daikon radish
ingredient / ingredient-daikon-radish
大根
Daikon radish used in Japan raw, grated, in simmered dishes, and more. When grated, sensory tests have measured that the intensity of pungency, bitterness, sweetness, and umami differs between the head and tail.
On this page (7 sections)
Reading the bitterness
Daikon is eaten raw, grated, and simmered. And its bitterness moves not with the word daikon but with the part of the root. In a ranking test by 20 people comparing the grated head and tail of 3 cultivars — aokubi, Mino wase and Shinshu-ji — the tail was stronger in pungency and bitterness and weaker in sweetness and umami than the head. For all 4 tastes, the difference by part was significant at the 1% level. This is a result for raw grated daikon, from samples of 1988 across growing areas and harvest times.
The kitchen has a record of choosing in the same direction. A cook’s account of ika daikon, squid simmered with daikon, writes that it is best to use the sweeter upper part. It is not a record that measured bitterness, but it shows that the premise of taste differing by part is shared as an instruction for preparation.
The parboiling step is written concretely: half-moon slices 2.5 cm thick are brought to the boil with rice and water, simmered over low heat for 10 to 15 minutes, then rinsed. The explanation is that the starch of the rice draws out the harshness of the daikon and that parboiling removes excess water and aku so the seasoning soaks in. But this is a cooking record with no controlled comparison: there is no sensory comparison against a condition without rice, and no measurement of bitterness. The procedure survives; its effect has not been measured.
Sources for this overview
Checked for this overview: In all 3 cultivars the tail was stronger in pungency and bitterness than the head, with the difference by part significant at the 1% level for all 4 tastes
Checked for this overview: A cooking record stating that the sweeter upper part is best for ika daikon / The step of parboiling with rice and rinsing, and the explanation that it draws out the harshness
Structured claims — open a section to read each claim's confidence, evidence and limits
Composition and content (1)
Scope: Chemical analysis of the head and tail (Table 2). Aokubi, Mino-wase, and Shinshu-ji within 2–4 days of harvest; karami daikon within 2–5 days.
Note: No test directly related magnesium to bitterness intensity. This paper did not examine the relation between bitterness and any component other than magnesium.
Show data
ingredient-daikon-radish —has_composition→ "Composition by part. In 3 cultivars (Aokubi, Mino-wase, and Shinshu-ji), the head contained less water and magnesium than the tail, and more formol nitrogen and reducing sugars. Where they compare karami daikon with the Aokubi tail, the authors call magnesium a bitter component and formol nitrogen an umami component. For the difference between head and tail, they state only that the differences in component amounts by part appear in the taste."Sensory (2)
Scope: The head, middle, and tail of 3 cultivars were grated within 2–4 days of harvest and evaluated by 20 students and cooking-science laboratory members whose ability to discriminate tastes had been confirmed. Significance marks are given for the head and tail; the middle's position is the order of rank sums.
Note: A result for raw grated daikon. This does not measure the difference between parts in cooked daikon or the bitterness of a finished simmered dish.
Show data
ingredient-daikon-radish —has_perceived_bitterness_affected_by→ "Part of the root. In a ranking test by 20 panelists comparing the grated head, middle, and tail of 3 cultivars (Aokubi, Mino-wase, and Shinshu-ji), the tail was more pungent and bitter and less sweet and umami than the head. The differences by part were significant at the 1% level for all 4 tastes. In all 3 cultivars, the middle ranked between the head and the tail."Scope: Samples of 50 g of domestic dried shredded daikon, 250 g of water and 3.9 g of oil in a vacuum pack, heated at 100°C for 60 minutes. 30 people chosen at random for each experiment from a trained panel group (89 people) evaluated one sample at a time on its own. Repeated-measures one-way analysis of variance and Tukey's method
Note: This is a simmered dish of dried shredded daikon, not raw daikon or a dish of thickly cut daikon simmered. The oil was put into the bag with the dried shredded daikon and water and heated from the start at 100°C for 60 minutes; it was not added afterward to the finished simmered dish. The question was a 1-item rating of "bitterness of daikon", not an evaluation by a trained panel measuring bitterness intensity on a scale. In the same report, the simmered dried shredded daikon cooked with added deep-fried tofu (aburaage) had a significantly higher overall preference than that without; in free comments on the simmered dish without aburaage, 23 of 89 people wrote undesirable tastes such as bitterness, pungency, saltiness and off-odor, whereas for the dish with aburaage there were no comments on undesirable tastes (not comments on bitterness alone). The authors consider this consistent with a report that oleic acid is involved in suppressing the bitterness of cheese.
Show data
ingredient-daikon-radish —has_perceived_bitterness_suppressed_by→ "A small amount of rapeseed oil put into the bag with dried shredded daikon (kiriboshi daikon) and water and simmered (heated) from the start. Simmered dishes of dried shredded daikon were made with no oil (a control with water added), with unheated rapeseed oil, and with rapeseed oil heated at 190°C for 7 minutes, and 30 people answered "Do you feel a strong bitterness of daikon?" on a 5-point scale (1 = not at all, 5 = very much). The means were 3.57 with no oil, 2.53 with unheated oil and 2.43 with heated oil; the 2 with oil were significantly lower than no oil (analysis of variance p<0.01, with p<0.05 between no oil and with oil in Tukey's multiple comparison). The difference between unheated oil and heated oil was not significant."How processing and cooking change it (5)
Scope: Ika daikon, as published in Kikkoman's 「基本の和食、おうちの和ごはん」 (in translation: "Basic Japanese Cuisine, Japanese Home Cooking").
Note: This is a cooking record, not a sensory test comparing simmered dishes made with different parts of the daikon.
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ingredient-daikon-radish —is_prepared_by→ "In a cooking record of 「いか大根」 (in translation: "squid and daikon") by a cooking expert, the upper part with its strong sweetness is used, in a composition meant to let the flavors blend."Scope: The preparatory step for ika daikon by a cooking expert.
Note: This is not a controlled comparison of bitterness intensity. It is not extended to rice-rinsing water in general, or to rescuing a finished simmered dish that turned out bitter.
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ingredient-daikon-radish —is_prepared_by→ "Half-moon slices 2.5cm thick are parboiled with rice and water — brought to a boil, then simmered over low heat for 10–15 minutes — and rinsed with water. The stated reason is to remove the daikon's egumi and improve how the flavor blends in."Scope: Grated karami daikon. Only pungency was rated; bitterness was not compared.
Note: The authors suggest that a fine grater breaks down the tissue more thoroughly, so more of the pungent compound is formed. The same comparison was not made with ordinary daikon (such as Aokubi).
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ingredient-daikon-radish —has_flavor_affected_by→ "Grater coarseness. In a paired-comparison test by 20 panelists, karami daikon grated on a fine metal grater was more pungent than karami daikon grated on a coarse plastic grater, significant at the 0.1% level."Scope: Grated karami daikon left for 0, 20, 40, and 60 minutes; 20 panelists compared pungency. Bitterness was not compared.
Note: The authors state that this agrees with earlier work (Esaki et al.) showing that the pungent compound decreases fastest right after grating. The same comparison was not made with ordinary daikon.
Show data
ingredient-daikon-radish —has_flavor_affected_by→ "Time after grating. The pungency of grated karami daikon was strongest immediately after grating and weakest after 60 minutes (ranking test, significant at the 1% level). In paired-comparison tests, the differences between 0 and 20 minutes (5% level), 0 and 40 minutes (0.1% level), and 20 and 60 minutes (1% level) were significant, while there was no significant difference between 20 and 40 minutes or between 40 and 60 minutes."Scope: Karami daikon was grated into the seasoning liquid and mixed; 20 panelists compared pungency. Adding seasoning afterward, and bitterness, were not compared.
Note: The authors suggest that the seasonings did not change the amount of the pungent compound, but that saltiness, sweetness, umami, and sourness suppressed the pungency. The same comparison was not made with ordinary daikon.
Show data
ingredient-daikon-radish —has_flavor_affected_by→ "Seasoning. 2 tests were run. With water (control), salt, soy sauce, or tentsuyu added to grated karami daikon, water was the most pungent and tentsuyu the least. With water, salt, salt plus vinegar, or sanbaizu, water was the most pungent and sanbaizu the least (both ranking tests, significant at the 1% level)."