MOISTURE-ABSORPTION CHARACTERISTICS OF LAIRD LENTILS AND HARDSHELL SEEDS

Moisture absorption and water imbibition tests were conducted to inves tigate the characteristics of moisture uptake in Laird lentils (Lens c ulinaris Medik.) and to study the role of moisture content in the deve lopment of hardshell lentils. The widths of lentil hilum openings at a range of lentil moisture contents were examined using scanning electr on microscopy. The initial moisture contents of lentils markedly affec ted the route of moisture migration, rate of water absorption, imbibit ion time, and proportion of hardshell lentils. At moisture contents of 16-24% (on a dry basis), moisture diffused mainly through the seedcoa t, and the absorption behavior was predicted accurately by a one-dimen sional diffusion equation. The premeability of lentil seedcoat decreas ed with decreasing moisture content because of reduced pore and fissur e sizes in the cuticle layer over the seed surface. When lentil moistu re content was at 12%, the hilum opening was the dominant route for mo isture to enter lentils. The widths of lentil hilum openings also decr eased with moisture content, some hila were closed at 12% moisture con tent. Impermeable seedcoat and concurrent closing of the hilum opening resulted in hardshell lentils. Increasing the soaking temperature fro m 12 to 22-degrees-C resulted in greater seedcoat permeability and red uced the percentage of hardshell lentils by about one half over the 24 -hr soaking period.