What’s In a Tomato

tomatoes

What a strange state of affairs that we know the precise chemical makeup of distant stars yet we don't really know what's in our food most of the time. What makes a meal, and what makes it healthy, or unhealthy? I have decided to break down one of my favorite foods and try to look at what it's really made of, and why I enjoy it. Besides personal preference this is a good specimen to study because it is currently the world's most popular fruit, with over 145 million tons produced annually, is used in a wide variety of dishes, and as of last year has had its genome sequenced. Behold, Solanum Lycopersicum, the tomato.

Of course there is no "real" or essential tomato. Thousands of cultivars are produced in differing climates and conditions. Tomberry tomatoes are only 1/2000 the size of massive beefsteak tomatoes, though most are somewhere in the middle, around 5cm in diameter. Some variants are grown specifically for canning. Tomatoes are acidic, making them easy to preserve in a can, and canned tomatoes are sealed at the peak of freshness. This gives them a higher antioxidant content and preserves the vitamins and minerals, making them even healthier than their fresh counterparts most of the time.1

Tomatoes possess one of the most powerful known antioxidants, lycopene. Lycopene is a type of Carotene, substances which transmit light energy in photosynthesis. With the chemical formula C40H56, tomatoes produce lycopene from 8 instances of isoprene (C5H8), which is itself made from a series of chemical reactions called the MEP pathway in the chloroplast. Its long, straight structure lowers the required energy for electrons to transition to higher energy states. This makes lycopene effective at absorbing higher frequency, and thus higher energy, wavelengths of light, only reflecting photons with longer wavelengths, i.e. red light. This also gives lycopene, and the tomato, its characteristic red color. As an effective antioxidant, a substance that quenches highly reactive ions of oxygen, there is evidence lycopene has a wide variety of positive health benefits, including a reduced risk of cancer.

Like most fruits and vegetables, tomatoes are almost entirely water by weight. Here is an image showing the approximate contents of a typical tomato.2

tomato_breakdown

The sweetness and most of the calories in a tomato come from the glucose and fructose, which add up to about 18 calories. The protein adds another 7 calories. The fiber is almost entirely insoluble, which accelerates the movement of food through the digestive system. It is not digested itself, but it does feed bacteria in the colon, which produce a variety of healthy products from it like short chain fatty acids. The "ash", pretend it's red, contains the lycopene, beta carotene (Vitamin A precursor), the minerals Phosphorous, Sodium, Potassium, Calcium, and Magnesium, and the trace elements, Iron, Copper, Zinc, and Manganese. There are also trace amounts of substances called "flavonoids", chemicals used in plant metabolism like quercetin and rutin. Despite extensive study, these flavonoids in tomatoes have been found to have no physiological role in humans.3,4 Flavonoids are a type of "phytochemical", non-essential chemicals produced by plants that may one day be found to have an effect on human health. Lycopene is generally accepted as an effective antioxidant but currently there is very little evidence others have positive roles. Some may even be harmful.5

I purchased this tomato at a farmers' market in San Francisco. It cost me 60 cents, which is about half the price of a supermarket tomato, and contains 25 calories. That's 2.4 cents / calorie. By comparison, a double cheeseburger from McDonald's costs 99 cents and contains 440 calories6, which is 0.225 cents / calorie, more than an order of magnitude more cost effective. It would cost me $130/day to live on supermarket tomatoes, $65/day to live on farmers' market tomatoes, and $6/day to live on cheeseburgers. It's no wonder the poor eat poorly.

The tomato genome was sequenced in 2012. It was found that the 'domesticated' tomato differs from a wild tomato by only 0.6% of its genome, and has about 900 million bases. By comparison, the human genome has about 3.2 billion bases. The tomato genome is unique in that relatively little of its genome consists of repeated sequences of information, which is common in plants. The researchers also found evidence that tomatoes, potatoes, and grapes likely share a common ancestor, and that the tomato has undergone two whole-genome triplications.7

I have experimentally verified that tomatoes are delicious. To test, I purchased two additional tomatoes from a supermarket, one grown in a greenhouse, one outside. Both were about twice as expensive as the farmers' market tomato, though nearly identical in mass. Both are softer and have a stronger scent than the farmers' market tomato. I blindfolded myself and took two bites out of each, picked at random, with a minute break in between after taking notes. The outside tomato was the sweetest, and softest. The greenhouse tomato was juicier, had slightly firmer flesh, and the strongest scent once I bit in to it. To my surprise the tomato from the farmers' market was relatively dry, firm, and bland, my least favorite. The greenhouse tomato was my preferred cultivar, and curiously appears to have noticeably more seeds inside. This sample size is small so if you do this experiment yourself please post your findings in the comments.

Flavor depends on a combination of the sensations of taste and smell. Volatile chemicals are released when food is chewed and react with olfactory receptor neurons, while nonvolatile chemicals react with special skin cells, taste buds, on the tongue. There is evidence the majority of flavor humans experience comes from smell. Azondanlou et al. found that of its 400 identifiable volatile chemicals, only about 30 contribute to the tomato's flavor. The taste comes from the glucose and fructose, identified as sweet, and citric acid, identified as sour. As onmnivores, humans enjoy the taste of sweets, which signify the consumption of carbohydrates, the body's primary source of energy. Carnivores, like cats, cannot taste sweets at all.

We are not the only ones vying for the nutrients in food. These tomatoes were likely already teeming with bacteria when I bought them. Don't worry though, our saliva and stomach acids make short work of them. Unless food appears or smells spoiled our defense mechanisms should have no problem rendering the food harmless. After a couple of days however the bacteria, thriving on the water and carbohydrates, reduced my tomatoes to mush and "spoiled" them. Scientists around the world are working to improve our tomatoes through genetic engineering, making them larger, tastier, more robust, more nutritious, and perhaps even more resistant to pathogens and spoilage.

When I was a child I kept a tomato garden with my father. It was a lot of work keeping the pests away, keeping them in sunlight without choking their stems, and watering them daily. The final product ended up being much smaller and blander than those bought at the supermarket, though of course that was not the point. Tomatoes, like transistors, are much better when produced at scale. Perhaps one day I will show my son how people used to produce food, but I'd much rather teach him to code.

References

1: http://onlinelibrary.wiley.com/doi/10.1002/jsfa.2824/abstract
2: http://www.sciencedirect.com/science/article/pii/S0308814607007108
3: http://www.cancer.org/…
4: http://en.wikipedia.org/wiki/Rutin
5: http://www.cancer.org/…
6: http://nutrition.mcdonalds.com/getnutrition/nutritionfacts.pdf
7: http://www.nature.com/nature/journal/v485/n7400/full/nature11119.html

  • Dorag

    How can you know for sure that when you send your Soylent to costumers there wouldn't be any mix-ups in the amounts or nutrients?

    • Sgv

      The guy's taking so damn long to do it, he's probably trying to figure this out currently.

      Seriously, we want a kickstarter.

      • Unorthodox Blackbox

        Mr Rinehart has only been at this and documenting for a few months at this point. I think what makes me most interested in his work is precicely that he is not rushing or trying to promote it as some magical diet. It isn't. He is being upfront about the problems and promoting the criticism a project like this will face, and rightly so.

        The Kickstarter will be to fund research and study this method of nutrient ingestion, not to sell it. He has goals that are optimistic but he is being realistic.

        Be patient. 

  • Crimson

    Have you considered the fact that you're now a "food engineer"? 

  • Sofia Sterzi

    Hi, I loved this post about the tomato, so full of detail and interesting curiosities! Why don't you do it with other vegetables?

  • wouterr5

    " carbohydrates, the body's primary source of energy"

    I enjoyed your post, but what do you mean by this? 

    • tsenaku

      The body converts carbohydrates to energy faster than any other macro molecule.

    • Gar

      Basically, carbohydrates are the only source of fuel for your cells, to be plain. Your cells break down carbohydrates into glycogen which is used when your muscles current ATP stores are depleted. 

      Take a quick read online. Look up Glycogen and ATP and you'll get a really good idea of how your body breaks down carbs and what it does with them.

  • Michael Terry

    Carbs are only the primary source of energy for societies for whom that's true. The traditional Inuit and Maasai diets are documentedly not. It is under debate whether pre-Agrigultural diets were mostly carb, I suppose, althought it almost certainly depended on the environment and almost certainly was not in many places. Where there was only seasonal availability of non-animal foods, it is quite likely that carbs did not make up the bulk of the diet, and this likelihood is strengthened when considering societies that did not yet have food preservation technologies.

    • Ben

      The body does convert fats and protiens to carbohydrates in a carbohydrate deficent diet however. So they are still the major source of energy.

      • negativezero

        The body converts fats in ketones, and proteins into glycogen only if it's specifically required.

        • Matt

          Where can I read more about this? 

          I'm curious about the priority with which the body pulls energy from different molecules. 

    • Donny54

      The body requires carbohydrates to function, particularly glucose, which can be formed by the body from non-carbohydrate carbon sources through gluconeogenesis and glycogenolysis. Carbohydrates are the human body's primary source of energy in all cases, irrespective of what's consumed.

  • Dick Morello

    "I have experimentally verified that tomatoes are delicious."

     

    Well funny.

  • Harry

    GMO tomatos are not better.

    When you cut a tomato and have it transport miles it loses nutrients.
    When the soil has a lot of nutrients the tomato becomes in a way its own pesticide since bugs can handle the lardge dosage.

    Tomatoes in the US compared to one in a village outside have a noticable differece especially when eaten fresh.

    Canned tomato builds up methain which is why canned goods I assume expand over time.
    Just because it hard  does not mean its good due to being picked too soon and chemicals sprayed to make it red, and plenty of pestisides, so the supermarket ones my seem good but also have the bad side. It may look perfect but is far from it.

    I would figure the greenhouse would be better but it depends on the condition which even that is not as good as other ones. The farmers market does not guarantee anything and they depleated their soil, which the tomato was just sucking water than nutrints.

    Best to grow you own with good soil and store bought defeats the purpose of cost, taste and nutrients. All in all a good experiment.

    • Gar

      Do you have any sources for this? 

      • harry

        find both videos. there are other videos about it those are the 2 I remember now.
        food inc

        http://www.imdb.com/title/tt1286537/
        Back to Eden Gardening
        http://www.youtube.com/watch?v=7CjptUYhEdU

         

      • Paul

        I assume he's spouting "common knowledge".

        In fact, there is strong evidence to support GMOs as promoting a healthy diet in the general population.  They are cheaper and easier to produce, due to their resistance to pesiticides and vermin.  Additionally, many, such as some strains of rice, have been engineered to provide additional dietary requirements for poor populations where rice is eaten as an extreme portion of their diet.

        All of that means that on the whole, GMOs will provide an increased standard of living for billions of people.

        • ws

          Many people I know are alergic to GMO. The stuff you say have not been proven and the only results that show what  you say have conflict of interest. If you look online at independant lab results on rats they have serious health risks, and the 3rd generation become sterile.

          You wont be able to grow your own food if GMO crop spread since it's pattented. It also requires more water and costs more which many miss, but you dont see the cost due to gov subsidies.

          Money can buy good pr to spin it anywhich way and plenty that do not research will eat it up. Not even gmo companies can defend it well which is why they gave hundreses of millions to politicians to make laws to prevent them from being sued which not even the government has those privlages.

          The honey bee is getting  wiped out by gmo, virused are mutating where antibiotics can't fight it, it threatens to wiped out entire species of crops, GMO in banned in other counties, the list goes on if people take the time to do research, and if they dont well then it works out for them to not have offspring. maybe its a win win lol

          • berdario

            If you're telling the truth, about

             

            "independant lab results on rats they have serious health risks, and the 3rd generation become sterile."

            please provide links, because it's surely interesting as hell!

            otherwise, I'll just have to assume you're spreading FUD

  • Harry

    correction
    bugs can't handle the lardge dosage.

  • Julie

    If the tomatoes you grew in your garden were actually blander than the ones you bought at a supermarket, then you are seriously doing it wrong. Or maybe you just have a taste preference for bland, mealy tomatoes.

    • silkcom

      honestly.  I grow tomatoes because store bought ones are bland and home grown ones are awesome :). However tomatoes are delicious we definitely agree on that one :)

  • Irene

    I agree with your post in principle, but completely disagree with your methodology for your tomato experiment.

    Were all three tomatoes the same cultivar?  Different tomatoes taste differently.  

    Where all three tomatoes at the same degree of ripeness?

    Plus, no matter what the tomato (GMO, organic, whatever), plant health and flavor is incredibly affected by soil conditions, daily care, and climate.  Speaking of which, generally garden tomatoes taste best if you take good care of them, so I'm wondering what happened to yours.  Maybe using the wrong sort of fertilizer, or the plants may have been diseased.

    There are simply too many variables, and no control.  

  • Steve

    Tomatoes are among the most expensive items at the supermarket, measured by cost per calorie. The McDouble, by that measure, may be the cheapest item on the McDonald's menu. An analysis comparing Wonder Bread to home-baked bread, and a Quarter Pounder to lentils, found that food prepared at home can be far less expensive per calorie.

  • http://Biggerfastermore.com Minderbinder

    Your writing is fun to read because of the way you relate natural processes across scientific disciplines.  I may not be allergic to wheat, gmos, salt, sugar, antibiotics and chem trails, but I don't believe tomatoes are better produced as microchips. If you grew tomatoes that weren't obviously better than store bought, then something went wrong.   Thanks for the great reading!

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  • Alex

    Have you thought about trying (or at least looking into) drip-feed products? Those are probably pretty similar to what you are making. Jevity is one of the brand names and can be bought on Amazon, though it's probably more expensive than making it yourself.
    I've lived on products like Jevity for about three months when I was getting chemotherapy and couldn't eat a bite (as regular food would get out as soon as it got in).

    • Brenda

      Very good point, Alex. A formula diet is not a new concept at all. I'm a Registered Dietitian with a PhD in nutrition, and we in the field of nutrition have been using formula diets for years to feed those who cannot tolerate food. There are several companies that make formula diets for various needs. The only thing new about Soylent is that it was developed by an individual on his own, and he's writing a blog about it. Could be that his formula differs from others, but it was developed according to the same principles. Back before we had formula diets, we made blenderized tube feedings out of foods. This was inferior to the formula diets due to higher risk of contamination, less consistency in formulation, and probably less nutritional completeness. When you think about it, milk is a formula diet intended by nature for babies, with the composition of the milk being exactly what that species of baby needs.

      As for me, I enjoy food. I can relate to the desire for convenience, for sure, but I'd rather use frozen convenience foods than drink a bland formula. Think Optifast, Slimfast, etc, etc. It's all based on the same concept other than saving  money, of course.

  • Aalex Gabi

    I love the way you write. Thank you for this post and keep going.

  • http://andowebsit.es/blog/noteslog.com/ Andrea

    My cat simply loves canned tomatoes.

  • e

    You may be interested in this link  <http://fourmilab.ch/documents/health/supplements/&gt; about nutrition. I hope you press on with your experimentation.

  • hxka

    When describing tastes, you missed the umami taste of glutamate ions.

  • harry

    GMO info for people too lazy to look up info people.
    Over 800 world scientists agree: GM crops are nothing short of a bio-war on our food
    http://www.naturalnews.com/040447_GMO_biowar_food.html#ixzz2U4jGBCJ0

    independent reserch on GMO food and mice results  http://www.youtube.com/watch?v=4J8CYVNkH98

  • harry

    You notice the multiple flaws in your link? I'll let you assume that you are right.

    As Plato said "Preserve the natural"
    even the bible has multiple refrences/metaphores, which one is "thou shalt not sow thy field with mingled seed"