Miso: “A mealy Pap, which they dress their Victuals withal, as we do butter.”
Thus wrote Engelbert Kaempfer in 1727, the first appearance of the word ‘miso’ in an English-language publication. He sounds a little sceptical doesn’t he?
To his credit, Kaempfer was a widely travelled and curious fellow who embraced, and indeed was embraced by, Japan. His History of Japan, researched during the two years he spent there while on a ten-year tour of the East, served as the primary source of Western understanding of Japan for most of the 18th, and much of the 19th, century when Japan was all but closed to foreigners. He was also the first European to write detailed descriptions – in Latin, no less – of how miso and soy sauce are made.
My own formative experiences of miso were somewhat less ground breaking.
Miso and Me:
Living with two Japanese flatmates in London, I adopted their habit of eating miso soup – served in little lacquer bowls, scarlet on the inside, black on the outside – with every meal. Despite my inelegance in trying to fish out the last traces of wakame, tofu and spring onions from the bowl’s bottom, I grew to love the clacking of chopsticks on lacquer and the nourishing, warming, cleansing ritual of our pre-meal soup.
I was fascinated by the haze of dispersed miso particles, which cluster into little clouds that gently warp and morph as the soup cools. Their formation and movement is actually caused by convection cells of hotter, less dense, liquid that rises and colder, more dense, liquid that falls and settles below it. It’s the same phenomenon that forms cumulonimbus storm clouds!
Our supplies of miso, and the dashi used to make it, were replenished regularly by packages sent by my flatmates’ mums in Japan, filled with, amongst other delights, bonito flakes and dried squid. With labels that read “CONTENTS: DEAD FISH. DEAD SQUID. VERY DRY.” it was often surprising that the boxes made it successfully through Her Majesty’s customs.
I’d been switched on to the charms of miso, but I still thought that most misos were pretty similar. Miso is miso is miso, right? Wrong. On the GEN trip I finally had the chance to appreciate how varied misos can be. We tasted chunky ochre ones, and smooth, sweet reddish-black ones; subtle ones with fruity notes of pineapple, and nutty, bitter, lip-smacking umami-bombs. We also got the chance to get our hands dirty, in workshops with miso producers whose families have been making miso for generations. The plan was that we’d bring home and share some of their knowledge and skills, just as Kaempfer did three centuries ago.
So, what exactly is miso?
Well, it’s a rich, savoury, fermented paste made from soybeans, salt and other grains or legumes, which is used as a condiment, adding its sweet, roasted, nutty flavour to soups and sauces. (So, yes, Kaempfer was correct, it is used a bit like butter.)
Along with rice, miso is arguably one of the cornerstones of the average Japanese diet. Rice provides carbohydrates and miso, by virtue of its high content of soybeans, is a great source of protein.
Soybeans are impressive little things. Dried soybeans contain about 37% protein. Compare this to chickpeas and lentils, which contain up to 25% protein, or even chicken and beef which typically have around 20-25%. But – and it’s a big but – they are quite bland and… well, a bit beany. Their lack of starch also means that, unlike most other legumes, they don’t go creamy when cooked.
For long stretches of its history, Japan had relatively limited access to protein sources. The country has therefore taken the humble soybean to its heart and embraced, and perfected, myriad ways of squeezing incredible flavours and textures out of it. The most famous of these include soy sauce, tofu, natto, tempeh and, of course, miso.
Fermented soybean pastes were originally introduced to Japan from China. Written references to the making, selling, and even taxation, of early relatives of miso in Japan can be traced to the early 700s CE. However the use of the modern Japanese characters for miso first appear in 901 CE (in the Nihon Sandai Jitsuroku or The True History of Three Reigns of Japan). The mi character represents ‘flavour’ and the so character means ‘throat.’
It seems that there are two likely reasons for this rebranding. Firstly, by that point, the proto-misos imported from China had been transformed so significantly into uniquely Japanese products – with their own recipes, tastes and gastronomic contexts – that people felt they deserved a uniquely Japanese name. Secondly, the use of the new name coincided with an era (the start of the Heian period, 894 CE) in which Japan isolated itself from the outside world and began a process of assimilating many Chinese cultural imports. This included developing a native Japanese writing system kana (consisting of hiragana and katakana), which was distinct from the original writing system used by the Japanese, kanji, which is based on Chinese characters.
How do you make it?
Making miso involves two steps.
In the first, koji is grown by adding dormant spores of the Aspergillus oryzae mold (referred to as koji-kin or tane-koji) to steamed rice, barley, soybeans or other grains. This mixture is separated into shallow wooden trays called buta, and kept warm and aerated. Fermentation takes place over two to three days, during which the spores germinate and grow over the substrate (the rice, barley or soybeans) into furry masses of cotton-candy-like hyphae. As they do so, they produce enzymes that catalyse the breakdown of components of the substrate – starches, proteins, and fats – into smaller, constituent molecules, like simple sugars, peptides, amino acids and fatty acid chains.
The ‘rice koji’, ‘barley koji’, or ‘soybean koji’ are then removed from the trays and can be used to start the second fermentation step. These kojis are also used to make Japan’s other iconic fermented products; sake, soy sauce, and amazake (a sweet non-alcoholic rice drink).
For miso, the second fermentation involves adding the rice, barley or soybean koji to ground, well cooked soybeans and 5 to 10% salt. Lactic acid bacteria (such as Tetragenococcus halophilus) and salt tolerant yeasts (such as Zygosaccharomyces rouxii) are added, or a portion of a previous unpasteurised batch of miso can serve as a microbial starter. The mixture is then sealed airtight, traditionally in barrels, and allowed to ferment at around 35ºC.
In the salty, oxygen-poor environment, the Aspergillus molds die but their enzymes live on. Along with the bacteria and yeasts, they cause the breakdown of proteins, carbohydrates, and fats in the grains or legumes producing new flavoursome molecules, and contribute to the development of colour via enzymatic browning. Furthermore, some of the newly formed products are precursors for additional flavour-making reactions. For example, amino acids derived from the proteins present, largely in the soybeans, react via the famous Maillard reaction – a nonenzymatic browning process – with reducing sugars, like glucose. Therefore, the longer the fermentation, the more additional layers of flavour are produced, the more complex the miso’s flavour and the darker its colour.
Traditional miso pastes are fermented for anywhere from three months to several years, but the modern mass produced stuff is only fermented for a few weeks, forcing industrial producers to compensate for its lack of flavour and colour with additives.
When the miso is ready, it is drained and packaged. The excess liquid, known as tamari, is also delicious and was actually the forerunner to Japanese soy sauce. In fact, it was only in the 15th century that soy sauce was produced in its own right.
The many types of miso:
There are hundreds of types of miso and they reflect the various regions of Japan, their climates and their traditions.
‘Regular’ misos are classified into three basic categories according to the substrate that the koji-kin is grown on in the first fermentation. If rice is used, then you are said to produce ‘rice koji’ and will end up with rice or kome miso. From barley koji is produced mugi miso, and from soybeans you end up with mame miso.
Rice koji, and thus kome miso, is by far the most common, accounting for around 90% of all miso produced. However, in Kyushu, the southernmost of the four main islands, a paucity of soybeans means that barley koji is predominantly used. Similarly, in central Japan it is traditional to find soybean-only misos, such as the famous hatcho, a dark brown miso with a distinctive sweet, bitter, almost chocolate-like, taste, which is made near Nagoya.
Rice miso tends to be lighter in colour than barley, which is in turn lighter than soybean. However, the colour of a miso is also heavily dependent on how long it has been fermented: longer aged misos are darker. Miso colours are usually described as white (shiro), light yellow (shinshu) and red (aka), although in reality this covers a spectrum from pale yellow to almost black. Furthermore, while all miso packs a healthy umami punch, it is categorised as salty, mellow or sweet, with the sweetest misos traditionally from Tokyo as well as Kyoto. (Shiro miso is now often used as the term for any white miso, although traditionally that term referred solely to Kyoto’s sweet white miso.)
The type of soybean used in the second fermentation step will also affect flavour and colour. There are thought to be some 300 local varieties of soybeans across Japan, although a few types are now very dominant.
In addition to the ‘regular’ misos there is a class of ‘special’ misos that are used more like condiments, rather than as ingredients in soups and sauces. These tend to be sweeter and incorporate chopped vegetables, nuts and seafood. The most notable of these is kinjanzi, the recipe for which is said to have been brought to Japan from China in the 13th Century by a Buddhist monk called Kakushin, who is also credited with discovering that the tamari which gathers at the bottom of miso vats can be used as a seasoning. Kinzanji miso is made from a koji containing a mixture of whole-grain barley and toasted soybeans, to which is added aubergine, white melon (shiro uri), ginger root, kombu and burdock leaf, and the whole mixture fermented in the normal way.
by Dr Johnny Drain
Food Science Researcher