# Bioactive Peptides from _Lupinus_ spp. Seed Proteins-State-of-the-Art and Perspectives
## 2 Lupins and Their Proteins  
Lupin belongs to the genus _Lupinus_ and the family _Fahaceae_ whose role in agriculture dates back to more than 4000 years [15]. Since ancient times, lupin has mainly been used as animal feed (for forage and silage) and for soil improvement, especially as nitrogen fixers [16], and over the last decade it has increasingly been used as a functional ingredient and protein supplement. There are more than 400 species described at present, and the most popular ones are the sweet lupin species such as white lupin (_Lupinus albus_), blue lupin (_Lupinus angustifolus_), yellow lupin (_Lupinus luteus_), and pearl lupin (_Lupinus mutabilis_) [17]. The plant grows in a very wide range of environments and regions--the Mediterranean, Northern and Eastern Africa, North and Central America, Andean South America, and Atlantic South America [15]. Australia is the world's largest producer and exporter of lupin seeds, accounting for 80-85% of the global lupin production [15]. Blue lupin (_Lupinus angustifolus_ L.) is a multipurpose legume, one of the 200 species of lupins, and is an alternative to soybean due to its high protein content. Beyond these qualities, lupin represents a good source of bioactive compounds including oligosaccharides and dietary fibre [18]. Lupin has higher content in fibre than soybean [19], and the oil content in _L. angustifolus_ is 5 to 6%. Moreover, lupin seeds contain polyphenols, carotenoids, and phytosterols, as highlighted by [PERSON] and [PERSON] [20]. Over recent decades, new genetic varieties of lupin appeared with improved protein content and thinner tastes [21]. The seed protein, which may correspond to 35-40% of the dry weight, is composed mostly of albumins and globulins in an approximate 1 to 9 ratio [22]. \(\delta\)-conglutin is the most represented albumin protein--5% of the total seed proteins--and it is involved in plant defence against pathogens [23]. The protein content depends on location, climatic variations, and time of sowing [16]. In _L. mutabilis_, the highest protein content was found (44%), followed by _L. luteus_, _L. albus_, and _L. angustifolus_[16]. It was observed that the protein content increased after dehulling, and in whole lupin seeds it is as high or higher than that of soybeans. Its quality depends mainly on its amino acid composition and protein digestibility. In Table 1, the amino acid profile of the four sweet lupins species _L. albus_, _L. angustifolus_, _L. luteus_, and _L. mutabilis_ is represented. The plant has a low content of sulphur amino acid (methionine and cysteine). Their content is more than three times lower than the suggested pattern of amino acid requirements [17]. The other essential amino acids (histidine, threonine, valine, isoleucine, tryptophan, leucine, lysine), however, cover or exceed these requirements. One study proved that lupin protein is high in glutamic, aspartic acid, and arginine [24]. [PERSON] et al. [16] suggested that the variation in the amino acid content in raw lupin species is imperceptible. The functional and technological properties of lupin proteins (solubility, emulsifying, and foaming ability, water holding capacity) represent a great interest in the food industry. Due to these properties, lupin flour can successfully replace butter and eggs and can participate in the preparation of pasta, bread, biscuits, muffins, and cakes [19,25], as well as fried sweets or salty snacks. As a result, a better flavour, texture, water binding capacity, and shelf-life is reported, and it is recommended in low cholesterol diets [25]. Lupin does not contain gluten and can be used as a functional ingredient in gluten-free foods [19,26,27]. The yellow colour of lupin flour has its value in the preparation of pasta and noodle dishes, but can be removed easily, if necessary. This can be done by the addition of an aqueous 1.0% citric acid solution as described by [28]. However, the presence of allergenic peptides is an important issue [19].