Development of a Process for Reducing the Content of b-N-Oxalyl a,b-Diamino Propionic Acid (b-ODAP) in Grass Pea (Lathyrus sativus) Seeds: Nutritional Consequences and Technological Aspects

Sammanfattning: Grass pea (Lathyrus sativus) is a leguminous food crop, grown mainly in the tropical and subtropical regions. It has valuable nutrients, however consumption of the seeds is reported to cause lathyrism, due to the presence of a non-protein amino acid (?-ODAP). The present study deals with the development of a process for reducing the ?-ODAP content in grass pea seeds. The consequences of processing on the chemical composition of the seeds, the quality of the protein, (in-vitro and in-vivo digestibility), physico-chemical and functional properties of starch have also been evaluated. Analysis of b-ODAP by using flow injection assay revealed that the major portion (93%) of the b-ODAP in the seed is located in the cotyledons. However, there is a significant variation in the b-ODAP content (from 520 to 942 mg/100g) among different varieties. The b-ODAP content in the whole seeds could be reduced (up to 87%) by roasting, cooking, autoclaving and soaking. The seeds contain 31% protein, 41% starch, 17% total dietary fibre (2% soluble and 15% insoluble), 2% fat and 2% ash, on a dry matter basis. The digestibility of the protein in the seeds was high (88%) and this could be further improved by removing the seed coat. However, the biological value (63%) and net protein utilization (53%) were low, possibly due to the deficiency in tryptophan. The digestibility of the starch in the raw seeds (21%) could be improved (up to 87%) significantly by soaking or germinating the seeds and followed by cooking or autoclaving. Soaking (12 h) of the grits (1.5-2 mm) from the cotyledons and roasting at a temperature of 200°C for a period of 37 minutes could be recommended for a significant reduction of b-ODAP in combination with improved in-vitro digestibility of starch. The seeds can also be processed by soaking (12 h) the grits (1.5-2 mm) from the cotyledons and cooking in water of pH 8 for 75 min, to achieve similar effect regarding reduction of b-ODAP and improvement of in-vitro digestibility of starch.