International Congress BIOLOGICAL PRODUCTS - Gruppo di ...

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LUPINUS ALBUS, AN ANCIENT EUROPEAN LEGUME PARTICULARLY SUITABLE FOR ORGANIC
FARMING, MAY BECOME AN USEFUL SOURCE OF FUNCTIONAL INGREDIENTS
Anna Arnoldi, Alessandra D’Agostina, Giovanna Boschin
DISMA, Section of Chemistry – University of Milan (anna.arnoldi@unimi.it)
Lupin is a protein rich grain legume typical of the Mediterranean region that produces seeds with a protein content, both
qualitatively and quantitatively similar to that of soybean. A very interesting advantage of lupin in respect to soybean is
that there are no commercially available genetically modified varieties, which makes it an ideal crop for organic
farming. In addition it is particularly valuable in Mediterranean areas, owing to its drought resistant properties, and,
being a legume, it may be used in rotation with other cultures to reduce the use of fertilisers. For these reasons the
European Commission has included it in the list of plants that merit specific research efforts (1).
The protein content of lupin, varying from species to species, is around 35 to 40% in Lupinus albus. About 10% of the
total protein content consists of albumins, while the rest is represented by globulins, showing a 1:1 legumin
(11S)/vicilin (7S) ratio. Ultracentrifugation of the protein solutions leads to 4 fractions with sedimentation coefficients
of 15S, 11S, 7S and 2S. The major fractions are the 11S and the 7S fractions, which account for about 33 to 37% of
total proteins (2). In addition, lupin contains a specific protein fraction, conglutin γ, which accounts for about 5% of
total proteins and has the exceptional characteristic of being a sulphur-rich protein, thus containing amino acids that are
scarce in other grain legumes.
In respect to soybean, lupin kernels contain lower amounts of antinutrients, potentially of consumer concern, when
using protein ingredients in food preparations. Trypsin inhibitor concentration is, in fact, 0.18 mg/g in lupin vs. 17.90
mg/g in soybean, phytate concentration is 0.44 mg/g vs. 1.59 mg/g, saponin concentration is 1.4 mg/g vs. 1.9 mg/g, and
the concentration of oligosaccharides of the raffinose family is 4.6 mg/g vs. 5.7 mg/g (3). Lupin alkaloids, which, also
for their bitter taste, represented a strong limitation for the human consumption of some old lupin varieties, have now
been reduced to very low levels in the “sweet lupin” varieties (4). Sweet lupin flour has been suggested for use in bread,
cookies and milk substitutes. Manufacturers advertise that these products have an increased dietary fibre content and
high protein value. Additionally lupin seeds do not contain phyto-hormones, in particular isoflavones that, according to
recent literature data, have serious toxicological potentials.
In the last decade, the increasing awareness of the health consequences of an incorrect diet and some scandals in the
meat market (BSE, epizootic aphtha, contamination with polychloro-dibenzodioxines and/or furans residues) have
encouraged the consumers to go back to legumes as a source of valuable proteins. In this situation, lupin seeds have all
the characteristics to become one of the main source of vegetable food ingredients in the Mediterranean area.
1. European Economic and Social Committee, Section for Agriculture, Rural Development and the Environment,
‘New impetus for a plan for plant protein crops in the Community’, Brussels, 4 December 2001.
2. Guegen J, Cerletti P. In New and Developing Sources of Food Proteins. Hudson, BJF ed., Chapman and Hall,
London 1994, 145-193.
3. Champ M. Proceedings 4th Europ. Conference on Grain Legumes, 2001, 109-113.
4. Muzquiz M, Pedrosa MM, Cuadrado C, Ayet G, Burbano C, Brenes A In Recent Advances of Research in
Antinutritional Factors in Legume Seeds and Rape Seeds. Jasman AJM et al eds, EAAP Publication N. 93,
Wageningen Press, 1998, 387-390.
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