Amino acid determination in pure proteins, foods, and feeds using two different acid hydrolysis methods

Chemical composition, nutritive value, and toxicology evaluation of Mexican wild lupins

The nutrient composition, toxic factors content, and nutritional and toxicological value of Lupinus splendens, L. rotundiflorus, L. elegans, L. simulans, L. exaltatus, L. reflexus, and L. madrensis species from Mexico were analyzed. The seeds of these species were a good source of protein. All the species showed a high lysine and tryptophan content, though sulfur amino acids were limiting. Cyanogenic glycosides were absent, and lectins, trypsin inhibitors, and tannins were present in low concentrations. Lupanine was the major alkaloid in almost all the samples, although sparteine was the major alkaloid in Lupinus reflexus (26.63 mg/g of sample). Cytisine was not found in any of the studied lupins. L. reflexus showed the highest acute toxicity, and L. elegans exhibited no toxicity as evaluated using a mice model. The alkaloid was reduced by hot-water extraction. The protein efficiency ratio in water-debittered seeds was relatively poor (1.1-1.5). These results suggest that the wild lupins studied represent a potential protein supply, and they could be domesticated and used for animal feed if the alkaloids were eliminated and the protein was supplemented with methionine, or if the lupins were used in mixture with cereals.

Comparative study of the chemical composition of wild and cultivated beans (Phaseolus vulgaris)

Five wild Phaseolus vulgaris beans were compared with five cultivated Phaseolus vulgaris beans in proximate composition, total (true) protein, amino acid composition, and toxic and antinutritional factors. The wild beans contained more protein (25.5% vs. 21.7%), ash (5.15 vs. 4.15%), crude fiber (7.08% vs. 5.04%) compared to cultivated beans while the former contained less fat (0.56 vs. 0.89%) and carbohydrates (61.64 vs. 68.05%). Sulfur amino acids were found to be limiting in both groups of bean as expected; however, the cultivated beans had a higher content of the limiting amino acids. Therefore, the cultivated beans showed a better amino acid profile than the wild beans. Toxic factors were not found in either type of bean; the determinations included saponins, alkaloids, and cyanogenic glycosides. The antinutritional factors investigated were hemagglutinins (lectins) and trypsin inhibitors. The wild beans presented a higher content of trypsin inhibitors (28 TUI per mg) and lectins (9.6) than the cultivated beans did (21 TUI per mg and 7 respectively). From the chemical point of view, domestication seems to be positive; however, the better protein nutritive quality of the cultivated beans should be further confirmed by biological assays.

Nutritional value and content of antinutritional compounds and toxics in ten wild legumes of Yucatan Peninsula

The chemical and toxicological composition of ten wild legumes collected in Yucatan, Mexico was determined. For each species the whole fruit, (seed and pod), were studied as well as the seed and pod separately. A higher protein content was found in the seeds of A. lebbeck and P. saman (37.07 and 37.60% respectively). In the seeds of L. longystilus, C. yucatanensis and P. keyense a high concentration of fat was found, especially in the first with 31.34%. A high quantity of fiber was found in the pods. In general, the samples were rich in lysine (especially seeds) and scant in sulfur amino acids and tryptophan. All the samples showed high concentration of potassium and calcium. Some of them exhibited significant concentrations of iron. The pods of P. saman and P. keyense showed a high content of lectins. In the seeds of C. yucatanensis and in the pod of P. keyense high concentrations of trypsin inhibitors were found 60 and 406.7 TUI/mg sample respectively. The presence of saponins, was detected in seven samples, of which the seed of P. keyense had the highest concentration. Alkaloids were found only in the whole fruit and pod of P. saman and cyanogenic glucosides were present in A. pennatula. In general terms, the whole legume showed better digestibility than the pods alone.