Both species cultivated for agriculture in Austria – the narrow-leaf or blue lupine, Lupinus angustifolius -- and the white lupine, Lupinus albus, are members of the Fabaceae / Leguminosae family or Pappilonaceae / Pulses. Both varieties grow as annual plants up to 1 m in height, the white lupine may even reach up to 180 cm.
The flowers of the narrow-leaf lupine are arranged in 10-20 cm long racemes. The corolla is mostly blue -- hence the name blue lupine -- but may also be pink, crimson, spotted or white. Unlike the white lupine, the upper labium of the calyx is deeply bipartite and the five to nine (rarely up to eleven) leaflets of the palm-shaped, elongated, long-stalk leaflets are narrow and straight (4-5 mm wide). The top side of the leaflet is smooth, the underside sparsely bristled. The stalk is also slightly close hirsute. Their yellow-to-black, bristly pods are 4-6 cm long. The seeds are smooth, grey-brown and with white spots.
The flowers of the white lupine, Lupinus albus, also form a raceme. Its corolla is mainly white with blue tips or tinted blueish to almost dark blue. The upper labium of the calyx is entire, the lower labium of the calyx three-toothed. The leaflets of the long-stalked, five-to-seven oblong leaflets are obovate (10-18 mm wide), nearly smooth above and hairy beneath and ciliated on the edge. The stalk has a close velvety-bristly hirsute. The pods contain four to six flat, white seeds, sometimes with black marks.
Then, there is also the yellow lupine, Lupinus luteus, which was cultivated primarily in north-eastern Europe, but plays a very minor role in agriculture today.
The three species are also referred to as sweet lupines because they are the main, low-alkaloid varieties with non-bitter seeds on the market. However, this term is not a botanic classification, but only denotes that these cultivated lupines are grown as a sweet variety. All edible lupines are sweet lupines -- i.e. lupines without alkaloids in their seeds. These varieties were discovered by Reinhold von Sengbusch, who developed a rapid chemical method to examine one and a half million individual plants among which he found five alkaloid-free examples.
Another species worth mentioning is the blue lupine, Lupinus pilosus, which was discovered in South Tyrol, where it has been used for many years as a coffee substitute ("Altrei coffee").
Additionally, the Andean lupine, Lupinus mutabilis, has always been used in the highlands of Peru and Bolivia in South America. The indigenous peoples of South American soaked the seeds in water before using them to remove the bitterness. This species changes the colour of its petals during the flowering stage, hence the Latin name "mutabilis", meaning "variable". It is considered a good source for lupine oil, as its seeds contain a relatively high amount of oil.
The many-leaved lupine or large-leaved lupine, Lupinus polyphyllus, is not edible. It is only cultivated as livestock feed and as an ornamental plant (garden lupine).
The lupine’s net protein content is similar to soy at 32-40 %. This includes all essential amino acids, in particular the sulfur-containing amino acids cysteine and methionine, as well as the crucial proteinogenic amino acids threonine, tryptophan and lysine.
Lupines have the highest net fat content (except soy wholewheat) with about 5-9 % compared to other cultivated legumes. The fat content of the white lupine is slightly higher than that of the narrow-leaved or yellow variety. The oil is rich in unsaturated fatty acids, of which 24-52 % are made up of the monounsaturated oleic acid and 15-48 % are made up of the polyunsaturated linoleic acid.
Moreover, the high levels of fibre (about 15 %) in lupines bears some significance from a nutritional perspective. Additionally, lupines contain vitamins A and B1, as well as minerals and trace elements potassium, calcium, magnesium, manganese and iron. The high levels of manganese of up to 1,200 mg/kg dry weight must be highlighted, in particular. Similar to the soy bean, phytoestrogens were discovered in lupines, though at 50 times lower concentrations.