Composition, protein quality, and toxins of seeds of the grain legumesGlycine max,Lupinusspp.,Phaseolusspp.Pisum sativum, andVicia faba

Abstract

Proximate analyses, amino acid profiles, and protein efficiency ratios (PER) from ratfeeding trials were conducted on samples from soya beans (Glycine max), lupin species (L. angustijo!ius, L. albus, L. mutabilis) , phaseolus species (P. lunatus, P. vulgaris), peas (Pisum sativum) , and field beans (Vicia jaba). These legume seeds were included as the ~olc protein source in diets fed to rats, with and without methionine, the first limiting amino acid. All three lupin species contained less lysine than P. vulgaris or P. sativum (as % total amino acids), and were marginal in valine. However, Lupinus angustifolius seed (with added methionine) gave growth and PER equal to reference casein and significantly superior to any of the other species when fed raw. The alkaloid content in the L. albus and L. mutabilis samples strongly inhibited growth; these lupin species ought not to be considered for food and feed use in their present form. Phaseolus lunatus (lima beans) and P. vulgaris (bl?ck, red kidney, navy, pinto beans) killed 37 of 50 rats when fed raw at 9% protein levels. Pisvm sativum (field and garden peas), with methionine, gave growth at 70% of reference ca&ein when fed raw. After cooking, all beans and peas gave very good growth and PER values. However, apparent protein digestibility was less than 80%. 457

Trypsin inhibitor contents of lupin seeds and other grain legumes

“…Other samples showing negative inhibitor contents were the peas and common beans that had been boiled for 1 h and freeze-dried (see Hove et al 1978), and a sample of lucerne leaf protein concentrate.…”

“…The pinto beans were the only variety of Phaseolus spp. that did not kill rats when fed raw (Hove et al 1978). However, this cannot be due to the lower amount of trypsin inhibitor in pinto beans, since raw soya bean, with eight times more inhibitor, did not kill rats.…”

“…Of the peas, the wrinkled variety of garden peas were significantly lower than field peas in inhibitor content; perhaps this can be related to the superior feeding value for rats of garden peas compared with field peas (Hove et al 1978).…”

“…Analyses of trypsin inhibitor were made on samples of grain legumes previously evaluated nutritionally by rat growth (Hove et al 1978). Most had been grown in 1976-77 at Lincoln College, but some commercial varieties of Phaseolus species were included.…”

“…Rats and other animals fed diets containing raw, ground legume seeds have an enlarged pancreas, depressed protein digestion, and poor growth. Salunkhe & Wu (1977) state that the protease inhibitors of raw soya bean are responsible for the poor growth; however, other toxins (e.g., phytohaemagglutanins) probably contribute to the overall anti-nutrient action of raw legume seeds (Hove et al 1978). To assist in apportioning the relative contribution of various toxins to the poisonous action of raw seeds we have assayed them for trypsin inhibitor contents.…”