Background. Lentil (Lens culinaris) is an important crop in many developing countries. Usefulness of protein isolates in the human nutrition and animal feeding have been also studied. Improvement of protein precipitation and fractionation efficiency by using different flocculants was the aim of this study.

Material and methods. The polyelectrolytes Magnafloc LT-22 and Magnafloc LT-25 were tested in the process of coagulation and fractionation of protein from lentil protein extracts. Proteins were extracted from flour with 0.5 M NaCl in the 50 mM Tris-HCl buffer pH 7.5 and 2 mM NaOH at ratio 1:10. Protein were coagulated at different pH (6, 5, 4, 3) using flocculants in three different concentration 0.1, 0.3 and 0.5%. Samples were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Results. Influence of extraction medium on the yield and quality of protein was visible.
In all studied cases proteins were the most effective precipitated with Magnofloc LT-25. Application of different pH condition for coagulation caused fractionation of lentil protein. Gel electrophoresis of protein of all studied samples showed different molecular weight subunit patterns ranging from 8 to 102 kDa.

Conclusions. Using of flocculants as coagulating factors allows obtaining a high concentrated protein isolates, however the yields of flocculation were determined by different extraction systems, concentration of flocculants and pH condition of process.