Inspired by a TV show we saw on Wednesday (NHK's Tameshite Gatten), I conducted a bit of an experiment in the kitchen yesterday. The show was about tomatoes, specifically Japanese tomatoes, and how to cook a good tomato sauce with them. Not a rich meat sauce or arrabiata, but a simple fresh sauce, the kind that is popular in the summer, loved by the Japanese, and very hard to recreate at home. Unlike the restaurant version, the home-cooked version tends to be watery and to lack flavour.
I paid attention from the beginning, since I've always complained about the tomatoes here, much to the surprise of most Japanese: people here are very proud of their toms, especially the momotaro variety. They love the sweetness of these tomatoes, but I find the flavour bland and un-tomatoey, the pinkish colour unappetizing, the texture mealy, and the quality unreliable. Even during peak tomato season there are still duds. Whenever the subject of Japanese tomatoes comes up with my students (more often than you'd think, since food is a perennial favourite topic), you'd think we were each talking about a completely different vegetable. (Or fruit. Depends on your classification system).
Turns out we kind of were. According to the TV show we saw, the typical supermarket Japanese tomato is grown in a greenhouse and picked while still green, which could explain not only the mealiness and blandness, but the fact that they never seem to come into season. What my students are probably talking about is the home-grown version, or the expensive kind that have to be ordered privately (nearly all of my female students are gardeners, and many get their produce delivered from private food co-ops). Roma tomatoes, however, are usually vine-ripened, and although this doesn't necessarily affect the sugar content (tomatoes will continue to ripen and sweeten on the shelf) it does affect the glutamic acid content. Both types of tomatoes were measured, and the vine-ripened romas had a far higher level of the stuff. Which may mean nothing to you, but glutamic acid produces the savoury flavour compound called umami, one of the five basic tastes. Think of it as nature's MSG.
Still, this show claimed to have found a technique to produce a good sauce with typical shelf-ripened Japanese tomatoes. Skeptical, I headed to the supermarket yesterday morning to find tomatoes for a taste test.
Here I should mention that the variety of tomatoes in Japan has improved a bit recently: years ago the only choices were the pink Japanese tomatoes and cherry tomatoes (called mini-tomato). Now you can buy midi-tomato, which are a bit bigger than cherries but taste the same; fruit-tomato, which are extra sweet and very good to eat raw; and roma tomatoes, which are usually called ryouri-yo-tomato or italian-tomato. The selection is still nowhere near as good as back home, but I was confident I would be able to find what I needed.
And I was able to find roma tomatoes. But strangely there were no regular Japanese tomatoes at all. Or perhaps not so strange at all: foods often sell out after being mentioned on health or cooking shows. What I bought instead was koutoudo-tomato (high sugar-content tomatoes), which seemed to be a special variety of momotaro, and were also likely vine-ripened. Both were domestically grown, a bit more expensive than regular tomatoes (and tomatoes are already very pricey here), and were in good condition, although the Japanese tomatoes seemed a bit fresher.
When I got home, I tried both of them raw. The roma was bitter and yucky, which I expected as it's not meant to be eaten raw, and the Japanese tomato was delicious: amazingly sweet and juicy and I was tempted to cancel the sauce cook-off and just make a salad. I finally understood what my students are talking about. This is a tomato that the Japanese can be proud of.
It seemed a little unfair to use these special tomatoes against the romas, but I went ahead anyway. The picture above shows the sauces being made: the Japanese tomatoes on the left, and the roma sauce on the right (the seeds and liquid that were removed are in the bowl at top right, and you can see how omitting them makes much less sauce).
With the romas, I followed the regular technique for a simple fresh tomato sauce: I peeled them, removed their stems, cut them in half and scooped out the seeds and liquid with a spoon. Then I pureed them in a blender and simmered them in a pan for a few minutes, until the sauce was reduced with there was no separation of water and sauce.
The Japanese tomatoes, however, weren't peeled or seeded. Normally the seeds and skin are removed for two reasons: they are bitter and hard, and they make the sauce too watery or cause the sauce to separate. But the show explained that, contrary to popular belief, the seeds don't really contain more water than the flesh (this was measured, with the flesh consisting of 94% water and the seeds 95%, a very small difference indeed). Not only that, but the skin of the Japanese tomato is thinner and softer than other varieties, with the skin and seeds being just as tasty as the flesh (the featured chef even said the seeds were the tastiest part of the tomato). Finally, the skin and seeds contain pectin, which if you've ever made jam you'll know is a gelling agent and would therefore help thicken the sauce and keep it together.
So I simply removed the stem and pureed them, and simmered the sauce in a pan. The show recommended 20 minutes, but it was thick enough in 15 and I thought any more cooking would ruin the fresh flavour.
Both sauces were finished with a pinch of salt and splash of good-quality extra virgin olive oil, with freshly cooked spaghetti added to the pan and mixed up to distribute the sauce evenly.
This is the sauce made from roma tomatoes.
And here is the sauce with the Japanese tomatoes. Although my presentation skills leave much to be desired, you can see that the two sauces look quite similar.
But they couldn't have tasted more different. On the first try, I vastly preferred the Japanese tomatoes. The sweetness was immediately appealing, and it was balanced with a sharp acidity, which I hadn't noticed at all when I tried them raw. The roma sauce didn't have the same big impact, and seemed a bit dull by comparison at first. But after a few more bites, I noticed that what the roma sauce lacked in aggressive sweetness and acidity was made up for by its tomato taste: that summery, viney, slightly bitter flavour that conjured up memories of sitting in the garden on a sunny late-summer day and biting into a just-picked tomato. (Never mind that I don't actually have such memories, since I used to hate raw tomatoes and always shunned the lovely ones my Dad grew. This fake memory just goes to show you how tomatoey this sauce tasted.) And after a few more bites, I noticed this sauce also had a certain hard-to-describe depth of flavour, which must have been the umami from the glutamic acid.
The Japanese tomato sauce I liked less and less. Its initially pleasant sweet and tart flavours intensified until it started to taste like ketchup, with little depth or true tomato flavour.
By themselves, I think both sauces would have been excellent, but trying them together sharply highlighted each sauces strengths and weaknesses. The main drawback to the roma sauce was a slight mushy, mealy texture. This could be due to the quality of the tomatoes, so I'd like to try it again with really good romas. And my tendency to use too much sauce probably contributed to the ketchupy flavours I found with the Japanese tomatoes, and a better sauce/pasta ratio would likely help a lot. So would using regular Japanese tomatoes, which probably have enough sugar already-- the high-sugar variety was likely overkill.
So overall, both Hideaki and I preferred the roma sauce, but also really liked the Japanese tomato sauce. For now I'll make fresh tomato sauce with Japanese tomatoes, unless I can find good romas. And I want to do several more experiments: I still want to try it with regular Japanese tomatoes, not the high-sugar kind. I want to see what happens if I use whole roma tomatoes, without removing the skin and seeds. I want to compare fresh romas to canned. And I want to try mixing romas and Japanese tomatoes, to get a sauce that hopefully highlights the best of both types: sweet, tart, and full of umami and tomato flavour.
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