Characterization of hyacinth bean (Lablab purpureus (L.) sweet) seeds from Indonesia and their protein isolate

Hyacinth bean (Lablab purpureus (L.) sweet) seeds from Indonesia were characterized for the purposes of usage as a protein source. Protein isolate was prepared from the seeds using an isoelectric method, which was also used to characterize the physicochemical and functional properties. Hyacinth bean seeds have a moderate concentration of protein (17.1 +/- 1.5%), and low concentration of HCN (1.1 +/- 0.1 mg/100 g). However, before using the seeds as food, some treatments are needed to reduce their antinutritional factors, since the contents of trypsin inhibitor and phytate are 0.15 +/- 0.02 TIU/mg and 18.9 +/- 0.2 mg/g, respectively. Using the isoelectric preparation, the yield of protein isolate was low (7.38 +/- 0.2 g per 100 g of the seeds), but the protein isolate had good colour, neutral odour, high protein content (89.8 +/- 0.82%), and low ash (2.97 +/- 0.36%). The protein isolate also had good functional properties, such as solubility, foaming capacity, and emulsifying activity. However, the foaming and emulsifying stabilities were low. (c) 2005 Elsevier Ltd. All rights reserved.