Sushi Rice Improver (Otuka Miola) Review

A can of Japanese sushi rice improver known as Otuka Miola.

Being a site that produces content on traditional edomae sushi based on knowledge from the restaurant I worked at, it was interesting to stumble upon Ohtsuka Chemical Industrial Co. Ltd.’s Miola rice improver (炊飯ミオラの大塚薬品工業株式会社). Their company website claims that by only adding a miniscule amount of their enzymatic powder to your rice, you can cook perfect rice or sushi rice every time that rivals Japan’s very best chefs. 

The part that piques my interest the most for this product however, is that their website claims that it’s, quote: “used in many sushi restaurants around Japan”. Their website then goes on to give the names of various restaurants that do use their product, as well as the fact that their product is endorsed by the Chairman of the All Japan Sushi Association. I personally have never even heard of Miola rice improver before this, and the restaurant that I worked at surely didn’t use it either. From what I can tell from their website however, it seems like it’s used mainly by the food service industry such as school cafeterias, sushi train restaurants or factory canteens, and less so by high end sushi establishments. As condescending as this may sound though, my personal hunch is that any famous sushi establishment that does use Miola rice improver would be too ashamed or bashful to admit it. I did however find a mention on a blog from the english-speaking side of the internet that the famous nobu restaurant in the USA uses it. But I would personally argue that Nobu itself is now not only a restaurant chain, but also a hotel chain, albeit one that served a very different clintel compared to a sushi train restaurant. I have actually seen famous food reviewers subtly scoff at the exorbitant prices that Nobu Matsuhisa charges in comparison to the actual quality of his meals and what you could get in Japan. 

This however, isn’t meant to be a criticism of Otsuka’s Miola sushi improver. In fact I have a keen interest in the use of artificial improvers in food provided they don’t cause harm to the human body. After all there is a fine line between what is considered adding chemicals to your food and molecular gastronomy. I personally am a big fan of using monosodium glutamate in food as given the right conditions, it has the ability to provide dishes with that rounded edge that it’s lacking. Whilst the over reliance and over use of MSG has given it a bad name, ingredients like kombu, soy sauce, miso and katsuobushi are basically ways of drawing on natural sources of these various umami enhancing chemicals, so why not just use the pure form? (Just to emphasise, Miola rice improver is not a flavour enhancer).

So before the verdict is delivered, a fair trial must first take place. As it turns out, this Miola rice improver is remarkably hard to get hold of in Japan. The very front page of their website in Japanese actually states: ‘当社の商品は業務用であり、一般販売はしておりません’, which translates to: ‘Our products are for business use and are not sold to the general public.’ When you google it in english however, it seems like you can buy it in most websites that specialize in Japanese ingredients, which makes me suspect that these companies are approaching Ohtsuka Chemical Industries and buying it wholesale, before selling it in individual cans to customers willing to fork out money, which is technically against the wishes of the Ohtsuka Chemical Industries. In fact, this is easily illustrated in the way that they only package their rice improver in 1kg cans, and given the fact that their website recommends you use 1g to 2g of their enzymes per 1.4kg of rice, you’d have enough for 14000kg of rice. Esme even pointed out that based on the assumption that an average Japanese person eats 14kg of rice in a year, the minimum quantity of rice improver you could buy could last one person 1000 years. With all that out of the way…

What is Otuka’s Miola Rice Improver?

As per the information on their website, their rice improver contains two types of enzymes which are:

  • α-amylase that serves to convert starch into sugar
  • And a cysteine protease Papain which converts proteins into amino acids

A protease is actually the generic name for any enzyme that converts protein into amino acids and papain are enzymes typically extracted from papaya (though my guess is that they artificially produce it rather than extract it from papaya).

The addition of these two enzymes is supposed to cook the perfect rice that is not only shiny and fluffy, but does not stick to the pot or stick to each other. This is supposedly due to (again taking information from their website) how the enzymes work on the outer parts of each rice grain, causing the rice to more easily absorb water into the core and also not stick to each other. By preventing each grain of rice from sticking to each other, they also claim that it allows water to better flow in between the grains of rice, causing them to cook evenly, creating holes on the surface of the cooked rice that they call “crab holes” as they are similar to the holes made by crabs on a beach. 

Does this actually make sense from a scientific sort of view? On first impressions, I’d give this product a 30 to 40% accuracy rating in terms of whether the explanation provided is actually what’s going on. Whilst the idea that the enzymes can break down the surface of the rice to make it more permeable is definitely plausible, I have doubts about whether or not the effect is big enough for it to make such a difference. As for the rest of the explanation, I do not understand how any of the enzymatic reactions occurring above will prevent rice grains from sticking to each other and even if it does, whether or not it actually causes the rice to heat more evenly. After all, when boiling rice, I think the various grains of rice don’t stick to each other until well after they’ve absorbed plenty of water and are almost cooked through. Lastly, their product also claims to remove the need for rice soaking times, as well as variation in soaking times depending on seasonal temperature variation and the age of the rice.

If anything, the bit in their entire website that I find the most convincing is the fact that they only ask for 1g to 2g of enzymes for 1.4kg of rice. For anyone that has worked in a lab before, you’d know that enzymes in their purified form are very potent and only a small amount is needed to effectively carry out what you want. And so the very fact that very little of their product is necessary to give the desired effect they claim to have gives me much more confidence that they’re really selling actual enzymes. 

Japanese Miola Rice Improver powder.

Does Miola Rice Improver actually work?

Otuka’s Miola rice improvers come in two different types, the standard green, red and white canned improver and the “gold” miola designed specifically for sushi. As far as I can tell, the only difference between the two cans is that the one designed for sushi contains powdered dried kelp and vinegar powder to remove the need of adding kombu to your sushi rice (some restaurants do that). As we typically focus a lot on sushi, we’ll best testing out Miola’s gold sushi rice improver following the instructions on their website which are:

  1. Wash raw rice and measure appropriate quantity of water
  2. Add 1g of Miola per 1.4kg of rice
  3. Stir gently and close lid
  4. Cook according to your rice cooker.

Of course, cooking 1.4kg of dried rice is a ridiculous amount even for high end sushi restaurant with 10 seats and you’d want to cook rice in smaller quantities to that they don’t squash each other and of course we’d be testing this with a claypot so we adjusted the amount of Miola added to 0.1g of Miola to 140g of rice, which for a standard 3 cup donabe rice cooker is 0.3g of Miola. I don’t even know where it’s possible to buy a 10 cup rice cooker for home use, and 0.3g is a very harm to measure accurately amount unless you own a specialised weighing machine for small amounts.

To test, we cooked 4 batches of rice, 2 from expensive premium hokkaido Yumepirika rice (ゆめぴりか) and 2 from just your everyday standard short grain sushi rice. One of each type of rice was cooked with the rice Miola added. The 4 batches of rice were cooked at the same time using 4 identical claypots. After cooking, the tasting was carried out in a blind trial where the tasters did not know which sample contained the rice Miola. 

The results? The results were subtle but actually quite impressive! It was easy to distinguish rice that contained the Miola improver because the grains were more evenly cooked and stuck less to each other. It definitely gave a much better mouth feel to the rice as you could taste each individual grain more rather than it being slightly sticky. However, it was still possible to distinguish both samples of the high end hokkaido rice compared to the normal rice in both cases. The safe conclusion to make is that the rice Miola definitely does improve the quality of the resulting rice cooked in the way that it reduces the variability resulting from the skill of cooking rice. It does not however work in a miraculous way to convert cheap rice into expensive rice. That of course, is too much to ask for any product and the fact that it improves the consistency of the rice cooked in a good way means I’d definitely add it to the way I cook rice from now on for day to day consumption. I personally only eat high quality sushi rice on special occasions and during home meals I simply each wholesale cheap short grain rice, so the addition of rice Miola is most welcome. 

There are a couple more interesting facts to note. Adding the rice Miola to the claypot not only made the rice grains stick less to each other, but also less to the pot when you scoop it out. There was also much less scorched rice on the bottom of the pot, okoge (お焦げ) in Japanese. This was not to my initial intuition as I assumed that if starch was being broken down by amylase into sugar, then surely it would be much easier for rice to scorch? It seemed like the non-stick quality of the rice took precedence however. 

When you cook rice in a claypot, especially in large amounts, there sometimes tends to be a problem where the rice in the centre of the pot is less cooked/fluffy compared to the rice on the outer rims of the pot, but this was clearly reduced when using the Miola which is a big plus. It probably has something to do with what they call the better flow of water in between the grains of rice, causing them to cook evenly. I did not observe the “crab holes” that they said would appear, though I think those would appear when using a rice cooker instead of a claypot. 

Lastly of course, is the addition of Miola gold compared to the normal Miola, which is the powdered dried kelp and vinegar powder. I was very sceptical about this at first, not because I doubted the addition of powdered dried kelp and vinegar powder into rice, that sounded perfectly fine, but the fact that you only added 0.3g to 0.6g of Miola for 3 cups of rice made me doubt that such small amounts of that stuff would actually impact the taste. That scepticism proved true as there was no traceable acidity to the rice, though I think if you focus very very carefully, you could identify a faint smell of kombu in the rice, though hardly noticeable at all, and definitely not a substitute of kombu and vinegar in actual sushi rice. 

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