Pearl Lupin, Tarwi

Lupinus mutabilis

Physical Characteristics

Lupinus mutabilis is a ANNUAL growing to 1.5 m (5ft) by 0.3 m (1ft in). See above for USDA hardiness. It is hardy to UK zone 9 and is frost tender. It is in leaf from May to October, in flower from June to August, and the seeds ripen from August to September. The species is hermaphrodite (has both male and female organs) and is pollinated by Bees. It can fix Nitrogen. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and can grow in nutritionally poor soil. Suitable pH: mildly acid and neutral soils. It cannot grow in the shade. It prefers moist soil and can tolerate drought. The plant can tolerates strong winds but not maritime exposure.

Distribution

S. America - Colombia.

Habitats

Cultivated Beds;

Edible Uses

Edible Parts: Oil Oil Seed Edible Uses: Oil Oil Seed - cooked[141]. Used as a protein-rich vegetable or savoury dish in any of the ways that cooked beans are used. The seed can also be ground into a meal and then used with cereal flours in making bread etc[196]. The seed contains up to 50% protein that is rich in lysine and cystine but very low in methionine[183, 196]. If the seed is bitter this is due to the presence of toxic alkaloids, these alkaloids can usually be removed by soaking the seed overnight and discarding the water[200]. Another report suggests that the seed needs to be soaked for 2 - 3 days in order to leech out the alkaloids[183]. An edible oil is obtained from the seed[141, 183]. It is relatively rich in unsaturated fatty acids, including the nutritionally essential linoleic acid[196].

Medicinal Uses

None known

Known Hazards

The seed of many lupin species contain bitter-tasting toxic alkaloids, though there are often sweet varieties within that species that are completely wholesome[65, 76]. Taste is a very clear indicator. These toxic alkaloids can be leeched out of the seed by soaking it overnight and discarding the soak water. It may also be necessary to change the water once during cooking. Fungal toxins also readily invade the crushed seed and can cause chronic illness[65].