Physicochemical and functional properties of lentil protein isolates prepared by different drying methods

Lentil protein isolate (LPI) extract was converted into powder by freeze drying, spray drying and vacuum drying. Differences in particle size distribution, protein subunit composition and colour and surface morphology were observed amongst the three drying methods. Spray and freeze-dried LPI powders exhibited higher solubility (81% and 78%, respectively) compared to vacuum dried powders (50%). The spray dried powders showed a low water absorption capacity (0.43 +/- 0.02 g/g) compared to freeze (0.48 +/- 0.02 g/g) and vacuum-dried (0.47 +/- 0.01 g/g) LPI powders. Spray and freeze-dried powders displayed better gelation ability and higher gel strength, compared to vacuum-dried powder. Both spray and freeze-dried gels showed typical viscoelastic gel characteristics, with G' dominating over G '' and very low loss tangent. The holding time required for gelation of vacuum dried powder at 90 degrees C was significantly longer, compared to spray and freeze dried powders. Hence, drying methods used for preparation of lentil protein isolate powders can affect physicochemical and associated functional properties. (C) 2011 Elsevier Ltd. All rights reserved.