glucoraphanin
compound / compound-glucoraphanin
グルコラファニン
4-methylsulfinylbutyl glucosinolate. A major glucosinolate of broccoli and a precursor to sulforaphane.
On this page (6 sections)
Reading the bitterness
Glucoraphanin is a 4-methylsulfinylbutyl-type glucosinolate, abundant in broccoli, and known as a precursor that yields sulforaphane upon degradation. In an analysis comparing 50 broccoli cultivars grown under uniform cultivation conditions, glucoraphanin content per dry weight ranged from 0.8 to 21.7 micromol/g, showing approximately a 27-fold variation among cultivars. In the same study, Brussels sprouts, cabbage, cauliflower, and kale had sinigrin as their predominant glucosinolate instead.
Glucoraphanin has been substantially increased through selective breeding due to interest in sulforaphane, but whether it can be treated the same way as a driver of taste and bitterness is being investigated as a separate question. In a test where 90 consumers from the United Kingdom evaluated 7 cultivars of rocket (Eruca sativa), glucoraphanin concentration itself showed no significant correlation with preference or perception of bitterness and pungency. The authors note that even in broccoli cultivars with substantially elevated glucoraphanin concentration, no significant effect on flavor has been reported.
In the same test, glucoalyssin, a minor glucosinolate with low content, showed significant correlation with peppery and pungent perception, and 4-hydroxyglucobrassicin showed significant correlation with pungent perception. The compounds driving taste were not glucoraphanin but a different group of compounds. However, this is a correlation in principal component analysis targeting only 7 cultivars, and it is not an experiment involving isolated glucoraphanin being tasted directly and threshold being measured. Therefore, the conclusion of 「無味」 (in translation: "no taste") remains only preliminary circumstantial evidence in this entry.
In a sensory evaluation by a consumer panel (n=100) comparing 2 rocket cultivars (Denver and Marte), the bitterness score was significantly higher for Marte (6.6) than Denver (4.8, p<0.001), and glucoraphanin content was also higher for Marte (3.11 versus 2.52 mg/100 g fresh weight, p=0.007). The authors attributed this bitterness difference to the difference in dimeric 4-mercaptobutyl glucosinolate content, which showed a larger difference (17.58 versus 11.84 mg/100 g fresh weight, p<0.001), and state that the contribution of glucoraphanin to bitterness has been repeatedly reported to be minimal.
Sources for this overview
Variation of glucosinolates in vegetable crops of Brassica oleracea
Checked for this overview: The range in which the 27-fold variation in glucoraphanin content among cultivars was confirmed.
Checked for this overview: Confirms the point that no correlation with bitter taste perception was evident. / The range in which minor glucosinolates showed correlation with perception.
Checked for this overview: The description attributing bitterness differences between cultivars to another glucosinolate.
Structured claims — open a section to read each claim's confidence, evidence and limits
Composition and content (1)
Scope: 50 broccoli cultivars among 65 Brassica oleracea cultivars grown under uniform cultivation conditions.
Note: Cultivation conditions were maintained uniformly, and the variation can be attributed to genotype. In the same study, the major glucosinolates of Brussels sprouts, cabbage, cauliflower, and kale were sinigrin instead.
Show data
compound-glucoraphanin —varies_by_cultivar_in→ "Broccoli: a 27-fold range from 0.8 µmol/g dry weight in cultivar EV6-1 to 21.7 µmol/g dry weight in Brigadier."Sensory (2)
Scope: 7 cultivars of Eruca sativa evaluated by 90 consumers from the United Kingdom. Phytochemical data fitted in principal component analysis.
Note: A single study on one species. Contrasting with health-oriented selective breeding focused on glucoraphanin, this shows that health-related and taste-related glucosinolates need not be the same compound. It was rather minor glucosinolates (glucoalyssin and 4-hydroxyglucobrassicin) that showed correlation with perception.
Show data
compound-glucoraphanin —does_not_significantly_influence→ "Consumer preference in rocket, or perception of bitterness and pungency."Scope: Layer: Food. HPLC quantification of glucosinolates in 2 rocket cultivars (Denver and Marte) and sensory evaluation by a consumer panel (n=100, evaluated as a single ingredient with nose pinched).
Show data
compound-glucoraphanin —does_not_significantly_influence→ "In a comparison of 2 rocket cultivars, Marte, which had a higher sensory bitterness score (6.6), also had higher glucoraphanin content (3.11 versus 2.52 mg/100 g fresh weight, p=0.007) than Denver, which had a lower score (4.8, p<0.001). However, the authors attributed this bitterness difference to the difference in dimeric 4-mercaptobutyl glucosinolate content, which showed a larger difference (17.58 versus 11.84 mg/100 g fresh weight, p<0.001), and state that the contribution of glucoraphanin to bitterness has been repeatedly reported to be minimal."