Lupin as a future protein source in Sweden – Food safety aspects, prospects and challenges

Abstract: The modern food system is a key driver of environmental and social burdens. A step towards becoming more sustainable has led to an increased demand for protein-rich leguminous crops. Lupin is a legume with a high nutritional value and well-adapted for cultivation in Sweden. The current view on lupins by producers and the market in Sweden was investigated. One of the challenges with lupin for human consumption is the lack of knowledge regarding its content of alkaloids. A purpose of this study was, therefore, to compare the alkaloid contents in cultivars of yellow lupin (Baryt, Bursztyn, and Mister), narrow-leafed (NL) lupin (Boregine, Mirabor, and Samba) and Andean lupin (Bolivian variety). For NL lupin, effects of year of harvest and of soaking time on alkaloid levels were also investigated. Another aim was also to determine if the alkaloids were present in the lupin seed cotyledon or the hulls. Alkaloids were extracted from lupin seed flour and the combined content of all forms of alkaloids was estimated based on the precipitation of an alkaloid-bismuth complex followed by solubilisation and spectrophotometric quantification. The total content of alkaloids varied from 0.29 to 1.37 %. The year of harvest strongly influenced the total alkaloid content in the two cultivars investigated. Soaking had an ambiguous effect on total alkaloid content. The lupin seed cotyledon contained the majority of the alkaloids. This study indicates that more research is needed to assure the safety of lupins for food purposes, which is essential to promote increased utilisation of lupin-based products.