Qual Plant Plant Foods Hum Nutr 32 (1983) 95-1 O0 95 © 1983 Martinus Nifhoff/Dr W. Junk Publishers, The Hague. Printed in The Netherlands

Current aspects on legumes as a food constituent in Latin America with special emphasis on lupines: Introduction

H-D. CREMER

Institut ffur Ernahrungswissenschaft, tier Justus, Liebig-Universit~it, D-6300 Giessen, Wilhelmstrasse 20, F.R.G.

Legumes have always been - besides grains - the most important source of protein for foods based mainly on plant origin, particularly in terms of concentration of protein, which varies beween 20 and 40%. Although the proteins of all legumes have a lower than optimal concentration of sulfur- containing amino acids, this plays a minor role in dietary practice, because with a mixed diet other vegetable proteins can make up for this deficiency. The legumes, however, supply the amino acids that are in low concentration in the various grains, e.g. lysine in wheat, threonine in rice and tryptophan in corn. Therefore, undernutrition will b~ found only" rarely where one or the other species of legumes is a staple food and for example 'maize and beans' are among the main dishes.

In this workshop we are dealing - as the title implies - mainly with lupines. Out of the large number of edible beans, we want to compare them with soy beans, with some characteristics of two 'old friends': common beans and faba beans, and with one legume which is rather new in Latin America: winged beans.

The most important comparison is that of lupines with the soy bean because of their very similar composition. Soy beans are not only rich in protein, but their protein seems to have an important property: induction of hypocholesterolemia. Speakers in another workshop dealing with differences between food protein of animal and vegetable sources claimed a blood cholesterol lowering effect of the latter on the basis of feeding experiments with soy proteins. This workshop is not the place for going into details of this effect, but it should be stated that the lowering of blood cholesterol concentration most likely is not a general effect of the consumption of vegetable or even of legume protein. We shall learn from the presentation of Dr. Fidanza later on that he compared the hypocholesterolemic effect of two food proteins: egg white and faba bean concentrate as a source of legume protein. He found, unexpectedly, that in man egg white protein seems to have a more hypocholesterolemic effect than a faba bean concentrate diet.

It will be very interesting to examine whether lupine protein has the same blood cholesterol lowering effect as soy protein. Such studies wilt be per- formed in our lupine program.

Among legumes, common beans (Phaseolus vutgaris) constitute in Latin America the main source of supplementary protein in the cereal diet of a

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large part of the population. Dr. Bressani is one of the most experienced scientists in that field. In his paper he will review as much information as possible on factors in common beans which have direct or indirect nutri- tional relevance. His paper will underline how desirable it would be to in- crease the consumption of common beans, particularly for those population groups requiring more food and better balanced diets. Though the protein and especially the oil content of common beans is lower than that of many lupines they have the advantage that they do not offer any problems in terms of acceptability because they have been part of the starchy food diets of large segments of the Latin American population for thousands of years.

The third legume we will be dealing with before we start discussing the use of lupines as a food is rather new in Latin America: the winged beans. Although its origin is South East Asia, experiments to cultivate it in tropical zones of Peru were successful. The legume is a very interesting food plant because almost all of its parts are edible: green pods, leaves, seeds and even the tuberous roots can be used for human consumption.

Dr. Rainer Gross will review some of its properties. His report will serve as a basis for further studies on this potentially valuable legume.

The main competitor of the lupine is the soy bean. It is not intended to review its properties within this workshop. I only want to stress some similarities and some differences between soy beans and lupines.

The two legumes differ basically in their potential for productive cul- tivation: soy beans grow mainly in subtropical regions, lupines on the other hand can be defined as 'the soy bean of temperate zones and of high al- titudes'. About 20 degrees latitude from the equator they grow in altitudes of up to 4000m.

Soy beans as well as lupines have been cultivated for thousands of years - but only in certain regions - and have been utilized in human nutrition. However, surprisingly, neither soy beans nor lupines, although part of man's diet, are grown as widespread as would be desirable by their nutritional value. The reason for this is probably due to the fact that both contain substances which affect their taste, digestion and ultimately health. The peculiarities of both plants will be briefly summarized and suggestions will be made for their use in human nutrition.

Soy bean

Of the foods produced which utilize soy beans that always have been a basic part of various diets in the Far East, only a few aspects will be men- tioned. All the unpleasant characteristics disappear with the sprouting of the soy beans, so that they can be prepared easily for a tasty meal. Other forms of special preparations are also known such as soy milk, soy cheese, soy sauce and other fermented products. Soy beans cannot simply be prepared for direct consumption, but require special methods of preparation.

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It was realized early on that the undesirable substances in soy beans have to be extracted in order to produce valuable and tasty food items. Methods were developed, especially in this country (USA), for processing isolated proteins of soy beans and other vegetable proteins for the manufacture of meat-like products of excellent quality.

Soy beans have been cultivated in most parts of the world, particularly as feed, i.e. for animal consumption. This is true especially for the USA. But in order to utilize their nutritive value - an average of 40% protein and 20-22% fat - directly, it was tried recently to introduce soy beans in human consumption. In Brazil, for example, the use of whole soy beans instead of other nutritious beans in gruels or soups in school feeding programs has been a great success. With proper preparation techniques tasty meals have been developed that are eaten by children without problems. By appropriate nutrition education soy beans can be introduced in the family's menu. Similar attempts are being made in the tropical regions of Chile where the cultivation of soy beans has played only a minor role so far; thus great efforts are being made to reduce Chile's dependence on food imports.

Lupine

Since soy beans grow only in subtropical regions, one tries to introduce a similar, valuable legume also in temperate zones or greater altitudes in the tropics where soy bean cultivation is not worthwhile: this is the lupine. The species that are particularly useful for human consumption are Lupinus albus, Lupinus luteus and Lupinus mutabilis. Lupinus albus and luteus is native in Southern Europe, Lupinus albus was already known to the Romans. Lupinus rnutabilis is one of the food and feed crops that have been cul- tivated in the Andes area for thousands of years. The protein and fat contents are nearly equal to those found in soy beans: protein content varies from 32 to 40% and the fat content from 17 to 23%.

Although the significance of the lupine as green-fodder or for silage has been accepted without reservation and the advantage of lupines as a soil improver in developing countries with ~ their scanty supply of mineral fer- tilizers is obvious, the use of lupine seeds in human nutrition has continu- ously decreased. The main reason for this is probably the fact that lupines contain bitter substances which influence their taste and digestion con- siderably; some of them are even toxic. The two possibilities of overcoming these disadvantages are:

the removal of the bitter substances; the breeding of species with low concentrations of bitter substances, the so-called sweet lupines.

Sweet lupines

The German plant geneticist, yon Sengbusch, was the first who succeeded in the early 1940's to cultivate sweet lupines. Out of a million seeds he

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was able to find some that were hardly bitter. As far as I know this precious material was lost. However, one of Sengbusch's associates resumed research in this area of plant breeding in Temuco, Chile, about 500km south of Santiago. He built a research station which is now managed by his son, Erik yon Baer. I had hoped that this successful plant breeder could report on his remarkable work himself, but he was not able to come. Therefore, I have to rely on the observations I made some years ago during my visits to Temuco and refer to the literature.

The amounts of sweet lupines produced at that time were sufficient to: conduct acceptability studies in large groups of consumers; test lupine flour as a component of high-protein diet mixtures used to rehabilitate protein-deficient infants;

use lupine flour as an ingredient for bread and bakery goods. The obvious idea of growing only sweet lupines for human nutrition is not practicable yet because of the danger of cross-pollination with the bitter lupines, the latter being cultivated in great amounts at the present time. On the other hand, the cultivation of sweet lupines can only be extended little by little because the required seeds must undergo careful selection.

Culture and eonsump tion of bitter lupines

'The Revival of the Lupine' is the title of an essay which was published in 'Food Technology' in August of t978. The authors write in the preface: 'Lupin-ancient grain legumes are being tailored by plant breeders and bio- chemists to fit the requirements of modern farming, giving rise to a valuable source of food protein, challenging food technologists and the food industry.'

Considering an average harvest of 2000 kg per hectar which can increase to 7500kg per hectar under optimal circumstances, the lupine is a note- worthy food source economically. The disadvantage, as mentioned before, is the content of bitter-tasting alkaloids averaging up to 3%. Amounts of 10-25rag per kg are toxic for small children, 25-45mg per kg are toxic for adults. Yet it must be stressed that the disease in animals described as lupinosis is not due to the consumption of the bitter substances, but caused by mycotoxins which are produced by mold fungi, growing on seeds which are not properly stored. Poisonings by the bitter substances are rare because, on the one hand, the bitter taste prevents consumption and, on the other hand, the removal of the bitter substances is relatively easy. Methods to remove the bitter substances will be described extensively in the contribution of Dr. Ursula Gross. I shall summarize the procedure briefly. The unpolished seeds are soaked in water, which is slightly acidified to reduce the solubility of proteins, boiled and then treated for several days with running water. The easiest way to do this is to put seeds into sacks, and place the sacks into a stream. By this treatment the bitter substances are extracted leaving only traces, whereas the loss of nutrients can be held to a minimum. After drying, which can be carried out in the sun in the arid atmosphere at an

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altitude of 3000 to 4000m, the lupines can be stored without losses for long periods of time.

Details on the main constituents will be dealt with in separate contri- butions. But I should like to say a few words on the use of lupine seeds as food and feedstuffs.

During several visits to Bolivia and Peru, I learned that debittered lupine seeds are utilized to a great extent as feed for pigs, sheep and poultry. Their use as human food has apparently diminished in the past years, yet could be encouraged if the population were instructed accordingly. For example, lupines are offered for sale everywhere on the markets in Bolivia, but the amount consumed is relatively small compared with other grains. Next to the vendor's booths along the street, soaked, boiled and watered lupines in a ready-to-eat form are offered for sale and eaten by hand, somewhat like we eat peanuts or roasted almonds.

In both countries, Bolivia and Peru, the German Federal Ministry of Economic Cooperation assisted a project to increase the amount of lupine cultivation, consumption and feed production. Private organisations partici- pate in these activities. A typical example of this cooperation is as follows: CARITAS in Bolivia supported the publication of a small pamphlet called 'Manual del Cultivo de Tarhue' (Tarhue is the name for lupine in the Quechoa- language), which has been written by two campesinos. This pamphlet is distributed to farmers who show an interest in the growing and the utili- zation of lupines. CARITAS has furthermore worked out a program for providing technical instructions so that campesinos can successfully grow lupines. The farmers learn how to:

prepare soil properly for cultivation; carefully attend seed and soil; control pests and plant diseases; harvest, store and dry the seeds.

The lupines that the campesino cannot sell or use for his own household are processed to make lupine flour. Recipes for the proper mixture of lupine flour with wheat, yuca (cassava), bananas and other products were developed. An especially successful recipe is that of a fiat bread: 40% wheat flour, 40% yuca flour and 2(F/~ lupine flour. Qualified nutritional advisors campaign for lupine consumption in the 'Clubs de Madres' by trying out various recipes together with housewives.

Lupine should become again - as it was for thousands of years in the Andean regions - a common component of the diet. This will be possible only if it will be well accepted by the consumer. There is some hope, as we shall learn from the paper that Dr. Ursula Gross is going to present.

The education programs of different governments and private organisa- tions dealing with the cultivation and consumptions of lupines have shown a noticeable success in the few years of their existence. The impetus from abroad contributed heavily to the success as can be seen especially in the

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Peru project, mentioned above. A similar education campaign in Bolivia would no doubt be just as successful. One can only hope that the lupine will at some time make the same important contribution to the nutrition of populations living at high altitudes, that the soy bean is making in sub- tropical areas now.