Production and Utilization of Lupinus spp.

Abstract

The various species of lupin or lupine (Lupinus spp.) are classified in the botanical family of legumes (Fabaceae) and in the agronomic crop grouping of grain legumes. Toxic and bitter substances in lupine plants and grain were the reason why it was used in the past mainly to improve soil fertility. With the sustainable focus of the agricultural policy of the European Union, there are real possibilities for sowing and using lupine in the future—and not only bitter varieties, which are suitable for green manure due to their rich foliage, but also selectively bred sweet varieties for grains and herbage, which are a new alternative source of protein (30 to 40%), resistant starch and dietary fiber. Sweet varieties of Mediterranean species of lupine are obtained from seeds that contain almost no alkaloids and therefore have no harmful effects on the health of humans and farm animals. Sowing of sweet lupine varieties provides an opportunity for local processing into soybean-like products. Roasted and ground beans of sweet lupine varieties can serve as an excellent coffee substitute.

1. Introduction

The genus Lupinus includes around 600 species, of which 200 are more important annual, biennial, and perennial species. Mediterranean species are used as economically important lupines for improving soil fertility, for human consumption, and livestock feed: white lupine (Lupinus albus L.), blue lupine (Lupinus angustifolius L.), and yellow lupine (Lupinus luteus L.) [1, 2, 3, 4].

The Andean lupine (Lupinus mutabilis Sweet) is cultivated among more than 100 American species, for now, limited to local production and consumption, and contains at least 10% more protein in the grain than the Mediterranean species [5]. The many-leaved or large-leaved lupine (Lupinus polyphyllus Lindl.) also originates in America; more specifically, its natural habitats are in the western parts of North America, from Alaska to northern California. As an ornamental plant, it has spread from Canada all over the world. Many hybrid cultivars are popular perennials in gardens, from where their seeds spread into the natural environment, where lupine plants displace native herbaceous species, such as wolf’s bane, devil’s claw, and lady orchid. Wild lupine reduces biodiversity, changes the original flora and fauna, and is therefore on the list of non-native invasive plants in the European Union and other countries around the world. Ecologists promote the removal of whole plants by uprooting and regular mowing before they flower or produce seeds.

Based on their origin, time of domestication, and use in the Old World, Mediterranean species of lupine are called Old World lupine species, while American species are called New World lupine species. Archeological findings indicate that the current cultivated lupine species were domesticated thousands of years ago, while the results of molecular genetic studies show that lupine species in the Old World developed earlier [1, 2, 3, 6, 7, 8].

With the cultivation and use of herbage and seeds, various names had developed throughout history. The name lupine is derived from the Latin word lupus, meaning wolf [1]. In Roman times, the plant was named after wolves that roamed the hilly areas of its natural habitats. This led to common names spread among European nations: volčjak, volčec, volčji bob, and volčji fižol (note: volk means “wolf” in Slovenian). Names for the plant that were associated with coffee, such as wild coffee, tall coffee, and Turkish coffee, came about much later when people realized that roasted lupine seed split into two parts that resembled a coffee bean. Roasted and ground lupine beans were used in Europe as a substitute for real coffee, especially during World War One and World War Two, when the import of coffee beans (Coffea arabica L.), the plant that grows in tropical and subtropical areas of the world, was restricted.

2. Morphological traits of Mediterranean species

All three Mediterranean species of lupine have common morphological, biological, and physiological characteristics, as well as their own distinctive features [2, 9, 10, 11, 12, 13]. Lupine has a strong and well-developed spindle-shaped root, which is capable of excellent penetration into compacted soil, to a depth of 1.5 meters, sometimes even more than 2 meters deep. Side roots spread out from the main root, with many root tubers or nodules forming when the plant’s flowers.

The herbaceous stem of the lupine is 50 to 150 cm high, robust, firm and upright, covered with fine, soft, and silvery hairs. Because the stem does not become prostrate during cultivation, lupine can be used as good support for cereals and other legumes. In the past, it was sown together with rye, rapeseed and white mustard, pea, spring pea, and vetch. Single-stemmed plants, without side branches, have a terminal or determinate growth, while plants with side branches form an indeterminate type, which in some varieties has a bushy appearance.

The long-petiolate leaves of all lupine species are finger-shaped, palmately lobed, usually consisting of 5 to 9 ovate-oval leaflets, but may have even more leaflets. A lupine flower consists of five fused sepals and five petals. The petals form the typical shape of a papilionaceous (butterfly-like) flower. The names of Mediterranean species are based on the color of their petals (white, blue, and yellow), but some varieties have multi-colored flowers. Blue, pink, and crimson shades predominate in Andean and many-leafed lupine. In a bisexual flower, there is a pistil with a superior carpel and ten fused stamens, which distinguishes lupine from other legumes, which have nine fused stamens and one solitary stamen. In white and blue lupines, the flowers are self-pollinating, while the yellow lupine is partially allogamous [9].

Because unwanted pollination must not occur when selectively breeding new varieties and producing lupine seed-producing crops, isolation between different crops is required. For white and blue lupines, which are almost self-pollinating, a distance of 200 meters between crops is sufficient, whereas the allogamous yellow lupine, which is pollinated by insects, requires a distance of 500 m. The American many-leaved lupine is also an allogamous entomophilous species.

The papilionaceous flowers at the top of the main stem or at the ends of the side branches are grouped into flat and erect raceme inflorescences. Toward the end of flowering, when the top flowers open, the lower fertilized flowers have already formed pods. A young green pod turns yellow over time and turns brown and woody as it becomes mature. It contains 3 to 10 seeds of different shapes and sizes. The white lupine has the longest and widest pods, up to 12 cm long. It contains up to 10 round, slightly flattened, rounded and wavy seeds, white, gray-white to creamy colored, with a diameter of about 1 cm. The yellow and blue lupine have shorter pods, the number of seeds they contain is lower (4 to 8), and the seeds are smaller. In terms of shape, the yellow lupine has oval seeds, while the blue lupine has reniform (kidney-shaped) seeds. Yellow lupine seeds are yellow-brown to ochre with spots on the seed coat, while blue lupine seeds are light to dark brown with larger to smaller spots. The thousand seed weights of the seeds of Mediterranean lupine species can range from 100 to 500 g.

Compared to the white lupine, the South American Andean lupine has similar-sized seeds with a thousand seed weight of 200 to 380 g, enclosed in a black, white, or gray-brown to green-yellow seed coat. The gray-brown to black seeds of the many-leaved lupine are very small with a thousand seed weight of 12 to 30 g (Table 1).

Species	Seed shape and color	Thousand seed weight (g)
White lupine	round, flattened, wavy seed up to one centimeter in diameter, white to creamy color	220 to 530
Yellow lupine	medium-sized oval seed, yellow-brown to creamy with a speckled pattern on the seed coat	110 to 165
Blue lupine	smaller reniform seed, light to dark brown with smaller spots	105 to 210
Andean lupine	round, bulging seed with a diameter of up to one centimeter, white, gray, black or green-yellow color	200 to 380
Many-leaved lupine	very small oval to reniform seed, gray to black color	12 to 30

Table 1.

Shape, color, and thousand seed weight of seeds of cultivated species of lupine (Lupinus spp.).

The internal structure of lupine seeds is similar to other legumes [9, 11, 12]. Almost everything that is contained in the seed (grain) inside the seed coat is a young plant. A young plant needs reserve materials to start growing upon germination. With the development of the first green leaves, the plant begins to produce organic substances through photosynthesis and is no longer dependent on the reserve materials accumulated in the leaves. Similar to soybeans and beans, lupine germination is above ground or epigeal. During germination, both cotyledons rise up with the stem and appear from the soil.

3. Cultivation prevalence depending on intended crop usage

Considering the scale of cultivation throughout the world, lupine is an almost unknown grain legume. The Mediterranean species of lupine, for which sowing data is collected in producing countries, occupy less than one million hectares of land, which ranks it ninth among dry grain legumes after soybeans, beans, peanuts, chickpeas, cowpea, peas, lentils, and broad beans [14] (Table 2). In recent years, over half of lupine is produced in Australia, where blue lupine is being cultivated on 95% of the land. Sweet varieties of blue lupine are successfully replacing imported soybean meal in cattle feed [15, 16]. The average yield of lupine grains in the world in 2020 was 1.2 t/ha [14].

Grain legumes for dry grain	Surface (ha)	Yield (t)	Yield (t/ha)
Soybean (Glycine max (L.) Merr.)	126,951,517	353,463,735	2.8
Common bean (Phaseolus vulgaris L.)	34,801,567	27,545,942	0.8
Peanut (Arachys hypogea L.)	31,568,626	53,638,932	1.7
Chickpea (Cicer arietinum L.)	14,841,941	15,083,971	1.0
Cowpea (Vigna unguiculata (L.) Walp.)	15,056,435	8,901,644	0.6
Pea (Pisum sativum L.)	7,190,442	14,642,466	2.0
Lentil (Lens culinaris Medik.)	5,009,933	6,537,581	1.3
Broad bean (Vicia faba L.)	2,671,497	5,669,185	2.1
Lupine (Lupinus spp.)	888,507	1.046.70	1.2

Table 2.

Lupine (Lupinus spp.) among the world’s most widespread grain legumes in 2020, land size (ha), and grain yield (t and t/ha) [14].

Interest in lupines for human consumption and livestock feed is also present in Europe, where all three Mediterranean species are cultivated. Sweet varieties of white lupine are mainly cultivated in southern Europe (in Portugal, Spain, and Southern France), where it thrives best. Sweet varieties of yellow lupine are cultivated in Northern Europe, Belarus, and Ukraine, and on a small scale in Southern France and Madeira. The main European producers of sweet blue lupine varieties are Germany, Poland, and the Netherlands. Compared to yellow and white lupine, blue lupine is more suitable for slightly heavier soils and is less sensitive to low soil and air temperatures.

Of the 222,220 hectares of lupine fields cultivated for dry grain in the European Union in 2020, most fields were in Poland (170,540 ha), whereas the number of fields was much lower in Germany (22,300 ha) and Greece (13,400 ha). In 2022, lupine was sown in France, Lithuania, Spain, and the Czech Republic on 5840 hectares to 1910 hectares, and between 570 and 80 hectares of lupine were in Italy, Slovakia, Austria, Hungary, Latvia, and Romania ha [14]. The average yield by country was 1 to 2 t/ha. There is no statistical data on the cultivation of old bitter lupine varieties for green manure (for mulch or churning) and new sweet varieties for fodder herbage, hay, and silage.

Compared to the association of soybean-producing countries in the Danube Soya Association (Dunau Soja) and occasional EU agricultural policy support for soybean production, the incentives for the production and use of lupine are much lower. Nevertheless, individual researchers and experts as well as local growers, processors, and users do not hide their enthusiasm for the properties of lupine as they discover the possibilities of its versatile use, noticing benefits for the soil, in human consumption, and livestock feed ha [2, 4, 17].

4. Ameliorative, fertilizing and phytosanitary importance of lupine

When it was first domesticated millennia ago, lupine was already recognized as a plant that increases grain yields. The ancient Egyptians, ancient Greeks, and Romans have sowed lupine, specifically in otherwise mono-cultural production of wheat and barley. From its original homeland in the Mediterranean, North Africa, and the Middle East, lupine was spread to the interior of Europe during the time of the Roman Empire. Historical sources most often mention white lupine, although people in the past sowed and used also blue and yellow lupine. All three still occur as self-sown today in areas of their original habitats; however, in the modern era, cultivation in the interior of Europe has caused them to spread to natural habitats, meadows, among bushes, rocks, and roadsides [2].

Farmers realized that it is an undemanding plant that has a great influence on soil fertility. A saying arose in Central Europe in the eighteenth and nineteenth centuries: “If wheat is the queen, the lupine is the king of the wheat.” All three best-known species of lupine were spread throughout Europe: white, blue, and yellow. On sandy and acidic soils, farmers were most impressed with the yellow lupine, which they named the miracle lupine. A combination of yellow lupine and rye worked very well. For green manure, a mixture of blue and white lupine was sown, and white lupine was called the backbone of green manure because of its good foliage. This involves mowing during flowering, mulching, and churning of herbage or burying cut herbage (plowing in) in order to increase soil fertility, as humus and nutrients are created over time from decaying organic matter [2].

In the twentieth century, scientific explanations were formed for the ameliorative, fertilizing, and phytosanitary importance of lupine cultivation in garden and agricultural rotation, as well as sowing in vineyards, fig plantations, southern and other fruits, which are still in use in some parts of southern Europe today [18]. With loosening, the water and air regime of soil increase the availability of nutrients, especially phosphorus. The exceptional regenerative effect of lupine on degraded and abandoned land, depleted by intensive agriculture, has been proven. Lupine makes such land usable once again. Although farmers used the fertilizing effect of lupine long ago, the process of biological nitrogen fixation was only explained in the nineteenth century [19]. After species-specific bacteria Rhizobium lupini and Bradyrhizobium lupini free-living in the soil find lupine roots, tubular growths, structures or nodules form on the roots about 20 days after sowing. Bacteria that live and reproduce in these nodules bind nitrogen from the air between the roots and convert it into the ammonium form [19, 20, 21]. Over time, these nodules increase in mass and can grow to the size of a hazelnut, which is larger than in other grain legumes [22, 23, 24]. Lupine uses 60 to 80% of nitrogen for the synthesis of its own proteins, and the bacteria get their life-sustaining carbohydrates from lupine plants. The amount of biologically obtained nitrogen with lupine is up to 100 kg/ha and is usually higher than in other annual grain legumes [25]. It depends on the lupine species and the duration of the growing season. Blue lupine has been found to fixate the most nitrogen [18, 22]. A crop that stays in the field for a longer period of time (the main crop) is more productive than a second crop, and autumn cooling of the soil can prevent the fixation process during the second crop.

Research results also indicate the great phytosanitary importance of lupine crops in suppressing weeds, pathogens, and pests and reducing their occurrence [16, 17, 19, 26].

5. Grain and herbage alkaloid poisoning

The ancient Greeks named lupine thermos, which means warm (hot), and warns of the bitter substances in the grain. Because of its bitter taste, lupine grain never became a commonplace dietary item in ancient times but was conditionally edible when properly prepared. Despite its bitter taste, lupine grains appeared in the human diet from time to time, especially during periods of famine when other foods were unavailable. Most cases of poisoning occurred among the poor, who gathered grain from the fields in times of scarcity, and—similar to dry beans and peas—soaked it in water, boiled it, and consumed it. However, several hours of soaking were not enough. The first signs of poisoning were a burning sensation and dry mouth, vomiting, and general malaise. Ingestion of large amounts of toxic substances caused tremors, problems with thinking, speech, movement of arms and legs, and other nervous system disorders until death by respiratory paralysis and cardiac arrest [2].

Soaking lupine grains in salt water or seawater for a few days, draining the water and rinsing the grains under running water, and cooking them until soft, made it possible to consume the grains without poisoning. This improved the flavor of the dish, especially if lupine was cooked together with grains of other legumes and cereals, and if spices were added to the dish. Only with the development of science have scientists identified the bitter substances in the grain as tannins, saponins, and quinolizidine alkaloids, the most common of which are albin, angustifolin, lupinin, lupanin, lupidin, and sparteine [25, 27].

In the past, lupine poisoning also occurred in farm animals. Grazing on sites with lupine plants and using grains or herbage as livestock feed often proved fatal for pregnant animals, resulting in frequent abortions of the embryo at the start of pregnancy, premature births, degenerative developmental disorders of the skeleton in offspring, and stillbirths. Based on experience in animal husbandry, poisonous lupine grain was also used in the planned abortion of human embryos; the most abortifacient substance was later determined to be sparteine.

Mycotoxins (phomopsins), decomposition products secreted by fungi, especially Diaporthe toxica and Diaporthe woodii, can also be the cause of poisoning when livestock are fed with infected plants. Signs of poisoning are loss of appetite, jaundice, and, in cases of severe poisoning, death due to liver failure. In the past, grazing on mature bitter grains or feeding with herbage and fresh ripe lupine grains have been shown to be particularly dangerous to small ruminants, sheep, and goats [8]. Tannins and saponins can also cause digestive problems and reproductive disorders if consumed in excessive amounts. Livestock poisoning due to various lupinotoxins was named lupinosis.

6. Sweet varieties of lupine were discovered at the beginning of the twentieth century

From the domestication of wild plants until the middle of the twentieth century, the variety of lupine cultivated contained a lot of bitter substances in grain and herbage [1]. With the discovery of natural mutants—plants that were not able to accumulate alkaloids in grains and herbage—a new possibility of lupine use in human consumption and livestock feed was discovered. In early 1930, German breeders used a recessive mutation of the bitter lupine to develop varieties with a much lower alkaloid content and named them sweet varieties (Weiße Süßlupine). The “Pflugs Gela,” “Pflugs Ultra” and other varieties proved to have tastier and more easily digestible grain but did not attract much interest in cultivation and use at that time. Industrialization and specialization of agriculture slowed their adoption of agriculture. Only with the development of new sustainable methods of agriculture since the end of the twentieth century, which require natural means for maintaining and improving soil fertility and provision of high-value protein foods to consumers, did the need to include sweet lupine in agriculture become more realistic and sensible [4, 25].

An important characteristic of such varieties is not the sweet taste of grains and herbage, but the lower content of toxic alkaloids and other bitter substances, such as tannins and saponins. Compared to bitter varieties, which have up to 6% alkaloids in their grain, the grain and herbage of sweet varieties contain hardly any alkaloids, or only in trace amounts, with a content of 0.001 to 0.06%. The permitted alkaloid content in grain depends on the respective national legislation. In some countries, the maximum permitted alkaloid content is 0.02 g per 100 g. Experts are not yet in agreement on the amount of alkaloids that has no harmful effects on human and livestock health [6, 8].

Most of the sweet varieties of blue lupine for grain and herbage feed are selectively bred in Australia. Selective breeding of all types of lupine aimed at obtaining sweet varieties also takes place in the European Union, mainly in countries where the cultivation of individual species is somewhat more widespread.

6.1 Sweet lupine varieties: New source of protein for human consumption

Compared to legume species that have 20–30% protein content in the grain, the grain of Mediterranean lupine species of lupine has at least 10% more protein with an excellent amino acid composition that contains almost all essential amino acids (lysine, leucine, phenylalanine, tryptophan, threonine, isoleucine, histidine, and valine [4, 28, 29]. This means that lupine is comparable to soybean, the world’s most important protein legume. Similar to soybean, proteins in lupine are composed of water-insoluble globulins (about 90%) and water-soluble albumins (about 10%). As there are no prolamins and glutelins in the grain, gluten is not formed, so the grain ground into flour is suitable for anyone who cannot consume wheat products [29, 30, 31].

Lupine contains less carbohydrates (around 40%) than most legumes (around 65%). The predominant carbohydrate is dietary fiber (about 30%), about 10% is resistant starch (amylose), while starch content is very low, that is, from 3 to 8% [32]. Insoluble cellulose and hemicellulose are the predominant fibers, followed by soluble oligosaccharides, which stimulate the reproduction of bifidobacteria in the intestine and have a beneficial effect on improving the immune system on the one hand, but on the other, undigested oligosaccharides in the large intestine undergo microbial fermentation, producing CO₂, H_2, and methane, thus causing bloating and flatulence. Because of bloating and flatulence, the public has a generally negative opinion of a legume diet [4].

The grain of blue and yellow lupine contains 2 to 6% fat, while the grain of white lupine contains up to 10% fat, and there are also differences between varieties (Table 3). Because lupine contains less fat than soybean (around 20%), it is easier to avoid fatty and high-calorie meals with lupine dishes. The lupine seed oil has an extremely favorable fatty acid composition, with a predominance of monounsaturated fatty acids and an appropriate ratio of ω-6 to ω-3 fatty acids, so it is not surprising that one of the objectives of the selective breeding of white lupine is to increase the share of fat above 10% [4].

Species	Protein content (%)	Fat content (%)
White lupine	35 to 40	up to 10
Yellow lupine	35 to 40	2 to 6
Blue lupine	28 to 35	2 to 6
Andean lupine *	35 to 50	15 to 25

Table 3.

Protein (%) and fat (%) conItent in the grain of different types of lupine.

*

In terms of protein content, Andean lupine grains exceed soybean and Mediterranean lupine species by at least 10%.

Lupine (3 to 4%) and soybean (around 5%) are also quite close in terms of mineral content and composition. Potassium, manganese, magnesium, calcium, iron, and phosphorus are the predominant minerals in lupine grain, while zinc, chromium, cobalt, nickel, copper, and lead are present in smaller amounts. The sodium content is low, which meets the guidelines for lower salt intake.

Lupine grain contains many bioactive substances (polyphenols, flavonoids, isoflavones, glucosinolates, phytoestrogens, phytosterols, squalene, terpenoids, carotenoids, and others) that are also found in soybeans. Antioxidants include: carotenoids, mainly α- and β-carotene, lutein, and zeaxanthin, with some carotenoids being converted in the liver into retinol or vitamin A. Lupine is a good source of B group vitamins, with folate, thiamine, and riboflavin being the most predominant. Lupine and soybean grains also contain isoflavones, which play an important role in the prevention of osteoporosis, cardiovascular diseases, and hot flushes during menopause, in lowering cholesterol and preventing the development of breast, cervical, and prostate cancer. The predominant isoflavone in lupine is genistein. Bitter varieties of lupine are richer in some compounds than sweet varieties [4, 33].

Lupine grains contain antinutrients (glycosides, enzyme inhibitors, lectins, oxalates, phytates, saponins, tannins, and alkaloids), which are non-nutritional substances known for their negative effects on the human organism, although they also have positive effects. For example, with improper preparation of food using a grain of bitter varieties, the amount of alkaloids in consumed food can prove fatal; however, trace alkaloids can promote appetite [8, 34].

Fortunately, the negative effect of non-nutritional substances in the diet can be prevented by choosing sweet lupine varieties, by properly preparing food, which begins with soaking the grain and draining the water, followed by cooking, roasting, and baking, or by using various techniques of microbiological processing of the grain into curd, cheese, and various sauces. When cooking, lupine grains do not become soft but retain a firm inner texture.

If you are not used to dietary fiber, lupine should be introduced into your diet gradually and in smaller quantities. Follow the rules for preparing dry grains of legumes for cooking and consider your diet. Bloating is caused not only by legumes and the substances they contain, but also by quick eating, swallowing food without chewing the grain completely, and also talking, as a result of which we swallow a lot of air with our food [35].

7. Foods prepared with lupine

Cooked lupine grains can be eaten in a salad with onions or pickled in brine or vinegar. It is used in spoon dishes, such as minestrone and pasta. Cooked and mashed grains can be livened up with spices and chopped vegetables for a spread on wholegrain bread. The taste of whole-cooked lupine beans in a salad is reminiscent of beans, while roasted and baked grains are reminiscent of nuts. Roasted lupine grains are suitable as a salty or sweet snack. Roasted and ground grains are used as a substitute for real coffee, which, unlike real coffee, does not contain caffeine. Lupine coffee has an excellent aroma and flavor, which depends on the temperature and method of roasting. The aroma and flavor have been impressing coffee lovers, who are promoting lupine coffee to new consumers. Cafés in Germany, which have recently started serving lupine coffee, are an example worth emulating. Lupine flakes, which are produced from rolled grain, match cereals in muesli and cereals for breakfast or other meals.

Various semi-finished products and products can be produced from lupine grains during artisanal or industrial processing [4, 8, 28]. The basic semi-finished product is flour, which is the raw material used for various bakery products, confectionery, and the thickening of dishes. Lupine bread is a special type of bread, with 15 to 20% of lupine flour added to wheat flour, which has been proven to improve the bread’s shelf life, keeping it fresh for longer. Globulin proteins can be prepared as fibrous, creamy, and spreadable products similar in appearance to meat and milk of animal origin, and can replace similar soy products. The creamy composition of flour is an excellent binder when added to ground animal meat for fresh products, such as ćevapčići (grilled minced meat), hot dogs, salami, and for dry meat products (sausages), which are therefore cheaper. In products for vegans and vegetarians, flour is the basis for the production of substitutes for milk and meat of animal origin [4].

Production of protein concentrates and isolates and dietary fiber isolates, which can be added to cereal flour for bread, pasta, sweets, snacks, and beverages, as well as to meat of animal origin, is more technically complex. The neutral taste of the protein isolate from lupine combines perfectly with various types of animal meat, without any after-taste being detected in the products.

Microbiological processing of lupine grains produces many products (curd, cheese, and sauce), which are difficult to attribute to lupine because of their appearance. Soybean curd, known as tofu, is called lopino when made from lupine. Similar to soybean, these products have higher nutritional value, better sensory properties, and longer shelf life [8].

Because lupine grain contains almost no normal starch but contains resistant starch, it breaks down slower. The slowly degradable starch regulates blood sugar, and prolongs the time of satiety, thereby reducing the need for quantitatively abundant meals and snacks, which contributes to reducing obesity or maintaining healthy body weight. Resistant starch and dietary fiber also prevent the development of cardiovascular disease and diseases of the large intestine [4, 36].

Sweet lupine grains can be prepared traditionally in modern cuisine: boiled, roasted, and baked. Roasted and salted lupine beans are a popular street snack or a beer and wine snack in the Mediterranean, Middle East, and India [8].

In Latin America, where bitter Andean lupines are grown (the locals call it tarwi, chocho, or lupino), and in some places in the Mediterranean, the Middle East, and India, where grains of bitter lupine varieties are still used for traditional dishes, dishes are prepared or processed with the help of well-established grain debittering procedures [5]. Lupine grains are first soaked in salt water for a few days, and then rinsed under running water for a long time. Cooked grains are preserved by pickling in brine or vinegar, as is common for olives or pickles. The grains are edible either with or without the husk, which is sometimes removed before pickling. Locals are used to removing the husk by rubbing the lupine grain between their index finger and thumb. In Portugal and Spain, the roasted grain, called tremoços (Portuguese) and altramuces (Spanish), is a popular snack while drinking beer and wine. In Egypt, lupine is known by its Arabic name termes, used for roasted and salted grain sold by street vendors [8].

7.1 Lupine allergenicity

Lupine is categorized as an allergen, so it must be listed as an ingredient on the food label according to the EU Directive (2007/68/EU). An allergy occurs as an immune system responds to lupine proteins. An allergic reaction is often triggered by structurally similar antigens of soybean, peanut, broad beans, or nuts. After consuming sweet varieties of lupine, some sensitive people experience rashes, inflammation of the eyes, and even breathing problems that can lead to anaphylactic shock. Particularly people with allergies should pay more attention to unpackaged lupine products, such as bread, cakes, pizzas, pasta, and ice cream [8]. It is better to avoid street food than to seek medical help, where physicians can help with anti-inflammatory drugs—antihistamines, if there is still time.

7.2 Incentives for use of lupine for human consumption

The market for lupine for human consumption is currently small, but experts believe that lupine has great potential for human consumption. Lupine products are an excellent replacement for various sweet, salty, or fatty carbohydrate snacks. In the food industry, when developing dishes from sweet varieties of lupine, the emphasis is on fermented products, which are similar to soybean products in terms of taste, nutrition, and digestibility. Lupine products are an alternative to soybean for people who either do not like soybean or are afraid that it is genetically modified. Although genetic technology has already been used in the selective breeding of lupine, no GM (genetically modified) varieties of lupine are currently in production [8].

In order to promote the use of lupine for human consumption, it is necessary to raise awareness among consumers, as it is a very promising food. Consumers need to be made aware that excessive consumption of animal meat has a negative impact on the environment and health. With the help of cooking courses, it is possible to present how lupine can be used in food and to explain how lupine, other grain legumes and cereal porridges can be used at home to prepare delicious meals. At the same time, we should raise awareness and connect all the links of the supply chain for lupine in the local environment, which affects shorter transportation and therefore a smaller carbon footprint that would result from remote cultivation. Cooperation between all stakeholders in the chain of cultivation, processing, and marketing of lupine is the only way to ensure that our good intentions are realized and observed in food [4, 17].

8. Lupine grain processing into nonfood products

Proteins in the form of globulin in lupine grain also allow industrial processing into nonfood products, from plastics to man-made fibers for fabrics and ropes. Similar to soybean, it is possible to industrially treat globulin using chemical reagents and biological enzymes and to process it into fibers. Antibiotics, anti-inflammatory, and UV protection agents are added during the spinning process. The produced fibers are mixed with cashmere fibers, silk, cotton, bamboo, and elastane fibers for fabrics for underwear, bedding, shirts, evening dresses, and children’s and sports clothes.

The higher fat content and the favorable fat composition in white lupine attracted some selective breeders to cultivate varieties with a fat percentage above 10%. In addition to cooking oil, there are also opportunities for producing nonfood products, such as soap, paints, and varnishes. In South America, where Andean lupine is grown, which contains 15 to 25% fat, it is traditionally processed into cooking oil, soap, and paints. Breeders believe that varieties with a higher proportion of fat are promising for the local population and beyond.

8.1 Importance of sweet lupine varieties for livestock feed

Selective breeding of lupine has made the grain of newer sweet varieties of all three lupine species suitable for livestock feed without the need for heat treatment [37]. Compared to soybean, lupine grain does not contain trypsin, hemagglutinins, and urease inhibitors [38]. Lupine grain also contains less fat than soybean (20%), in which the main feed for cattle is a low-fat meal (1 to 3% fat) obtained by extracting fats from the grain with the help of hot steam, solvents, and solvent extractions.

Compared to white lupine grain, which contains about 10% fat, blue and yellow lupine grain contains 2 to 6% fat. When preparing livestock meals with grains, care should be taken not to exceed the daily amount of 5% of raw fat per kg of dry matter for cattle feed; therefore, sweet varieties of yellow and blue lupine are preferred in livestock feed [38, 39, 40].

Although grain of sweet lupine varieties is also suitable for human consumption, for now, its importance is greater in animal husbandry. The beginnings of the cultivation of sweet blue lupine varieties for animal husbandry were in Germany in the first half of the twentieth century. A lot of experience with this kind of livestock feed (for cattle, small ruminants, poultry, and pigs) has been gained in recent decades in Australia, where half of the world’s lupine-producing fields are used to grow blue lupine. In recent years, Australian cattle farmers have successfully substituted fresh, crushed, or ground sweet blue lupine grain for soybean meal.

The usefulness of sweet lupine varieties in animal husbandry is supported by results of scientific research, which confirm the beneficial effect of lupine feed on appetite and growth in all species and categories of livestock [41]. Livestock farmers also feed whole plants to cattle and small ruminants, either as fresh herbage, hay, or silage alone or in a mixture with other plants. Protein utilization from lupine grain and herbage is almost 90% and 70–80%, respectively.

The world’s main source of protein of plant origin in animal husbandry is soybeans, of which 70% must be imported to meet all the needs of the European Union. Because lupine is quite similar to soybean in terms of protein composition, it is worth considering replacing soybean meal with lupine protein in animal husbandry. Sweet lupine varieties have the potential of protein feed from local fields.

9. Lupine varieties with at least some bitter substances and new options of use for bitter varieties

Producers of sweet lupine varieties have observed that crops and grain in storage are more susceptible to diseases and pests that were not present in older bitter varieties. Researchers have confirmed that the cause for these observations is the absence of alkaloids in herbage and grain. Alkaloids in old bitter varieties inhibit the reproduction of bacteria and fungi, repel pests and herbivorous wild animals from the crops, and prevent the germination of various weeds [34].

For green manure, it is increasingly recommended to churn in or lay lupine mulch between rows when growing other agricultural plants, as it has a beneficial effect on soil and plant health. For this purpose, bitter white lupine varieties with rich foliage are preferred because of their abundant crop.

Varieties of all species of bitter lupine, particularly blue lupine with a higher alkaloid content in the grain and herbage, are being studied by scientists as raw material for the production of biotic preparations for plant protection [34]. Plant protection products include biostimulants that use extracts of bitter lupine varieties to improve the rooting of cultivated plants, reduce the occurrence of fungal diseases and repel pests, which, together with other protective measures, contributes to increased quality and quantity of the crop [42]. Figure 1 presents the deviation between bitter and sweet varieties according to the intended use.

Figure 1.

Bitter and sweet varieties according to the intended use.

Despite the advantages of sweet variety feeds, which contain almost no alkaloids and other bitter substances (tannins and saponins), studies have shown that a low content that is not harmful to health has a beneficial effect on the appetite and health of livestock, particularly on the reduction of external parasites that linger on the skin and hair, as well as internal parasites (endoparasites), especially intestinal parasites.

A goal in developing new sweet varieties is to determine the amount of alkaloids in herbage and grain that has no harmful effects on livestock health. Some believe that the limit value for alkaloid content in herbage and grain should be higher than the existing value permitted by current legislation. This indicates the possibilities for growing varieties whose grain contains almost no alkaloids, while herbage would be rich in alkaloids and other bitter substances, which would reduce the occurrence of diseases during growth and development, and repel pests and herbivorous wild animals. Straw with a high bitter substance content after grain harvest can be a source for obtaining extracts for natural pesticides, as well as for traditional applications, such as mulching and incorporation into the soil.

Among the varieties of blue or narrow-leaved lupine (Lupinus angustifolius L.), sweet varieties are distinguished from bitter ones in Australia by using the term blue lupine for sweet varieties and narrow-leaved lupine for bitter varieties. Globally, the name blue lupine is used for both bitter and sweet varieties; as Australians explain, such use of names makes accurate communication easier when purchasing seed, developing and using production technologies, and defining crop used for grain or herbage.

10. Agrotechnical instructions for growing lupine

All three Mediterranean species of white lupine (Lupinus albus L.), blue or narrow-leaved lupine (L. angustifolius L.), and yellow lupine (Lupinus luteus L.) have common characteristics and distinctive differences that producers must take into account [3, 21, 43].

10.1 Soil pH can determine the success of cultivation

Lupine species have different requirements regarding soil type; the yellow lupine thrives best on light sandy soils, while white and blue lupines grow best on medium sandy loam to loamy sand soils; the blue lupine tolerates slightly heavier soils. Heavy, poorly drained soils are unsuitable for lupine cultivation. When choosing a field for a specific lupine species (white, blue, and yellow), the soil pH is an important indicator: acidic sites with a pH of 4.5 are still suitable for yellow lupine; however, slightly acidic to alkaline soils with a pH of 6.5 to 7.8 is more suitable for blue and white lupine, with white lupine tolerating more calcium in the soil (Table 4).

Species	Soil type	Recommended soil pH
White lupine	light sandy loam to medium soil	6.5 to 7.8
Blue lupine	sandy loam to medium soil, with sufficient moisture	6.0 to 6.8
Yellow lupine	light, sandy soil, dry locations	4.5 to 6.8

Table 4.

Differences between lupine species in terms of soil type and soil pH.

10.2 Basic tillage and fertilization

After choosing the species and variety of lupine for a particular soil, the soil must be properly tilled according to the type of soil and growing conditions; for spring sowing, traditional tillage with autumn plowing is more common. Shallow tillage with a plow and cultivator is sufficient for sowing lupine stubble crops, but conservation tillage without plowing is becoming increasingly widespread. With abundant weeds, traditional tilling is a better choice, especially in grain production.

Although lupine is a legume that acquires nitrogen during growth and development, nitrogen fixation will only take place under suitable growing conditions, that is, at a soil temperature of at least 8°C, sufficiently moist soil, if there is sufficient Ca, P, Fe, Mo, and B in the ground. Phosphorus in the soil increases nitrogen-fixing capacity and contributes to flowering, while potassium increases tolerance to disease and drought. Phosphorus and potassium peaks are not necessary [44]. In conventional tilling, pre-sowing fertilization with around 40 kg of nitrogen/ha is recommended, but many experts believe nitrogen fertilization is unnecessary with optimal nutrient concentration in the soil. Too much available nitrogen in the soil inhibits biological fixation by Rhizobium and Bradyrhizobium lupini bacteria [21, 24, 25, 45].

In organic production of lupine, well-rotted and composted farmyard manure (15 to 30 t/ha) is suitable for basic fertilization, which is suitable for autumn fertilization. There will also be much less problems with weeds when sowing lupine after potatoes, as long as the weeds have not spread with sowing seeds or fresh farmyard manure. If lupine is in the rotation after cereals and rapeseed, the stale seedbed technique can be used with one to three sweeps or harrows before sowing. This kills weeds at the small seedling stage, which can greatly reduce the seed supply of weeds in the soil.

The intensification and specialization of farming led to problems of narrow crop rotation (more diseases, pests, and weeds and less humus in the soil). Conventional producers have become accustomed to mineral fertilizers that work quickly, almost immediately. However, when deciding on a new paradigm of sustainable agriculture, the possibilities for sowing green manure crops reveal themselves.

Regarding the importance of sowing crops for green manure and incorporation, there is a claim made in Slovenian specialized literature: “What you give to the earth, you get back with interest.” Farmers at that time sowed a mixture of white and blue lupine on the stubble of cereal crops.

When sufficiently densely sowed, the abundant foliage of lupine maintains soil moisture, and reduces soil erosion and weeds. Due to too fast mineralization in summer, stubble catch crops are best suited for green manure crops for incorporation when the primary crop is harvested at the end of the growing season when growth is stopped by cold and frost.

The modern process of preparing a lupine crop for incorporation is rolling, followed by mowing with the repeated cutting of plants with a disc harrow and plowing. For the faster decomposition of herbage, compost or slurry is applied, as well as mineral nitrogen in conventional cultivation.

10.3 Time and method of sowing

Blue lupine is sown in March, or at the end of February in regions with a mild climate. The optimal time for sowing yellow and white lupine is the first half of April. In colder locations in cold years, it is better to wait until May, just like with soybeans. Sowing of stubble lupine crops should be done as soon as possible after harvesting the main crop.

Lupine sowing depth depends on the size of the seeds and the type of soil. White lupine can be sown at the greatest depth, yellow at medium depth, and blue lupine at the shallowest depth. Sowing on heavier soils should be shallower than on lighter soil. Due to the different thickness of seeds and soil properties, the amount of seed for sowing lupine ranges from 70 to 250 kg per hectare. The amount of seed for sowing is calculated using data for thousand seed weight, germination, and purity. With a certified seed of sweet varieties, it is necessary to adhere to the recommendations of the breeder and the seed dealer, to set up the sowing machine accordingly, and to check the coverage at the time of sowing.

Dense sowing of lupine for herbage and grain is carried out with a grain seeder for compact sowing. Sowing with a seeder for row spacing is suitable for white lupine in non-determinant varieties, where it is possible to till the soil before the development of side branches and ground cover. On sandy soils and in dry conditions, rolling is recommended, especially for sowing stubble crops. This increases the germination and emergence of seedlings. Sparse sowing for grain requires 40 to 50 germinating seeds per m2, whereas spaced sowing at an inter-row spacing of 25 to 40 cm and intra-row spacing of 5 to 10 cm, and cultivation for herbage requires double the number of germinating seeds, specifically 80 to 100 germinating seeds per m2. Dense sowing is carried out at an inter-row spacing of 15 cm and intra-row spacing of 2.5 to 10 cm. When sowing at greater inter-row spacing, the development of cover of the inter-row space is slower, and the greater spacing between rows enables mechanical treatment with a finger hoe until the ground cover develops (Table 5).

Species	Number of seeds per m^2	Amount of sowing seed (kg/ha)
White lupine	60 to 70	180 to 240
Blue or narrow-leaved lupine	90 to 100	140 to 160
Yellow lupine	70 to 80	120 to 140

Table 5.

Sowing density of lupine and amount of seed for sowing.

If the seed for sowing is certified, it has varietal purity, is healthy, undamaged, has a sufficiently large thousand seed weight, and high germination and purity. Standard seed purity and germination for lupine are at least 90%. Seeds for organic production must not be disinfected with conventional synthetic agents, but can be disinfected before sowing in a warm water bath at a temperature of up to 50°C or in a warm herbal bath for only a few minutes, after which they must be thoroughly dried at a temperature of up to 40°C. If soaked in a table salt solution, seeds can be sorted by removing unhealthy and damaged seeds that float to the surface, while healthy, heavier seeds sink.

If the soil becomes crusted before the emergence of seedlings, the crust must be crushed, either with a mesh or some other light harrow. When adjusting the depth, be careful not to set the wedges too deep, especially if the seeds are already germinating.

10.4 Similarities and differences between species in terms of requirements for successful growth and development

Lupine species differ in terms of plant height. The yellow lupine is the smallest (about 50 cm), the blue lupine is medium tall (50 to 120 cm), and the height of the white lupine ranges from 80 to 150 cm (Table 6). Compared to broad beans and peas, lupines do not require support and do not tend to become prostrate. Extremely tall varieties can become prostrate, especially after storms and downpours during the ripening period, when the weight of pods and grains increases significantly. Plant height is affected by growing conditions, soil type, and soil pH, nutrient concentrations in the soil and fertilization, seeding density, and lighting [12].

Species	Time of sowing	Duration of growing period	Plant height (cm)
Blue lupine	March	90 to 110 days	50 to 120
Yellow lupine	April	100 to 130 days	around 50
White lupine	April	140 to 180 days	80 to 150

Table 6.

Differences between lupine species in terms of the time of sowing, length of growing period, and plant height.

The growing period of lupine depends on the species and variety; the blue lupine has the shortest time from sowing to seed maturity (90 to 110 days), the yellow lupine has a slightly longer growing period (100 to 130 days), and the white lupine has the longest growing period, that is, 140 to 180 days (Table 6). Lupine is most often sown in spring. Exceptions are regions with mild winters, where lupine sown in autumn can withstand the winter perfectly, and the grain yield is usually higher than when lupine is sown in spring. Lupine sown in spring stays on the field for a longer time, so it is grown as a main crop; if sown after grain or early potatoes, it is used as a catch crop. Regardless of the time of sowing, winter cereals, grasses or grass mixtures, potatoes, rapeseed, field, and garden vegetables are the best-preceding crops in rotation. Bulb vegetables, such as garlic, onions, shallots, and leeks, should be avoided when rotating crops.

10.5 Ways to reduce crop weed and damage due to diseases and pests

The foundation of crop protection against weeds, disease agents, and pests is a properly composed and sufficiently long crop rotation [3, 16, 26] A suitable time until resowing in the same field is at least 4 years. Healthy seeds, a field with as few weeds as possible, sowing at the optimal time, and in a way that corresponds to the species and variety and the intended use of the crop, all play a preventive role in plant protection. Bands of bitter lupine around crops of other cultivated plants have been shown to deter pests and wild animals. The positive effect of bitter substances of plants incorporated into the soil-on-soil health has also been confirmed.

Reducing weeds by hoeing around young plants is only possible with greater inter-row spacing, otherwise, young crops are combed one to three times at weekly intervals. A comb harrow can be used to thin out crops that are too dense. There is a growing number of machines, tools, and know-how available for mechanical measures, among the newer ones, there is also the option of burning weeds. It is important that all agrotechnical measures are carried out precisely.

Although sufficiently dense sowing of lupine is beneficial because of less weed, the density must be adjusted to the species and variety, depending on the intended use of the crop. When growing grain with greater inter-row spacing, we must not miss the opportunity for hoeing.

Protection of lupine is based on a rotation and on varieties that are tolerant to specific pathogens. Lupine is susceptible to infections by various pathogens, such as Erysiphe, Fusarium, Rhizoctonia, Pythium, Colletotrichum, and Uromyces. They most often appear and spread when the soil is too moist and the sowing is too dense.

Low soil moisture, sparse sowing, sowing of healthy seeds, seed baths, and removal of infected plants are some of the measures to reduce infections. Compared to natural means, when reducing the occurrence of diseases includes several measures, the use of fungicides and insecticides is more effective. If you notice twisting and curling of the leaves, lice, and thrips, which carry viral diseases, have certainly reproduced excessively, and thrips can cause damage to the epidermis by sucking.

10.6 Herbage and grain harvest

Lupine yield ranges from 20 to 60 t of herbage and from 1.5 to 6 t of grain per hectare. It depends on the species, variety, growing conditions, and technology, that is, agricultural techniques and agrotechnical measures [9, 46, 47]. Ripe lupine pods of newer varieties usually do not open, while overripe pods burst much less than in other grain legumes, so seed losses at harvest are mainly due to improper combine harvester settings. Combine harvester adjustments include changing the mesh, and reducing operating speed and drum rotation speed. Harvesting is done when the grain is firm and resistant to pressure, that is, at a grain moisture content of 15 to 20%. Grain is stored at a moisture content of 12 to 14%. Lupine for hay is first mowed and dried; for silage, it is harvested by a forage harvester for corn when side shoots start flowering; it should be ensilaged alone or mixed with corn or sunflower.

11. Conclusions

Lupine has a positive effect on improving and maintaining soil fertility. Its ameliorating and fertilizing effect on the soil has been proven, as well as its phytosanitary importance in crop rotation in reducing the incidence of diseases and pests. Although sweet lupin varieties were discovered at the beginning of the twentieth century, new paradigms of sustainability offer them an opportunity in the production of food for humans and livestock. The substitution of soy protein is particularly emphasized. The grains of all three Mediterranean lupin species contain a similar amount of protein and have a similar amino acid composition to soybeans, and the grain has less fat than soybeans. As a food source, it is gluten-free, contains almost no starch but resistant starch, and is high in fiber, some minerals, and bioactive compounds. In the modern diet, sweet lupine beans can be prepared by cooking, pickling, roasting, or baking. Through various processes, products similar to soybean can be obtained from the grain: flour, fibrous proteins, protein isolate, milk and meat substitutes, and various sauces through fermentation. Processing focuses on the special properties of the proteins, such as creaminess, lubricity, and fiber. The market for lupin for human consumption is currently small, but researchers believe it has great potential. Lupin can be used to improve the composition of daily meals or even replace a predominantly meat-based diet with a plant-based one. For blue or narrow-leaved lupin is most commonly used for feeding livestock, either as a vegetable or as a grain, which has a better protein yield than soybeans. The main producer of lupins, Australia, is an example of a successful substitute for soybean feed.

Acknowledgments

The chapter preparation was partly supported by Research Program P4-0077 of the Slovenian Research Agency.