Quinoa saponins—analysis and preliminary investigations into the effects of reduction by processing

A gas chromatographic method has been developed for the analysis of saponins in quinoa (Chenopodium quinoa Willd). The method, which involves separation and quantitation of the trimethylsilylated sapogenols, has been applied to the analysis of the UK-grown crop obtained by selection from lowland Chilean ecotypes. Total saponin contents of 1·03 and 1·19% were found for material grown in 1987 and 1988. The major aglycone in the quinoa saponin mixture was identified as phytolaccagenic acid (>40% total), with hederagenin (∼25%) and oleanolic acid (30%) aglycones also being present. The effects of washing and abrasion on total and individual saponin content were investigated; the data obtained suggest differential cellular locations of the individual saponins. The processing of quinoa led to changes in sensory characteristics; removal of saponins was associated with reductions in bitterness and astringency. Microscopic analysis revealed considerable differences in washed and abraded samples, both before and after cooking; in particular the abraded samples showed a greater degree of cellular disruption.