Changes in colour, tocopherols and carotenoids during the germination of lupin seeds

Abstract

This study investigated the impact of controlled germination on colour, carotenoids and tocopherols of Andean lupin (Lupinus mutabilis Sweet) seeds. Two Andean lupin ecotypes, Cholo fuerte and Altagracia, were germinated in the dark for two, four and six days; colour coordinates (L*, a*, b*) were determined by colorimeter, while carotenoids and tocopherols were quantified by HPLC. The germination significantly modified the characteristics examined. The luminosity decreased with increasing germination time, while only minor changes were recorded for a* and b* . The sum of all carotenoids increased up to 12-fold during germination, with lutein always being the most abundant compound. The predominant tocol was γ-tocopherol; although total tocol content was almost unchanged, α-tocopherol increased from not-quantifiable up to 74.8 mg/kg dry matter, improving the vitamin E activity, while γ-tocopherol decreased progressively. Our results demonstrate that germination promises to be a cost-effective approach to improve the nutritional properties of lupin seeds.