Effect of aqueous and alkaline thermal treatments on chemical composition and oligosaccharide, alkaloid and tannin contents of Lupinus campestris seeds
C. Jimenez-martinez et al., Effect of aqueous and alkaline thermal treatments on chemical composition and oligosaccharide, alkaloid and tannin contents of Lupinus campestris seeds, J SCI FOOD, 81(4), 2001, pp. 421-428
The utilisation of Lupinus campestris seeds has been limited for some years
owing to the presence of toxic quinolizidine alkaloids (QAs) and antinutri
tional factors (ANFs). The oligosaccharide content was analysed by high-pre
ssure liquid chromatography (HPLC). Gas chromatography coupled with mass sp
ectrometry (GC/MS) was used to detect alkaloids, using caffeine (0.2mg ml(-
1)) as internal standard. Tannins were determined by the Folin-Dennis color
imetric method. Two methods were tested to reduce or eliminate the QAs and
ANFs, (a) aqueous thermal treatment and (b) alkaline thermal treatment (NaH
CO3 0.5% solution), both of them for 6h at boiling temperature. In both cas
es the removal of oligosaccharides, in amounts of 70 and 90% respectively,
was also achieved. The alkaloid contents were reduced to innocuous levels i
n both cases (less than 0.4-0.5%). The alkaline thermal treatment, in which
the seed had a final alkaloid content of 0.002%, was more efficient than t
he aqueous thermal treatment. The tannin content also showed a reduction of
71% with the aqueous treatment and 77% with the alkaline treatment. The re
sults show that alkaline thermal treatment is more efficient at eliminating
these ANFs. (C) 2001 Society of Chemical Industry.