Nutrient composition and biological evaluation of an unconventional legume, Canavalia cathartica of mangroves.

Seeds of an unconventional legume, Canavalia cathartica from the mangroves of the southwest coast of India, were screened for proximate composition, minerals, protein fractions, amino acid profiles, fatty acids and some anti-nutritional factors. The seeds consisted of 31.2%, 1.86%, 61.4% and 1580 kJ crude proteins, crude lipid, crude carbohydrates and calories, respectively. The crude protein content of seeds was higher than common cereals, whole-wheat flour (8.55%), parboiled rice (7.7%) and egg (12.6%). Essential amino acids, threonine, cysteine + methionine, isoleucine, tyrosine + phenylalanine and lysine were higher than Food and Agricultural Organization of United Nations/World Health Organization patterns. On comparing the amino acid profile of mangrove and sand dune C. cathartica seeds, the latter were found to be superior (total amino acid content, 123.5% versus 60.8%), while the result was vice versa with respect to the polyunsaturated/saturated ratio (105.9 versus 2.52). The seeds possessed 1420 mg/100 g total phenolics and strong hemagglutination activity, while tannins and trypsin inhibition activity were absent. Physical, nutritional and anti-nutritional features of seeds of C. cathartica of the mangrove have been compared with those of C. cathartica of the sand dunes of the southwest coast of India. A significant difference (P < 0.05) was observed between the physical, proximal and mineral composition except for ash, magnesium and copper. The protein efficiency ratio, food efficiency ratio, net protein retention, protein retention efficiency, biological value, net protein utilization and true digestibility of C. cathartica seeds were significantly different (P < 0.05) from casein. In spite of the high protein content, animal-feeding trials indicated low nutritional quality. Nutritional, anti-nutritional factors and protein qualities of seeds C. cathartica have been discussed in comparison with other species of Canavalia.