Daikon Oroshi (大根おろし)
Daikon oroshi is a food made by grating daikon radish with an oroshigane (Japanese grater).
It is often served as a relish or a condiment with Japanese food. Its distinctive pungency neutralizes the smell of fish dishes.
Also, as daikon oroshi can aid digestion, it goes nicely with dishes that are considered as heavy such as tempura (Japanese deep-fried dish), fried food and meat dishes. Daikon radish contains large amount of digestive enzymes such as amylase, protease and lipase. However, as these enzymes are sensitive to heat, they cannot be effectively utilized if cooked. It is only when daikon radish is grated raw that the digestive effects can be exploited.
It is more of a sweetness than a pungency that can be tasted when daikon radish is eaten raw in the form of a vegetable stick. The pungency of daikon oroshi derives from the pungent component allyl isothiocyanate (mustard oil). However, this substance does not exist in ungrated daikon. Isothiocyanate is only produced from a chemical reaction when the cells of the daikon radish are broken by grating or cutting them. More specifically, the pungency is produced by the chemical reaction when the precursor substances (glucocinolate and mustard oil glycoside) of isothiocyanate and an enzyme called myrosinase, which exist separately inside a daikon radish, are mixed by the breaking of the cells. The tip of the daikon radish contains approximately ten times as much of these isothiocyanate precursors than the part close to the leaves. There are greater quantities in young daikon, and it decreases as it grows. Therefore summer daikon is more suitable for making daikon oroshi.
In order to obtain the pungency mentioned above, it is necessary to break the cells of daikon radish effectively. For this reason it is best to grate the cross section of the daikon in order to sever the fibers. Greater pungency is obtained when the daikon radish is grated vertically against the oroshigane in a single stroke. The traditional saying that "Daikon oroshi becomes more pungent if grated while angry." is probably true.
The pungency of daikon oroshi reaches its peak at five minutes after being grated, after which it decreases. Its pungency further increases if it is grated with its skin.
Conversely, in order to reduce pungency, it is best use the bottom section and slowly grate it in a circular motion beginning with the long side of the round slice. This is because daikon radish is grated along the fibers, which makes it difficult to break the cells. As mentioned above, the skin is more pungent, so it is possible to reduce the pungency by using only the core of the daikon radish.
The sweetness of daikon oroshi can be brought out by heating it straight after grating, and heating for ten minutes will double its sweetness.
Because isothiocyanate is volatile, the pungency decreases if daikon oroshi is left to stand after being grated. The amount of vitamin C also decreases over time. In order to avoid these effects, it is preferable to grate daikon radish just before it is to be eaten.
Daikon Oroshi Keeps the Doctor Away
As attested to by the old saying 'Daikon oroshi keeps the doctor away.', daikon oroshi is considered beneficial to many aspects of health.
First of all, as mentioned above it has digestive effects. It is rich in a variety of nutrients including vitamin C. Refer to the footnotes of 'Diastase'.
It is also said that gargling with daikon oroshi juice is effective for the treatment of inflammations within the mouth including stomatitis, dental caries and gingivitis. This is thought to be due to the sterilizing activity of isothiocyanate. This sterilizing activity is sometimes used for cleaning raw oysters.
Daikon oroshi mixed with honey and drunk is also known as a folk remedy said to be good for coughs, sore throats, hoarseness and hangovers.
It was also valuable in ancient times for removing fish toxins. This is why grilled fish is often served with daikon oroshi.
Momiji oroshi is made by grating a whole daikon radish with a chili pepper notched inside. Its red color looks attractive, and its spiciness is exploited as a condiment. In addition, the mixture of daikon oroshi and grated carrot is also called momiji oroshi. In this case, however, it is not a good combination for eating at the same time because both daikon radish and carrot destroy each other's nutrients.
Dishes incorporating daikon oroshi
Because of it appearance, the names associated with mizore (sleet) or shirayuki (white snow) are given to dishes.
Grilled fish (saury, mackerel, sardine etc.)
Shirasuboshi (dried young sardines)
Karamimochi (deep-fried rice cakes)
Oroshi soba (soba with daikon oroshi), oroshi udon (udon with daikon oroshi)
Oroshi spaghetti (spaghetti with daikon oroshi)
Nabemono (Japanese steamboat dishes):
Such a dish containing daikon oroshi is called Yukinabe (lit. Snow Pot). Daikon oroshi is also used as a marinade.