Cyanogenic D-amygdalin contents of the kernels of cultivated almonds and wild Amygdalus webbii Spach.

SUMMARY

D-amygdalin is a toxic compound found in the kernels of some bitter almond cultivars.This compound is toxic because of its potential to release poisonous hydrogen cyanide. The D-amygdalin contents of the kernels of 18 commercial almond cultivars (Prunus dulcis Mill. = Amygdalus communis L.) and three wild genotypes (Amygdalus webbii Spach.) were determined by HPLC. In initial tests, two extraction procedures 100% (v/v) methanol or 4% (w/v) citric acid)], two different kernel cutting sizes (powdered or roughly-cut pieces), and two shaking techniques (mechanical shaking or sonication) were assessed. The results obtained showed that the method of extraction can have a strong effect on the extent of recovery of the potentially toxic compound, which varied by a factor of approx. 20-fold across the different extraction techniques.The greatest recovery of D-amygdalin from wild almond kernels was achieved with mechanical shaking of roughly-cut kernels in 100% (v/v) methanol, and this procedure was applied for all subsequent analyses of the D-amygdalin contents of all genotypes. The highest amounts of D-amygdalin were found in “bitter” cultivars and wild genotypes (716 – 23,025 mg kg^–1), with lower values in “sweet” cultivars (0 – 158 mg kg^–1). High levels of variability were observed both among the 18 almond cultivars and the A. webbii genotypes tested.