Tannins, water-soluble phenolic compounds, have been reported to have the ability to form complexes with nutritionally important nutrients such as protein and mineral elements thereby making them unavailable for absorption and utilization. Toxicity of tannin has been demonstrated in experimental animals although no deleterious effect of ingestion of legume tannin on human physiology has been reported. This report highlights the processing effects of soaking and hydrothermal techniques on some underutilised hard-to-cook legume crops and the importance of tannin in legume nutrition. Soaking and hydrothermal processing reduce the tannin content of processed legume seeds and hence improve the availability of protein and mineral elements. In view of the recent findings of the health benefits, classification of tannin which is traditionally regarded as an antinutrient should be reconsidered. Provision of these information will enhance knowledge of legume nutrition and economic utility. Increasing consumption of underutilized nutritionally important legume seeds, it is hoped, will alleviate the problem of protein energy malnutrition in many developing nations.

Phytic acid (IP6), also known as inositol hexakisphosphate, a naturally occurring component of legume seeds, is traditionally regarded as an antinutrient. This report was aimed to provide information on hydrothermal processing effects and nutritional importance of phytic acid in legumes. As a strong chelating agent, phytic acid has the ability to form complexes with protein and mineral elements (e.g. Ca, Fe, Zn and Mg) and thus makes the nutrients unavailable for absorption and utilisation. Reduction of IP6 using soaking and hydrothermal methods enhances the bioavailability of protein and mineral elements. Low level of phytic acid in diets have some health benefit effects and thus classification of phytic acid as an antinutrient needs to be reconsidered.

Amala, a staple food among the Yoruba people of South West Nigeria, is mostly produced from yam. Since yam is known to be mostly carbohydrate and soybean is a legume with an appreciable quantity of protein, efforts have been made to prepare amala from the blends of cocoyam and soybean flours. The protein content of the flour blends ranged from 3.73% to 13.81%. In general, there was increase in the concentration of protein with increasing level of soy flour substitution. Unlike protein, the crude fibre content of the flour blends decreased with increasing supplementation of soy flour. Increase in oil content of the flour samples, with increasing addition of soy flour, predisposes the samples to shorter shell life and off flavor because of liability to rancidity. The lowest bulk density of 0.78 g/cm3 was recorded for sample A (100% cocoyam flour) and hence none of the flour blends could be considered as a complimentary infant substitute. In general, supplementation of cocoyam flour with soy flour enhanced the concentrations of protein, ash and dietary fibre. Therefore, it is hoped that consumption of cocoyam amala supplemented with soy flour, a cheap source of plant protein, will not only create dietary diversity, it will make more protein available for the consumers and thus help in alleviating the problem of protein energy malnutrition in developing regions of the world.