Isolation of Protein from Defatted lentil flour

Abstract

The main purpose of this research work was to isolate the most refined form of protein from lentil for food processing. In this research work, lentil (Lens culinaris L.) was collected from Monywa Township, Sagaing Region and nutritional characteristics such as moisture content, ash content, fat content, carbohydrate content, protein content and fiber content were determined. The fat of raw bean flour was removed by bulk soaking in ethanol and also by soxhlet extraction using ethanol as solvent before isolating the protein. In addition, the fiber and starch from defatted lentil flour was removed by alkaline extraction and acid precipitation method to isolate the protein (isoelectric precipitation). Protein solubility, water and oil absorption capacity, emulsifying capacity and stability, foaming capacity and stability of lentil protein isolate have been determined. The solubility curve corresponding to the lentil protein isolate indicated the minimum solubility at pH 4 (protein solubility of 20 %) and maximum solubility at pH 12 (protein solubility of 85 %) respectively. The lentil protein isolate had water absorption capacity of 1.82± 0.07 mL H2O/g. protein and oil absorption capacity of 1.95±0.06 mL oil/g. protein. It was found that emulsifying activity and stability of isolated lentil protein were 73.44± 0.03 % and 41± 0.07% while foaming capacity and stability were 22.67± 0.06 % and 50.11± 0.05 %. Isolated lentil protein improved texture appearance and taste than the lentil flour and thus it can better be used as nutrition and functional ingredients in many food products.