Glucosinolates occur in all Brassica vegetables but the distribution of individual glucosinolates as well as their relative amounts vary considerably.
Some glucosinolates are important precursors for flavour, while others are unwanted as their breakdown products have undesirable sensoric or physiologic characters.
Sinigrin and its degradation product are both bitter substances.
Progoitrin and gluconapoleiferin are tasteless, but their hydrolytic products, oxazolidinethiones, are very bitter.
They are also goitrogenic substances and may contribute to hypothyroidism even if there is enough iodine in the diet.
Selected cultivars of white and red cabbage, brussels sprouts, cauliflower, kale and swede have been analysed by gas chromatography in a preliminary one-year study (table 1).
Total content of glucosinolates was highest in brussels sprouts, and lowest in kale.
All samples contained sinigrin.
White cabbage had the highest amounts, but there were great varietal differences.
Progoitrin occurred in white and red cabbage, brussels sprouts and swede with the highest amounts in the last mentioned crop.
Gluconapoleiferin was found only in swede.
The varietal differences indicate the possibility to select material with low contents of undesirable glucosinolates, but the environmental influence must be investigated.
Analysis of individual glucosinolates of the seed would give more reliable results and facilitate selection in a breeding material.
No correlation between seeds and leafy heads was, however, found in the investigated material of white cabbage.
Analysis of the first leaf/leaves might give a better relationship.