 408 00:30:45,640 --> 00:30:49,760 Up to 80% of the deadly solanine is produced close to the skin, 409 00:30:49,760 --> 00:30:52,200 and the treading process breaks the skins 410 00:30:52,200 --> 00:30:54,960 enough to allow an escape route for the poison. 411 00:30:59,120 --> 00:31:03,080 During the day, when the scorching sun is high in the sky, 412 00:31:03,080 --> 00:31:04,880 the potatoes begin to thaw. 413 00:31:07,920 --> 00:31:10,720 With the cell walls ruptured and the skins broken, 414 00:31:10,720 --> 00:31:14,800 water leaches out, carrying the deadly solanine with it, 415 00:31:14,800 --> 00:31:19,160 leaving a dried, shrivelled product, known as "chuno". 416 00:31:21,400 --> 00:31:23,640 This is it. This is the end result. 417 00:31:23,640 --> 00:31:28,000 And, OK, they might not look irresistible, but this is magic. 418 00:31:28,000 --> 00:31:33,000 In this form, they can be stored for a decade and still be eaten. 419 00:31:33,000 --> 00:31:35,760 It is the ultimate in food security. 420 00:31:40,960 --> 00:31:44,360 So, even if the winter destroys the bulk of their crop, 421 00:31:44,360 --> 00:31:48,160 Martin and his family will be sure to have enough food. 422 00:32:11,320 --> 00:32:14,360 The flavour's great. It's kind of floury, like a chestnut, 423 00:32:14,360 --> 00:32:19,120 like a roasted chestnut, but with kind of smoky, oaky richness to it. 424 00:32:19,120 --> 00:32:20,800 I've got to say... 425 00:32:26,960 --> 00:32:29,800 The Quechua have learnt to outsmart 426 00:32:29,800 --> 00:32:33,400 the incredible bitterness of poisonous potatoes, 427 00:32:33,400 --> 00:32:37,520 and they've also helped all of us enjoy mash and chips. 428 00:32:38,760 --> 00:32:41,480 Thanks to them, nearly all the bitter solanine 429 00:32:41,480 --> 00:32:46,040 has been bred out of the humble spud over hundreds of generations. 430 00:32:58,320 --> 00:33:00,160 Our sense of taste, then, 431 00:33:00,160 --> 00:33:03,600 is far more than just about what we enjoy when we eat. 432 00:33:10,840 --> 00:33:14,080 It's actually a powerful survival mechanism. 433 00:33:19,600 --> 00:33:21,960 Our sense of taste evolved to guide us 434 00:33:21,960 --> 00:33:25,160 through a very different world to the one we live in now. 435 00:33:25,160 --> 00:33:28,440 It was a world where things that tasted sweet were good for us, 436 00:33:28,440 --> 00:33:30,200 because they gave us instant energy, 437 00:33:30,200 --> 00:33:32,720 and where things that were bitter were often bad, 438 00:33:32,720 --> 00:33:34,560 because they might be poisonous. 439 00:33:34,560 --> 00:33:38,000 In the modern world, of course, it's often the other way round. 440 00:33:38,000 --> 00:33:40,360 There's another really important taste, 441 00:33:40,360 --> 00:33:43,040 which is also often confused by the modern world. 442 00:33:43,040 --> 00:33:47,480 It is a taste which is both an invitation and a warning. 443 00:33:47,480 --> 00:33:49,720 It is salt. 444 00:33:53,720 --> 00:33:55,760 We're so used to the taste of salt 445 00:33:55,760 --> 00:33:59,080 that we sometimes forget just how weird it is. 446 00:33:59,080 --> 00:34:02,720 Let me show you something which is really quite surprising. 447 00:34:02,720 --> 00:34:05,840 I'm going to whizz up some coffee. 448 00:34:05,840 --> 00:34:07,960 BLENDER WHIRRS 449 00:34:09,400 --> 00:34:11,000 Bit of boiling water. 450 00:34:13,360 --> 00:34:18,760 I've got a fresh brewed coffee here. Let's give it a go. 451 00:34:22,680 --> 00:34:24,920 And that is really quite...bitter. 452 00:34:26,120 --> 00:34:28,720 'This time, I'm going to add a pinch or two of salt 453 00:34:28,720 --> 00:34:30,560 'to the coffee grounds.' 454 00:34:36,640 --> 00:34:38,120 Let's give it a go. 455 00:34:42,360 --> 00:34:45,400 Now, that's quite strange, because that's very different. 456 00:34:45,400 --> 00:34:47,240 The bitterness has been removed. 457 00:34:47,240 --> 00:34:50,080 It doesn't actually make it pleasanter, I have to say. 458 00:34:50,080 --> 00:34:54,400 It just makes it very different because, oddly, what is happening 459 00:34:54,400 --> 00:34:59,320 is that the sodium in the salt is blocking the bitter receptors. 460 00:35:02,920 --> 00:35:06,440 And so, it really doesn't taste anything like as bitter as it did 461 00:35:06,440 --> 00:35:09,320 which, for me, is a shame because I actually like bitter coffee. 462 00:35:09,320 --> 00:35:12,000 But if you don't, then this is a very neat trick. 463 00:35:13,080 --> 00:35:16,640 And it's this ability to make food more palatable, 464 00:35:16,640 --> 00:35:21,680 more delicious, that gives salt such a powerful hold over us. 465 00:35:22,920 --> 00:35:27,440 And we've also evolved a liking for salt because it's essential to life. 466 00:35:44,240 --> 00:35:48,160 Billions of years ago, life evolved in the oceans. 467 00:35:53,120 --> 00:35:56,280 Exactly HOW it began, no-one knows. 468 00:35:57,520 --> 00:36:00,480 But, as the first simple cells took shape, 469 00:36:00,480 --> 00:36:04,520 they entrapped a little bit of the salty water inside themselves. 470 00:36:06,920 --> 00:36:12,320 Today, every cell in our bodies still carries a little salty water, 471 00:36:12,320 --> 00:36:16,880 a distant echo of our ancient origins in the sea. 472 00:36:18,400 --> 00:36:20,880 Sea water might taste terrible 473 00:36:20,880 --> 00:36:26,080 but the taste of a little bit of salt has this universal appeal. 474 00:36:26,080 --> 00:36:29,240 We like it because we need it. 475 00:36:29,240 --> 00:36:32,240 Salt is vital for life. 476 00:36:35,280 --> 00:36:37,960 This biological need has driven us 477 00:36:37,960 --> 00:36:43,040 to coax salt out of the ocean for thousands of years, 478 00:36:43,040 --> 00:36:47,840 transforming landscapes, like this corner of Brittany. 479 00:36:49,720 --> 00:36:53,920 Over time, this salt marsh has been painstakingly sculpted 480 00:36:53,920 --> 00:36:57,480 into a vast network of evaporation ponds. 481 00:36:59,920 --> 00:37:05,240 Sophie Bonnet-Questiot is one of 250 salt farmers, 482 00:37:05,240 --> 00:37:09,880 each tending to their own network of ponds, called a "salina". 483 00:37:12,960 --> 00:37:18,080 It's the traditional way because it has started in the 9th century. 484 00:37:18,080 --> 00:37:20,840 The technique is really the same. 485 00:37:22,720 --> 00:37:24,360 When the tide is high, 486 00:37:24,360 --> 00:37:29,680 sea water flows 5km from the ocean into a reservoir. 487 00:37:29,680 --> 00:37:33,680 It's then channelled through a patchwork of ponds, 488 00:37:33,680 --> 00:37:36,800 each just slightly lower than the last. 489 00:37:38,120 --> 00:37:40,800 As the water moves down from one pond to the next, 490 00:37:40,800 --> 00:37:42,800 it becomes more concentrated, 491 00:37:42,800 --> 00:37:45,840 until it's ten times as salty as it started. 492 00:37:47,920 --> 00:37:52,520 And then, from the briny water, salt crystals emerge. 493 00:37:53,840 --> 00:37:57,720 I'm collecting very famous salt of Guerande... 494 00:37:59,040 --> 00:38:02,440 ..that is crystallising at the bottom of the pond, 495 00:38:02,440 --> 00:38:04,440 directly on clay. 496 00:38:06,000 --> 00:38:09,960 The highly-prized, beautiful, crystalline flakes of salt 497 00:38:09,960 --> 00:38:12,560 contain more moisture than common salt, 498 00:38:12,560 --> 00:38:16,200 which means the taste lingers for much longer. 499 00:38:19,160 --> 00:38:21,560 And being unrefined, other minerals, 500 00:38:21,560 --> 00:38:24,280 like calcium and magnesium chloride, 501 00:38:24,280 --> 00:38:26,600 give it a more complex flavour. 502 00:38:28,440 --> 00:38:30,280 It's the taste of the sea. 503 00:38:37,320 --> 00:38:41,280 And this is it. This is the end result. 504 00:38:42,600 --> 00:38:44,520 After billions of years, 505 00:38:44,520 --> 00:38:48,080 our bodies still rely on the same basic chemistry 506 00:38:48,080 --> 00:38:51,720 that evolved in those first blobs of life in the sea. 507 00:38:59,240 --> 00:39:03,120 Inside the body, salt controls the amount of water in each cell. 508 00:39:05,560 --> 00:39:08,040 Where there's more salt, water will go. 509 00:39:10,640 --> 00:39:13,400 It's a process called osmosis. 510 00:39:13,400 --> 00:39:16,320 It makes cells swell and shrink. 511 00:39:17,840 --> 00:39:20,360 Elsewhere, the sodium in salt is crucial 512 00:39:20,360 --> 00:39:22,360 for the functioning of our nerves. 513 00:39:26,240 --> 00:39:30,320 It's the movement of trillions of sodium ions in our brain 514 00:39:30,320 --> 00:39:35,120 that allows us to think, move and sense the world around us. 515 00:39:42,840 --> 00:39:46,880 And these sodium ions also interfere with our taste buds... 516 00:39:49,640 --> 00:39:52,160 ..not just bitter, 517 00:39:52,160 --> 00:39:53,960 but sweet too. 518 00:39:56,440 --> 00:39:58,520 As well as the finest salt, 519 00:39:58,520 --> 00:40:03,480 Brittany is also home to caramel au beurre sale - salted caramel, 520 00:40:03,480 --> 00:40:06,880 that stuff that's taken the world by storm over recent years. 521 00:40:06,880 --> 00:40:12,240 We are hardwired to love sugar and hardwired to love salt, separately. 522 00:40:12,240 --> 00:40:15,680 But when you put them together, something magical happens. 523 00:40:17,680 --> 00:40:22,440 The sodium in a tiny amount of salt actually makes sugar taste sweeter 524 00:40:22,440 --> 00:40:26,040 because, alongside our regular sweet receptors, 525 00:40:26,040 --> 00:40:29,680 we also have some additional receptors that are only activated 526 00:40:29,680 --> 00:40:33,160 when both sugar and salt are present. 527 00:40:33,160 --> 00:40:35,920 So, for the maximum sweet sensation, 528 00:40:35,920 --> 00:40:38,320 seek out the salty taste combinations 529 00:40:38,320 --> 00:40:41,760 found in ice cream, sweets, chocolates and, of course, 530 00:40:41,760 --> 00:40:46,680 in the gooey liquid filling inside a thin French pancake - 531 00:40:46,680 --> 00:40:48,400 a crepe. 532 00:40:50,760 --> 00:40:53,560 It's not polite, but it's delicious. 533 00:40:55,680 --> 00:40:57,200 Salt, 534 00:40:57,200 --> 00:40:59,160 bitter, 535 00:40:59,160 --> 00:41:01,000 sweet, 536 00:41:01,000 --> 00:41:02,920 sour 537 00:41:02,920 --> 00:41:04,480 and umami. 538 00:41:06,600 --> 00:41:08,880 Together, these five tastes form 539 00:41:08,880 --> 00:41:12,320 the foundation of our experience of food. 540 00:41:18,400 --> 00:41:20,600 Because we put food in our mouths, 541 00:41:20,600 --> 00:41:24,720 we tend to think of all the action happening there, on the taste buds. 542 00:41:24,720 --> 00:41:26,840 But, in fact, when we experience food, 543 00:41:26,840 --> 00:41:29,240 we also see it and critically... 544 00:41:29,240 --> 00:41:31,480 HE INHALES DEEPLY ..we smell it. 545 00:41:31,480 --> 00:41:35,680 And it's all of that which adds up to what we call flavour. 546 00:41:35,680 --> 00:41:38,000 COWS MOO 547 00:41:41,680 --> 00:41:46,920 Curiously, flavour isn't just about taste. It's also about the nose. 548 00:41:46,920 --> 00:41:49,200 And around this part of the world, 549 00:41:49,200 --> 00:41:53,160 there's a kind of food that's defined by it's nose - cheese. 550 00:41:54,960 --> 00:41:58,960 Which is odd, because most cheese starts out life the same way, 551 00:41:58,960 --> 00:42:00,880 smelling of almost nothing. 552 00:42:00,880 --> 00:42:03,240 COWS MOO 553 00:42:03,240 --> 00:42:06,080 So, this is where it all begins. 554 00:42:07,560 --> 00:42:10,120 And for someone who's used to knowing 555 00:42:10,120 --> 00:42:12,480 cows on packets in supermarkets, 556 00:42:12,480 --> 00:42:14,640 it's a dose of reality for me. 557 00:42:17,440 --> 00:42:21,120 To make cheese, lactic acid is added to fresh cow's milk 558 00:42:21,120 --> 00:42:22,800 and it's allowed to curdle. 559 00:42:24,320 --> 00:42:28,600 Then the fragile curds are put into moulds where the whey runs off. 560 00:42:28,600 --> 00:42:32,120 - You can take more cheese. - OK, bigger scoops. 561 00:42:34,320 --> 00:42:36,240 Yes, very good. 562 00:42:36,240 --> 00:42:39,160 'These curds will become the finished cheese, 563 00:42:39,160 --> 00:42:43,280 'but it begins with very little taste and no smell. 564 00:42:44,320 --> 00:42:46,320 'And yet, from this beginning, 565 00:42:46,320 --> 00:42:50,200 'the French produce more than 400 different kinds of cheese... 566 00:42:53,000 --> 00:42:55,520 '..each with their own unique flavour.' 567 00:42:57,200 --> 00:42:59,320 Oh, whoa! 568 00:42:59,320 --> 00:43:01,040 That's intense. 569 00:43:01,040 --> 00:43:03,320 It's like a furry animal. 570 00:43:05,880 --> 00:43:10,600 So, how do all these distinctive cheeses end up being so different? 571 00:43:10,600 --> 00:43:12,720 Well, more than anything else, 572 00:43:12,720 --> 00:43:16,600 the flavour of each cheese is determined by the way it smells. 573 00:43:18,320 --> 00:43:21,000 Take a bit of cheese, cover up your nose, 574 00:43:21,000 --> 00:43:24,160 and even now I can't smell anything, but I can still taste. 575 00:43:26,160 --> 00:43:29,680 This comte, which is normally incredible, 576 00:43:29,680 --> 00:43:32,680 it's kind of like eating a salty candle. 577 00:43:32,680 --> 00:43:35,960 You have this waxy texture, you have a bit of salt, 578 00:43:35,960 --> 00:43:39,560 a bit of bitterness, but it's like eating in black and white. 579 00:43:39,560 --> 00:43:42,120 - HE INHALES - And it's incredible. 580 00:43:42,120 --> 00:43:44,040 The second you uncover your nose, 581 00:43:44,040 --> 00:43:47,200 this rush of complexity and flavour comes back. 582 00:43:47,200 --> 00:43:49,800 It's like eating in technicolour. 583 00:43:49,800 --> 00:43:53,800 The massive difference between the thousands of different types 584 00:43:53,800 --> 00:43:56,960 of cheese on the planet is all about smell. 585 00:43:58,680 --> 00:44:01,440 This simple experiment reveals the powerful effect 586 00:44:01,440 --> 00:44:04,280 that smell can have on the flavour of food. 587 00:44:04,280 --> 00:44:08,760 'And to better understand how each cheese arrives with its own pong, 588 00:44:08,760 --> 00:44:13,720 'I'm in Burgundy, where they produce one particularly notorious cheese.' 589 00:44:14,840 --> 00:44:18,600 It's the cheese known as the king of cheeses, 590 00:44:18,600 --> 00:44:23,080 Napoleon's favourite and one of the world's smelliest. 591 00:44:23,080 --> 00:44:26,200 There are stories that this stuff smells so bad 592 00:44:26,200 --> 00:44:29,600 that it was actually banned from the Paris Metro. 593 00:44:29,600 --> 00:44:31,120 Nice(!) 594 00:44:32,920 --> 00:44:37,440 'It's a soft rind-washed cow's cheese and it's called Epoisses. 595 00:44:39,200 --> 00:44:44,080 'So, what's responsible for making its uniquely powerful smell? 596 00:44:46,200 --> 00:44:50,040 'For it to develop, the embryonic cheese needs salt, 597 00:44:50,040 --> 00:44:52,800 'it needs time and it needs bacteria. 598 00:44:54,080 --> 00:44:57,360 'Each cheese starts its journey of transformation 599 00:44:57,360 --> 00:44:59,920 'with a specific type of bacteria. 600 00:45:02,280 --> 00:45:05,120 'But it's how these young cheeses are treated next 601 00:45:05,120 --> 00:45:07,800 'that creates their flavour and texture. 602 00:45:09,000 --> 00:45:12,400 'With Epoisses, the rinds are regularly washed 603 00:45:12,400 --> 00:45:16,000 'with water-down pomace brandy, made from the skins, seeds 604 00:45:16,000 --> 00:45:19,240 'and stalks of grapes left after winemaking.' 605 00:45:19,240 --> 00:45:23,680 - It's very fragile. - Yeah. - So, you take it slowly. - OK. 606 00:45:23,680 --> 00:45:27,720 'The brandy imparts some of its own flavour to the cheese 607 00:45:27,720 --> 00:45:29,480 'but, most importantly, 608 00:45:29,480 --> 00:45:32,320 'it affects which bacteria thrive on the cheese.' 609 00:45:39,800 --> 00:45:44,840 One kind of bacteria is called Arthrobacter arilaitensis, 610 00:45:44,840 --> 00:45:48,960 which builds long chain molecules that make the rind go orange. 611 00:45:52,280 --> 00:45:55,000 Another is Brevibacterium linens, 612 00:45:55,000 --> 00:45:59,760 and these break down the proteins in the cheese into smaller molecules, 613 00:45:59,760 --> 00:46:02,840 including stinky, sulphur-based compounds 614 00:46:02,840 --> 00:46:05,360 that give cheese its funky, sweaty aroma. 615 00:46:07,040 --> 00:46:11,240 It's closely related cousin, Brevibacterium epidermidis, 616 00:46:11,240 --> 00:46:14,320 can be found growing on human feet, 617 00:46:14,320 --> 00:46:18,760 giving them THEIR funky, sweaty aroma. 618 00:46:33,680 --> 00:46:35,240 Voila. 619 00:46:36,640 --> 00:46:37,720 Ooh! 620 00:46:40,720 --> 00:46:43,440 They weren't kidding about the way it smells. 621 00:46:45,000 --> 00:46:48,760 It's intense, it's kind of sulphur-like. 622 00:46:48,760 --> 00:46:52,680 It's kind of an instant flashback to the rugby socks 623 00:46:52,680 --> 00:46:56,320 I left in a PE kit once in school for a whole week. 624 00:47:00,960 --> 00:47:06,000 'Volatile aroma molecules from cheese or feet float into the air 625 00:47:06,000 --> 00:47:08,280 'and get sucked up into your nose. 626 00:47:09,360 --> 00:47:13,400 'Each smell compound stimulates a unique combination of receptors 627 00:47:13,400 --> 00:47:16,680 'that allow us to identify the smell. 628 00:47:18,600 --> 00:47:22,200 'In the case of Epoisses, it's the smell of stinky feet 629 00:47:22,200 --> 00:47:25,960 'and it's not particularly pleasant or appetising. 630 00:47:27,640 --> 00:47:33,000 'So why, if it smells so bad, would anyone put it in their mouth?' 631 00:47:38,080 --> 00:47:39,440 But... 632 00:47:41,560 --> 00:47:45,200 ..when you eat it, something magical happens. 633 00:47:45,200 --> 00:47:47,560 The aroma compounds are released in your mouth 634 00:47:47,560 --> 00:47:50,040 and they waft up the back of your nose 635 00:47:50,040 --> 00:47:53,960 and they're detected there by the same smell detectors. 636 00:47:53,960 --> 00:47:56,760 But weirdly, your brain perceives them as very different 637 00:47:56,760 --> 00:47:58,600 from if you were to smell forward 638 00:47:58,600 --> 00:48:00,840 and sniff them up the front of your nose. 639 00:48:03,280 --> 00:48:05,920 It's called backward smelling. 640 00:48:07,200 --> 00:48:09,480 Rather than simply smelling the pong, 641 00:48:09,480 --> 00:48:12,800 the brain now combines the smell with the creamy taste 642 00:48:12,800 --> 00:48:16,320 it's experiencing on the tongue at the same time. 643 00:48:16,320 --> 00:48:19,720 This combination of taste and smell 644 00:48:19,720 --> 00:48:21,320 'has a dramatic effect 645 00:48:21,320 --> 00:48:25,200 'on how we perceive a particular odour molecule. 646 00:48:25,200 --> 00:48:29,000 'And for the full effect, always eat the rind, 647 00:48:29,000 --> 00:48:32,000 'since this is where many of the smells lie.' 648 00:48:32,000 --> 00:48:33,440 This stuff... 649 00:48:34,800 --> 00:48:39,920 ..no longer is pungent and kind of animalic, like your body. 650 00:48:39,920 --> 00:48:44,960 It's suddenly sharp, garlicky, eggy. 651 00:48:44,960 --> 00:48:48,320 It's just warming, comforting deliciousness. 652 00:48:57,520 --> 00:49:00,920 This is the full flavour experience. 653 00:49:02,440 --> 00:49:06,320 Only by combining taste and backwards smells in our brain, 654 00:49:06,320 --> 00:49:10,640 so we unlock the food's full flavour potential. 655 00:49:16,640 --> 00:49:19,480 Breathe normally in there. 656 00:49:19,480 --> 00:49:23,600 'We may have only five types of taste receptors on our tongue, 657 00:49:23,600 --> 00:49:25,560 'but our noses are packed 658 00:49:25,560 --> 00:49:28,560 'with around 400 different smell detectors. 659 00:49:28,560 --> 00:49:33,320 'I'm testing how good my smell detectors are by sniffing aromas 660 00:49:33,320 --> 00:49:37,480 'extracted from a mystery meal, one of the nation's favourites.' 661 00:49:37,480 --> 00:49:39,480 Whoa, that one's strong. 662 00:49:42,480 --> 00:49:45,760 This one, for some reason, is making me think of wet mackintoshes. 663 00:49:47,240 --> 00:49:50,440 'The twist is, I'm not going to eat even a spoonful.' 664 00:49:50,440 --> 00:49:52,160 Quite aromatic. 665 00:49:52,160 --> 00:49:56,120 'Instead, I'm inhaling wafts of the individual aroma molecules 666 00:49:56,120 --> 00:49:58,320 'that make up this mystery meal.' 667 00:49:58,320 --> 00:50:01,760 It smells almost faecal. I'm trying to work out what it is. 668 00:50:01,760 --> 00:50:03,280 That's weird. 669 00:50:05,000 --> 00:50:07,120 Almost aniseedy. 670 00:50:09,840 --> 00:50:12,920 Smells a damp basement smell. 671 00:50:14,480 --> 00:50:16,920 Not like you can say that's lemon or that's... 672 00:50:18,560 --> 00:50:20,480 ..pine cone or... 673 00:50:22,080 --> 00:50:23,760 They're sort of spicy. 674 00:50:23,760 --> 00:50:26,920 'It's only when all the smells are brought together 675 00:50:26,920 --> 00:50:30,520 'at the end of the test that I can finally hazard a guess.' 676 00:50:32,040 --> 00:50:34,960 - Would you like to smell this one? - OK, yeah. - Yeah. 677 00:50:36,360 --> 00:50:37,840 Whoa, that's strong. 678 00:50:37,840 --> 00:50:41,920 So, that is definitely curry and it smells like... 679 00:50:41,920 --> 00:50:45,600 - Is that chicken korma? - Yes, exactly. 680 00:50:45,600 --> 00:50:51,080 We broke down all the aroma components of this curry 681 00:50:51,080 --> 00:50:54,240 and you smell them one after the other. 682 00:50:54,240 --> 00:50:56,360 - And I couldn't put them all together. - Yeah. 683 00:50:56,360 --> 00:51:00,960 There are many spices so you can get many spicy notes, many meaty notes. 684 00:51:00,960 --> 00:51:05,400 - Some strange notes, like rose, like potato. - OK, yeah. 685 00:51:05,400 --> 00:51:08,600 - And the pigsty. - Maybe it was the pigsty I was smelling 686 00:51:08,600 --> 00:51:10,600 - at the beginning. - Sweaty. - Yeah. - Yeah. 687 00:51:10,600 --> 00:51:14,000 Very, very odd, having them as distinctive things 688 00:51:14,000 --> 00:51:16,080 and then trying to add them up to something. 689 00:51:16,080 --> 00:51:18,560 I would never, ever have guessed that was chicken korma. 690 00:51:18,560 --> 00:51:21,880 And yet, when I smell that, I know straightaway it's chicken korma. 691 00:51:21,880 --> 00:51:23,440 - It just smells like it. - Yep. 692 00:51:23,440 --> 00:51:26,320 It's one of the things I'm quite familiar with. Yeah. 693 00:51:29,160 --> 00:51:33,160 This experiment reveals how our noses help us enjoy food. 694 00:51:37,080 --> 00:51:40,640 Rather than singling out individual notes... 695 00:51:41,920 --> 00:51:46,400 ..all the individual aromas come together to form one unified, 696 00:51:46,400 --> 00:51:50,880 instantly identifiable and delicious pong. 697 00:51:57,720 --> 00:52:01,200 Using just 400 different smell receptors... 698 00:52:02,360 --> 00:52:04,880 ..our noses are so powerfully tuned, 699 00:52:04,880 --> 00:52:07,560 that it's been estimated we can identify 700 00:52:07,560 --> 00:52:09,960 a trillion different smells. 701 00:52:12,080 --> 00:52:14,160 Like pizza, 702 00:52:14,160 --> 00:52:16,320 roast chicken 703 00:52:16,320 --> 00:52:18,960 or an oak-aged Bordeaux. 704 00:52:26,480 --> 00:52:30,240 In our search for evermore delicious and satisfying things 705 00:52:30,240 --> 00:52:32,800 to indulge our senses, 706 00:52:32,800 --> 00:52:35,640 we've created extraordinary processes 707 00:52:35,640 --> 00:52:40,680 that alter the taste, texture and aroma of our food. 708 00:52:43,520 --> 00:52:47,320 But one has profoundly changed the course of civilisation. 709 00:52:48,920 --> 00:52:52,720 It has transformed our experience and our enjoyment of food. 710 00:52:52,720 --> 00:52:54,880 It is, of course, cooking. 711 00:52:58,800 --> 00:53:02,880 There's evidence our remote ancestors began cooking food 712 00:53:02,880 --> 00:53:05,040 at least 400,000 years ago. 713 00:53:06,320 --> 00:53:10,320 And from the start, they were unwittingly triggering, in our food, 714 00:53:10,320 --> 00:53:13,720 one of the most complex chemical reactions on Earth. 715 00:53:15,280 --> 00:53:18,520 Now, this is a truly wonderful piece of meat. 716 00:53:18,520 --> 00:53:22,480 It's a local speciality, known as "bistecca Fiorentina". 717 00:53:22,480 --> 00:53:25,120 In its raw state, like this... HE INHALES 718 00:53:25,120 --> 00:53:27,680 ..it really doesn't smell of anything very much. 719 00:53:27,680 --> 00:53:29,720 But put it on the grill over there, 720 00:53:29,720 --> 00:53:32,120 something truly wondrous will happen. 721 00:53:32,120 --> 00:53:36,040 It's called the Maillard reaction, named after a Frenchman, 722 00:53:36,040 --> 00:53:39,400 but I prefer to call it the "science of the sizzle". 723 00:53:44,000 --> 00:53:48,400 - Fantastic. You don't put salt? - No, no. - No? 724 00:53:48,400 --> 00:53:51,080 - No, no. - Oil? - No, nothing. 725 00:53:53,520 --> 00:53:56,240 The key to unlocking the flavour in the meat 726 00:53:56,240 --> 00:54:00,120 is the smells that will be generated by the Maillard reaction, 727 00:54:00,120 --> 00:54:04,480 and you can actually see it happening right before your eyes. 728 00:54:10,120 --> 00:54:12,840 So, all this lovely brown stuff you can see over here, 729 00:54:12,840 --> 00:54:15,640 that is the results of the Maillard reaction. 730 00:54:18,160 --> 00:54:20,480 It starts off simply enough. 731 00:54:20,480 --> 00:54:23,440 In the intense heat, the building blocks of protein, 732 00:54:23,440 --> 00:54:25,040 the amino acids, 733 00:54:25,040 --> 00:54:28,600 react with naturally occurring sugars in the meat. 734 00:54:28,600 --> 00:54:31,240 And the beauty of the Maillard reaction is that, 735 00:54:31,240 --> 00:54:34,320 once it kicks off, everything goes completely crazy. 736 00:54:39,240 --> 00:54:42,440 The reaction becomes more and more complex 737 00:54:42,440 --> 00:54:46,120 and intensifies as the products of each reaction 738 00:54:46,120 --> 00:54:48,680 get involved in their own reactions. 739 00:54:50,440 --> 00:54:53,280 Eventually, the whole thing cascades wildly 740 00:54:53,280 --> 00:54:56,320 and generates thousands of different molecules. 741 00:55:03,360 --> 00:55:06,560 Lots of lovely aroma molecules that I am now... 742 00:55:06,560 --> 00:55:09,480 HE INHALES ..hungrily hovering up. 743 00:55:14,760 --> 00:55:17,320 Smells absolutely fantastic now, I have to say. 744 00:55:17,320 --> 00:55:19,920 Complete transformation from that piece of meat, as it was, 745 00:55:19,920 --> 00:55:23,080 - to what it is now. - Ora, sale grosso. 746 00:55:26,440 --> 00:55:28,800 - Oil. - OK. Olive oil, splash on. 747 00:55:34,080 --> 00:55:36,800 - It's perfect. - Perfect. - Perfect. 748 00:55:43,520 --> 00:55:45,600 And it's not just about meat. 749 00:55:47,320 --> 00:55:49,840 Baking bread, 750 00:55:49,840 --> 00:55:51,920 roasting coffee, 751 00:55:51,920 --> 00:55:54,760 frying onions and garlic. 752 00:55:57,600 --> 00:56:00,120 If it smells good when you cook, 753 00:56:00,120 --> 00:56:03,720 the secret chemist inside you is actually analysing 754 00:56:03,720 --> 00:56:06,600 the results of a Maillard reaction... 755 00:56:10,920 --> 00:56:15,960 ..a reaction so complex it takes a whole textbook to describe it. 756 00:56:15,960 --> 00:56:17,760 THEY CHEER 757 00:56:24,000 --> 00:56:26,520 Our understanding of food 758 00:56:26,520 --> 00:56:31,120 and how it seduces our senses is deepening all the time. 759 00:56:33,120 --> 00:56:36,840 In the past, when eating the wrong thing could be a threat, 760 00:56:36,840 --> 00:56:40,520 our senses guided us to swallow what was nourishing 761 00:56:40,520 --> 00:56:43,160 and to spit out what might harm us. 762 00:56:45,360 --> 00:56:46,920 'For modern humans, though, 763 00:56:46,920 --> 00:56:50,440 'taste is no longer merely a guide to survival. 764 00:56:53,400 --> 00:56:55,760 'Today, we transform food in ways 765 00:56:55,760 --> 00:56:59,000 'our ancestors would never have recognised... 766 00:57:00,200 --> 00:57:03,200 '..to create combinations that stimulate our eyes, 767 00:57:03,200 --> 00:57:06,480 'noses and all our taste buds... 768 00:57:07,840 --> 00:57:11,000 '..to create the ultimate mouthful of flavour.' 769 00:57:11,000 --> 00:57:13,480 THEY CHEER 770 00:57:13,480 --> 00:57:18,000 These days, taste is mainly about pleasure, the enjoyment in food. 771 00:57:18,000 --> 00:57:22,240 And it's that enjoyment which brings communities and families together. 772 00:57:22,240 --> 00:57:26,200 It's because we really understand what makes food work 773 00:57:26,200 --> 00:57:29,000 that we're able to create unusual combinations, 774 00:57:29,000 --> 00:57:31,920 really make our taste buds zing. 775 00:57:33,480 --> 00:57:37,000 Next time, we explore why we have food on the brain. 776 00:57:38,600 --> 00:57:43,760 We discover how it ignites powerful, irresistible cravings in us... 777 00:57:43,760 --> 00:57:45,200 That is truly delicious! 778 00:57:45,200 --> 00:57:47,640 ..and sometimes disgust, 779 00:57:47,640 --> 00:57:50,120 why we welcome pain 780 00:57:50,120 --> 00:57:54,360 and have learnt to love the hottest food on the planet. 781 00:57:57,160 --> 00:58:00,120 Can science affect your perception of food? 782 00:58:00,120 --> 00:58:02,120 How instinctive are you? 783 00:58:02,120 --> 00:58:04,160 To find out more about the foods you eat, 784 00:58:04,160 --> 00:58:07,040 go to the BBC website on the screen 785 00:58:07,040 --> 00:58:10,120 and follow the links to the Open University.